re: #395 recusancy

Here’s the current model. As you can see there are deviations from the trend, as there always will be on any long term model. But the trend is down. And that so far has been absolutely what has happened.

The text to go along with that graph:

One potential analog for the future evolution of the arctic ice pack comes from the work of Holland, Bitz and Tremblay (2006), based on the September extent from a seven-member ensemble of the Community Climate System Model Version 3 (CCSM3, Figure 3). If one examines the ensemble member shown in black in Figure 3, periods of stagnation in ice decline as long as ten years can be discerned between major ice loss events. Is 2009 simply part of such an extended pause, as it will take another near-perfect synchrony of summer weather conditions to provide another major drop in sea ice extent (Overland)? Or does the background trend in Figure 3 represent the global warming “forced” signal of an ever-increasing sea ice loss, plus natural variability (Bitz)? Or are these two interpretations of the same thing? The data from 2007-2009 suggest further lively discussions on the future of the Arctic at meetings during the coming year.

When looking at the collective output from a variety of runs of a physical model that includes chaotic elements (as well as truly random elements), it is good to keep in mind that we are looking at a representation of a probability, since the number of actors in the system are way too large to calculate each and every change at every moment in time.

Still, the point remains, when looking at climate projections we always are looking at a range of possibilities, and the range normally covers a large share (maybe even 95%) of the possible outcomes.