In the next few months, I will be writing about climate and climate change. My purpose is to discuss the various ways we influence climate both locally and globally. The plan is to start locally, with the effect of cities on climate. I will follow with a discussion of our effects on regional climate, and then close with a look at the global climate. This sequence will probably be interrupted by other topics if they come up.
1. Local climate
Local climate is probably the easiest for us to understand because we can see it in our daily lives. It has been known for decades that cities affect climate. Before air conditioning, the cities would get so hot in the summertime that people who had the money would leave the cities during the weekends for cooler weather in the countryside.
The figures show two examples. In Figure 1, an infrared image of Salt Lake City, notice how the urban area (yellow and red) is warmer than the suburbs (mixed greens and blues) which are warmer than the surrounding mountains. Iâ€™m not sure why some of the mountains (upper right) look warm â€“ perhaps there are rocks there. Figure 2 is a satellite image from MODIS (MODerate Resolution Imaging Spectroradiometer) showing the surface temperatures in Beijing in the afternoon. The MODIS pixels are much larger, so the picture looks blurrier, but the message is the same: Bejing is also warmer than the surrounding area.