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Print articleThe two reports, both co-authored by controversial climate scientist, James Hansen, say that ?only moderate additional climate forcing is likely to set in motion disintegration of the West Antarctic ice sheet and Arctic sea ice.?
'Climate Forcing' occurs when the amount of energy stored by the climate system is forced to change. A change can either be natural or man-made, and it can either increase the temperature or decrease it. Man-made change is caused by the accumulation of warming greenhouse gases, such as CO2, in the atmosphere.
The report, 'Climate change and trace gases', says:
?The imminent peril is initiation of dynamical and thermo-dynamical processes on the West Antarctic and Greenland ice sheets that produce a situation out of humanity's control, such that devastating sea-level rise will inevitably occur.?
There is much debate in the scientific community about the speed and degree of melting of the ice-sheets. The report raises the stakes by suggesting that it is not enough to cut emissions, but concludes ?that a feasible strategy for planetary rescue almost surely requires a means of extracting greenhouse gases from the air.?
Conceding that ?the convenience of liquid and gas fuels? means their continued use, the report emphasises ?the need to phase out coal use, except where the CO2 is captured and sequestered, and to impose the same constraint on development of unconventional fossil fuels.?
Hansen has, for a number of years, quoted a 10 year time-frame for change to occur. In the report he says:
?It is difficult to predict time of collapse [ice sheet disintegration], but we find no evidence of millennial lags between forcing and ice sheet response in palaeoclimate data. An ice sheet response time of centuries seems probable, and we cannot rule out large changes on decadal time-scales once wide-scale surface melt is underway.?
The report continues:
?With greenhouse gases continuing to increase, the planetary energy imbalance provides ample energy to melt ice corresponding to several metres of sea level per century. With this danger in mind, it is appropriate to closely monitor ice sheet conditions.?
Indeed, the condition of the arctic and antarctic ice sheets are being closely monitored and reported on.
According to a separate report from ecologists working in Greenland, spring-time in the Arctic is arriving two weeks earlier than it did a decade ago. Processes that mark the beginning of spring, such as flowers blooming and birds laying eggs, are now happening an average of more than 14 days earlier in the calendar than they did as recently as 1996, as a result of rising temperatures.
Toke H?ye of the University of Aarhus, Denmark, who led the research, said, ?We suddenly realised that the trends are dramatically stronger than elsewhere.? Previous worldwide studies of animals and plants have suggested that, globally, the beginning of spring is advancing by around five days per decade.
But in the frozen valleys of Zackenberg, northeastern Greenland, the rate of change is almost triple the world average, H?ye's team has discovered. ?This is the first study of its kind in the high Arctic,? he says. ?It's quite a surprise to see such a huge difference.?
During that decade, average June temperatures at Zackenberg have climbed by 1.1 ?C - more than double the global average. And that has an impact on the timing of the annual snowmelt, which in turn affects the wildlife. ?There's a very conspicuous pattern in which spring is initiated by snowmelt - that's when biological activity starts,? H?ye explains. As warmer temperatures cause snow to melt earlier, plants and animals are flowering and reproducing earlier too.
Overall, the effect could potentially extend Greenland's short, cold summer by as much as 25%, H?ye predicts. Currently, there are just three or four months between snowmelt and the onset of the winter freeze.
?Initially, this may have a positive effect on extreme northerly ecosystems, as the longer summer allows greater productivity. But ultimately, warmer summers could lead to extinctions, as temperatures drive cold-loving species further north,? H?ye says. ?There are still 500 kilometres from the study site to the northern tip of Greenland, but eventually there will be nowhere to go,? he says. ?What's more, as temperatures rise, more southerly species could migrate north to colonize the area.?
