Global Warming - for a Change
Listening to Open Source - Politics of Climate Change, and looking at some of the referenced material. The Open Source programs are often quite interesting (whether you agree or not with the opinions). I was a bit creeped out by the guys advocating more laws and big government at the end of this program.
Found a reference to rising sea levels from melting ice:
- IPCC 2001 “central estimate” of ~0.5 meter further sea-level rise by 2100 now looks like an underestimate…maybe a big underestimate.
- All the ice on Greenland ~7 m increase in sea level; ice in WAIS ~5 m.
- Rates at which this ice could become sea water are still highly uncertain, but 12 m in 350-500 years is possible (~3 m per century); some think even faster is possible (Hansen 2005).
- East Antarctic Ice Sheet could add another 60 m, presumably only over many centuries…but recent surprises indicate science uncertain here.
OK, now I do in fact suspect that CO^2^ emissions from human activity may indeed be the cause for the recent global rise in temperatures. I believe we should aim to use a lot less of non-renewable resources (which would include fossil fuels, midwestern topsoil, old growth timber, and the like). I also believe it is a good long-term bet to invest in and promote the development of solar, nuclear and other power sources.
On the other hand, I find a lot of fuzzy thinking in publications like the above referenced presentation.
First, the science basis for assigning global warming to increased CO^2^ emissions is a little uncertain. We should not assume that the Earth's climate was always constant - or that the rate of change was always constant. Climate change occurs over many tens of thousands of years. We have really detailed information from just the past couple decades, and fairly sketchy information for longer periods. Making projections from that extremely short or thin basis is risky.
Before you can make any sort of projections, there are a lot of questions that need asking. Did the Earth have warmer periods in the past? Did the Earth have higher CO^2^ levels in the past? What change was already occuring in the climate before human activity became significant? Was the rate of change itself changing? What evidence do we have about past changes?
Is warming a bad thing? I'm not convinced either way. Certainly warming means change, and no doubt this will disrupt a lot of established folks. On the other hand, sometimes change is a good thing. Why does it seem that warming is assumed to be a bad thing?
Warmer temperatures should translate to a shift in climate - some wet areas will become drier, some dry areas will become wet. Crop-growing regions that become dry is a bad thing. Some currently dry areas will become better for growing crops. If you drive around the American West, or poke around the planet using Google Earth, you will see huge, dry, largely unused tracts of land. As an American I would be particularly interested in how much the total precipitation might change for the entire country, and how the moisture would be distributed. Is the change in distribution a net profit or a net loss?
As a guess, warmer temperatures should lead to more evaporation from the oceans, which in turn should mean more fresh water from precipication on the land. There are lots of folks who think we need more fresh water. Will warming solve a looming problem?
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So far as I can tell, no one is asking this sort of question.
Here in southern Orange County (California) - presuming the above numbers for sea rise are somewhat accurate - warming means a lot of rich folks might lose their house on the beach. My sympathy is limited - especially since my house is at 800-odd feet elevation. Besides, this sort of change will make a lot more folks interested in the environment... :)
Then there are the odd conclusions.
- While there’s still no formal consensus, it’s increasingly clear that the current level of anthropogenic interference is dangerous. Significant impacts in terms of floods, droughts, wildfires, species, and melting ice are already evident at ~0.8°C above pre-industrial T~avg~, and current GHG concentrations commit us to ~0.6°C more.
- It is now all too plausible that…
- ΔT~avg~ ~ 1.5°C will mean the end of coral reefs & polar bears
- ΔT~avg~ ~ 2°C will mean catastrophic melting of Greenland & Antarctic ice, with commitment to multi-meter rises in sea level
- ΔT~avg~ ~ 2.5°C will sharply reduce crop yields worldwide
Yes, some areas will become drier - and yield more wildfires, for a time. On the other hand some areas will see more moisture and new growth.
So ... a ~ 1.5°C rise will kill off all the coral reefs? Somehow it seems likely the ecosystem of a coral reef can adapt to a small change in temperature. Surely the change in temperature and sea level will make changes in the ecosystem, but assuming no adaption seems unreasonable.
It does seem likely that some existing farms will see reduced yields. It also seems likely that some (large) new and existing farmed areas limited by available water will become more productive. What I don't see is mention of areas expected to become more productive. Without attempting to measure the gains, we cannot reasonably say in balance whether the change is a profit or loss to humankind.
OK - I will admit to one bit of amusement. Between rising temperatures and sea level, Florida may largely disappear, and Texas become less habitable. Given the location of the current President's political base - I'm not feeling badly about this :).