The politics and the science of global warming remain far apart. International climate negotiators in Doha, Qatar this week began talking about a climate treaty to be agreed by 2015 and implemented by 2020, when all that was supposed to be finished in Copenhagen three years ago. Inspiring. Meanwhile, the evidence supporting the broad international scientific consensus on climate change is only becoming more compelling, with three big, peer-reviewed studies out this week alone.
In the early online edition of the Proceedings of the National Academy of Sciences on Thursday, scientists from the Lawrence Livermore National Laboratory and elsewhere further solidified the link between human activity and rising global temperatures. The researchers compared the findings of complex climate models against three decades of direct satellite observations. In response to human-related emissions, the models show a particular pattern of temperature change — cooling in the upper atmosphere, warming in the lower atmosphere. That pattern, the scientists found, is also present in the satellite record. Using similar methods, they also found that natural climate variability is extremely unlikely to explain the modeled and observed results.
What about the effects of this warming? In the journal Science on Thursday, an international group of 47 glaciologists concluded that the world's massive ice sheets are currently losing 344 billion tons of ice a year, three times the rate of two decades ago. Greenland's ice sheet is worst off — shrinking at five times the 1990s rate, it accounts for most of the ice loss. Together, melting ice sheets account for about 20 percent of current sea-level rise, the glaciologists found. "Some ice sheets," a summary of the study warns, "are disconcertingly sensitive to warming."
Better understanding how the planet's great glaciers react to climate change will also produce better estimates of how much higher the oceans will rise, and how quickly. In Environmental Research Letters on Wednesday, a third set of researchers demonstrated that work is badly needed. Three climate scientists calculated that the sea-levels are rising 60 percent faster than the UN's Intergovernmental Panel on Climate Change predicted in 2007, when the panel issued its last comprehensive climate report. The AFP notes that previous uncertainty about land-ice melting — Greenland — might explain the UN's low predictions five years ago.
As scientists continue to articulate the risks of global warming, the best policy response is obvious — put a common price on carbon emissions and apply pressure on big polluting countries who refuse. But it's still anyone's guess when the politics will finally catch up.