This January, Nature, the renowned international weekly science journal, published two articles that provide strong evidence that climate change is affecting the world's plants and animals. By looking for a climate "fingerprint" - an overall biological pattern in a wide range of species - the two articles show that global warming is forcing plants and animals to shift their ranges and affecting the timing of spring-related events such as egg-laying and migrations.

Dr Terry L. Root, from the Center for Environmental Science and Policy at Stanford University in California, is the lead author of one of the articles.

We asked Dr Root about her study:

QUESTION: What were the general findings of your study?

80% of the species that were found to be changing were changing in the direction expected for global warming, and those species with changes in events in the spring, the average result was 5.2 days earlier per decade. Also, the species at higher latitudes are changing more per decade than those at lower latitudes--a result expected with global warming, because the higher latitudes warm more quickly than areas closer to the equator. You'll need to look at the article to get the exact number of days per decade each group changed.

QUESTION: Some people might be happy if spring started a little

earlier. Why is this a problem for plants and animals?

For some plants and animals earlier spring may not be a problem, but for others it could be. For example, the Pied Flycatcher, a bird in Germany, is not arriving earlier in the spring - it is probably cued by day length as to when to migrate - but the caterpillars that it feeds to its young are reaching maximum abundance earlier - probably triggered by temperature - so the flycatcher is having to nest more quickly in order to have enough caterpillars to feed its young. As the globe continues to warm, the caterpillars may reach highest abundance before the flycatcher even gets to

its breeding area.

With species arriving earlier you would think that that would be good for birds because they would have time to have 2 broods rather than just 1.

A new study by Visser et al. shows that this is probably not the case.

So because species will show different changes to global warming, the natural communities we know of today will probably be torn apart - causing, possibly, the separation of predator and prey species (good for the prey, but could be bad for humans if the prey is a pest on our crops, for example or good for us if the prey is say a lady-bird beetle).

QUESTION: What about the shift in ranges? Why is this a problem for plants and animals?

Shifts in ranges could be a problem, because with habitat fragmentation, species will probably have a lot of difficulty shifting their ranges. It will be harder for species to cross farm fields, freeways or cities. So if there is not any way for the species to shift, it could go extinct if it cannot adapt to the hotter climate. Adaptation is certainly possible, but not on the time scale that we are talking about here. Also, if the predator can shift and the prey cannot, there could be problems or not, as I discuss above.

QUESTION: Can you give an example of a species that is particularly

affected by climate change and global warming?

I found that the Common Murre shows a phenological change of 24 day per decade.

Another example that is not really extreme, but is a nice example is the

Tree Swallow, a bird that breeds in middle to northern US and southern

Canada.. The authors of the study (Dunn and Winkler) examined over 3500 nest cards - a card that is filled out by a person who finds and watches a nest of a bird. They had 24 years of cards and found that the Tree Swallow is nesting on average about 8 days earlier per decade--so about 20 days earlier 24 years ago than now.

QUESTION: What can be done to help species that are threatened by

climate change?

The best way is to stop using the atmosphere as a free sewer, as Steve

Schneider likes to say. This is a global problem and must be solved at a global level. The Kyoto Protocol is not perfect, but it is a first step. It is embarrassing that the country that has poured more CO


into the atmosphere than many other countries put together--even those with very large populations (China for example)--is not doing anything about

it. Each of us can do our part--drive hybrid cars, use fluorescent bulbs, when replacing furnace, water heater, appliances, windows or roof, replace them with the most energy efficient. BUT we need to put pressure on our policy makers to start negotiations on a global level.

QUESTION: Your study provides evidence that climate change is already happening and already affecting living systems, yet President Bush and his administration believe more research is needed to determine if

climate change is real. What do you think of this?

As I heard in a skit last night, "Bush says to do more research. But the world is going to hell in a hand basket! Well I guess that more research will tell us what color the basket is!"

We all have insurance if we can afford it. My values as a human being are that we do things now to help us ensure that we avoid catastrophic surprises in the future. The contrarians say if we spend $$ on fixing a problem that we are not sure is a problem we will cost future generations

10s of trillions of $$. But that cost needs to be put into the prospective of the overall typically projected growth of the world's economy in a century: a few 100 trillion $$ a year. Therefore, future generations could achieve a standard of living that is 5 times what we have today in 2102 with climate protections rather than in 2100 without climate protection.

(This is work by Christian Azar and Steve Schneider.) A 2 year lag seems to me to be a pretty inexpensive planetary insurance policy!

QUESTION: Where do you think further research is most needed?

Continue to look for changes in animals and plants. It would be nice to have some studies that look at elevational transects up mountains at different latitudes.

QUESTION: Are you currently pursuing any other research on climate change?

I am looking at migration data and trying to understand how climate - primarily wind - has and could influenced migration times.

--- Interview ends here---