Friday, January 1, 2010

Global warming and global cooling

When volcanos erupt it lets off a bunch of gases into the atmosphere. A big volcanic eruption can actually cause global cooling - light waves that would otherwise have reached the earth's surface and caused some warming were instead deflected by particles in the atmosphere put up there by the volcanic eruption. When we burn some fuel, greenhouse gases are emitted which are known to act as an insulator for the earth (helping us to stay warm by retaining heat).
But having more particles up there in the atmosphere should also contribute to some cooling due to the same effect observed after a volcanic eruption (the extra particles in the atmosphere will intercept some light that otherwise would have made it to the earth's surface and contributed to warming - there's plenty of soot and garbage in the exhaust of our cars etc.).

Here are 3 example ways that burning fuel causes changes in global temperatures.
1) Standard greenhouse gas emissions (ex. carbon dioxide) increases in the atmosphere and acts as an insulator keeping our planet warmer.
2) The act of burning lets off a significant amount of heat into our atmosphere (making the planet warmer)
3) The exhaust from the burnt fuel contains soot etc. that get into the atmosphere which then reflect light that otherwise would have made it to the earth's surface (making the planet cooler). To the best of my knowledge, this is thought to be very small.

It would be cool if we could evaluate the relative dominance of each of these issues. For instance if it turns out that the heat output from burning fuel is contributing a large amount towards global warming then perhaps we could develop technologies that simply trap heat that otherwise would have been expelled (say out the tailpipe of a car). Or use one of the new electricity generating inventions that operate based on a temperature differential - theoretically such devices could be used to charge a hybrid car's battery.