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Re: On The Cretaceous "Hot-house"



The most pessimistic predictions of sea level rises as ice sheets are melted by global warming may have to be scaled back as a result of an extraordinary discovery that ice persisted when the Earth was much hotter than today.

The most pessimistic prediction I'm aware of is that Greenland and West Antarctica would melt completely within the next few centuries. That would give us the situation we had about 400,000 years ago: a sea level 22 m above today's. Nobody has AFAIK suggested that all or most of East Antarctica would melt, so confirmation that it won't is not a surprise.


Besides, the Real Climate post linked to yesterday says that other explanations for the isotopic evidence cannot be completely excluded. Oh, you cite it:

mjmurphy <4mjmu@rogers.com> wrote:
 Mostly, the RealClimate blog deals with issues around modern AGW but this
post

http://www.realclimate.org/index.php/archives/2008/01/the-debate-is-just-beginning-on-the-cretaceous/langswitch_lang/in

concerns the apparent fact that

"...that there appears to have been a 200,000 year period right smack in the
middle of one of the warmest periods of the past half billion years, when
there were ice sheets (presumably in Antarctica) that were up to 60% the
volume of today's Antarctic ice sheets. How in the world do you get such
large ice sheets in a high CO2 climate warm enough for crocodiles to survive
in the Arctic at the other side of the planet? And this apparent glaciation
is not the result of a global cold snap. As in the Eocene results quoted
earlier, the tropical ocean surface temperatures are again on the order of
35C - courtesy once more of the wondrous Tex86 proxy."

It goes on after (and before) that for several more screens. Read the whole thing.