August 2, 2012 11:30 am
Ancient Climate Change Meant Antarctica Was Once Covered with Palm Trees
This palm frond fossil dating to the the Eocene period was found in Utah’s Green River Basin. Photo: USGS
Known for its expansive glaciers and the coldest temperatures on Earth, the Antarctica of today is a far cry from its tenure as a subtropical paradise 53 million years ago, replete with palm trees, summer highs near 25°C (77 F), and frost-free winters sitting near 10°C (50 F) despite the endless darkness.
Describing a recent study lead by Jörg Pross, Jason Palmer writes about the anomalous warm bubble known as the Eocene, noting that soaring atmospheric carbon dioxide levels drove the global average temperature to increase by 5°C.
Drilling into an offshore site near Wilkes Land, a part of eastern Antarctica that lies south of Australia, Pross and his team collected sediment from deep below the sea floor that was laid down and subsequently buried over the past 53 million years. In that ancient material, says Palmer, the researchers found “pollen and spores and the remains of tiny creatures.”
With the sediment came pollen grains from palm trees and relatives of the modern baobab and macadamia.
Palmer writes that in this much-warmer Antarctica, “the lowland coastal region sported palm trees, while slightly inland, hills were populated with beech trees and conifers.”
Though scientists think the atmospheric carbon dioxide levels at the beginning of the Eocene period 55 million years ago were as high as 1000 parts per million, trumping today’s value near 400 parts per million, they’ve not quite worked out what triggered this lurch.
As to whether Antarctica will ever return to such a lush clime given modern global warming, the proposition is rather unlikely. Palmer, again:
Dr Bendle said that as an analogue of modern Earth, the Eocene represents heightened levels of CO2 that will not be reached any time soon, and may not be reached at all if CO2 emissions abate.
It’s not only carbon dioxide that needs to be taken into account, either. During the early Eocene when these palm fronds lined the shore, Antarctica and Australia were still connected at the surface. It wasn’t until millions of years later that the powerful Antarctic Circumpolar Current took shape, a strong ocean current that essentially prevents energy or heat from moving in and out of Antarctica, and one of the major reasons why the polar continent is so cold today.
More from Smithsonian.com:
The Wild Extremes of Antarctica
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Proofread! THird paragraph — it would be deep BELOW the surface, not deep BLOW the surface.
Thanks.
/E
Comment by Emmett Schmarsow — August 2, 2012 @ 12:42 pm
Thanks for the careful eyes!
Comment by Colin Schultz — August 2, 2012 @ 1:15 pm
The Antarctic area was warm. Was it cold somewhere else on earth? Where?
Comment by janye — August 2, 2012 @ 1:16 pm
Though there may have been some specific regions on Earth that got colder during this time (which I just can’t seem to find), the general trend was that the whole planet went through a burst of sudden warming. Also, there wasn’t such a huge difference between equatorial and polar temperatures like there is now.
http://pangea.stanford.edu/researchgroups/paleoclimate/research/eocene-latitudinal-gradients
Comment by Colin Schultz — August 2, 2012 @ 1:35 pm
Thanks for the link.
Comment by janye — August 2, 2012 @ 1:43 pm
Where was Antarctica relative to the earth’s equator at 53M yrs ago? Are you assuming no movement in the earth’s crust in the intervening interval?
Comment by John Collins — August 2, 2012 @ 9:17 pm
Though the continents during the Eocene were much different than they are today, the differences were mostly due to changes in sea surface height rather than plate tectonics.
The beautiful paleogeographic photos of Dr. Ronald Blakey show that during this period the continents were more-or-less in their present positions: http://www2.nau.edu/rcb7/50moll.jpg
Blakey’s site: http://cpgeosystems.com/index.html
Comment by Colin Schultz — August 2, 2012 @ 10:41 pm
John Collins, I hear you. There has been some speculation that earth experienced a major impact in the remote past that caused the crust to slip on a global scale, shifting previously equatorial regions into polar realms and vice versa. I would love to find out what ancient life or artifacts might lie beneath the Antactic ice.
Comment by WriterSP — August 3, 2012 @ 10:12 pm
Perhaps these types of climate changes would be more comprehensible if one takes into account the periodic shifts of the magnetic north pole, which takes place every 13,500 years or so. For instance, within the last 26,000 years, the north pole has resided in the Yukon Territory as well as the Hudson Bay area. Antarctica has likely been warm more than a couple of times. It makes a decent candidate for the lost continent mentioned in widespread tribal records.
Comment by Benjamin Baldwin — August 3, 2012 @ 11:58 pm
well, who’s to say that antarctica wasn’t the south pole way back when? crustal shifts are quite possible. antarctica might’ve been in an “australian” position in the past.
Comment by Dr. John Smallberries — August 4, 2012 @ 7:53 pm