How Bad Data Contribute to Global Warming Hysteria
08/17/2012 Leave a comment
On the web when you start a project you never know how much influence it might have. Some of my photos and plots on the Tahoe Urban Heat Island issue were posted on the Power Line Blog, via Watts Up With That.
Have you ever wondered, when you see an assertion along the lines of “The Earth has warmed by 1.62 degrees over the last 100 years,” how anyone could know that? The literature of global warming alarmism is littered with faux precision; the truth, as you might imagine, is that it is very difficult to get reliable data for the whole Earth over a period of decades if not centuries.
Climate realists are generally willing to assume, for the sake of argument, that the Earth has warmed somewhat in recent decades. In fact, though, it is not obvious that even this modest claim is true. Satellite data show no net warming for as long as such data have been collected, i.e., back to 1979. Ocean measurements show no net warming over that period, either; the evidence for warming is based on land measurements. But the accuracy of land measurements depends on proper siting and maintenance of weather stations. One obvious factor is the urban heat island effect: many weather stations are located in cities, which grow warmer as more people and buildings accumulate. Thus, increasing temperatures at such stations may be measuring urban development rather than the climate. We all know that the urban heat island effect is real–”chance of frost in outlying areas”–yet the data that alarmists rely upon do not take it into account.
Apart from that broad issue, the siting and maintenance of weather stations is crucial to the accuracy of the data they generate. This was nicely illustrated in a recent post on Watts Up With That:
Some of my pictures and temperature plots were used in the both the Watts Up With That and Power Line blog posts. More details HERE.