New NSF paleo research claiming Arctic was warmer fails to take major ocean circulation changes 3 million years ago into account

I covered this story earlier today, and it was presented much differently in that press release. This press release takes a different tack. IMHO, it looks like a big “ooops” from the National Science Foundation. See what I found after the jump on why I think they didn’t perform due diligence on this research – Anthony

Climate Record From Bottom of Russian Lake Shows Arctic Was Warmer Millions of Years Ago

Unparalleled sediment record is “most continuous archive” of ancient Arctic climate

The Arctic was very warm during a period roughly 3.5 to 2 million years ago–a time when research suggests that the level of carbon dioxide in the atmosphere was roughly comparable to today’s–leading to the conclusion that relatively small fluctuations in carbon dioxide levels can have a major influence on Arctic climate, according to a new analysis of the longest terrestrial sediment core ever collected in the Arctic. 

“One of our major findings is that the Arctic was very warm in the middle Pliocene and Early Pleistocene–roughly 3.6 to 2.2 million years ago–when others have suggested atmospheric carbon dioxide was not much higher than levels we see today,” said Julie Brigham-Grette, of the University of Massachusetts Amherst.

Brigham-Grette is a National Science Foundation- (NSF) funded researcher on the sediment core project and a lead author of a new paper published this week in the journal Science that describes the results.

She added that “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 data come from the analysis of a continuous cylinder of sediments collected by NSF-funded researchers from the bottom of ice-covered Lake El’gygytgyn, pronounced El-Guh-Git-Kin, the oldest deep lake in the northeast Russian Arctic, located 100 kilometers (62 miles) north of the Arctic Circle. The drilling was an international project.

Drilling took place in the early months of 2009. The Earth Sciences and Polar Programs divisions of NSF’s Geosciences Directorate funded the drilling and analysis.

Analysis of the sediment core provides “an exceptional window into environmental dynamics” never before possible, noted Brigham-Grette.

“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,” she said. “Like 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.”

Results of the core analysis, according to Brigham-Grette, have “major implications for understanding how the Arctic transitioned from a forested landscape without ice sheets to the ice- and snow-covered land we know today.”

“Lake E,” as it is often called, was formed 3.6 million years ago when a meteorite, perhaps a kilometer in diameter, hit the Earth and blasted out an 18-kilometer (11-mile) wide crater. The lake bottom has been accumulating layers of sediment ever since the initial impact.

Location of Elgygytgyn Lake

The lake also is situated in one of the few areas of the Arctic that was not eroded by continental ice sheets during ice ages. So a thick, continuous sediment record was left remarkably undisturbed. 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.

Important to the story are the fossil pollen found in the core, including Douglas fir and hemlock, clearly not found in this part of the Arctic today. The pollen allows the reconstruction of the vegetation living around the lake in the past, which in turn paints a picture of past temperatures and precipitation.

Another significant finding is documentation of sustained warmth in the Middle Pliocene, with summer temperatures of about 15 to 16degrees Celsius (59 to 61 degrees Fahrenheit), about 8 degrees Celsius (14.4 degrees Fahrenheit) 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 from the ANDRILL project have shown the West Antarctic Ice Sheet did not exist,” the authors point out.

Hence both poles share some common history, but the pace of change differed.

Along with Brigham-Grette, her co-authors Martin Melles of the University of Cologne, Germany, and Pavel Minyuk of Russia’s Northeast Interdisciplinary Scientific Research Institute, Magadan, led research teams on the project. Robert DeConto, also at the University of Massachusetts, led the climate-modeling efforts. These data were compared with ecosystem reconstructions performed by collaborators at University of Berlin and University of Cologne.

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,” she added.

Minyuk notes that they also observed a major drop in Arctic precipitation at around the same time large Northern Hemispheric ice sheets first expanded and ocean conditions changed in the North Pacific. This has major implications for understanding what drove 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. “Most importantly, conditions were not ‘glacial,’ raising new questions as to the timing of the first appearance of ice sheets in the Northern Hemisphere,” the authors add.

This week’s paper is the second article published in Science by these authors using data from the Lake E project. Their first in July 2012 covered the period from the present to 2.8 million years ago, while the current work addresses the record from 2.2 to 3.6 million years.

“This latest paper completes our goal of providing an overview of new knowledge of the evolution of Arctic change across the Western borderlands back to 3.6 million years and places this record into a global context with comparisons to records in the Pacific, the Atlantic and Antarctica,” Melles points out.

The 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 carbon dioxide may well be higher than suggested by the 2007 report of the Intergovernmental Panel on Climate Change.

-NSF-

Principal Investigators

Julie Brigham-Grette, University of Massachusetts Amherst (413) 545-4840 juliebg@geo.umass.edu

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What else happened 3 million years ago? A major change in ocean circulation, that’s what.

The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal. Like many isthmuses, it is a location of great strategic value.^{[citation needed]}

The Isthmus was formed some three million years ago during the Pliocene epoch. This major geological event separated the Atlantic and Pacific oceans and caused the creation of the Gulf Stream.

http://en.wikipedia.org/wiki/Isthmus_of_Panama

So, three million years ago the ocean circulation patterns changed when the isthmus formed, which our intrepid researchers have not mentioned, because in their minds, it couldn’t be anything but CO2 that made it warm then.

But, all they had to do was look around. From NASA in 2003:

Scientists believe the formation of the Isthmus of Panama is one of the most important geologic events to happen on Earth in the last 60 million years. Even though it is only a tiny sliver of land, relative to the sizes of continents, the Isthmus of Panama had an enormous impact on Earth’s climate and its environment. By shutting down the flow of water between the two oceans, the land bridge re-routed currents in both the Atlantic and Pacific Oceans. Atlantic currents were forced northward, and eventually settled into a new current pattern that we call the Gulf Stream today. With warm Caribbean waters flowing toward the northeast Atlantic, the climate of northwestern Europe grew warmer. (Winters there would be as much as 10 degrees C colder in winter without the transport of heat from the Gulf Stream.) The Atlantic, no longer mingling with the Pacific, also grew saltier. Each of these changes helped establish the global ocean circulation pattern we see today. In short, the Isthmus of Panama directly and indirectly influenced ocean and atmospheric circulation patterns, which regulated patterns of rainfall, which in turn sculpted landscapes.

The formation of the Isthmus of Panama also played a major role in biodiversity on our world. The bridge made it easier for animals and plants to migrate between the continents. For instance, in North America today, the opossum, armadillo, and porcupine all trace back to ancestors that came across the land bridge from South America. Likewise, the ancestors of bears, cats, dogs, horses, llamas, and raccoons all made the trek south across the isthmus.

There’s no mention of this “most important geologic events to happen on Earth” in the NSF research that coincided with their paleo record.

And there’s more, from Wood’s Hole:

How the Isthmus of Panama Put Ice in the Arctic

Drifting continents open and close gateways between oceans and shift Earth’s climate

The long lag time has always puzzled scientists: Why did Antarctica become covered by massive ice sheets 34 million years ago, while the Arctic Ocean acquired its ice cap only about 3 million year ago?

Since the end of the extremely warm, dinosaur-dominated Cretaceous Era 65 million years ago, heat-trapping greenhouse gases in the atmosphere have steadily declined (with the anomalous exception of the last century), and the planet as a whole has steadily cooled. So why didn’t both poles freeze at the same time?

The answer to the paradox lies in the complex interplay among the continents, oceans, and atmosphere. Like pieces of a puzzle, Earth’s moving tectonic plates have rearranged themselves on the surface of the globe—shifting the configurations of intervening oceans, altering ocean circulation, and causing changes in climate.

The development of ice sheets in the Southern Hemisphere around 34 million years ago seems fairly straightforward. The supercontinent of Gondwana broke apart, separating into subsections that became Africa, India, Australia, South America, and Antarctica. Passageways opened between these new continents, allowing oceans to flow between them.

When Antarctica was finally severed from the southern tip of South America to create the Drake Passage, Antarctica became completely surrounded by the Southern Ocean. The powerful Antarctic Circumpolar Current began to sweep all the way around the continent, effectively isolating Antarctica from most of the warmth from the global oceans and provoking large-scale cooling.

The Northern Hemisphere is more problematic. From sediment cores and other data, we know that until about 5 million years ago, North and South America were not connected. A huge gap—the Central American Seaway—allowed tropical water to flow between the Atlantic and Pacific Oceans.

A growing body of evidence suggests that the formation of the Isthmus of Panama partitioned the Atlantic and Pacific Oceans and fundamentally changed global ocean circulation. The closing of the Central American Seaway initially may have warmed Earth’s climate, but then set the stage for glaciation in the Northern Hemisphere at 2.7 million years ago.

I think the researcher simply skipped over this important detail is pushing the idea that CO2 was the only issue.

I’m sure Steve McIntyre will be interested in getting a look at the sediments and the dating methods to see if there are errors there. Lately, it seems that paleo research has made some very broad assumptions, and almost always in the favor of the theory.