The future of the Arctic is now almost set in stone now — warmer, wetter, ice-free, and greener. The last time that CO2 levels were this high, the Arctic temperatures stabilized at temperatures quite a bit warmer than they are now, according to new research done by an international team of researchers led by the University of Massachusetts at Amherst. New sediment cores taken from the ice-covered Lake El’gygytgyn — the oldest deep lake in the northeast Russian Arctic, have now given us the longest continental sediment core ever collected in the Arctic, and further reinforced previous research.
Analyses of the new core provides “absolutely new knowledge” of the Arctic climate from about 2.2 to 3.6 million years ago. And greatly clarifies how exactly “the Arctic transitioned from a forested landscape without ice sheets to the ice- and snow-covered land we know today.”
“While existing geologic records from the Arctic contain important hints about this time period, what we are presenting is the most continuous archive of information about past climate change from the entire Arctic borderlands. As if reading a detective novel, we can go back in time and reconstruct how the Arctic evolved with only a few pages missing here and there,” says Julie Brigham-Grette, the lead researcher from UMass.
As stated before, the new sediment cores came from the ice-covered Lake El’gygytgyn, and were collected back in the winter of 2009. Lake El’gygytgyn is located about 100 km north of the Arctic Circle, and was formed about 3.6 million years ago as the result of a meteorite impact. That meteorite may have been as large as a kilometer in diameter, it blasted out an 11-mile wide crater when it impacted. And ever since, has been collecting sediment layers.
The significant upside to this location is the fact that it lies in one of the only areas in the Arctic that hasn’t experienced significant erosion as a result of continental ice sheets during ice ages. As a result, there is a thick, continuous sediment record there that been almost undisturbed for the past couple of million years. “Cores from Lake E reach back in geologic time nearly 25 times farther than Greenland ice cores that span only the past 140,000 years.”
“One of our major findings is that the Arctic was very warm in the middle Pliocene and Early Pleistocene [~ 3.6 to 2.2 million years ago] when others have suggested atmospheric CO2 was not much higher than levels we see today. This could tell us where we are going in the near future. In other words, the Earth system response to small changes in carbon dioxide is bigger than suggested by earlier climate models,” the authors state.
The sediment cores also shed a great deal of light on the vegetation in the area during this time, thanks to the fossil pollen found in the core, which includes Douglas fir and hemlock. This pollen helps to shed further light on the temperatures and precipitation in this region during these times.
It’s been predicted that within only a couple of decades, much of the now un-forested Arctic will experience a massive greening because of warming temperatures. The warming temperatures and melting ice will also open up the large fossil fuel reserves in the region to exploitation.
Back to the research… “Another significant finding is documentation of sustained warmth in the Middle Pliocene, with summer temperatures of about 59 to 61 degrees F [15 to 16 degrees C], about 14.4 degrees F [8 degrees C] warmer than today, and regional precipitation three times higher.”
“We show that this exceptional warmth well north of the Arctic Circle occurred throughout both warm and cold orbital cycles and coincides with a long interval of 1.2 million years when other researchers have shown the West Antarctic Ice Sheet did not exist,” Brigham-Grette notes. Hence both poles share some common history, but the pace of change differed.
“The Lake E cores provide a terrestrial perspective on the stepped pacing of several portions of the climate system through the transition from a warm, forested Arctic to the first occurrence of land ice,” Brigham-Grette says, “and the eventual onset of major glacial/interglacial cycles. It is very impressive that summer temperatures during warm intervals even as late as 2.2 million years ago were always warmer than in our pre-Industrial reconstructions.”
It’s worth noting that an observed major drop in Arctic precipitation occurred at about the same time that the large Northern Hemispheric ice sheets first expanded and ocean conditions changed in the North Pacific. Acoording to the researchers this observation has important implications with regards to the scientific understanding of what forced the onset of the ice ages.
“The sediment core also reveals that even during the first major ‘cold snap’ to show up in the record 3.3 Million years ago, temperatures in the western Arctic were similar to recent averages of the past 12,000 years.” But at the same time, the conditions weren’t glacial. This raises new questions about the timing of the first appearance of an ice sheet in the Norther Hemisphere.
“The new Lake E paleoclimate reconstructions and climate modeling are consistent with estimates made by other research groups that support the idea that Earth’s climate sensitivity to CO2 may well be higher than suggested by the 2007 report of the Intergovernmental Panel on Climate Change.”
The new research was just published in the journal Science.