December 11, 2006

Seal’s Hair Skins Hockey Stick?

We have written probably a dozen essays over the past few years on the crazy “Hockey Stick” favored by global warmers showing virtually no global temperature variation over the past 1,000 years followed by a substantial increase in temperature over the past 100 years. Who could ever forget Al Gore’s performance pointing to a few minor bumps on the “stick” 1,000 years ago and kidding about how others claim that the world was warmer than today a millennium ago? Al’s prop with the hoist was a highlight for us during the epic film that by now must have surpassed Ben Hur in terms of audience excitement.

The science literature is always alive and well, and we are fairly certain you have not seen this classic in many places before visiting us at World Climate Report. The elephant seal (Mirounga leonina) has an interesting story to tell us about the Hockey Stick and the global temperatures over the past few thousand years. In a recent article in the very prestigious Proceedings of the National Academy of Sciences, a team of scientists from the United States, United Kingdom, and Italy reveal an amazing discovery that further challenges the shape of the hockey stick.

The team went to Antarctica funded by the Office of Polar Programs at the United States’ National Science Program and the Italian Antarctic Research Program and they poked around for hair and skin from elephant seals who visited the area in the past. They also examined where the elephant seals exist today; the Hall et al. team notes that “Relatively few elephant seals have been observed in Antarctica, and these consist primarily of seals on foraging excursions or isolated molting groups.” However, at many times in the last 10,000 or so years (the Holocene), elephant seals felt more at home in Antarctica thanks to much warmer temperatures.

Hall et al. examined sand and gravel from raised beaches in Antarctica and found a substantial amount of hair and skin from our poster boy’s ancestors. The research team writes that “Both visual inspection and DNA analysis confirm that the material is from southern elephant seals.” Hall et al. date the material found on the Victoria Land Coast (VLC) of Antarctica and find “The period between 1,100 and 2,300 14C yr B.P., marked by significant expansion of elephant seal colonies and a disappearance of Adélie penguins, represents the greatest sea-ice decline (and probably the warmest ocean and air temperatures) in the Ross Sea in the last 6,000 yr. This was followed by an increase in sea ice and the development of land-fast ice ≈1,000 yr ago on the VLC, which we propose led to the abandonment of seal colonies. The ice regime remains too severe for either elephant seals or penguins to occupy the southern VLC today.” They note that during this warm period “Foraging excursions into the Ross Sea are unlikely to explain the concentrated deposits of skin because elephant seals forage alone. The large amount of molted hair/skin suggests that the region was used for molting. Mummified pup remains suggest that the region also was used for breeding.”

Their abstract is amazing stating “We show that southern elephant seal (Mirounga leonina) colonies existed proximate to the Ross Ice Shelf during the Holocene, well south of their core sub-Antarctic breeding and molting grounds. We propose that this was due to warming (including a previously unrecognized period from ≈1,100 to 2,300 14C yr B.P.) that decreased coastal sea ice and allowed penetration of warmer-than-present climate conditions into the Ross Embayment. If, as proposed in the literature, the ice shelf survived this period, it would have been exposed to environments substantially warmer than present.”

Well isn’t that interesting. Hall et al. find that Antarctica was “substantially warmer than present” in the past, and the ice shelves failed to collapse during the Holocene warming periods and the “delicate” ecosystems of the most southerly latitudes of our planet apparently survived.

Denying the existence of the Medieval Warm Period borders on silly, for as we see in this article (along with hundreds of others), the planet was so warm 1,000+ years ago that elephant seals moved south to a much warmer Antarctica. The case is occasionally made that the Medieval Warm Period was a European event, or maybe an event confined to the mid-to-high latitudes of the Northern Hemisphere. The skin, hair, and mummified offspring of elephant seals found in Antarctica clearly show that the entire planet was substantially warmer than today 1,000+ years ago.

We feel for the elephant seals who cannot occupy Antarctica today because conditions are “too severe” at present. With a little global warming, maybe our poster boy shown above can go home again? His ancestors would simply be amazed to see the old homestead in Antarctica now locked in ice and too cold for habitation.

Reference:

Hall, B.L., A.R. Hoelzel, C. Baroni, G.H. Denton, B.J. Le Boeuf, B. Overturf, and A.L. Töpf, 2006, Holocene elephant seal distribution implies warmer-than-present climate in the Ross Sea, Proceedings of the National Academy of Sciences, 103, 10213-10217.




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