Eemian global mean temperatures were ~1 C warmer, with polar
temperatures 2-4 C warmer than now. For global warming predictions of
~3 C at 2100, polar temperatures may increase 5-8 C above modern.
It is entirely plausible that we will exceed the conditions of any
reasonable Eemian analog before the end of this century.
-Robert
Alastair McDonald wrote:
> The ice in Greenland did not melt during the Holocene otherwise there would
> be no ice cores stretching back to the Eemian 120 k years ago. OTOH it
> does seem likely that the ice they did melt during the Eemian when global
> temperatures were 2-3C higher than today, which explains why the ice cores
> from Greenland only go back 120,000 years.
>
> Coby is right. It is a lot more complicated than is generally believed.
>
> This also applies to the forcing. For an ice sheet to form it needs a
> cold summer when the snow never retreats, but for an ice sheet to
> melt it needs a warm winter, which implies an increase in greenhouse
> gases. Those gases are CO2 and H2O, and their increase is caused
> by warm oceans during the summer. The current melting of the ice
> is a result of the increased CO2 thanks to Man.
>
> Land and sea behave differently.
> Land ice and sea ice behaves differently.
> Summer and winter have different effects.
> Greenhouse gases and solar radiation have different effects.
>
> Of course the last point is not widely recognised since it is generally
> believed that the forcing occurs near the tropopause for both solar and
> greenhouse gases.
>
> Although a rise of 2C will not melt the Antarctic ice at the high altitude
> of the South Pole, it could cause a warm South Pacific ocean to emit
> more CO2 which would melt some ice exposing a low albedo surface
> which also causes warming and more melting of the ice.
>
> Cheers, Alastair.
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