MISSOULA - University of Montana researchers have contributed to a study forecasting significant ice loss in Greenland. According to the study just published in the journal Nature, Greenland will lose more ice this century than in the past 12,000 years if greenhouse gas emissions are not curbed.
Through a multiorganizational collaboration, the study brought together climate modelers, ice core scientists, remote sensing experts and paleoclimate researchers.
The team used ice sheet modeling to reconstruct the ancient climate, measuring the accuracy of the model against real-world measurements taken by satellites, aerial surveys and field work. Focusing on the southwestern sector of the Greenland Ice Sheet, they traced the ice sheet from the Holocene epoch 12,000 years ago and projected the ice sheet's future into 2100.
Jesse V. Johnson, a UM professor of computer science, and Jacob Downs, now a UM postdoctoral researcher in applied mathematics, joined the study.
While other researchers focused on discovering how the ice sheet has changed over time, Johnson and Downs measured past climate and temperatures through studying concentrations of gases trapped in the ice. By integrating data from ice sheet retreat and past temperatures into a numerical model of ice dynamics, they then estimated how snowfall has fluctuated with temperature changes the past 12,000 years and could impact the study's modeling results.
Working with such a large, diverse team was eye-opening to Johnson and Downs and helpful for contextualizing their research.
"There is so much incredible science that we were totally ignorant of," Johnson said. "We learned how the climate of the past can be found by measuring the waxes in leaves trapped in the mud under lakes and how micro-fossils found in the ocean can tell you the water's temperature. We really didn't know much about this area of paleo-climate proxies going into this project, but came away fascinated with what they can tell us about Earth's climate history."
The results of the Greenland Ice Sheet study, however, were sobering.
"Basically, we've altered our planet so much that the rates of ice sheet melt this century are on pace to be greater than anything we've seen under natural variability of the ice sheet over the past 12,000 years," said Jason Briner, professor of geology at the University at Buffalo and study lead.
Johnson said the results of the study can't be underscored enough, and comparing today's enormous potential loss with past loss over 12,000 years is important to put it into perspective.
"Such comparisons are critical in understanding what we are living through now," Johnson said. "These changes are much greater than what has been experienced in more than twice the recorded history of homo sapiens. We often wonder what our ancestors would have done when faced with similar circumstances. In this case, the answer is that we don't know. Our ancestors never experienced anything like this."
Briner said the answer lies in the world curbing greenhouse gases. Currently, the Greenland Ice Sheet is set to lose four times its largest loss in 12,000 years in the high greenhouse-gas emissions scenario known as RCP8.5 by the Intergovernmental Panel on Climate Change.
Under a reduced-emission RCP2.6 scenario, however, the ice loss will only be slightly bigger than what the ice sheet has experienced the past 12,000 years.
"Our findings are yet another wake-up call, especially for countries like the U.S.," Briner said. "Americans use more energy per person than any other nation in the world. Our nation has produced more of the CO2 that resides in the atmosphere today than any other country. I think Americans need to go on an energy diet."
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Researchers on the study came from the University at Buffalo; the University of California, Irvine; NASA's Jet Propulsion Laboratory; the University of Washington; Columbia University; Université du Québec à Montréal; the Geological Survey of Denmark and Greenland; and NASA's Goddard Space Flight Center.
The research was supported by the National Science Foundation, NASA, the Natural Sciences and Engineering Council of Canada and the Québec Research Funds.
Journal
Nature