If God-eh is keeping global warming at bay like Sen. James Inhofe assures us, then perhaps the rustbelt has been forsaken. A new study comparing station data and satellite photos concludes winter ice cover on America’s Great Lakes has plunged by 70 percent since 1973:

(MSNBC) — The study doesn’t include the current winter, but satellite photos show that only about 5 percent of Great Lakes surface froze over this winter, the Detroit Free Press said. That’s down from years such as 1979, when there was as much as 94 percent ice coverage. On average, about 40 percent of the surfaces freeze over, the newspaper said.

Annual variability in temperature and precipitation can explain some of the decrease. But the red plots in the NASA GISS temperature record above aren’t coincidence. They indicate average temperatures in the Northern Hemisphere over the last 130 years. Note the sustained uptick beginning in the mid 1970s.

On average, annual temperature readings in the northern half of the globe have increased by about 1.7° F, way over half of that delta has been in the last 40 years, and that figure may be a little on the low side for the Great Lakes. Climate change tends to be more extreme in boreal and polar regions because of a process called Polar Amplification. Ice and snow reflect more incident solar light back into space than darker land or water. In a warming trend, as ice cover decreases, less visible light is bounced back by shiny white snow and more energy is absorbed and radiated as heat by earth and sea, which is trapped by greenhouses gases before it can escape into space. This would be true even if GHG concentration were stable, let alone when they’re increasing. Researchers say the result of this positive feedback in the Arctic could be temperature increases two or even three times the global average and lead to ice-free summers in the next decade or two.