Er 'the tipping point' 450 PPMv CO2
| Er 'the tipping point' 450 PPMv CO206-09-2008 00:42 | |
GLAR ★★★★☆(1023) |
eller er det starten til en meget kold periode? Dr Andrew Glikson from the Research School of Earth Science at the Australian National University sent a brief submission to Crikey yesterday. It crunches some sobering numbers: According to leading US climate and paleo-climate scientists, the current CO2 levels of 387 ppm (433 ppm CO2 + CH4 equivalent) are dangerously close to the 450 ppm CO2 level at which the polar ice sheets formed 34 million years-ago. This projection is consistent with the current fast ice melt rates in the Arctic Sea, Greenland and west Antarctica, including melting of the Wilkins ice shelf last July -- one of the first times mid-winter ice shelf breakdown was observed. The sensitivity of the atmosphere has been underestimated. Ice core studies of the Pleistocene (1.8 Ma to 11,700 years-ago) glacial-interglacial cycles display abrupt global warming and cooling events on time scales of few years to decades, including sharp climate tipping points at 14,700, 12,900 and 11,700 years-ago. IPCC climate projections and plans for emission caps restricting temperature rises to two or three degrees and time tables for carbon emission reduction targets such as 15 percent by 2020 or 60 percent by 2060, take little account of the rates of ice sheet melt/water feedbacks loops and carbon cycle feedback loops, including release of methane hydrates from sea bottom sediments and from bogs. Plans for climate stabilization at 450 ppm may not be able to prevent melting of the polar ice sheets. Plans for stabilization at 650 ppm may not be able to stop runaway greenhouse effects and associated extinctions. Today Ross Garnaut has reduced expectations of Australian climate change action to a point below which anyone other than Andrew Bolt and a handful of suddenly sweating penguins could object. According to Garnaut, the best we can hope for is substantial international cooperation and an aspirational atmospheric carbon target of 450ppm. 550ppm is more likely and looks like being the mark the Australian Government will pursue. This constitutes surrender ... politically, to the forces that will rage against any diminution of their capacity to dig, burn, export and boil, and environmentally to the silent but more deadly forces that by scientific consensus are placing our eco-system in almost irreparable peril. The Garnaut targets mooted today are as clear an indication as any that our political process seems incapable of delivering the stern medicine required to arrest climate change, even under the stewardship of a government elected with a clear mandate to act. They acknowledge that we will always move first to pursue comfort and compromise. It looks, sadly, as though we will do that to our cost. Klima tips: Undgå sex i lukkede rum - du forgifter din partner med CO2 |
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