BBC State of the Planet – Is there a crisis
We live in extraordinary times, we’re surrounded by more species of animals and plants
than have probably existed at any one time in the history of the earth. For nearly 50 years
I’ve been lucky enough to spend my time travelling around the earth documenting those
animals and plants but it is now increasingly apparent that one species, our own, has
developed a unique ability of so altering its surroundings that it can destroy whole species
indeed whole environments.
How great is the damage we are actually doing to the world? Why is it that what we do
has such a destructive effect and how can we change what we do in order to ensure that
our children and grandchildren inherit as wonderful and as varied a world as we were
lucky enough to do. I'll be putting those questions to some of the worlds leading scientists
in order to discover the very important answers. I will be looking for clues all over the
world, some can be found on the savannahs of Africa others are to be sought under the
sea, we will visit our own past and consider our future and scientists will talk about their
own most recent research in order for us to understand the truth about the current state of
our planet. First we have to establish the facts about the scale of the damage we have
done to the earth so far.
40 years ago our curiosity about the worlds beyond our planet lead to one of the most
stupendous achievements in human history “we have ignition, sequence time, 5, 4, 3, 2, 1
we have lift off.” Paradoxically sending a rocket towards the moon made us aware in a
radical way of the true nature of the world it left behind. For most of human history our
world had seemed vast and its resources infinite but those men in space saw something
different “that is the most beautiful sight, what a view, its absolutely unreal, I have never
seen… all I can say is its spectacular”
The astronauts view made us realize more vividly that ever before that the earth is limited
in both its space and its resources. From that it follows that there will also be a limit on
the amount of life our planet can hold. Living creatures on this planet have always had to
endure natural catastrophe and change yet now there is a greater variety of life on earth
that there has ever been so change and damage are not necessarily destructive to life as a
whole and the view from space showed us why. Its because such damage even on a scale
that seems disastrous for those of us in the midst of it is usually local in extent. Indeed,
we now realize that such change is the spur that has created life’s richness by presenting
new opportunities and challenges to which animals and plants have responded. Life in
fact can recover from or adapt to even very great damage but today the damage inflicted
by humanity is global and it is taking place at a speed that is without precedent in the
whole three and a half billion years of the earth history.
To understand the scale of our impact on the rest of life we have to discover just how
great the diversity of life really is. For the past 500 years scientists and explorers have
travelled the world cataloguing its natural wonders. We can still see the biggest creature
that has ever lived, the blue whale, and the simplest, microscopic bacteria. On land, in the
air and under the sea we have discovered an astonishing variety of life forms. That work
is still going on giving us a better understanding of this astonishing variety of life, this
biodiversity. So how many different kinds of living things are there? Biologist, Sir Robert
May has made a special study of this question. Amazingly we don’t even know how
many distinct species have been named and recorded, for the major groups like the birds
and mammals, the furies and the featheries, we really do know but for most groups they
are on scattered records in different museums not yet co-ordinated into one computer
base. Best guess would be about one and a half million different plants, animals, fungi,
algae. This listing and cataloguing of the natural world has occupied the lives of many
experts and still does. A total of one and a half million species might seem to suggest that
we have discovered the majority of life forms on the planet, but that is not so, again and
again new discoveries make us aware of just how limited our knowledge really is. No
where demonstrates this better than the Savannah grasslands of east Africa. In this
environment as in many others it is the big mammals that have captured out attention.
They have become so famous owing to books television programs and safari holidays
that you might well think that they represent the majority of the animals here. The scale
of biodiversity on the African grasslands is a bit deceptive if you go out during the day
you are probably looking for spectacular animals like these elephants. You will also see a
few smaller things like butterflies and beetles and bugs but the overwhelming impression
you have of sheer mass of life is of herds of just a few kinds of big animals. The truth as
research has recently shown is quite different. For evidence of that just look in the grass.
This is a column of driver ants there ferocity so great and their appetite so huge that they
have given rise to all kinds of legends, stories about human beings and horses stumbling
into their paths and being striped to skeletons within minutes. These are perhaps a little
exaggerated but non the less the appetite of these ants is so huge that they will attack
anything that cant get out of their way. They prey mainly on other small animals and
move across the grasslands in columns that may contain 20 million individuals. So many
ants need vast quantities of prey, so their abundance is living proof that the savannas
team with smaller life. When scientists recently began to study these smaller creatures.
They found that 50% of the insects they were seeing were new to science. Simple
calculations suggest that driver ants alone consume more animal matter per year on the
grasslands than all the famous big predators put together. The reason why it is difficult to
appreciate the scale of biodiversity on the savannahs is that many of the creatures that
live here are both nocturnal and very very small. You get some impression of what they
are if you come out at night with a lamp like this. But to get an idea of the full range of
those creatures you have to use a light of a very special kind like this one. The bulb that is
illuminating this sheet produces a high proportion of ultra violet light and many night
flying insets find that absolutely irresistible. There are moths, small ones, big ones, here’s
a kind of silk moth, beetles, more moths a mantis, a great fat sausage fly, an ant lion lots
of tiny little insects I can hardly see what they are oh and mosquitoes. Recent work has
shown that there is a far greater variety of insect life on the savannahs than was
previously thought. There may not be as many species as are found in a tropical rainforest
but in terms of sheer quantity the savannahs are their equal.
It is in the famously rich rainforests of South America that research first revealed the
scale of our ignorance. If you walk slowly and look carefully in a rainforest like this one
in Ecuador you can find all kinds of small interesting creatures and that is how the first
explorers and naturalists worked and it is still possible to find new species that way. I
picked up this little stick insect from over there and in order to discover whether it is a
new species or not I will have to show it to an expert in stick insects and if he could not
match it exactly then he would describe it, give it a new name and I would have
discovered a new species. However, I can only search an area from the ground to a
couple of feet above my head but the trees here grow to over 100 feet tall. What might be
up there? Well birds and monkeys because I can see them from down here but what else
might there be? Until very recently that was a matter of pure speculation but then
Professor Terry Erwin invented a way of finding out. He decided that in order to discover
what actually lived in a canopy of a single tree or even a single branch he had to use a
machine known as an insecticide fogger. This was originally designed for mosquito
control but it can be used to sample other insect equally well. When we first started
fogging in Peru the results were just absolutely fantastic, we just never imagined we were
going to get so much. The fog, harmless to anything but insects drifts up into the canopy
and the insects drop down. The results of Terry Erwin’s early work dramatically altered
our estimates of how many animals there might be on this planet. This might seem a quite
drastic way of discovering what lives in the trees, however as well as providing
information that is important for conservation this work has also shown that insects
reproduce so fast here that within four months of a tree being fogged insects living in it
had returned to their previous numbers. From all of the studies I have made over the past
25 years and the little bit that we have been able to analyze in the laboratory it seems that
at least 80% of the species that we are getting out of the canopy are new species, new to
science and the reason that’s true is because the average size of a beetle is only 3 mm
long and so the small stuff hasn’t been studied. And its not just small things in rainforests
that are still being discovered. We are still finding things even among the primates,
among the mammals, our closest relatives. There are about half a dozen new species of
primate that have turned up this decade, small marmoset things. It really underlines what
we don’t know. Most of those small primates were found in the Amazon rainforest. Until
very recently European explorers could only penetrate any distance into these vast forests
by travelling up the rivers. Now however, using powerful machinery roads have been cut
though the forests that enable scientists to reach even the least known areas in their
search for biological gold, new species. And it is here that they discovered new
Marmosets. One way of enticing a primate to show itself is to play back the calls of a
closely related species. This can trick it in to thinking that its territory has been invaded
by rivals so it may emerge from the forest to investigate. In 1992 this technique revealed
a new species of marmoset in this area of Southern Brazil. Since that discovery no one
has been back again to look for it and until now it has never been filmed. This kind of
waiting game can go on for weeks or months usually without success. But there it is, the
call of a new species. This is the black faced marmoset. We have no idea how this animal
lives or what kind of social interactions take place in its groups. It has yet to be studied.
And as quickly as they appeared the black faced marmosets melt back again into the
forest. It is not just on land that the scale of recent discoveries have amazed scientist, the
oceans too have been found to contain a far greater diversity of life than was previously
thought. The sea covers two thirds of the planet. In some parts it is filled with a huge
range of species. The famous coral reefs which occupy a tiny fraction of the oceans are
probably its best known most closely studied habitat. Would it be fair to suggest that here
at least we have discover most of its inhabitants? Silvia Earle is an expert in marine
biology. Just as with what we have begun to understand about rainforests that there are
thousands perhaps millions of species that have yet to be discovered, described or even
named, so it is with coral reef systems that are enormously complex and diverse but
diverse on a scale that exceeds rainforest. If so much remains to be discovered even about
coral reefs which occupy the most shallow and accessible parts of the sea what about the
rest of it. The average depth is two and a half miles. The depth where the titanic rests, the
maximum depth is seven miles and we are still nibbling around the surface. Scuba divers
go to 100-150 feet/ 50m or so. We have a few submersibles that can go down to half the
oceans depth and one that has been to full ocean depth once but most of the ocean
remains a mystery. What does this tell us about the scale of discoveries still to be made in
the sea? The greatest era of discovery is just begun, with the oceans less than 5% have
really been looked at. Mapping has been done, we know where the valleys are, where the
mountains and plains and so on but who lives in the sea? What do we really know of how
the natural systems actually function? We are just beginning to understand the magnitude
of our ignorance. How little we know has been brought home to us in research in the deep
ocean where conditions are so severe that it was once thought that no life of any kind
could possibly exist. In fact there are great numbers of creatures in these ocean depths.
Some recently discovered are so strange that it can be difficult to see any relationship to
organisms that live in shallower water.
Even in the best known environments there are still discoveries to be made. Surprisingly
the greatest may come from underground. The top most layer of the land in many places
is of course soil. This is crucial because quite simple it is what most plants grow on and it
is vital to us as we plant our crops in it. We might think that it is just dead matter with a
few worms in it but actually it is full of the most extraordinary creatures. Beneath the
surface of the soil the abundance of life is breath taking. In this small patch just in front
of me there could well be 2000 different species a quarter of a million different
individuals. Most of them of course are very small. Some are microscopic but on their
own scale the drama of their worlds is just as great as you can find on the plains of East
Africa or the rainforests of South America. Here there are predators and prey just a few
millimetres long with their own complex systems of attack and defence. This world lies
directly beneath our feet but we know little more about it than we do the deepest depths
of the ocean. Nematode worms so small they can only be properly seen under the
microscope are armed with piercing weaponry and protected with amour. What is the
significance of all the small forms of life that are being constantly discovered these days?
Biologist Edward Wilson is an expert in biodiversity. What is important about bugs and
weeds is not just that they have most of the biodiversity around the world but that they
are the foundation of the ecosystem. If you were to remove all of the biggest animals, in
fact humanity is very much in the process of doing that, there would be important
changes in the forests and the grasslands and the other major habitats but they would
survive. If you removed all of the insects, however, probably the entire thing would
collapse. It is the little things that make the world work. Bacteria are among them; they
are also probably the most abundant but remain the least studied of all forms of life. If a
visitor from another planet were to analyze all the cells that make up my body he or she
would come to the conclusion that I am only 10% human. That is because 90% of the
living cells in my body are bacteria. Bacteria are the most numerous living organisms on
earth; they are also among the smallest. To understand just how small they are let me take
a perfectly clean pin and put it in this scanning electron microscope. At low
magnifications the pin seems perfectly clean, it is only when we zoom in and magnify it
to 10,000 times that the size of the bacteria becomes clear. Every living thing on the
planet depends on bacteria in one way or another but we still have no accurate idea of
how many kinds there are. Recently extraordinary discoveries deep below ground have
shown that all our previous estimates were far too low. These pumps in California are
pulling up oil from 1000 feet below the surface bring up evidence that there is life down
there as well, mostly in the form of bacteria. Indeed other evidence suggests that other
microscopic forms of life may exist two miles, three and a half kilometres below the
surface. Such bacteria may grow so slowly that an individual bacterium may only
reproduce once every 500 years. Among the most extraordinary claims for this new and
unexpected wealth of life deep below ground is that if one were able to gather it all
together then it would weigh more than all forms of life, animals and plants that live on
the surface. The discoveries are so new that we cannot yet be sure, and as for how may
different kinds of life there is down there we simply have no idea, all of which goes to
show that we still have a lot to learn about the planet on which we live. So what might be
the final total of all the different kinds of living organisms that presently exist on earth?
Different specialists in the field using different methods have produced estimates of the
number of species out there, plants animals, bacteria and other micro-organisms that fall
anywhere from shall we say 5 million up to as high as 100 million. Now that we
appreciate, if only roughly, how great life’s diversity really is we can begin to judge the
scale of threat it faces from human activities. The sad fact is that even though we have
only identified the minority of species even some of those we have named have already
become extinct, some so recently that we have their images on film. Including the
Tasmanian tiger and the Golden Toad. Many more are now so rare that there is real
danger that they too will be lost before long. To assess the rate at which species are now
disappearing we need to know a little more about the way such losses happen. What does
extinction actually mean? Nothing could illustrate it more dramatically than the sad and
infamous case of the Dodo. This is a kind of giant ground living pigeon; it was
discovered by Portuguese sailors at the beginning of the 16th century living on the island
of Mauritius. They didn’t think much of it, in fact they called it fat and lazy and stupid.
But that didn’t stop them clubbing it over the head in vast numbers and eating its flesh,
then they introduced pigs and monkeys which ate its eggs. By the mid 1600s the Dodo
was teetering on the brink of extinction. A few Dodos were captured and shipped back to
Europe as curiosities most of them died on the way. How long the last Dodo survived
alone on its island, we don’t know, it could have been hours days or even years. But
eventually that one also died and at that point the Dodo as a species was extinct. The
Dodo was particularly prone to extinction because it lived only on the relatively small
island of Mauritius. The process of extinction becomes more difficult to chart when the
species has a wider distribution.
In May 1980 Mount St Helens on the Pacific North West Coast of the United States
erupted. A huge area of the landscape was virtually scoured clean of life. In hours after
the eruption rocks and mud flows swept almost every living thing off the mountain
slopes. But within weeks life began slowly to return to the devastated landscape. The
scale of damage was astonishing; within minutes of the eruption beginning a superheated
blast of gas travelling at 500 mph had flattened 250 square miles of virgin forest. No
species was exterminated because there was none that were restricted to Mount St
Helens. Even though the blanket of ash looked so sterile some plants were able to grow in
it and soon the landscape was repopulated from the surrounding areas. Some
environmental losses however, though they look less dramatic are more permanent. In
recent times virtually the whole of Southern England was covered by woodland, a small
patch of which survives behind me. It was home to a great range of species of plants,
birds, insects and mammals. Now however most of that woodland has been felled in
favour of agriculture and fields like these are totally unsuitable for those woodland
species so they have disappeared. When the species disappears over a small part of its
range it is known as a local extinction. If you have too many local extinction s the
population level will fall dangerously low and then that species may be on the road to
total extinction. There comes a time in the life of a species when it has been reduced to a
point that it can’t be recovered even by strenuous efforts. A lot of species are in that
condition and ecologists call them the living dead. An animal that nearly became one of
the living dead still lives near the city of Rio de Janeiro in Brazil. In this area 90% of the
forest that once spread for 100s of miles along the coast has been lost. The remains have
been split up into small patches. One of the most famous inhabitants of this forest is the
beautiful Golden Lion Tamarind. It was in imminent danger of disappearing because it
had lost most of its home. At the last moment a major captive breeding program was
started and strict controls introduced to conserve the last remnants of its habitat so the
species may have been pulled back from the brink of extinction. Most living dead species
do not receive this kind of intensive help. One of the difficulties of measuring the current
rates of extinction is that animals classed as living dead may be doomed yet they can
hang on in slow decline for many years. John Lawton is a biologist who is specialized in
the study of animal populations. Some extinction is instantaneous, some will happen over
a 20 or 30 year time period when the population gets hit by a sudden extreme event and
some may take over 100 years as the last adults of a non-reproducing species finally dies
out. These estimates of extinction are bedevilled by the fact that it is very hard to be sure
that something has really gone. Several species that were thought for many years to have
been lost have reappeared. An example occurred recently in Australia. Brisbane museum
holds the preserved remains of many Australian mammals including three dried skins of a
small marsupial known as the mahogany glider. They were collected by a clergyman in
1886 at a place called mount Echu in Queensland, but they were never recorded again.
Was this animal extinct? That seemed very likely but then in 1989 some unidentified
mammal skins collected 15 years earlier were by chance re-examined and one was
recognized as a mahogany glider. The skins came from Barrats Lagoon near the
Queensland town of Tully. But even when the specimens were being collected their
environment was being destroyed. Surely the Mahogany Glider must now be extinct.
Then this stuffed animal was noticed in a house near Barrats Lagoon. The farmer who
had collected it thought it was a squirrel so he had had it mounted with a nut in its hand.
But it was a Mahogany Glider; the trail was obviously still warm. Eventually on the 5th of
December 1989, 103 years since it was last officially recorded the Mahogany Glider was
re-discovered alive at Barrats Lagoon. Today it has been provided with nest boxes but it
remains critically rare. Although mostly nocturnal individuals do appear during the day
and put on a stunning display of aerobatics gliding between the trees. There was great
excitement and not only among scientists that this beautiful creature was still around.
This was a narrow escape. Is it something about which we should be greatly concerned,
haven’t such losses always been happening? Extinction is a natural event. These draws
and wracks at the Natural History museum in London are full of the fossilized remains of
creatures called ammonites. They first appeared about 250 million years ago. Over the
millennia some species died out other ones appeared. 65 million years ago all the
ammonites disappeared and with them went a great number of other species of animals
and plants. Such mass extinctions have happened 5 times in the history of our planet. The
question arises, are we ourselves on the verge of such an event? In some groups such as
the birds all recent extinctions have been recorded so we can estimate the rate at which
extinctions are happening and compare it with the past. There is absolutely no doubt in
my mind and in the mind of all my professional biological colleagues that the earth is
facing a massive extinction crisis. The extinction rate is at crisis proportions, perhaps 100
to 1000 times higher than before humanity came along. That’s the kind of acceleration in
extinction rate, 100 to 1000 fold that characterizes the lead in to the five great extinction
events on the fossil record. The last of those 5 great mass extinctions took place 65
million years ago when the dinosaurs disappeared. Studying that event reveals the scale
of loss that a mass extinction can inflict on life’s diversity. Palaeontologist Peter Ward
has made a study of these events. What we have got here on a beach in France is
evidence of one of the worlds mass extinctions. We had a global catastrophe and that
catastrophe is written in the rocks with this very thin layer through here. This is the end
of the age of dinosaurs, this is the start of the age of mammals, that differentiation is
deposited as this very thin band of strata, in that band of strata we have evidence of a
meteor impact. We had bits and pieces of Mexico which had been thrown into space,
come down, deposited on the deep sea bottom here in France. Age of dinosaur creatures
are found in the strata right up to this point and they suddenly go extinct. This mass
extinction was sudden it was catastrophic, it wiped out about 60-70% of all species on
Earth. Can we define such an event? Mass extinctions are very short intervals of time
when huge numbers of species go extinct. They are over say 1000s of years maybe 10 of
1000s of years when over half of the biodiversity then on earth goes extinct. And now
due to the spread of the human species over the Earth it seems we are on the verge of an
even more dramatic one. The difference from the last five great mass extinctions and the
6th which some scientists think we are on the verge of, is one of speed. Each of the last
took place over many thousands of years. The next, according to some predictions could
happen within 100. It will take a great deal of will power and economic strength if we are
to significantly reduce the damage we are doing to biodiversity. In order to decide if that
is worthwhile we must ask ourselves, does the disappearance of a species really matter. In
a very few cases the species that go extinct are likely to prove to be what we call
keystone species, that is, like the keystone of an arch if it is pulled out a lot of the
remaining structure changes and usually not for the good. It is often extremely difficult to
know before hand which species will be keystone species. Sea otters are a clear example.
They live off the Pacific coast of North America. In the Southern part of their range, a
huge sea weed the giant kelp grows up from the sea floor and creates a kind of
underwater forest. Many different animals depend on these kelp forests. They are the
spawning ground for fish. Seals live here as well and many smaller creatures such as
snails clams and urchins. Sea otters feed on these clams and urchins they bring them to
the surface and open them by smashing them on stones balanced on their stomachs.
During the 18th and 19th centuries sea otters were intensively hunted for their skins and
exterminated over huge areas. Their disappearance lead to dramatic changes in the
environment. The sea urchins with no sea otters to keep their numbers down increased
explosively. Urchins eat kelp and their vast numbers soon began to destroy the under
water forests. As the kelp disappeared so did all the animals that depended on it. What
was left was a bare sea bed carpeted with urchins. Species do not exist in isolation, they
are linked to one another in complex ways and when those links are cut a crisis may
result eventually hunting the otters was banned, they spread back into this area from
further a field and the kelp forests slowly recovered. Clearly many of the species on the
verge of extinction, when they are taken out are not going to cause the collapse of an
ecosystem. We should lament their passing for other reasons but there are many that
might cause serious repercussions and until we understand the whole process better, we
are rolling a dice, we are taking chances whenever we let a species go extinct. So how
would the loss of species and environments affect us? First of all if you want to be
completely practical there is the matter of wild species being an almost bottomless source
of new antibiotics and other pharmaceuticals yet to be discovered and developed, new
crops, new fibres and other new natural products, we are just getting underway the whole
effort to make use of biodiversity in this way. An example of a useful product from a
surprising source comes from Cape Cod in the United States. Horseshoe crabs are
collected here daily from the sea bed for their blood contains a substance that can save
human lives. The crabs are taken to a laboratory and here in what looks like a scene in a
science fiction film, they are restrained in racks and some of their blue blood is extracted
from them. One of the substances in the blood is used about the world to test if batches of
inoculants are healthy or contain lethal bacteria. The crabs are then released unharmed in
a part of the sea that will not be harvested again for a year. Clearly many individual
species can be of great use to us but are there benefits to be gained from conserving
natural environments? There is this whole matter of ecosystem services, you know an
ecosystem like the one we are sitting in here is doing a tremendous amount for humanity
it is creating soil, it is cleansing water, it is creating the very air we breathe and the
important thing is that it is doing it all for free. Many reasons given for preserving
biodiversity are selfish ones to do with our health and comfort but is there any other
reason that we should be concerned about the loss of species? It is a clear and ethical
argument, an argument of stewardship, an argument of handing on a world as rich as the
one we inherited and that is an argument we in the first world have the luxury to consider.
We would have a different perspective if we are struggling to get the next meal. It is an
extraordinary gift that our generation received, this natural heritage and to destroy a large
part of it just fundamentally seems wrong especially when you think of what we are
doing to future generations. Scientists have a word for an environment that has lost many
of its animals and plants, they call them, impoverished. Some of them may have lost
almost all of their species as has happened recently on many coral reefs. Other
environments may appear to be largely intact even though many of their original
inhabitants have become critically rare or lost altogether. Future losses could include
many smaller kinds of life yet to be discovered as well as some of the best known
animals on the planet. There is a spiritual value an aesthetical value a psychological
benefit for having a large diversity of life on earth we should not be removing it. I believe
it could conceivably be possible that in a few hundred years time we reduce that
dependence and we lived in an almost wholly science-fictiony artificial world, the world
of the cult movie blade runner. The question you have to ask is, do you want to live in
that world? The view the astronauts gave us when they looked back at Earth enabled us to
see more vividly than ever before, just how limited space is on this small planet for life.
We now know that we are seriously damaging biodiversity and there is the risk that the
world that we hand on to our next generation will be less rich, poorer in biodiversity than
the one we inherited. Why is it that the activities of our one species aimed at no more
than living in reasonable comfort and avoiding hunger should cause such devastation on
the rest of the natural world?
BBC State of the planet part 2 – Why is there a crisis?
65 million years ago an environmental catastrophe wiped out the dinosaurs and over half
of all of the other species then living on the planet. There is now strong evidence that
similar losses are about to happen again.
This is Hawaii, it is the most isolated group of islands on the planet. 2400 miles away
from the Californian coast. From the air it may look like an island paradise but the history
of its animals and plants since humanity first reached it 1700 years ago, is very alarming.
It can be seen as an example in miniature of what mankind has done to the planet as a
whole. In environmental terms it is tragically impoverished. Small islands are especially
vulnerable to the environmental changes that so often follow the arrival of humans.
Hawaii not so long ago had more unique kinds of plants and animals than any other group
of islands on earth. But this lush beauty is deceptive. These mountainous forests and
lowlands which once teamed with such unique species have today been emptied of their
biological riches. The islands give us all a dramatic warning of the level of losses that
could soon occurs right across the planet. 100s of species of both animals and plants have
disappeared since humanity first came to Hawaii and its now absolutely clear from
research that here on Hawaii and on other islands that when ever human beings settle on
an island great loss of species occurs. If we are to control our impact on the environment
it is absolutely essential that we should understand why this should be.
Across the world from the tropics to the ice caps we are surrounded by an extraordinary
variety of life. We have so far named one and a half million different species. There
could be as many as 100 million. This great abundance of life is known as biodiversity. It
is this richness that today is threatened as our species attempts to fulfil our biological
needs. In this program we will identify the five human activities that are causing such
destruction that it leads some experts to foresee a mass extinction of species during this
present century.
To begin with it may help to get an idea of the scale of environmental change necessary
to cause a massive global extinction of life. To do this we can look back 65 million years
to the last great wave of extinctions that left the dinosaurs as nothing more than fossils for
us to study and display. Many scientists believe that this event was due to the
environmental after effect of the collision with the earth and a 10 mile wide meteor
travelling at 25 thousand miles an hour. This was the equivalent to the simultaneous
detonation of 10,000 times the world’s total arsenal of nuclear warheads. Superheated
fragments of rock set half the worlds plants on fire. Dense clouds of dust blocked out the
sun for months on end sending temperatures plummeting in what had previously been a
largely tropical world. The rain that fell was acid and poisonous. The cumulative effect of
all that was the extinction of over 50% of all species on the planet. There is a place in
Arizona where a meteor only a fraction of the size of the one that is thought to have lead
to the disappearance of the dinosaurs has left its mark. On a global scale it is a mere pin
prick. But that mark is enormously impressive. Many are now suggesting that the impact
of our own species may represent for the rest of life on earth, the biological equivalent of
a modern meteor strike. It may seem somewhat fanciful to compare the effect that
humanity is having on biodiversity with the world wide catastrophe caused by a massive
meteor impact. There is a lot of evidence to show that we are on the very brink of an
extinction event. So the comparison is not without relevance. If we want to see what
humanity has done to its environment a very good place to start is where humanity itself
started, in Africa.
Here on the Savannas we can still see great herds of what scientists call mega fauna. The
big mammals. Why is it that if you want to see big herds of large mammals, you have to
come to Africa? Well the answer is pretty obvious, it is the only place where there are
such things. If you went anywhere else you would be in for a big disappointment. It
wasn’t always that way. 50,000 years ago there were big herds of big animals on every
continent on the planet except Antarctica and then around that time in a very short period,
those animals began to go extinct. At the same time human beings were beginning to
expand from the continent where they began in Africa right across the planet. Was that a
coincidence or was it the first evidence that human beings could have an effect on the rest
of the animals on Earth unlike that of any other species. In North America 2/3s of all big
mammal species were lost. What was it like there before that happened? Biologist Jared
Diamond has made a detailed survey of the mega fauna extinctions worldwide.
Here around us in Los Angles, the mega fauna that went extinct consisted largely of
mammals there were camels, we had a lion here. If we had been standing here 14
thousand years ago it would have looked like the Serengeti plains with Lions and
Cheetahs and Elephants. Could the hunting of big mammals by those ancestral humans
really have played a role in their disappearance? The one correlation around the world is
that the mega faunal extinctions happened whenever humans arrived in the area. Arriving
in Australia 40,000 years ago in the Americas 13,000 years ago, in New Zealand 1000
years ago that I think is enough to convict humans.
There are still a few kinds of big mammals left in North America such as these carefully
protected bison on the plains of South Dakota. These are big animals and potentially very
dangerous which is why I must stay in a car if I approach them as closely as this. These
however, are small compared to some of the huge animals that roamed these plains.
There was the mammoth, the size of the African Elephant, Sabor tooth cats, a ground
sloth weighing 3 tonnes, a beaver the size of a bear. And that raises the question of how
humans, on foot, armed with nothing more than bows and arrows and spears could hunt
such monsters so successfully that they contributed significantly to their extinction.
Surprisingly the answer is to be found back in Africa by investigating why big animals
did not die out here despite this being the very place where humans developed their
hunting skills. The big animals of Africa had been evolving along with humans for 5
million years as humans started out as ineffective hunters and gradually evolved to be
effective hunters so the animals of Africa had a long time to learn fear of humans
whereas unfortunately the big animals around us here in Los Angeles were the best
professional big game hunters that there have ever been in human history. None of the
big animals outside Africa had ever seen human beings before and didn’t recognise them
as predators so instead of being fierce they probably appeared almost tame, as a
consequence they were easy to hunt. But that is not all, Human beings are what
biologist’s call, switching predators.
John Lawton is an expert in the study of animal populations. A switching predator is a
predator with a variety of prey available to it, able to attack a wide array of prey items so
that if one prey gets rare it can switch to an alternative kind of prey, that way it can work
its way through a smorgasbord of prey items sustaining its population on whatever
happens to be common at the time.
To get an idea of how a switching predator like those early humans can have such a
damaging effect of species we can look at a modern story involving another rather
surprising switching predator from Europe. In the mid 1970s 5 hedgehogs were taken
from the Scottish mainland where they are common and released as garden pets on the
island of South Ewest off the west coast. It is an island too remote for the hedgehog ever
to have reached by itself. They and their descendants took to living in old rabbit burrows.
The island turned out to be an almost perfect place for hedgehogs with no predators to
control their numbers. Being a switching predator the hedgehog will feed on anything of
the right size that it can find. Slugs, snails and worms are among its favourites and their
hugely abundant in the damp climate here. So well did the island suit the hedge hog that
those five have given rise to around 10,000 hedgehogs. Originally other animals also
benefited from the lack of predators, the dunlin had always nested here successfully for
although it lays its eggs on the ground there is nothing here to take them. But the
hedgehog changed all that, in the way of a switching predator it is always looking for
new kinds of food. It turns out the hedgehogs will happily switch from slugs and worms
to Dunlin eggs. This switch led to a drastic collapse in the Dunlins breeding success.
Unfortunately the story doesn’t end there, at low tide South Ewest is connected to other
islands by sand bars, hedgehogs can simply walk from one island to another devastating
the populations of breeding birds as they go. Some islands that are not naturally
connected by sand bars have now been joined by causeways and then the hedgehogs do
not even have to wait for low tide.
Humans are no ordinary switching predator. The loss of the mega fauna was just the first
sign that they can kill their prey at a faster rate than their prey can reproduce. Over
harvesting of both animals and plants is the first in the fives ways in which we are
affecting the diversity of life on earth. As the growing human population devises ever
more efficient technology its ability to over harvest becomes ever greater. Trees illustrate
this tendency only too clearly. If we cut them down faster than they can grow then a
forest will inevitably get smaller or disappear altogether. The natural processes of
regeneration will no longer be sufficient to maintain them. This over harvesting will
inevitably affect all the species that interact with trees or depend upon them. Today trees
are being harvested 10 times faster than they are being replaced with new growth. The
sea is being over harvested too.70% of the major fish species are being removed at a rate
at or above the rate at which they can reproduce. Sylvier Earle is an expert in marine
biology. We are getting too good at removing wildlife from the sea. Fish have no escape
any more. Perhaps there was a time 50 years ago certainly 100 years ago when our
numbers were smaller and our ability to capture wildlife in the sea was less sophisticated
than now but with acoustic methods we can find ever last tuna, every last squid, every
last shrimp in the sea. This kind of use of technology is wonderful in some respects but
terrible in others because it is encouraging us to just take too much out of the natural
systems. Recent figure suggest that each year up to half of the planets new plants and a
large proportion of animals too is harvested for the use of one species, our own.
The second way in which human activities are changing the diversity of life also began,
like over harvesting, when humans spread across the globe. This is the damage that is
caused when animals are introduced into places where they have never lived before.
Australia is famous for the number of alien species that have gained a foot hold on its
land, often to the determent of its native species. A dramatic example is the European
rabbit. Without their natural predators and diseases rabbit populations in Australia
sometimes explode. These rabbits can graze bare 100s of square miles of grassland
affecting everything else that lives there. Overgrazing eventually affects the rabbits too
and they die of starvation by the million. However alien species cause the most damage
on small oceanic islands and no where more so than on Hawaii. Here one alien
introduction after another has driven many native species to extinction. When you arrive
on Hawaii it looks wonderful, it is a tropical paradise and what most tourists don’t realize
is that almost everything they see there in the lowlands is introduced and there is
essentially no native birds and very little native vegetation. Many of those that remain
have now become isolated on mountain tops by this tide of introduced animals and
plants. Hawaii once had about 100 species of bird that were found no where else on earth.
More than half have gone forever and many of those that survive are critically
endangered. Snails better than any other Hawaiian animal illustrate how one introduction
after another can devastate local wildlife. Millions of years ago a small number of snails
arrived here on floating vegetation. From them 1000 other species evolved all unique to
Hawaii. Today only a small fraction of these still survive. Some that produce these
colourful shells are now so rare that their total world population number less than 10
individuals. These huge collections of Hawaiian snails are a product of a collecting craze
in the late 19th century. Many of them will never be seen again, they’re extinct. Some of
those were driven onto extinction by the sheer intensity with which they were collected
others undoubtedly had their population sizes reduced. But the final blow that drove so
many of Hawaii’s snails to extinction was the introduction of alien species. The rat was
just one of the more damaging arrivals eating its way through the great populations of
ground living snails and doing considerable damage to those that lived up in the trees.
Things became worse with the introduction of pigs and goats which damaged or
destroyed the plants on which the snails lived and so caused many extinctions. But this
was not all. Alien snails now appeared. These are giant West African snails and they
were introduced into Hawaii about a century ago because some people thought they were
particularly delicious to eat. Unfortunately snails as big as this have pretty good appetites
themselves and before long they were out of control and chewing up peoples gardens and
so it was decided to try and control them by introducing killer snails, including this one
from Florida. Unfortunately nobody though to check whether the introduced cannibal
snails would prefer the giant West Africans or the native Hawaiians. In the event they
chose the Hawaiian snails and so another series of extinctions began in Hawaii. These
killer snails glide over branches looking for the trails left by the native species they track
them down and then they eat them. Killer snails are now moving across Hawaii at a rate
of 1 km a year destroying native snail populations as they go. One might question
whether the disappearance of a range of species of snails in Hawaii really matters. After
all there have been no ecological consequences or damage as far as we know. It could be
that we won’t be aware of any damage for some time to come but even if there is none,
surely it is sad indeed that our descendants will inherit a world that is more impoverished
than the one we inherited. The introduction of alien species which we often make so
thoughtlessly is the second in which we are damaging life’s diversity.
The third and the most damaging of all is the destruction of habitats. There is a very clear
example of habitat destruction in South Africa this is Cape Town. Surrounding the city
on this tiny corner of the African continent is a habitat known by the Afrikaans name of
fynbos. It is one of the most remarkable plant communities on earth with a higher
concentration of species than even the Amazon rainforests of South America. It is what
scientists call a biological hot spot. There are over 5 and a half thousand plants growing
here that are found no where else on the planet. It is a remarkable place too because some
of the plants here have ranges so small that the entire world population may be crammed
into an area the size of a football field . This peculiarity, sadly, provides a clear
demonstration in miniature of habitat destruction.40% of the original area of fynbos have
been destroyed by human activities such as agriculture and the spread of the city. Clearly
if a plant has a world range of only a few 100 square meters and that area is destroyed
then the plant will become extinct. It’s a simple idea, take away the home of a species
and that species vanishes. That is habitat destruction. And the damage may not stop there.
Other plants or animals may also use that patch of land or depend on that rare plant so
they too will be affected even if their range is larger than the area destroyed. We
ourselves are not immune from the effects of habitat destruction. There is a startling
example of how that can happen in the United States. This is Charko canyon in the state
of New Mexico. It is part of a desert that covers 100s of square miles. When the first
European travellers reached here on horseback about 350 years ago they found very little
water, hardly any trees to provide fuel for fires or timber for housing and a soil that was
very very infertile. The place seemed virtually uninhabitable and then they entered this
canyon and were greeted by the most extraordinary sight. This is the settlement of Puebo
Bonito and it is just one of a number of structures in this desert. They were built about
1000 years ago by the Anazarzi Indians and they were abandoned a mere 300 years later.
Ever since they were discovered the same questions have been asked about them. Why
should the Anazarzi build their cities in a desert and why should their civilization be
abandoned a mere 300 years later? We now know the answers to those questions and they
still retain the power to shock as they’re as relevant to our civilization as they are to that
of the Anazarzi 1000 years ago. Pueblo Bonito was five stories high the tallest building in
North America until the advent of steel sky scrapers in the late 19th century. About
215,000 wooden beams were used in the buildings that ones stood in the canyon. It’s not
just a question of why the Anazarzi lived here, but how. Where did they find the timber
for their construction work and fuel for their fires? There are signs of fields and irrigation
systems round here but the water table is well below the surface and the Anazarzi didn’t
have pumps to raise it. It required an inspired piece of detection work to solve the
mystery of Charku canyon and rather surprisingly the key to it was a little mammal called
the pack rat. The pack rat is nocturnal and very shy. Just to see it we have to use a
sensitive night vision camera. They live in burrows, at night they emerge to collect sticks,
pine needles and pretty much anything else they can carry which they deposit on a mound
on top of their burrow. This mound is their toilet area. Such middens may be used
continuously for over 100 years before being abandoned. Over the years the nitrogen in
their droppings crystallises and their middens solidify and can survive for thousands of
years in this hot dry climate. Fossil middens are like time capsules. They carry an
accurate record of the plant life at the time that the midden was created. Scientists have
analysed the contents of 52 such middens which between them covered a period of
10,000 years. What they found was a revelation. By dissolving the crystallised nitrogen
and studying the plant remains the history of a civilization was unravelled. It was
discovered that when the Anazarza first arrived in Charka canyon the area was woods
with pinion and ponderosa pines. These trees were cut down for fire wood and building
materials. When the canyon had been cleared of all its trees the Anazarzi built roads to
bring timber back from up to 70 miles away in the mountains but by then the damage had
already been done. This is one of the few trees still standing. It seems that the destruction
of the trees combined with an ill timed period of drought caused the water table to drop
below the level of the irrigation systems in the fields until they could no longer produce
crops. The land became the desert that we know today and the Anazarzi were forced to
leave. The collapse of this civilization is in itself an alarming story but Chaku canyon was
by no means unique. There are dozens of examples, there were collapses in the fertile
crescent on East Riload at Ankoa What in the Indas vally and great Zimbabwe, in Greece
in the mississipi valley, it goes on and on and on. The destruction of habitats is doing
more damage to biodiversity around the world than any other human activity. As our
population increases and we cover more of the earth’s surface with our buildings and our
cultivated fields we will inevitably loose more wild habitat.
The damage we have inflicted on the world environments have lead many to question
whether the human species is deliberately destructive. Edward Wilson is a biologist that
has made a special study on the effect of human behaviour on the rest of life. I think it
would be a grave injustice to speak of the human species in some sense evil even though
we are destroying the environment so efficiently at the present time. Basically that’s not
our intent, it never was. It was very natural in fact it was necessary for survival for the
ancestral human being to throw everything they had against the wilderness in an attempt
to conker it, to utilize it. That is the nature of human kind, to expand the population, to
gain security to control, to alter and for millions of years that paid off without undue
damage. Then what happened was as we developed a modern industrial capacity then the
techno-scientific capacity to eliminate entire habitats quickly and efficiently. We
succeeded too well. At long last we broke nature and almost too late we are waking up to
the fact that we’ve over done it and we are destroying the very foundation of the
environment on which humanity was built. Habitat destruction is the third way in which
humans are damaging life’s diversity.
A process called islandisation is the fourth. When we destroy habitats we tend to leave
undisturbed pockets. Whenever you fly over any bit of the globe now you can see what
we are doing to it. Basically the process can be thought of as one of islandisation. Islands
of undisturbed habitat in a sea of totally modified habitat. What happens to habitats that
have been cut up and reduced to islands. To answer that a huge and ingenious experiment
was set up in the rainforests of Brazil by conservation biologist, Tom Lovejoy. Well
basically its like you have this carpet of green forest and you took a cookie cutter and put
it down in a few places and cut away all the forests around the cookie cutter and you are
left with these green patches of forest. Although the cleared areas have now begun to
grow back the re-growth consists of just a few weedy species so the islands of rainforest
like this dark green rectangular patch still remain isolated. It was found that these islands
of forest changed from the centre to the edge. The nearer the margins the more species
will have gone. Species are continuing to disappear 20 years later because of changed
conditions or because the islands are simply not big enough to sustain their populations.
The results were usually the same whether in an experimental island or in an area of
forest bisected by nothing more than a road. One clear example of the effects of
islandisation that has been studied here involves a group of birds that habitually follow
the swarms of army ants. Studies have been made to discover whether these ant birds will
fly from one patch of forest to another. Antbirds rely for their food on the army ants
which range over the forest floor hunting insects. The antbirds follow them picking off
whatever insets they can. A colony of ants needs a large area of forest to provide it with
enough insects. If an island of forest is not big enough then the ants will simply leave and
cross to another one. This presents a problem for the ant birds. They are psychologically
adapted to staying in dark shady forest and they simply will not go out in the open. They
are unable to follow an army ant colony if it leaves a fragment. If they are then left in the
fragment they will starve and die. One species after another will be lost where ever you
create an island in any kind of habitat. You are going through a simplification of an
ecosystem an impoverishment of the number of species. So in the end you end up with
something which is quite less than what you started out with. Islandisation is happening
more and more around the world, even nature reserves are islands. The smaller an island
the more vulnerable its inhabitants and a large species may need very big islands indeed.
There is a small but clear example on the chalk grasslands which once extended right
along the whole length of the downs of Southern England. Changes in agricultural
practises here have had a dramatic effect on this little insect. Like many animals and
plants the silver spotted skipper butterfly is very particular about where it lives. In
England it can only survive where the grass is very well grazed as it is here on box hill in
Surry. That grazing keeps the grass very short and allows a full range of down land
flowers to bloom. More importantly for the butterfly it also creates areas of bear earth
where there is no grass and no flowers. These bare patches of earth are crucial to it
because they warm up very quickly in the sun. The butterflies bask on them and so raise
their body temperature. Only when they have done that can they fly away and lay their
eggs on the surrounding grass. The silver spotted skipper’s home has now been reduced
to a number of small grassland islands. They wont fly more than a short distance over
unsuitable ground so don’t move from one island to another. Each butterfly population is
now isolated from the others a typical consequence of islandisation. If a bad season or
disease eliminates one colony that area cannot be naturally restocked from elsewhere.
The danger for species living in isolated populations is that one after another those
populations may die out. If nothing is done to save them then before long the species has
disappeared over quite a wide area and if its range was not large to start with quite soon it
becomes totally extinct. The piece meal destruction of populations caused by
islandisation of habitats is the 4th way in which humans are effecting the environment.
The 5th way is pollution. There is pollution in many parts of the world. Its damage to the
habitat may be great but often it is only local. There is one kind of pollution however that
could have world wide consequences. That is the global warming that results in the
human activities that pump carbon dioxide into the atmosphere. Carbon dioxide is a green
house gas that is to say, it traps the suns heat. The more carbon dioxide there is in the
atmosphere the warmer it becomes. Stephen Schneider is a scientist who has studied
both climate change and its effects on the natural world. It is absolutely certain that
humans, when they use the atmosphere as a free sewer and we dump our smoke stacks
and our tail pipes in it and we chop down our trees and we have cement plants, are adding
to that envelope of green house gasses. It is virtually certain that that traps enough heat to
make a significant difference. There’s probably damages already, we know that sea levels
now are probably 10-20 cms higher than they were. That mountain glaciers are melting.
That there is probably a little added intensity to hurricanes so it is already possible to
argue plausibly that we have started to crank up the stress in terms of added droughts and
floods and so forth. Global warming has occurred naturally many times before. You can
see the effect on animals and plants of just one such happening if you go a few miles out
to sea and back in time by 10,000 years. I’m in a fishing boat in the North Sea just off the
Dutch coast and we are trawling at a depth of about 30 m 90 feet for mussels. Sometimes
the nets bring up more than mussels, they bring up vivid evidence of an ancient global
warming. Starfish, razor shells, star fish, now that’s more like it, that is a bit of bone, and
a huge bone too, that would have been an articulating surface like that. That looks like a
tooth, that’s a tooth of a small horse but this is nothing compared with what has been got
out of this particular sea. Over here, all these have come out from just here. A tusk, a
mammoth tusk, and this is the joints from the top of the shoulder also from a mammoth.
And this perhaps is the most convincing of all, no one could have doubts that this is very
strange, this is a mammoths tooth. These are its roots and this is the substantial body of
the tooth that was in the jaw and this was the grinding surface. A spectacular
demonstration that 9, 10, 11 thousand years ago, this patch of the sea was dry land with
mammoth wandering over it. That global warming lead to a great rise in sea levels which
drowned much low lying land and changed the characters of many areas by altering
weather patterns. Finding the bones of a great land animals like a mammoth underneath
the sea makes it perfectly clear that global warming can bring about great profound
changes in the distributions of animals and plants and equally obviously and future global
warming is likely to do the same. When it happens temperatures change all over the
planet as we can se on this thermal image. This is a problem for many animals and plants
because most can only live within a very limited temperature range so if climate changes
they must move to keep pace of it. For example when the climate warmed after the last
ice age, oak forest moved north or south to keep up with their shifting temperature zones.
How does an oak forest move? The answer is, very slowly by having its seeds transported
by animals. In the autumn squirrels and Jays bury acorns as food stores for the winter
months but they forget where many of them are and those acorns will germinate. When
global warming happens acorns buried in the north of the forest will grow where those to
the South will die. And so a forest slowly creeps north. This process took thousands of
years but today it seems that global warming is happening faster than ever before. Its not
like it was when the ice age ended, you know 15,10, 12 thousand years ago and the trees
marched north, marched in the sense that the seeds spread and the animals literally flew
and walked, now we are saying, go ahead and redo that not in 1000 years or 5000 years
like in history but go ahead and do that in a century and do it when you have to cross
factories, farms and urban settlements and all the human disturbance and its that
combination of factors the disturbance combined with the climate change that makes
most of us in environmental science very concerned about the ability of the earth to
support anywhere near the current level of biodiversity in the next century.
So these are the 5 ways in which we are damaging the planet. Over harvesting,
introducing alien species, destroying the places where species live, creating small areas of
habitat and finally by polluting the atmosphere. Change in itself is not necessarily
destructive when it happens slowly. However these five factors are all happening at
unprecedented speed. It seems that the reasons behind the loss of species today make the
impending change unique amongst the great waves of mass extinction that have
happened so far. Scientist Sir Robert May is a leading authority on the current biological
crisis. The dinosaurs were probably done in through an asteroid impact. An external
environmental impact. What we are seeing at the moment is something unique in the
history of life, a single species, us, sequestering to our use for example a quarter to a half
of all the plant material that grows on the earth in any one year. Our activities are creating
the conditions that are driving this 6th great wave of extinction, the wave on whose tip we
stand. It is both literally the best of times and the worst of times. There has never been a
more exciting time to be alive when we are beginning to actually read the book of life
itself and we have the potential to apply that understanding for good stewardship and
husbandry of this marvellous world that we are heir to. Or we can just thoughtlessly bend
it for creating more bits of garbage to amuse ourselves. I don’t think that there is going to
be some major environmental catastrophe some major Armageddon, the world isn’t going
to stop tomorrow, the world will simple become a grotty less interesting place. If you like
rats and cats and house finches and a few things like this and you would like to see them
everywhere you go then biotic impoverishment is for you but if you or your descendants
would like to live in an interesting world in which there is richness of life, variety of life
and wild environments full of surprises and aesthetic delight then conservation of
biodiversity is for you. My belief is that given enough education, enough awareness,
enough sensitivity to the problems presented to them people have the capacity to do
amazing things and change their attitude.
We began our investigation in Hawaii, the very image of a tropical paradise. The
vulnerability of its native animals and plants has much to do with the fact that they
evolved on islands but none the less their fate should be taken as a warning. We now
understand which of humans activities inflicts the greatest damage on the diversity of
animals and plants on the planet. That knowledge is going to be crucial if we are going to
meet the great challenge of the next century. How to provide a good living standard for
the ever growing number of human beings without inflicting a grave impoverishment on
the planet.
State of the planet 3 – The Future of Life
This is Nairobi National Park. Ten years ago Black Rhino were being poached quicker
than they were reproducing, it seems certain they were doomed to extinction, yet here
they are. How has that happened? Well it has happened because one species, ourselves,
decided it could happen and should happen. Today we have the ability to make a
difference and what the human species does to the planet over the next 50 to 100 years
will determine the future of all life on Earth.
In the case of the Rhino we may have saved the species but not necessarily its habitat.
This city was once far away, but over recent years its grown so much its now hard against
the park fence. It’s a scene that has been repeated over and over again across the planet.
The rhino is just one of the more obvious endangered species but if things go on as they
are its likely that over half of all species will become seriously endangered or extinct
within the next 100 years. As the human species increases in numbers so do inevitably
the demands that it makes on the Earth and the other creatures that live there. Somehow,
we must find ways of reducing the pressures we are putting on the planet. In only too
many places our interests and those of wildlife seem to be in direct conflict. Rwanda in
Africa is one such place. There the Verunga Mountains are home of one of the
charismatic of all species, the Mountain Gorilla. Just over 20 years ago, I went to Rwanda
to see them myself as part of a documentary that we were making. Then it was
comparatively easy to see Gorillas in the wild in their very rough country, and even to
interact with them.
And so if ever there was a possibility of escaping the human condition and living
imaginatively (mmmggggmmm), in another creature’s world it must be with a Gorilla.
There were only about 240 of them in the Verunga Mountains at that time. This friendly
youngster was known as Pablo, but he and his family were in real danger. Part of their
Forest was being felled for farms, and they were being killed by poachers. It was only
when their plight was brought to international attention in the 70’s, that things began to
change. Park guards supported by conservation charities reduced poaching and so many
tourists paid to come and see the Gorillas that the government recognized officially that
these magnificent animals were a major economic asset.
But during the 1990’s another much bigger tragedy started to unfold. Rwanda was
devastated by civil war and genocide. Immense refugee camps formed on the slopes of
the mountains where the Gorillas lived. Humanitarian aid provided food but not the fuel
to cook it, so the people took that from the forests. They had no choice. What had been
lush mountain vegetation where the Gorillas came to forage became a wasteland. Some
of the Gorillas were killed, but despite the shooting and the reduction in the size of their
forest, the Gorilla community survived. Pablo is now fully grown. Miraculously he and
his family came through the turmoil relatively unscathed, but there are still dangers in
this forest. This Gorilla lost its hand in a poacher’s snare. Even so, the Verunga
population has begun to increase. At the last count there were 320, what future do they
have? Ian Redmond is a biologist who has being studying and working to protect the
Gorillas for over 20 years. “Now that those Gorillas are seen as an economic resource,
then the quality of lives of all the people associated with the park is going to be increased
by the fact that there are still Mountain Gorillas there. And more important, the Gorillas
are part of the ecosystem of those mountains and that’s one of the most densely populated
parts of Africa most people are farmers, they depend on the rainfall that those mountains
generate and they depend on the streams that flow out of those mountains which wouldn’t
flow year round if the forest was gone. So you have got to save the forest which means
you need the animals in the forest which means the people around that forest can benefit
from it.” Its not just in developing countries that humans and wildlife can be at odds, that
could also happen in prosperous parts of the world.
The state of Oregon in the north-west of the United States still has vast wilderness areas,
but even here there is a species that has been threatened with extinction. This time it’s a
bird, the Northern Spotted Owl. Its diet is quite varied for an Owl. Frogs, lizards even
insects, but it relies mainly on small rodents. One pair of Spotted Owls needs around 8
km2 of old growth forest in which to catch enough prey to feed themselves and their
chicks. But part of this territory in recent decades has become a major centre for logging.
When the forest is cleared the Owl can no longer hunt and it takes about 60 to 100 years
for an area to recover sufficiently for the Owl to return. Around 60% of its former habitat
has now been lost. The timber industry here is big, powerful and very important. If it
were to go entirely over 30,000 jobs and millions of dollars of revenue will be lost. Its
hardly surprising that the issue caused bitter divisions among the people of the area,
many of whom couldn’t accept that they should lose their jobs just because of a bird. But
fundamentally the argument was not just about a bird, but about the whole complex
community of animals and plants living in these magnificent forests and eventually it was
decided that logging should be restricted. However, shutting off large areas of land to
protect wildlife and finding local people new jobs is not always an option. Elsewhere
there may not be enough space to give each its own territory.
In Africa in Kenya’s Shimba hills there is such a problem. What was once wild bush is
gradually being taken over by farms. The area, however, is particularly rich in animals
such as Elephant and also contains a great range of plants. Within the Shimba Hills
Reserve, there is an area of 35 km2 containing a once migratory population of 500 or so
elephants, this has been fenced off to protect growing numbers of farms from crop
raiding by Elephants. Fortunately, closed reserves may be beset by many problems and
this area has one, too many Elephants. Elephants may push over trees to get to the leaves
of the higher branches, but with so many animals restricted to this small area there is a
risk, that the carefully protected environment will be severely damaged. So a solution has
to be found. In this case around 30 of the worst offenders are tracked by helicopter,
tranquilized to be moved elsewhere. Even so this solution is only temporary because the
population that remains is still too large, it does however buy time until a more long term
solution can be found. This is a dangerous procedure that can only be tackled by
specialists such as the Kenya Wildlife Service. Paula Kahumbu is their scientific advisor.
“This is a particularly difficult area to work in because it is forest and bush land. We have
a team from the Kenya Wildlife Service which includes our chief vet and his veterinary
assistants, um, and the capture team with all the equipment. We are planning to move 30
bulls, so it is one of our biggest operations that we have ever conducted. This may be a
distressingly undignified procedure, but its the only way to translocate an Elephant. The
Elephants will go to Tsavo East National Park, 200 km away. It’s a much larger reserve
less densely populated by Elephants. But is there a danger of having increasing numbers
of small isolated patches of natural environment. “I do think it will happen more and
more. We’ve been, um, unable to stop the fragmentation of these habitats all across
Africa, um, in Kenya it is particularly bad because our protected areas only cover 7.9 %
of the total landscape.” But more small reserves may require evermore damage limitation
exercises like this. Even small areas of natural habitat may contain thousands of animal
and plant species, they may be smaller and less glamorous than Elephants but equally
important for the health of the area. Over several weeks 28 elephants were translocated.
So what are the benefits of concentrating great effort and expense on just a few of the
largest species? An expert in African conservation is Walter Lusigi. Although we must
use a single species as a flagship but we must always remember that the species survive
within an ecological system and they are related to their surrounding environment and
protecting that species means protecting that whole environment for it to be able to
survive. But to conserve an elephant on its own, that does not work.
We now know that many of the reserves created in the past are too small. One way to
deal with that is to join them up. Across Africa there are several hundred protected areas
and national parks. At the moment they are isolated from one another. Here in Southern
Africa where Zimbabwe, Mozambique and South Africa meet their borders are being
opened up to connect existing parks so that wildlife can migrate between them as they
once did. There is now a plan to link this huge area with other reserves across southern
Africa. Its known as the peace parks initiative and its headed by zoologist John Hanks.
We stress three important things about the peace parks the first is of course the role that
these larger areas play in the conservation of global biological diversity. The second is
that peace parks really do promote a culture of peace and that is something Africa needs
and the third things we stress about all of this is bringing in the local people as partners so
they benefit from it. That hasn’t always been the case. This is all that is left of one of the
villages belonging to the Makaleki people after they were forcibly removed to make way
for the Kruger National park 3 decades ago. 30 years on the Makaleki have achieved
something unique. They appealed to the law and won back their land, now they have
decided to manage it to encourage wildlife. They hope that in the next few years such a
wild and beautiful area as this, if properly conserved will attract tourists and bring money
and jobs. So both people and wildlife will benefit. Trying to get across the message that
biological diversity is not just a bunch of conservationists saying we’ve got to conserve
these spectacular mammals because we like to look at them. We are talking about quality
of life, we are talking about human survival and we are talking about the commercial
value of a range of species that really can make a difference to communities living in
some of these marginal areas
Conservation tends to focus on protected areas and protected areas are fine as an absolute
bottom line but they are not enough so we have to develop methods of living in amongst
nature not separating humans from nature and all those projects where communities
benefit from wildlife and from natural resources in a sustainable way are the way
forwards.
Enabling both wildlife and people to live alongside one another appears to be working in
parts of Africa but in many densely populated countries places where wildlife can
flourish are now only tiny patches. This is Eastern England, part of Cambridgeshire. Over
the past 50 years pasture and woodlands highlighted here in green have been greatly
reduced and it now has some of the largest fields in the country. This has had a
considerable effect on many species. Bats can live for up to 25 years so many individual
bats in Cambridgeshire have had to make major adjustments to their lives in order to
survive. They feed on moths and are able to detect them by listening for the sound of
beating wings. One bat may catch up to 20 moths a night. Bats depend upon hedgerows
for their food, insects, and for shelter but hedgerows are extremely important from
another point of view. They act as corridors between the bats roost and the woodlands in
which they feed. After the Second World War new agricultural machinery was
introduced that needed big fields. So hedgerows were torn up and with them went many
of the bats highways and feeding grounds. It takes only a few minutes to rip up a
hedgerow. But over a century for a hedgerow to build-up a richly varied population of
animals and plants. This may be a rather odd and special example but in fact corridors
can be crucially important for animals both small and big. We now recognize the
importance of hedgerows and other wild habitats and laws have been passed to protect
them even in the overcrowded English landscape.
The natural environment can be destroyed in less obvious ways by alien species that have
infiltrated some of our seemingly unspoilt wildernesses. This is the Snowdonia national
park. Set aside as a national treasure and protected for its wonderful landscape and its
wildlife and the public appreciation. This welsh park has one of the highest
concentrations of different mosses in the country. It is also a place where Rhododendrons
in flower bring vivid colour to whole hill sides. But rhododendrons are not native to this
part of the world. They were introduced to Britain 200 years ago as an ornamental shrub
for gardens originally from Spain and Portugal and then from the Himalayas. They like
high rainfall and humidity with an acid soil and in these conditions they thrive.
Rhododendrons combine the characters of beauty and the beast. Here they grow into a
great wall of foliage 20 to 30 feet high. Nothing grows beneath them, the ground is
absolutely bear, they simply take over from native species. Removing them is a very big
job, but you might think that was the end of the matter. Not so. The reason that nothing
else grows here is not just because of the lack of light. Rhododendrons like many plants
rely for their nourishment on a partnership between their roots and a fungus. The fungus
that grows on rhododendrons produces a chemical that is highly toxic to anything other
than rhododendrons. So the plain fact of the matter is that this soil is poisoned and dead.
Not only that but most British mammals birds and insects that tried to live here would
also be poisoned. The park is getting rid of the rhododendron but it is a massive task.
Once you have cleared an area you cant immediately plant it with native species because
the rhododendron fungus remains poisonous for up to 7 years. The only thing that can
come back into the soil at that time is more rhododendrons. The rhododendron is the most
widespread invasive plant in Britain. What may appear to be a harmless and pretty shrub
is in fact and implacable invader that exterminates everything in its way. Biologist
Edward Wilson is an expert in plant and animal communities. A growing problem for
biodiversity world wide is the problem of invasive species. We are just also waking up to
the fact that due to the increased commerce all around the world quarantine systems of
many countries are weak and more and more species are getting introduced to places
where they are not native. And a small percentage of those species become destructive to
the environment and also economically. How do we prevent aliens taking over new
territories? Biologist Sir Robert May has a solution. Some of the answers for invasive
species the answer is just tighter regulation but that gets harder and harder in a more and
more crowded world with more movement. The root of the problem is that we ourselves
have become incessant intercontinental travellers. Each year there are around 8 million
commercial flights. As our technology makes the world a smaller place and as it becomes
easier for us to move around it also becomes easier for animals and plants to do so. Each
year around 10 million reptiles 3 million captive wild birds, 30,000 monkeys and apes
and many other species are transported around the world, some legally and some not.
There are regulations trying to control their movement. Customs officers working for
CITES, the convention on international trade of endangered species are responsible for
monitoring the movement of endangered wildlife. Here at London’s Heathrow airport
they check to see if a cargo is legal. None of these are endangered are they, no none of
this lot, there’s a bag down there. Detecting the import of species that are endangered or
potentially invasive is a tough and skilled job. Last year customs officials made over
30,000 seizures of cites listed plants and animals illegally entering the UK. Its an old
controlled one isn’t it , Berchelli. These are just some of the illegally exported animals
products, ivory and skin, feet, fur, coral, that have been confiscated here in London’s
Heathrow airport. As creatures like these become rarer in the wild so the value of their
products increases and the price on their heads goes up.
If you over harvest a species taking away more than can be replaced by natural
reproduction then that species is heading for disaster. That is happening in the West
African forest. Many monkeys apes and other animals are already threatened by loss of
habitat but in the last 10 years new threats appeared, the commercial bush meat trade.
Meat from wild animals, bush meat has always been part of the staple diet of people who
live in the forests. As the population grows and people move increasingly into towns they
all still want their traditional bush meat and commercial hunters supply it. It is a multi
million dollar business, the selling of bush meat but great apes have such slow
reproductive cycles that losing a part of a group can have a huge effect and populations
are declining
Taking too much out of the wild to sustain the human population isn’t something that just
happens in less developed countries. Across the globe forests are being cut down faster
than they can regenerate and stocks of fish are being plundered so heavily that whole
populations are being exterminated. The obvious way to prevent over harvesting is to
bring in regulations to control the amount we take from the wild. Whales have been
hunted for centuries but the introduction of explosive harpoons and electronic techniques
for finding the animals have reduced many species to dangerously low numbers. At the
height of the hunt 50,000 whales were being killed each year. One species, the grey
whale, was reduced to a few hundred individuals. Then an international ban on
commercial whaling was introduced and some species were rescued from the brink of
extinction but now after 14 years that ban maybe lifted. Over harvesting is a particular
concern of biologist John Lawton. I believe that it will be in the interests and it is in the
interests of rich developed nations to help developing nations move to more sustainable
development to pay for the protection of forests, to pay for the protection of wildlife and
so on and that is exactly what has happened in the far distant corner of Indonesia in the
Arfat mountains of Western New Guinea. Birdwing butterflies live here. They are among
the largest butterflies in the world with a wing span of up to a foot across. Ever since they
were first seen by Europeans they have been highly prized by collectors. The forests are
also home to the Moylay people. They earnt money by catching and selling butterflies
which fetched big prices around the world. So many of the birdwings were being taken
that their numbers fell dangerously low. Now with the aid of a conservation organization
the Moylay are being encouraged to harvest the butterflies in a different way. Inggris
Wonggor and other men in his village recognize that the bird wings rely on one particular
vine Alestolocia. They plant it in special gardens on the edge of the forest. Wild
butterflies come to lay their eggs in these gardens and then fly off. Caterpillars hatch
from the eggs, feed on the Alestilocia leaves and eventually turn into pupae. A few days
before the adults emerge the pupae and taken down to the nearest town a days walk away.
Here there is a butterfly co-operative that helps the villagers get the best price from the
world market. Inggris is paid 5000 rupear, just less than one dollar for each butterfly
pupae that he brings in. The co-operative has special temperature controlled rooms.
Where the adults emerge without any problems. The butterflies are killed packed and sent
to collectors around the world. The income from the butterfly co-operative is the only
source of income for most villagers like Inggris Wonggor. The environment is very
important to us, if the forest is devastated; it means no butterflies so we can get nothing.
The project also helps wild butterflies. Not all the pupae in the gardens are collected a
significant proportion hatch there and the adults fly off into the forest where they
replenish the original population. Both the people and the butterflies in these mountains
now have a more secure future. There is another strange and romantic species that has
found a market internationally; you can find examples of it if you know where to look in
Chinese communities all over the world. Including London’s China Town. At least 50
different countries are involved in the trade for sea horses. Some are caught for keeping
in aquaria or curios but many like these dried ones are for use in traditional medicine.
World wide up to 20 million seahorses are caught each year and the demand for them
seems to be limitless needless to say this is having a dramatic effect on some local sea
horse populations. In the Philippians there are some local peoples who depend upon sea
horse trade for their living. So there a conservation program has been started. Which tries
to ensure that there needs as well as those of the sea horses are being considered. Most of
the sea horses are gathered at night. They rely for their defence on camouflage but these
divers are very skilled at spotting them among the coral and the seaweed. Few escape
their practiced eye. Sea horses are more prone to the dangers of over harvesting than most
species of fish because of the extraordinary way in which they breed. Instead of laying
several thousand eggs like many fish seahorses produce only a few hundred. Incredibly it
is the male that becomes pregnant and gives birth to the young alive. Males and females
form bonds for life so if one of them is taken the other may not find another mate for a
long time. But commonly both partners are caught as they tend to live close to one
another. In this village a new method of seahorse fishing has been introduced thanks to
the support of an international conservation group organized by a marine biologist, Dr
Amanda Vincent. Project seahorse is trying to ensure the long term persistence of healthy
seahorse populations healthy populations of their relatives and healthy habitats in which
sea horses live. We are doing this in a way that respects human needs and we are also
very focused on education. The fishermen bring their catches to a local buyer in the
village. On a good night a man can reckon to earn a couple of dollars. The seahorses will
be dried and sent abroad. Careful reports are made on what was caught so the effects on
the population can be monitored. Scholarships have been set up for local students who
help with the record taking. With this information the harvesting of seahorses can be
properly planned to prevent the over fishing of any one area and to conserve a healthy
breeding population. The villagers still go out fishing for seahorses but the project is
helping them to make a better living through associated crafts and some tourism. Now a
chain of carefully guarded sanctuaries has been created where the seahorses can breed in
safety. Both the seahorse and the birdwing butterfly projects are concerned with
sustainability. That means not taking too much out of the wild so that species of animals
and plants will continue to flourish. If you do take too much of course then those
populations can decline dangerously sometimes beyond recovery and then there is
nothing for anyone to take out now or in the future.
Protecting a population from overexploitation is essential but even that may not be
enough if another threat to their environment is not tackled quickly. That threat comes
from pollution. Pollution is often localized and even sometimes reversible. One kind is
not reversible. The continuous release of carbon dioxide and other green house gasses
into the earth’s atmosphere. This has a long term effect on the earth’s temperature.
Stephen Schneider is a climatologist. The world is going to warm up 1 to 5 degrees in the
next century, one being mild, 5 being catastrophic. Not very satisfying but we have to tell
the truth and the truth is it is very likely something significant will happen but it gets
much more complicated. The big problems occur when the warming gets to several
degrees because that starts to be the number where some species really want to move 100
to 1000s of kilometres and it is going to be very difficult for those migrations to take
place across the factories, freeways and urban settlements of the world at the rates at
which climate could change. Is there any real evidence that species might be able to move
in this way? Here in Kings Canyon and California’s Sierra Nevada, there is proof and it
comes in the form of a butterfly called Edith’s checker spot. Like most butterflies this
species is very sensitive to changes in temperature and climate. It is at its most
vulnerable, not when it flies as an adult but when it feeds as a caterpillar. It lays its eggs
in summer, when the caterpillars hatch out they feed on a particular plant, figwort, as they
prepare to hibernate until the next spring but if spring comes too early due to climate
change then the plants flower and die before the caterpillars have a chance to eat them.
Studies going back as far as 20 years have shown that in order to survive the species has
gradually moved its range further up the mountains to get to the cooler temperatures
where the plants put out their leaves at the right time for the caterpillars to feed. It has
been found that the butterflies have extended their range northward by 200 km.
The earth has gone through many changes in temperatures and climate in its history but
now conditions are changing at such speed that some species will have to move really
rapidly. So what happens if they cant do so. These are the Maldives islands in the Indian
Ocean. They have one of the least polluted habitats on the planet. Their spectacular reefs
make them one of the top spots for divers. Although coral reefs occupy less than 1% of
the vast space taken up by the oceans they support 25% of all species of marine fish.
Corals are extremely sensitive to changes in water temperature. This is what on of the
many coral reefs in the area usually looks like but during the month of April 1998 it
suddenly changed. The whole reef turned white, exposing its naked skeleton the majority
of the tiny coral polyps that had built these structures had been killed by a rise in the
water temperature of just 1 degree centigrade. Marine biologists believe this to have been
caused by a fluctuation in the earth’s climate known as El Nino combined with the
beginnings of global warming. 18 months later this is what the same reef looked like,
between 80 and 90% of the corals were dead their skeletons covered with brown slime. It
may be decades before the reefs of the Maldives are re-colonised. 10% of the world’s
coral reefs were severely damaged during this one episode when the ocean temperatures
for a short time changed. We know from fossil evidence from earlier mass extinctions
like the one during which the dinosaurs disappeared. Many coral species also vanished
probably as a result in a change in temperature. So what can be done about global
warming? The solution to global warming is more sustainable energy sources so that we
are not burning past fossil fuels and releasing green house gasses it is also having fewer
people and more efficient energy and having less patterns of consumption. All the
problems we have recognized so far are being made greater by the increase in human
population. 100 years ago the worlds population was around 2 billion people today it
stands at just over 6 billion, that’s six thousand million, and the last thousand million was
added in the last 12 years. Ian Diamond is a demographer studying population growth. If
we don’t see increases of the use of family planning and declines in child bearing as we
have started to see in many parts of the world in the last few years then we will have
much much bigger populations that 9 or 10 billion. In the long term into the 22 century
the world’s population will flatten out at around 11 billion. What does that mean for the
future of the planet? As far as food is concerned agricultural technologists say that crop
yields could be improved significantly to sustain around 11 billion people. But if 6 billion
people are already damaging the planet and its biological diversity a population of 11
billion would put intense pressure on global resources far beyond anything we have yet
witnessed. Are we content that that should happen? We understand what the problems are
and what we can do about them and we have the ability to minimize the damage to
biodiversity but how many species can we afford to loose during this immense increase in
the human population without seriously compromising the future. Conservation of
biodiversity will depend on how we scale down our excesses in consumption but if things
are decidedly done on a political level on a local level at the governmental level to be
able to address this problem head on without political excuses and different people
getting excuses then I think we have a chance. If we don’t take those measures then we
risk loosing up to 50% of all species on earth among them would be some of the most
well known but also there would be many others which haven’t been discovered yet.
We all like to save biodiversity and the environment but preservation of the creation as it
were, we have to learn a new ethic that allows us to care as much about the Brazilian
rainforest as our own local reserve and to think beyond a few years or a generation, to
future generations and what it is we would like to leave to them.
A warning of what the future could old can be seen on one of the most remote places on
earth a tiny island in the middle of the Pacific Ocean two and a half thousand miles from
anywhere. This is Easter Island and these astonishing stone sculptures are vivid evidence
of the technological and artistic skills of the people who once lived here. How did they
survive with hardly any large animals to provide them with meat, there are very few
different kinds of plants. There are no trees to provide timber with which to build houses
or ocean going canoes. In terms of human survival this island is very baron indeed. Easter
Island was not always like this. 1500 years ago when the first Polynesians settlers landed
here they found a miniature world that had ample resources to sustain them. They lived
well, erected their spectacular monuments and over the centuries their population grew to
around 20,000. So what went wrong? These are the remains of an early Easter Islanders
house and from excavations from the refuse dumps and around the kitchen we can get a
pretty good idea of what they had for meat. There was a lot of fish and there was also
shellfish and rats and chickens and there was a lot of pollen grains too and that tells us
what kind of trees there were on the island, there were a lot of then. About 500 years ago
things changed. This fish almost disappear from the diet and changes in the pollen and
the reduction in its quantity give us the reason why. Almost the last of the trees had been
felled by them, so the islanders no longer had timber to build sea going canoes and at
about the same time the carving of the great stone statures came to an end. Without wood
to make canoes the people couldn’t leave their shores, even to fish. Starvation threatened,
warfare broke out between rival clans as they fought over the remaining food and the
remaining productive soil. The old culture that had sustained them was abandoned and
the statues toppled. What had been a rich fertile world in miniature had become a barren
desert.
It seems that we will have to make further changes in our behaviour and attitude if we are
not to inflict lasting damage on the other animals and plants with which we share this
planet. We ourselves as a species may well survive come what may but it could also be
that unless we change we like the ancient Easter Islanders will be condemning
generations to come to live in a poorer and impoverished world. The future of life on
earth depends on our ability to take action. Many individuals are doing what they can.
But real success can only come if there is a change in our societies and our economics
and in our politics. I have been lucky in my life time to see some of the greatest
spectacles the natural world has to offer, surely we have a responsibility to leave for
future generations a planet that is healthy and inhabitable by all species