Five ways to save the world and Creating a sulphur screen (BBC)

Five Ways To Save The World
Climate change is being felt the world over and if
designed a fleet of remote-controlled yachts.
global warming continues to increase the effects
could be catastrophic. Some scientists and
engineers are proposing radical, large-scale ideas
that could save us from disaster. The first three
proposed ideas featured in a new BBC
documentary, Five Ways To Save The World, look
at reducing the power of the sun—thereby cooling
the planet. The other two men in the programme
want to tackle the problem of excess carbon
dioxide—the cause of global warming.
These will pump fine particles of sea water into
the clouds, increasing the thickness of the clouds
and reflecting the sun’s rays.
Sydney engineer Professor Ian Jones proposes
to feed plankton with gallons of fertiliser. This
will make the plankton grow and absorb carbon
dioxide from the air.
And New York-based Professor Klaus
Lackner has designed a carbon dioxide capturing
machine and his plan is to locate more of them
Professor Roger Angel from Arizona—the
designer of the world’s largest telescope—is
proposing to put a giant glass sunshade in space.
Professor Angel’s sunshade will deflect a small
across the globe. They would suck in carbon
dioxide, turn it into a powder and he would bury it
deep under the ocean in disused oil or gas fields.
Most of the scientists are reluctant advocates
percentage of the sun’s rays back into space.
Dutch Professor Paul Crutzen won the Nobel
Prize for chemistry when he discovered the causes
of the hole in the ozone layer. His plan is to fire
hundreds of rockets loaded with tons of sulphur
into the atmosphere creating a vast, but very thin
of these ideas, and all believe we should be cutting
down on our use of fossil fuels to heat our homes
and drive our cars. But is time running out for
planet earth? Although these ideas might have
unknown side effects, some scientists believe we
may soon have no choice but to put these radical
sunscreen of sulphur around the earth.
British atmospheric physicist Professor John
Latham and engineer Stephen Salter, have
and controversial plans into action.
reducing the sunlight
reducing carbon dioxide
(BBC 361 words)
proposed by
Creating a ‘sulphur screen’
Launching rockets to create a sulphur screen high in the
stratosphere (regarded as the second layer of Earth’s
atmosphere, above the troposphere but below the
mesosphere, positioned at 10-50 km altitude above the
Earth’s surface) is one way to counter global warming
explored in a new BBC documentary, Five Ways To Save
The World.
In 1995, Professor Paul Crutzen won the Nobel Prize
for helping to explain how the ozone layer is formed and
depleted. Partly as a result of his work, world
chlorofluorocarbons (CFCs)—chemicals used in fridges
and aerosols—that were thinning the ozone’s presence
over Antarctica.
Now the chemistry professor has a solution to
mitigate global warming. He believes that sulphur
particles similar to those erupting from volcanoes could
act as a natural cooling device for the planet, by creating
a “blanket” that would stop the Sun’s rays from reaching
the Earth.
Perfect model
In 1991, there was a massive eruption in South East Asia.
Mount Pinatubo ejected about 10 million tonnes of
sulphur into the stratosphere at about 10-40km above the
Earth’s surface.
Scientists like Professor Crutzen could measure how
much sulphur dioxide was injected into the stratosphere,
where it was injected and what happened to it over time.
“After the injection at high altitude, it started to
move around the globe with the air motions; first in an
east-west direction, but also with time in a north-south
direction. After about a year, the initial input of pollutants
in the stratosphere by the volcano had spread rather
evenly around the world,” the Nobel Laureate said.
For two years after Pinatubo erupted, the average
temperature across the Earth decreased by 0.6ºC. The
volcano’s location close to the equator helped make
Pinatubo the perfect model for explaining how sulphur in
the stratosphere could reduce global warming. But
Professor Crutzen does not want to wait for another
volcano. Instead, controversially, he wants to duplicate
the effects of volcanic eruptions and create a man-made
sulphur screen in the sky.
His solution would see hundreds of rockets filled
with sulphur launched into the stratosphere. He envisages
one million tonnes of sulphur to create his cooling
blanket. “Hydrocarbons are burnt to lift the rocket
material, and the rocket then goes into the stratosphere. In
the stratosphere, hydrogen sulphide is burnt, and the
sulphate particles reflect solar radiation,” he explains.
Devastating effects
But at low altitudes within the Earth’s atmosphere,
sulphur has been known to create a lot of damage. Since
the industrial revolution began over 200 years ago, the
combustion of fossil fuels has put just over a trillion
tonnes of carbon dioxide, as well as sulphur, into the
atmosphere. By the mid-1950s, the effects of sulphur
were killing thousands of people through respiratory
disease. It also caused acid rain and had devastating
effects on plants and animals.
To combat this, clean air acts were introduced and
filters were put in place to reduce sulphur emissions. The
chemistry professor finds it ironic that prior to these clean
air acts, filthy factories actually shielded us from the Sun.
He explains the paradox: “We want to clean up the
environment because air pollution is unhealthy. But this
pollution also cools the Earth by reflecting solar radiation
into space.”
Professor Crutzen is not proposing a return to the
bad old days; rather, he wants to avoid the previous
problems by making sure the sulphur is injected into the
atmosphere at high altitude.
Unknown consequences
Nevertheless, the consequences of putting gargantuan
quantities of sulphur into the atmosphere as he proposes
are unknown. It could increase acid rain, or even damage
the ozone layer—the very thing Professor Crutzen has
dedicated his life to protecting. Neither does his solution
tackle—or offer a way of reducing—the increasing
amount of CO2 that is still being emitted.
But Professor Crutzen believes global warming may
reach such critical levels within the next 30 years that a
radical strategy will be needed. He thinks we should at
least test his plan, so we know now what the risks might
be if we face a catastrophic situation in the future. “I am
prepared to lose some bit of ozone if we can prevent
major increases of temperature in the future, say beyond
two degrees or three degrees,” he says.
Whether other scientists agree that a sulphur screen
is a viable solution remains to be seen.
(BBC 734 words)