Plan
to avert global warming by cooling planet artificially 'could cause
climate chaos'
Worthwhile watching, if you haven't already seen it -
Proposal to inject tiny reflective particles into the upper atmosphere to block out sunlight could lead to droughts, warn scientists
9
January, 2014
A
controversial proposal to cool the planet artificially by injecting
tiny reflective particles into the upper atmosphere which block out
sunlight would cause droughts and climate chaos in the poorest
countries of the world, a study has found.
One
of the more serious plans to “geoengineer” the global climate
would in effect create another climate catastrophe that would result
in misery for millions of people, according to a computer model of
the plan.
Some
climate researchers have suggested that mimicking the cooling effects
of volcanic eruptions with massive injections of sulphate particles
into the atmosphere may be necessary in an emergency if global
temperatures and carbon dioxide levels continue to rise unabated.
It
is known that the sulphate particles produced by volcanoes, which are
relatively quickly washed out of the atmosphere, can reduce incoming
solar radiation significantly, and so cause average global
temperatures to dip.
However,
a study by scientists at Reading University has found that the effect
of a massive and continuous injection of sulphates into the air would
be to alter the rainfall patterns over vast regions of the world,
notably Africa, South America and Asia which could as a result be
devastated by drought.
“We
have shown that one of the leading candidates for geo-engineering
could cause a new unintended side-effect over a large part of the
planet,” said Andrew Charlton-Perez of the University of Reading, a
co-author of the study published in the journal Environmental
Research Letters.
“The
risks from this kind of geo-engineering are huge. A reduction in
tropical rainfall of 30 per cent would, for example, quickly dry out
Indonesia so much that even the wettest years after a man-made
intervention would be equal to drought conditions now,” Dr
Charlton-Perez said.
“The
ecosystems of the tropics are among the most fragile on Earth. We
would see changes happening so quickly that there would be little
time for people to adapt.
“Discussion
of geo-engineering often prompts heated debate, but very often there
is a lack of understanding of what putting large amounts of aerosol
in the stratosphere will do to the complex climate system. Our
findings should help to fill in some of the gaps about one of the
leading candidates,” he said.
Volcanoes,
such as the Mount Pinatubo eruption in 1991, can cool average global
temperatures significantly for short periods, but to reverse the
expected 4C rise in global temperatures as a result of global warming
would need large quantities of sulphate aerosols to be injected into
the upper atmosphere over the course of several years.
“To
reduce global temperatures enough to counter effects of global
warming would require a massive injection of aerosol – the small
particles that reflect sunlight back into space. This would be
equivalent to a volcanic eruption five times the size of that of
Mount Pinatubo every year,” said Angus Ferraro of Exeter
University.
“Previous
predictions of how stratospheric aerosol injection would affect
climate were based on a number of assumptions. By actually modelling
what would happen if aerosol were to be pumped into the atmosphere
around the equator, we have revealed a new impact of geo-engineering
on tropical climate,” Dr Ferraro said.
“As
well as reflecting some of the incoming energy from the sun and
cooling surface temperature, the aerosol also absorbs some of the
heat energy coming from the surface which warms the stratosphere. We
have shown for the first time that warming the stratosphere makes the
troposphere below more stable, weakening upward motion and reducing
the amount of rainfall at the surface,” he said.
Professor
Ellie Highwood of University of Reading, a co-author of the study
said that there is an understandable desire to explore alternatives
to deep-cuts in carbon dioxide emissions, which do not seem to be
materialising as a result of the failure of countries to reach a
binding international agreement.
“Climate
scientists agree that cutting carbon emissions is still necessary to
curb the damaging effects of future climate change. However, since
such cuts are far from certain to materialise, proponents of
geo-engineering research argue that whatever the world decides on its
carbon emissions, it would be prudent to explore alternatives that
might help us in the decades ahead,” Professor Highwood said.
“On
the evidence of this research, stratospheric aerosol geo-engineering
is not providing world leaders with any easy answers to the problem
of climate change,” she said.
Worthwhile watching, if you haven't already seen it -
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