"Appy Sluijs1, Stefan Schouten2, Timme H. Donders1,5, Petra L. Schoon2, Ursula Röhl3, Gert-Jan Reichart4, Francesca Sangiorgi1,2, Jung-Hyun Kim2, Jaap S. Sinninghe Damsté2,4 & Henk Brinkhuis1"
Several episodes of abrupt and transient warming, each lasting between 50,000 and 200,000 years, punctuated the long-term warming during the Late Palaeocene and Early Eocene (58 to 51 Myr ago) epochs1, 2. These hyperthermal events, such as the Eocene Thermal Maximum 2 (ETM2) that took place about 53.5 Myr ago2, are associated with rapid increases in atmospheric CO2 content. However, the impacts of most events are documented only locally3, 4. Here we show, on the basis of estimates from the TEX86′ proxy, that sea surface temperatures rose by 3–5 °C in the Arctic Ocean during the ETM2. [37-41F] Dinoflagellate fossils demonstrate a concomitant freshening and eutrophication of surface waters, which resulted in euxinia in the photic zone. The presence of palm pollen implies5 that coldest month mean temperatures over the Arctic land masses were no less than 8 °C, in contradiction of model simulations that suggest hyperthermal winter temperatures were below freezing6. In light of our reconstructed temperature and hydrologic trends, we conclude that the temperature and hydrographic responses to abruptly increased atmospheric CO2 concentrations were similar for the ETM2 and the better-described Palaeocene–Eocene Thermal Maximum7, 8, 55.5 Myr ago."
10/26/2009, "Palms once grew in ice-free Arctic," Reuters, Alister Doyle, via ABC.net.au
"Palms flourished in the Arctic during a brief sweltering period about 50 million years ago, according to a study that hints at gaps in our understanding of modern climate change.
The scientists, sampling sediments on a ridge on the seabed about 500 kilometres from the North Pole and up to 53.5 million years old, found pollen from ancient palms as well as of conifers, oaks, pecans and other trees.
"The presence of palm pollen implies that coldest month mean temperatures over the Arctic land masses were no less than 8°C [46.4F]", the scientists, based in the Netherlands and Germany, write in the journal Nature Geoscience.
That contradicts computer model simulations, also used to predict future temperatures, that suggest winter temperatures were below freezing even in the unexplained hothouse period that lasted between 50,000 and 200,000 years ago during the Eocene epoch.
Climate surprisesSluijs says that it was also striking that palms, which do not lose their leaves in winter, grew in an area where the sun does not shine for about five months. Experiments with modern palms indicate that they can survive prolonged darkness.
The scientists say the presence of palms, it was not clear if they were trees or plants, hinted that the modern climate system could yield big surprises.
According to the UN Intergovernmental Panel on Climate Change, global temperatures are rising, due in part to human-made greenhouse gases, mainly from burning fossil fuels.
In 2007, Arctic ice shrank to its smallest size since satellite measurements began in the 1970s.
One possibility for the ancient spike in temperatures was an abrupt rise in carbon dioxide levels, far beyond current concentrations. That might have been caused by volcanic eruptions, or a melt of frozen methane trapped in the seabed.
"We cannot explain this with the current knowledge of the climate system," says Sluijs. One possibility was that new types of clouds formed in the Arctic as it warmed, acting as a blanket that trapped ever more heat and accelerated warming.
"If the ocean was very warm it's possible that these clouds form at a higher latitude than now," he says. Such effects caused by new cloud formation could be an unexpected tripwire in accelerating modern climate change."
6/12/2009, "Ancient Arctic beasts ate rotting matter," abc.net.au, Michael Reilly, Discovery News
"Creatures roaming the balmy swamps and forests of the prehistoric Arctic survived the long dark season by switching diets, according to a new study.
The research, which was led by Jaelyn Eberle, an assistant professor at the University of Colorado in Boulder, appears in the latest edition of the journal Geology.
Canada's Ellesmere Island is a frigid tundra. But 53 million years ago it resembled a swamp, teeming with plants and crowded with alligators, turtles and tapirs. Even lemur-like creatures swung from the trees.
Scientists have long wondered how the animals survived the long winter.
Though temperatures didn't often get below freezing, plants must have gone into hibernation during the six months of darkness.
New evidence extracted from the teeth of the hippopotamus-like Coryphodon suggests they subsisted on leaf litter, decaying fruits and twigs through the winter.
Eberle and colleagues sampled carbon isotopes from the teeth of nine Coryphodons, three tapirs and two rhinoceros-like brontotheres, all of which lived on ancient Ellesmere.
The results show the plant-eaters lived off of abundant flowering plants, leaves and greenery in the spring and summer months. But in the winter they switched to eating dead and dying plant matter and fungi.
"People first discovered alligators in the high Arctic in 1975, and I've been going up there since the 1990's," says Eberle. "But we never thought to stop and ask 'why?' or 'how?' How were these animals able to survive up there - what made them special?"
Eberle speculates the land-bound creatures evolved a unique digestive system.
Dead plant matter is mostly low in nutritional value, so the animals must have compensated each winter by eating huge amounts of food, and thoroughly digesting it.
"In a way this is a case of truth being stranger than fiction. We don't have an ecosystem like this extinct ecosystem. It's amazing how resistant to changes in light these animals can be," says Christopher Beard of the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania.
He says Eberle's theory is "a persuasive, interesting hypothesis," though he stresses that it's still far from certain.
As global warming affects the Arctic, Eberle expects animals will again move north. But she says it's unlikely alligators or hippos will soon return.
The early Eocone climate of Ellesmere was drastically warmer than present day, averaging temperatures 25°C [77F] more back then."