Lines of Evidence for Climate Change

A great place to begin understanding climate change and the human factors disrupting the natural cycle is a video from the National Academy of Science called "Lines of Evidence" which details the many sources of data proving that climate change is real and that human activity is a major cause. Click here to view the video.

The basics as I understand them are as follows: when the earth was formed most of the carbon molecules were trapped in basaltic rock. Burning fossil fuels releases that carbon in the form of carbon dioxide into the atmosphere. Carbon dioxide, along with some other manmade contaminants (like aerosols) trap the Sun's infrared rays in the form of heat. The Earth has had the perfect level of carbon dioxide for billions of years: a small amount of CO2 (about 0.04% of the atmosphere today) is needed to absorb heat from the Sun and protect us from the harsh temperatures of outer space. Too much carbon dioxide leads to overabsorption of the Sun's infrared rays.

Venus's atmosphere is a perfect example of overabsorption of heat from the Sun. It is believed to have occurred because of a runaway greenhouse effect. Currently, 96.5% of Venus's atmoshpere is made of carbon dioxide (remember ours is only 0.04%). It is believed that early in Venus's history, the planet looked similar to ours with little carbon dioxide in the atmosphere and oceans similar to ours with carbon trapped in basaltic rocks. However, Venus is closer to the Sun so its oceans were heated, gradually at first, evaporating the liquid and releasing the carbon molecules from their trapped solid form into a gaseous form (carbon dioxide). A feedback loop was created with the carbon dioxide released from the oceans heating Venus more and more until finally all of Venus's oceans were boiled away and all the carbon previously trapped in the ocean was released into the atmosphere. The surface of Venus is now hotter than Mercury, even though it is further from the Sun because of the heat Venus's carbon dioxide atmosphere absorbs.

If we continue to burn all the CO2 that is naturally trapped in the basaltic rock of the Earth, and we continue releasing other pollutants like aerosols into our atmosphere, it is not unlikely that we could develop our own runaway greenhouse effect, making the surface of Earth closer and closer to the hellish one of Venus.