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It's been said that 55 million years ago, a massive carbon surge raised global temperatures by five to eight degrees (or, in a more preferable translation, nine to 14.4 degrees Fahrenheit). This catastrophe was known by scientists as "The Paleocene-Eocene Thermal Maximum", or PETM. It showed how warm the Eocene was before the opening of the Drake Passage which left Antarctica to be iced, yet it never mentioned what the weather or climate was like BEFORE the PETM.

So the simple question is: How warm was the Paleocene epoch?

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    $\begingroup$ Please provide references to your claim that "it's been said...". Who said it? $\endgroup$ – arkaia Sep 15 '16 at 14:54
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    $\begingroup$ Same for "never mentioned". The stuff I read (things like Geoscientist articles) have talked about no ice caps before the PETM, but during the PETM tropical plants growing in the polar regions. $\endgroup$ – winwaed Sep 16 '16 at 13:14
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Redrawn after Zachos et al. 2001 Redrawn after Zachos et al. 2001.

This is a plot of the Cenozoic variations of $\delta\ce{^{18}O}_{Cibicidoides}$ according to Zachos et al. 2001 (this is a bit outdated now but the Paleocene is roughly the same in more modern curves such as Zachos et al. 2008 or Cramer et al. 2011). It is supposed to follow variations in deep ocean temperatures and thus reflect the climate state at a given time. The Paleocene is the timeframe delimited by the two vertical bars (you can see the PETM quite clearly on one of the two bars).
From that plot it seems the Paleocene deep-sea temperature prior to the PETM is roughly at the same level at it is during the Middle Eocene (ca. 45 Ma), i. e. warmer than most of the Cenozoic but colder than the Early Eocene or most of the Cretaceous.
There isn't actually that many studies focussing on the Paleocene itself, this is clearly a time interval that is studied so far mostly because of the K/T boundary or the PETM, i. e either because of its start or its end.

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    $\begingroup$ Just an addendum to mention that this answer might have to be changed in a couple of years as a few researchers are currently shifting their focus toward the mid-Paleocene climate and oceanography (in particular I saw a poster last month at ICP12 in Utrecht, by Peter Bijl if my memory is correct, investigating the colder interval of the mid-Paleocene and exploring the possibility of a short glaciation during that period). $\endgroup$ – plannapus Sep 16 '16 at 14:29

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