But - but - but - the snow!

Okay, so it appears I can't get away from the global warming kick just yet. On Thursday, the Washington Post reported that

[t]he United States faces the possibility of much more rapid climate change by the end of the century than previous studies have suggested, according to a new report led by the U.S. Geological Survey.

The survey - which was commissioned by the U.S. Climate Change Science Program and issued this month - expands on the 2007 findings of the United Nations Intergovernment Panel on Climate Change. Looking at factors such as rapid sea ice loss in the Arctic and prolonged drought in the Southwest, the new assessment suggests that earlier projections may have underestimated the climatic shifts that could take place by 2100. ...

Thirty-two scientists from federal and non-federal institutions contributed to the report, which took nearly two years to complete. The Climate Change Science Program, which was established in 1990, coordinates the climate research of 13 different federal agencies. ...

In one of the report's most worrisome findings, the agency estimates that in light of recent ice sheet melting, global sea level rise could be as much as four feet by 2100. The IPCC had projected a sea level rise of no more than 1.5 feet by that time, but satellite data over the past two years show the world's major ice sheets are melting much more rapidly than previously thought. The Antarctic and Greenland ice sheets are now losing an average of 48 cubic miles of ice a year, equivalent to twice the amount of ice that exists in the Alps.

That IPCC estimate accounted only for sea level rise from warming of ocean waters, not from glacial melt. Because an earlier prediction had tried to estimate the effects of melt, the later estimate of a maximum rise of 1.5 feet was lower than the previous one, which lead to a lot of inappropriate and scientifically-nonsensical smirking among global warming denialists. But as Konrad Steffen, lead author on the study's chapter on ice sheets, notes, much more now is understood about "lubrication," where melt gets under ice sheets, making it easier for them to move and thus accelerating loss of those sheets to the ocean.

The report also considered droughts. It concluded that while it can't yet be said if human activity is responsible for current drought conditions in the southwest US, "nearly all" of 24 computer models examined concluded that the North American Southwest, which includes Mexico, is already transitioning to a more arid climate. Richard Seager of Columbia University's Lamont-Doherty Earth Observatory said that

such conditions would probably include prolonged droughts lasting more than a decade.

The study did say that abrupt, massive releases of methane from melting permafrost and the shutdown of the Atlantic Ocean circulation are unlikely to happen before 2100 - but I was under the impression that was already to general belief, so that's not really reassuring.

In fact, in an unplanned demonstration of the vapidity of those who would deny the warming has to do with human activities and yes some of them do still exist, Ed Brook, the lead author of the methane chapter, said that the amount of methane escaping from natural sources "could possibly double" by the end of the century - but that would still be less than the current level of human-produced methane emissions, thus poking a finger in the eye of those who try to divorce methane production from human activity.