*As I’ve said in the past, I accept that the Earth has been getting warmer as a historical matter, but there are several more steps required from that simple proposition of historical global warming to the proposition that such warming (1) constitutes a man-made phenomenon (2) with predictable future consequences (3) that can be altered by future human actions (4) at a cost we can all live with compared to the marginal benefits of such actions. Dale Franks at the outstanding blog QandO offers a lengthy look at reasons to doubt that the current climate models have really proven much of anything about (1) and (2). Among his less technical objections:
1. Despite the fact that, since the end of the 19th century, human produced CO2 emissions have increased exponentially, the earth’s temperature has increased in basically linear fashion since 1800, despite the fact that modern industrialization did not add any signifigant amounts of CO2 into the atmosphere until well into the 20th century.
2. Despite the fact that huge increases in fossil fuels—and commensurate increases in CO2 output occured during the last part of the 19th and early 20th centuries, global temperatures cooled signifigantly between the 1940s and 1960s.
3. The abrupt global temperature rises in the last few years of the 1970s occured far too fast to be the result of any linear relationship with CO2 output.