An Ice Age is coming! Crazy? If you were alive in the 1970s you might remember that people were worried about global cooling and a new Ice Age in the future. What happened and where did they go wrong?
Well, part of it was that there was some cooling between 1940 and 1970 which was part of normal long term temperature fluctuations. You actually need to look a longer term trends to see more accurately what is going on. Plus, there was another group of scientists who were working on global warming theories who eventually won out.
Part of the problem was the media, which is often the case with science stories. They ran stories about ice ages etc. but they didn’t run any corrections or opposing views of the global warming scientists. Ninety percent of scientists in the 1970s felt that there would be global warming and 10% thought there would be global cooling.
Why was there a cooling period from 1940 to 1970? There were two reasons put forward and one of them is now considered to be the main reason. This was the effect of aerosols. These are particulates that are put in the air by power plants and other sources. Whereas greenhouse gases trap the heat, the aerosols / particulates reflect sunlight so less of it reaches the earth.
The other was called orbital forcing. Orbital forcing are the changes in climate changed by slight changes in the earth’s tilt and orbit. Apparently, this is the main cause of the ice ages and has a cycle of 20,000 years or so. Since geologists frequently deal in millions of years, 20,000 years is soon. But when the media heard soon, they took it to mean right around the corner.
More recently, a professor by the name of Don Easterbrook has claimed that we were about to have global cooling. He claims the data support this and uses in part the 1940-1970 cooling. But he also says more recent data shows cooling. Most scientists don’t understand how he is intrepeting the data since they feel that the data strongly shows a warming trend. There are others besides Easterbrook, but they are in the distinct minority.