Hot flash

Lordy, and here I was thinking I could move to something else besides global warming for a time. But the news won't let me just yet. This is from today's The Independent (UK):

The long-term stability of the massive ice sheets of Antarctica, which have the potential to raise sea levels by hundreds of metres, has been called into question with the discovery of fast-moving rivers of water sliding beneath their base.

Scientists analysing satellite data were astonished to discover the size of the vast lakes and river systems flowing beneath the Antarctic ice sheets, which may lubricate the movement of these glaciers as they flow into the surrounding sea. ...

"We've found that there are substantial subglacial lakes under ice that's moving a couple of metres per day. It's really ripping along. It's the fast-moving ice that determines how the ice sheet responds to climate change on a short timescale," said Robert Bindschadler, a Nasa scientist at the Goddard Space Flight Centre in Maryland, one of the study's co-authors.

A couple of meters per day? Wow. That is really moving and no, that is not sarcasm. Scientists admit that the relationship between the water movement below and the ice movement above is not well understood. It could be that this is the way it has been for many years. Or this could be a recent change driven by global warming. If it is, it's an extremely ominous change.

But in either event, it's a troubling discovery because, as Dr. Bindschadler noted, there being a greater amount of faster-moving water than previously thought also means that movement of the ice sheets is more sensitive to climate change than previously thought.

It also means that the charge by some scientists prior to its release that the IPCC report was sugarcoated may well be right and our situation is more dire than even that report argued.

The dispute here revolves around the numbers in the report for predicted sea level rise. The predictions in the new report are below those of the previous one. The reason, apparently, is that not enough is known about ice sheet melting to accurately model a prediction, so to be as scientifically conservative as possible, that factor was left out and the projected rise of between 5 and 23 inches is based solely on expansion of water due to warming and glacial melt. (Glaciers and ice sheets are not the same.) Which means the figures

"don't take into account the gorillas - Greenland and Antarctica," said Ohio State University earth sciences professor Lonnie Thompson, a polar ice specialist. "I think there are unpleasant surprises as we move into the 21st century." ...

The prediction being considered this week by the IPCC is "obviously not the full story because ice sheet decay is something we cannot model right now, but we know it's happening," said Stefan Rahmstorf, a climate panel lead author from Germany who made the larger prediction of up to 55 inches of sea level rise. "A document like that tends to underestimate the risk," he said.

Some speculate that the ice sheet melting may be temporary and will ultimately have little effect. If so, good. But if they're wrong, if we experience more cases like the loss of the Larsen B ice shelf in Antarctica in 2002, we could easily within the century be seeing sea level rises more efficiently measured in meters rather than inches.