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No. 2798
>>2675
yeah ok, you realize that (major) ice age cycles last about 100,000 years? Historically the temperatures would start out by dropping slowly for a few thousand years (or a little more) then drop sharply by several degrees, ending the interglacial. They'd then drop slowly and not too steadily for tens of thousands of years and then skyrocket, ending the ice age in a couple thousands of years. The last ice age ended around 10000 years ago. Taking CO2 out of the picture, I think it's quite possible that we'd be in for a major ice age in the next 0-10000 years and a minor ice age (~2C drop in global temperatures) in the next 0-200 years.
As for CO2 not preventing ice ages, the little ice age cycles cause temperatures to go +/-1C from the normal. At the peak of most ice ages, temperatures are 4C lower than they are today. I don't think the CO2 concentration changes we're talking about would be enough to stop ice ages either, but only because I don't think it has as much of an effect as people make it out.
The climate has changed a lot in the past, and while there were extinctions at times, the world didn't end and recovered. You also have to consider how the earth reacts to forcing, there are all kinds of negative and positive feedbacks which should be looked into. Permafrost, vegetation, arctic albedo... One of the most important ones is the feedback with clouds and water vapour, which is actually a much more important greenhouse gas than CO2 or methane and amplifies changes in temperature (positive feedback). If a temperature increase due to CO2 had no effect on water vapour and clouds, the warming predicted by climate models would have to be many times smaller, so from 2-6C to maybe 0.5-1.5C... If the feedback between temperature and water vapour was negative (acting to prevent temperature changes), then we'd have absolutely nothing to worry about.
Back in 2001, even the IPCC report admitted they didn't know if the feedback was positive or negative. They now (2007) claim it is positive but there is still a lot of uncertainty in the science and disagreement.
RE climategate: I don't think it disproves the mainstream theory regarding climate change, but some of the scientists involved (esp. James Hansen) are widely quoted in reports, articles, blogs, etc. But mostly I think it shows that scientists can tweak their findings to try to win grant money or because they believe they are right even though their initial results might say otherwise, so they think the results are somehow invalid. Basically they aren't saints, they're human and you should take what they say with a grain of salt and look into the science yourself.
Regarding the OP's question... This is something I haven't looked into as much as I'd have liked.
Some things I know for sure is that you can basically disregard the claims of apolyptical changes in sea level. As far as I know, the main causes of sea level changes would be expansion of the oceans (things expand when they warm) and sea ice melting. Note: sea ice is around 1m thick, the ice caps of Greenland and Antarctica are thousands of times thicker. The arctic sea ice holds 0.01% of the world's ice, the Antarctic about 89% and Greenland about 9%. The Antarctic and Greenland ice is melting at the edges but the centers of these ice caps are pretty fucking cold and the ice there is actually getting thicker.
There is just no way they'll change by several meters (3m=10ft). Even the IPCC only expects a rise of a few inches to a couple feet.
In most parts of the world that isn't going to be much of a problem. I mean in most places the tides cause greater changes in sea levels. Places like NYC, the Netherlands, San Fran shouldn't have a too hard time increasing their dikes/seawalls to deal with that. And a lot of the places that can't afford that and are low lying are in river deltas (ex Bangladesh). If these aren't canalized (like in New Orleans), the rivers dump tons of sediments in the deltas, which should counter the rising sea levels.
As for global warming CAUSING an ice age (a la Day After Tomorrow) that's very unrealistic. There have been events in the past where large amounts of freshwater suddenly entering the oceans caused ice ages that lasted 100-1000 years but those involved lakes up to twice the size of Texas bursting into the ocean in months or days. That's a lot more freshwater in a lot less time than what we're talking about.
I've also read somewhere about how mountain glaciers melting is mostly caused by desertification. I'll have to look into that more.
re: droughts/desertification. I also haven't looked into this very much, but I do know that the climate has gotten dryer in the past when it got cooler. I also know that most of the world's deserts are located next to cold ocean currents and rainforests next to warm ocean currents. There are also many other causes for desertification like deforestation or poor agricultural practices and poor use of water. I'm not ruling out the possibility that global warming could mean an all round increase in desertification though and I think it's one of the most legitimate concerns regarding global warming.
Storms/hurricanes: global warming would be more significant in the poles, so the difference in temperatures between the poles and equator would be smaller. Storms need a big temperature difference. While increased ocean temperatures would mean stronger temperatures, wind shear is also an important factor. High wind shears is very bad for hurricanes, and global warming is expected to cause it to increase. It should also be noted that hurricane activity in the North Atlantic doesn't increase at the same times as in the Pacific or Indian ocean. It's a bit of an oddball... Also, hurricanes follow multi decadal cycles of high and low activity. The cycle of high activity started in 1995. Not sure if this cycle's ended or starting to come to an end now, but it would explain the strong hurricanes we got in the earlier in the decade and in the late 90s. Many skeptics also argue that we get the impression hurricane activity is particularly unusual recently (but not in last couple years) because of increased developement and population growth in areas that get hurricanes and because of increased media reporting.
Re: extinctions/biodiversity. I think this depends a lot on desertification. While there might be some extinction as a result of unusual climate change (though a lot of species can just migrate), I think all of us know that biodiversity is much greater in the tropical rainforest than in the far North. Northern boreal forests have basically one kind of tree: black spruce. The Antarctic has only penguins, a few sea birds, fish and marine mammals. The tropical rainforests have millions of species. In the Northern areas, there won't be much desertification so biodiversity will increase and people will be able to farm further North. The issue imo is if desertification will affect the most diverse tropical areas.
PS: Oxygen isn't something we'll have to worry about. :/ There's so much more of it than CO2 than converting all the CO2 to oxygen and organic material would have very little effect on oxygen concentrations.
Something you might not know is that plankton actually takes in more CO2 than all the forests in the world combined. I think it would be interesting to find out how climate change would affect them.
PPS: In age of the dinosaur the world was at times 6C warmer and had 10x higher CO2 concentrations. The oceans still had fish in them (dunno about corals though).
tl;dr
Not a problem: Hurricanes and shutting down of the gulf stream, earthquakes, volcanoes (some people don't know they're unrelated)
Not too bad: rising sea levels
Maybe bad: desertification, if it is due to climate change and not other human factors and if we actually have much of an effect on climate change --> could be a problem for biodiversity
pH change and it's effect on corals (haven't looked into this much) which some - but not all - fish species depend on
Good: spread of warmer climate and agriculture in Northern regions
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