Distrusting climate models - it cuts both ways

The newest rational attack on global warming fears is to denounce climate models as unreliable predictors. It's true that these attacks are often motivated by tribal allegiances, perversity, fear, denial and bribes -- but they're still important. Semi-rationalist opposition helped establish that CO2 is rising, and helped establish that we have been warming for over a 100 years, and warming faster over the past 10-20 years.

Now that those battles are done, we have to justly fight the battles over the reliability of climate simulation. I'm not making bets on this one, I think the deniers may have a case. Simulation is hard, the models may not work.

Of course (insert evil laughter), this cuts both ways. The models may exaggerate climate change, or they may underestimate it. Observational data from the arctic shows that in that region the models have been consistently too conservative (emphases mine)...

The North Pole Is Melting: Scientific American

... As a result of atmospheric patterns that both warmed the air and reduced cloud cover as well as increased residual heat in newly exposed ocean waters, such melting helped open the fabled Northwest Passage for the first time [see photo] this summer and presaged tough times for polar bears and other Arctic animals that rely on sea ice to survive, according to the U.S. Geological Survey. Such precipitous loss of ice cover far outpaces anything climate models or scientists have predicted.

This new record low continues the trend of steadily shrinking summer sea ice. "We're already set up for a big loss next year," Serreze notes. "We've got so much open water in the Arctic right now that has absorbed so much energy over the summer that the ocean has warmed. The ice that grows back this autumn will be thin."

In fact, a German expedition on the icebreaker Polarstern has revealed that existing Arctic sea ice in the center of the ice cap is only about three feet (one meter) thick, 50 percent thinner than it was just six years ago. As a result, more melt water is mixing with the salty seawater and pulses of warmer Atlantic seawater have intruded into the Arctic Ocean.

Whereas the South Pole remains protected by differing geographic, atmospheric and oceanic conditions, the North Pole is undergoing rapid change not seen in at least 6,000 years and perhaps as much as 125,000 years, and which may spread to lower latitudes. "It is reasonable to think that if you lose the sea ice cover that is going to have an impact elsewhere, in the midlatitudes," Serreze says. Some modeling studies of such effects have suggested drought in the western U.S. or changes in precipitation patterns across Europe.

Serreze expects the ice will bounce back somewhat next year, if only because he cannot imagine it shrinking any more so swiftly. But ice-free summers in the Arctic may become the norm in the near future. "At this point, I'd say the year 2030 is not unreasonable" for a summer without sea ice in the Arctic, Serreze says. "Within our lifetimes and certainly within our children's lifetimes."

When that occurs, the Arctic Ocean may become a spooky, foggy place, haunted by diminished populations of spectrally thin polar bears clinging to life in residual habitat. "It's going to be a different world," Serreze notes. "The observed rates of change have far outstripped what we projected."

The antarctic is mercifully protected, but as goes the Arctic, so goes Greenland. That may lead to faster sea level changes than the simulations predict, but I expect they will be in line with estimates of ancient climate impacts on Greenland.

Meanwhile, in Minnesota, we live the future. Our climate in the continental center is very affected by arctic conditions. The Feds have moved southern MN into a new climactic zone, outdoor ice skating is disappearing, Nordic (cross-country) skiing is finished in the metro area, snow sledding now requires artificial snow, the northern snowmobile industry has collapsed and we're building lots of indoor water parks to get the kids through increasingly dull winters.

Carbon tax, anybody?