It's also worth putting this in a bit of geologic perspective. The article mentions this, but doesn't explain it.<p>The Eocene is just before the earth went into a period of "icehouse" climate (that's still going on). During the part of the Eocene this article refers to, the earth was in a "greenhouse" phase, and global temperatures were much warmer than they've been any time since.<p>At that time (and throughout the majority of Earth's history), there likely weren't any significant ice caps on the planet.<p>On very long timescales, the Earth goes through periods of icehouse and greenhouse climates. We're currently in an "interglacial" within a period of icehouse climate that has persisted since the late Eocene. Most of Earth's history is dominated by long phases of greenhouse climate. During these, the global climate is more stable and much warmer. We don't have ice ages, and there probably aren't any ice caps at the poles.<p>The last period of icehouse climate began just after this, in the late Eocene. (Again, the "ice ages" you hear about are glacials and interglacials within a period of icehouse climate.)<p>Also, as other folks have mentioned, the Eocene is relatively recent, and Antarctica was essentially in its present-day position (the coals and other "warm-weather" rocks in Antarctica date from much earlier when it was near the equator).<p>Regardless, it is quite interesting that sea surface temperatures were as warm as this evidence shows! I just wanted to put this into a bit of perspective.<p>*Caveat to all of this: I'm a geologist and not a climatologist.