Wednesday, September 17, 2014
AMHERST — Studying glacial geology is a tantalizing mystery that can offer up a treasure trove of information if you know how and where to dig, believes University of Massachusetts Amherst professor Julie Brigham-Grette.
“It’s like trying to put together a 1,000-piece puzzle and having only 300 pieces to work with,” Brigham-Grette said during a two-day stop last month in Amherst between a field study trip in Norway and presenting her work at a conference in New Zealand.
An expert in climate evolution and sea-level history in the Arctic over the last 3.6 million years, Brigham-Grette has taught for 27 years in the Department of Geosciences at UMass after earning her master’s and doctoral degrees in geology from the University of Colorado in Boulder. Among the courses she teaches are glacial geology and oceanography.
Her research has produced new and compelling information about global climate change, and on Aug. 1 she began a three-year term as chairwoman of the U.S. National Academy of Sciences’ Polar Research Board.
Brigham-Grette, 59, is the chief United States scientist for the International Lake El’gygytgyn Drilling Project in the Arctic. In 2009, researchers there collected one of the longest core samples of sediments ever found in the Arctic, which revealed new information about climate change.
Lake E, as it is called by scientists, was formed an estimated 3.6 million years ago when a meteorite crashed into the Earth 60 miles north of the Arctic Circle in what is now Northeast Siberia. The impact produced a crater 11 miles across.
The lake provides scientists with a continuous record of time, dating back to the meteorite’s impact. Because glaciers did not cover Lake E ,the sediment has been continuously building up since it was formed.
“We can learn more about the entire Earth from marine sediments, because they have been collecting for millions of years,” Brigham-Grette said. “Those sediments contain fossils that tell us about changing water temperatures.”
The cores from Lake E reach back nearly 30 times farther in geologic time than the Greenland ice cores that cover the past 140,000 years. Findings from the initial study, published in Science during 2012 and 2013, were a surprise to scientists.
“What we found that at Lake E, is that 3 million years ago the landscape was forested, and the temperatures were 4 to 6 degrees Celsius warmer than it is now,” Brigham-Grette said.
“So the forested Arctic at that time can be viewed as the long-term equilibration of where we are headed. In other words, in a warming world, the arctic will become forested again,” she said.
Brigham-Grette also said that the difference between the tundra and permafrost Arctic of today, and the forested Arctic of 3 million years ago, suggests that there is a “lag time” between carbon dioxide levels changing and the consequences on the planet.
“The ocean-atmosphere-land system takes time to adjust. The Arctic is now showing it is greening and melting because of what we started decades ago,” she said.
The precise lag time between the changes in carbon dioxide levels and the resulting effects on the planet is debated. “Tipping points vary in different parts of the Earth. The West Antarctic ice sheet, however, has probably passed a tipping point and is now undergoing an unstoppable retreat,” Brigham-Grette said.
The findings of the Lake E study strongly suggest that the response to small changes in carbon dioxide is larger than suggested by earlier models, she said.
Other UMass scientists
Along with scientists from Russia and Germany, three other UMass scientists are involved in the Lake E project.
Isla Casteneda, professor of biogeochemistry and molecular paleoclimatology is leading the work on fossil biomarkers that are used for estimating temperatures of the past. Robert DeConto, professor of climatology, paleoclimatology and Earth system modeling, directs the modeling aspects of the work. Geoscience professor Stephen Burns is an isotope geochemist and works on the isotopic signatures of the organic matter.
Burns said that work was done for a decade on the Lake E project before drilling actually began. He credited Brigham-Grette with having the skills and leadership to keep it moving forward.
“This project would never have happened if it weren’t for Julie and her perseverance,” Burns said. “This is a huge project that required an immense amount of work. She had to pull people together from different countries and get everyone to work collaboratively. I don’t think anyone else could have done that.”
He added, “The records from the sediments in Lake E are entirely unique. There is nothing else like that in the entire Arctic,” Burns said.
According to Brigham-Grette, 65 million years ago when the dinosaurs existed the carbon dioxide level was at about 1,000 to 1,500 parts per million.
That level began to decrease naturally over time through the process of mountain building and the “weathering” of rocks and minerals which use up carbon dioxide and lead to a cooling effect.
From the fossil record of air trapped in ice cores, scientists know that over the past 800,000 years, the carbon dioxide in the atmosphere was between 180 and 280 parts per million.
“Today our Earth’s atmosphere measures carbon dioxide at 400 parts per million because of what humans have done in only a few hundred years. That rate is accelerating because of our use of fossil fuels,” Brigham-Grette said.
“We have not seen natural long-term levels of 400 parts per million for over 3 million years. Humans are putting CO2 into the air much, much faster than the oceans and the Earth’s surface can process,” she said.
To interpret the information contained in the Lake E core samples, researchers need to look no further than the Hartshorn Laboratory for Quaternary Research that opened in the fall of 2011 at UMass.
The state-of-the-art facility features instrumentation for the analysis of geologic samples and sediment cores including a $300,000 Geotek core splitter and a multi-sensor core scanner used for producing high resolution photography, color scanning, and magnetic susceptibility.
According to Brigham-Grette, researchers and teachers from the United States and other countries come to the UMass research lab which is one of a handful of facilities with such advanced technology.
“This room used to be just an ugly classroom with aluminum tables and no cabinetry,” Brigham-Grette said as showed off the lab named for geology professor Joseph Hartshorn who recruited her to take his position when he retired in 1987.
“When students come in here, I want them to know who Joe was and about the contributions he made,” she said, pointing to a large photograph of Hartshorn and several maps that he created during his tenure at UMass.
Embracing climate change
Brigham-Grette spent part of the summer in Svalbard, a Norwegian archipelago midway between continental Norway and the North Pole. With her were six undergraduate students from across the country as part of the Svalbard Research Experience for Undergraduates. It was established by the National Science Foundation to encourage and fund student research opportunities in polar science.
The program focuses on understanding how high-latitude tidewater glaciers, meltwater streams, and sedimentation in fjords respond to a changing climate.
Since 2005, undergraduate students have been selected to participate in the summer field program during which they work on individual projects with faculty advisers and other student researchers.
Brigham-Grette said her career began when she received an “A” in her first geology class at Albion (Michigan) College where she received her bachelor’s degree. She said she enjoys the mystery and challenges in searching for answers in her field.
“It never feels like a job, it’s more like making my contribution,” she said. “I feel very privileged to be doing the kind of work I do.”
She and her husband Roger Grette live in Amherst and have two sons, Karl, 24, who graduated from UMass with a degree in geology, and Erik, 21, who attends Greenfield Community College.
“My family will say that work is my fun,” Brigham-Grette said. “But I enjoy jogging, gardening and getting into cooking. I have also been teaching confirmation classes at Immanuel Lutheran in Amherst. Faith and science can mix.”
Before her teaching responsibilities started this semester, Brigham-Grette traveled to Auckland, New Zealand, to attend the Scientific Committee for Antarctic Research conference. There she gave a presentation titled “Understanding Inter-Hemispheric Polar Linkages Suggested by the Arctic Lake El’gygytgyn Paleoclimate Record of the Past 3.6 Million Years.”
She explained, “Climate change is something that we have to embrace, not fear. I think some people avoid dealing with it in the same way that they avoid going to the doctor. It’s like health avoidance — they don’t want to know anything because they know they could be ill.”
Brigham-Grette said that she remains optimistic as more countries take leadership roles in addressing global climate change. “I think we have to see it as a tremendous opportunity to invest in alternative energy like solar and wind and to create energy-efficient buildings,” she added.
Brigham-Grette said that continued education on the subject will inevitably lead to changes on how we tackle the issue of a changing climate.
“It’s here and its undeniable. Europeans understand the science, they get it,” Brigham-Grette said. “What they don’t get is why we don’t get it.”