Climate chaos predicted by CO2 study
World will have exceeded 2050 safe carbon emissions limit by 2020,
scientists say
By Steve Connor, Science Editor
Thursday, 30 April 2009The world will overshoot its long-term target on
greenhouse gas emissions within two decades. A study has found that the
average global temperature will rise above the threshold that could cause
dangerous climate change during that time.
Scientists have calculated that the world has already produced about a third
of the total amount of carbon dioxide (CO2) that could be emitted between
2000 and 2050 and still keep within a 2C rise in global average
temperatures.
At the current rate at which CO2 is emitted globally – which is increasing
by 3 per cent a year – countries will have exceeded their total limit of
1,000 billion tons within 20 years, which would be about 20 years earlier
than planned under international obligations. "If we continue burning fossil
fuels as we do, we will have exhausted the carbon budget in merely 20 years,
and global warming will go well beyond 2C," said Malte Meinshausen of the
Potsdam Institute for Climate Impact Research in Germany, who led the study,
published in Nature.
"Substantial reductions in global emissions have to begin soon – before
2020. If we wait longer, the required phase-out of carbon emissions will
involve tremendous economic costs and technological challenges. We should
not forget that a 2C global mean warming would take us far beyond the
variations that Earth has experienced since we humans have been around."
It is the first time scientists have calculated accurately the amount of
greenhouse gas emissions that can be released into the atmosphere between
2000 and 2050 and still have a reasonable chance of avoiding temperature
rises higher than 2C above pre-industrial levels – widely viewed as a "safe"
threshold.
The scientists found the total amount of greenhouse gases that could be
released over this time would be equivalent to 1,000 billion tons of CO2.
This is equivalent to using up about 25 per cent of known reserves of oil,
gas and coal, said Bill Hare, a co-author of the study.
The study concluded that the world must agree on a cut in carbon dioxide
emissions of more than 50 per cent by 2050 if the probability of exceeding a
2C rise in average temperatures is to be limited to a risk of 1 in 4.
"With every year of delay [in agreeing on further cuts], we consume a larger
part of our emissions budget, losing room to manoeuvre and increasing the
probabilities of dangerous consequences," said Reto Knutti of the Swiss
Federal Institute of Technology in Zurich, a member of the research team.
Myles Allen of Oxford University said the total emissions of CO2 that have
accumulated in the atmosphere since the start of the Industrial Revolution
in the mid-18th century are the really important figure for future climate
change.
"Mother Nature doesn't care about dates. To avoid dangerous climate change
we will have to limit the total amount of carbon we inject into the
atmosphere, not just the emission rate in any given year," Dr Allen said.
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