Quote:
Originally Posted by AstralTraveller
Solanum,
I agree with the thrust of everything you have said. However I am unaware of any extinction event where 95% of species went extinct. Even the 'Great Dying' at the P-T boundary did not do this. The figures I've seen are about 95% of marine species, 70% of terrestrial vertebrates and a smaller number of invertebrates.
As far as extinctions from possible anthropogenic warming _alone_ is concerned I find it hard to believe there will be much impact. Temperatures may rise to what they were during the last interglacial (120,000 years ago - virtually yesterday) or a bit higher and I've never heard any palaeoscientist suggest that extinction occurred due to that. Of course, warming has to be added to the other changes we are causing and so increase somewhat the number of extinctions we are causing. But I agree, in 30 years time >95% of presently extant spp will still be here.
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Sure, 95% of marine spp., though I suspect marine spp are over-represented in the fossil record due to the nature of it (though I am a long way from a paleo- anything!) In reality these numbers are based on what disappears from the fossil record, which is surely only a fraction of the spp extant at that time. Doesn't really matter in regards to my point, but I accept your correction!!
I think temperatures are expected to exceed the last few interglacials (120 kyears was the last but one BTW), certainly CO2 is way above anything seen in the last 600 kyears already - not that CO2 is the only driver of global temps of course.
Quote:
Originally Posted by AstralTraveller
I am bemused by the predictions that global warming will make the global climate drier. It is well known that the climate during glacials was cold and dry. During interglacials (like now) the climate is warm and wet. The mechanism is pretty simple. Hotter winds blowing over warmer oceans cause more evaporation, and what goes up will come down. That is a vast simplification (and, yes, some places were wetter when the climate was cooler) but it should hold true at the global scale.
Can anyone comment on whether the climate change models really do predict a global drying, or is it just a common misconception? If they do predict a general drying by what mechanism is that supposed to be achieved?
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You can go to the IPCC link in my first post. Some places are expected to by drier, some wetter. Looking at the global figures, more places will be wetter than drier. Southern Australia is expected to be slightly drier, but not by much.