6/04/2006

06-04-06 - 2

06-04-06

There are two things about Global Warming that you may not be aware of and are horrific.

1. Pollution from burning fossil fuels is not only adding CO2 and such to the atmosphere, which contributes to Global Warming via the greenhouse effect, they also add a huge amount of particulate pollution, which has greatly increased the cloud cover of the Earth in the last 50 years. The cloud cover has lowered the temperature. What that means is if not for the particles, the warming would be much greater. What's worse, we can remove and control the particles much more easily than the CO2; the particle-cloud-formation effect is relatively short term, but the CO2/green house effect sticks around. If we were to stop using fossil fuels right now, the earth would very quickly get *much warmer* as the particulate pollution settles out. (this is called "Global Dimming")

2. Warming is a self-accelerating effect (positive feedback). The more we warm the earth, the more it warms itself. There are a lot of factors that contribute to this. One is glacier sliding - as they melt, they develop a layer of water under the glacier which makes it slide faster into the sea. As it gets warmer still, arctic glaciers will start to break apart. Melting ice and permafrost releases large amounts of trapped carbon. Also supposedly once we get up another 5 degrees or so there's this catastrophic thing that happens where hydrocarbons at the bottom of the sea come out and we get a big acceleration of the process.

The self-accelerating nature of the warming seems to be a natural thing that has happened many times in the history of the Earth. Most of the time has been spent in an ice age. For some reason after 200,000 years or so of ice age, the Earth kicks itself into a warming phase, and it rapidly warms over a few thousand year period up to our current temperature, then rapidly gets warmer and warmer, and once it gets a bit warmer than where we are now, it kicks itself back to an ice age.

From some quick web browsing I can't actually find why the earth oscillates between these warming and cooling snaps. One thing is clear - once it's warming or cool it tends to self-perpetuate, and it's a very delicate system, it can easily be kicked into warming or colling from outside forces. It's suspected that in the past warming & cooling phases have been kicked off by variation in the sun's output, by major volcanic eruptions (from the particles blocking the sun), etc. Another factor seems to be small variations of the Earth's orbit caused by gravitational interactions with the other planets. The more I read about it the more complicated I see it is.

UCSD has an okay site and The Wikipedia article is good as ever. It's hip to trash wikipedia these days, but only morons do it; if the wiki's wrong, you can fix it!

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