Report: No 'silver bullet' for climate but rapid emissions cuts

Climate negotiators meeting in Copenhagen next month might or might not come up with an agreed-upon treatment for the planet’s fever, but the diagnosis from the world’s scientists is loud and clear: the globe is warming faster than anyone predicted and it’s vital that we start cutting carbon emissions fast.

“Our available emissions to ensure a reasonably secure climate future are just about used up,” said Matthew England, a co-author of the new study, ARC Federation Fellow and joint director of the Climate Change Research Centre of the University of New South Wales, Australia. “Within just a decade global emissions need to be declining rapidly.  An urgent binding treaty is needed to ensure unilateral action among the high emitters.”

In a special report called “The Copenhagen Diagnosis,” 26 of the globe’s top climate researchers, most of whom are authors of published Intergovernmental Panel on Climate Change (IPCC) reports, conclude that several important aspects of climate change are occurring at the high end or even beyond the expectations of only a few years ago.

Among their findings: global ice-sheets are melting at an increased rate, Arctic sea ice is disappearing much faster than recently projected, and future sea-level rise is now expected to be much higher than previously forecast.

The report also notes that global warming continues to track early IPCC projections based on greenhouse gas increases. Without significant mitigation, the report says global mean warming could reach as high as 7 degrees Celsius by 2100.

“The climate system does not provide us with a silver bullet,” said another co-author, Nicolas Gruber, a professor of environmental physics at ETH Zürich. “There is no escape but to start reducing greenhouse gas emissions as soon as possible.”

One year in the making, the Copenhagen Diagnosis documents the key findings in climate change science since the publication of the landmark  IPCC Fourth Assessment Report in 2007.

The new evidence to have emerged includes:

• Satellite and direct measurements now demonstrate that both the Greenland and Antarctic ice sheets are losing mass and contributing to sea level rise at an increasing rate.
• Arctic sea-ice has melted far beyond the expectations of climate models. For example, the area of summer sea-ice melt during 2007-2009 was about 40% greater than the average projection from the 2007 IPCC Fourth Assessment Report.
• Sea level has risen more than 5 centimeters over the past 15 years, about 80% higher than IPCC projections from 2001. Accounting for ice-sheets and glaciers, global sea-level rise may exceed 1 meter by 2100, with a rise of up to 2 meters considered an upper limit by this time.  This is much higher than previously projected by the IPCC.  Furthermore, beyond 2100, sea level rise of several meters must be expected over the next few centuries.
• In 2008 carbon dioxide emissions from fossil fuels were ~40% higher than those in 1990. Even if emissions do not grow beyond today’s levels, within just 20 years the world will have used up the allowable emissions to have a reasonable chance of limiting warming to less than 2 degrees Celsius.

The report’s authors conclude that global greenhouse gas emissions must peak then decline rapidly within the next five to 10 years for the world to have a reasonable chance of avoiding the very worst impacts of climate change.

To stabilise climate, global emissions of carbon dioxide and other long-lived greenhouse gases need to reach near-zero well within this century, the report states.

“This is a final scientific call for the climate negotiators from 192 countries who must embark on the climate protection train in Copenhagen,” said Hans Joachim Schellnhuber, another co-author, director of the Potsdam Institute for Climate Impact Research and chair of the German Advisory Council on Global Change. “They need to know the stark truth about global warming and the unprecedented risks involved.”