What is Happening to the Climate? Part 1: The Evidence

There is an overwhelming consensus among climate scientists that the earth is getting warmer at an alarming rate and an overwhelming consensus among Republican presidential candidates that it's all a hoax. Take a look at the accompanying chart and see what you think. The data, from two respected government agencies, show that for the last 40 years or so the earth's temperature in the northern latitudes has been rising steadily while the size of the north polar ice cap has been declining--and the decline appears to be accelerating. 

There also is other evidence of warming. The sea level is rising, glaciers are shrinking all over the world, and the climate zones where different plant and animal species flourish are moving towards the poles, so if there is a hoax afoot, the Department of Agriculture must be in on it.

 Is the warming "anthropogenic'--i.e., caused by humans? That is not 100% certain, but almost. Scientists in the 19th century discovered that CO2 (carbon dioxide) is a greenhouse gas and we now know that world CO2 levels for the last 700,000 years track very well with the large swings in temperature levels that occurred. And we know that throughout that period CO2 levels stayed in the range of about 200 to 300 parts per million (ppm). In the 19th century it was about 280 ppm but is now around 380 and will reach at least 450, even under the most optimistic forecasts.

 That is the scary part--we are in completely unknown territory. Plus there are negative feedback effects that can accelerate warming even more. Less ice means less heat reflected back into space. Moreover, methane is a far more potent greenhouse gas than CO2 and there are huge amounts of methane--in permafrost layers and in methyl hydrate deposits on the seabed--that could be released by rather small increases in temperature.

 But the idea of an international conspiracy of scientists is preposterous and the notion that they could get away with it, without anyone blowing the whistle is even more preposterous. While there are occasional instances of scientists fabricating data, they are rare and they are almost always uncovered by other scientists because claims are never accepted until they have been cross-checked and verified by other scientists.

 Next--Part 2: What--if anything--w can do about it.