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Politics : Politics of Energy -- Ignore unavailable to you. Want to Upgrade?

To: Brumar89 who wrote (7526)	4/24/2009 9:22:26 PM
From: Sam	1 Recommendation Read Replies (1) \| Respond to of 86356

Positive and negative feedbacks are always possible, depending on circumstances. The issue right now is that we are pumping large amounts of CO2 into the atmosphere, which is what has various consequences that initiate a number of positive feedbacks. We are putting this CO2 into the atmosphere even more quickly than volcanic activity has done in the past--it is estimated that by the end of the century, if we continue BAU (along with the BAU increases that we have seen over the past 2 decades), we will have put as much CO2 into the atmosphere as volcanic activity did in over 30,000 years preceding one of the extinctions, I forget offhand which one. That doesn't mean that negative feedbacks won't happen, they will. But they take time. The CO2 that we are pumping will eventually be sopped up. But it will take at least thousands, possibly even millions of years. It depends on how much is there, and how much methane also gets released from the permafrost and deep ocean regions. As I've said before, that is one of the biggest positive feedbacks--the permafrost melts, the ocean gets warmer, and the methane that is locked in each of them gets released, which creates more warming and more melting and more methane (which will break down into CO2 and water vapor after 10-15 years; the water vapor won't last long although it too is a GHG, but the CO2 will last a century or more, and of course the higher temperature will lead to more evaporation, and more water vapor etc). No one that I have read thinks it will actually become runaway warming, as Venus did. But it will create over a relatively short period of time (a couple of centuries) a radically different planet, and will lead to widespread dislocations and extinctions. That is one way to solve the population problem, but frankly, not my preferred way. It is important to understand timing. I've pointed to this essay before, but it is very readable and not that long: aip.org My understanding of climate change is heavily informed by reading Weart's essays, among others.