Climate change far worse than thought before
New Delhi: Global alarm over climate change and its effects has risen manifold after the 2007 report of the Intergovernmental Panel on Climate Change (IPCC). Since then, many of the 2,500-odd IPCC scientists have found climate change is progressing faster than the worst-case scenario they had predicted.
Their studies will be considered for the next IPCC report, but since that will come out only in 2013, the University of New South Wales in Sydney has just put together the main findings in the last three years. Most are by previous IPCC lead authors "familiar with the rigour and completeness required for a scientific assessment of this nature", a university spokesperson said.
The most significant recent findings are:
Carbon dioxide is the main greenhouse gas (GHG) warming the atmosphere.
More specifically, the average annual per-capita emissions will have to shrink to well under one tonne carbon dioxide by 2050. This is 80-95 percent below the per-capita emissions in developed nations in 2000.
They also show that the intensity of cyclones has increased in the past three decades in line with rising tropical ocean temperatures.
New estimates of ocean heat uptake are 50 percent higher than previous calculations. Global ocean surface temperature reached the warmest ever recorded in June, July and August 2009. Ocean acidification and ocean de-oxygenation due to global warming have been identified as potentially devastating for large parts of the marine ecosystem.
The sea level will continue to rise for centuries after global temperatures have been stabilised, and several metres of sea level rise must be expected over the next few centuries.
The contribution of glaciers and ice-caps to global sea level rise has increased from 0.8 mm per year in the 1990s to 1.2 mm per year today. The adjustment of glaciers and ice caps to present climate alone is expected to raise sea level by about 18 cm. Under warming conditions they may contribute as much as around 55 cm by 2100.
The net loss of ice from the Greenland ice sheet has accelerated since the mid-1990s and is now contributing 0.7 mm per year to sea level rise due to both increased melting and accelerated ice flow. Antarctica is also losing ice mass at an increasing rate, mostly from the West Antarctic ice sheet due to increased ice flow. Antarctica is currently contributing to sea level rise at a rate nearly equal to Greenland.
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