Geologic Time Lords
Results recently published in Science provide new knowledge that has major implications for understanding how the Arctic transitioned from a forested landscape to the ice- and snow-covered land we know today.
Brigham-Grette, a Professor in the Department of Geosciences and a senior member with the Climate System Research Center, has made trips to the Arctic roughly every othersummer since 1978 to research natural bluff exposures and sediment cores that contain geological snapshots of the climate in prehistoric times. More recently, her body of research has focused on Lake El’gygytgyn (EL-gee-git-gin), a large lake in Northeast Russia that rests inside a crater formed by a meteorite strike 3.6 million years ago. After more than a decade of planning and $10 million in logistical funding, Brigham-Grette and a team of scientists from the U.S., Russia, Germany, and Austria have drilled into the lake to uncover sediment cores that contain the longest, most continuous record of climate in the current geologic time period.
“There’s nothing like it anywhere in the entire northern hemisphere, and [it’s] absolutely unique to the Arctic,” says Brigham-Grette, the U.S. chief scientist on the project, funded by the International Continental Drilling Program and the US NSF. “It’s the first time we have a terrestrial record, on land, of what climate change is like across the western Arctic. All the other information we have so far has come from the deep ocean, far from the arctic borderlands.”
Within this record is the Pliocene, the last major warm period 3.0 million to 3.6 million years ago when carbon dioxide levels in the atmosphere were similar to today and the Arctic was completely forested, according to Brigham-Grette. She hopes her research will also uncover explanations for why summer sea ice has been shrinking faster in the Arctic than models have predicted previously. “For us to understand that, why it’s happening so fast, we need to understand how sea ice changed in the recent geologic past and why it changed and what drove that,” she says.
Brigham-Grette is also working with graduate students to study microscopic fossils of organisms in sea ice and their biomarkers that may lead to further clues about past conditions, as well as provide insight into climate changes we may face later this century. “Having concrete information about natural variability may help us understand the present sensitivity of the Arctic sea ice to change.”
Brigham-Grette’s research on Lake El’gygytgyn has shown that “the Greenland ice sheet can come and go much more easily than we ever thought.” She says the ice sheet has disappeared many times during natural warm periods and that there is an urgent need for further study. Additionally, her team has been able to link warm periods when the Greenland ice sheet disappeared to periods when the West Antarctic ice sheet also disappeared. These geologic records of warm and cold periods provide data for climate modelers to test hypotheses about expectations for present day climate change at either pole.
Some of these implications may be further investigated in collaboration with the new Northeast Climate Science Center based at UMass Amherst. Brigham-Grette says that Center work can lead to better predictions for events like this year’s La Niña, which has resulted in reduced snowfall, as well as better climate communication at the local level.
Some of the most serious effects of climate change, such as a rise of a meter or more in sea level that threatens coastal locations, may not be fully realized until later in the century. This temporal shift makes it difficult for some people to comprehend why they should be worried about the issue now. “We’re so geared toward four years of college, four years in an election cycle … We don’t think very far ahead to see irreversible change,” says Brigham-Grette,
Brigham-Grette describes herself and other geologists as “geologic time lords,” like Doctor Who. Instead of a time machine, the geologists use proxies such as ice cores and sediments containing layers if information, like pages in a book, to go back and forward in time.
Meanwhile, as retreating sea ice in the Arctic is a major concern, it also presents a major opportunity for Brigham-Grette and other geologists. Now, research vessels are able to make their way in summer to areas of the Beaufort and Chukchi seas they could never reach before. Brigham-Grette sees these vessels as “ships of opportunity” for students and faculty researchers to jointly study past climate change from sediment cores from offshore on the continental shelf.
Scientists on these research vessels are also studying the effects that methane bubbling up to the surface from the sea floor will have on the atmosphere. The release of these frozen gas hydrates has also sparked the interest of the oil industry. Brigham-Grette says drilling in the National Arctic Wildlife Refuge is probably inevitable, and thus should be partnered with good science. “If we can partner more of what we do with industry and get them to appreciate and share and also gain from the knowledge we have and vice versa, then that’s a win-win situation for everyone.”
Jed Winer ‘12