The world will overshoot its long-term target on greenhouse gasemissions 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.
the total amount of carbon dioxide (CO2) that could be emitted between
2000 and 2050 and still keep within a C 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 C," said Malte Meinshausen of the Potsdam Institute
for Climate Impact Research in Germany, who led the study, published in
"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 C 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 C 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 C rise in average temperatures is to be limited to a risk
of 1 in 4.