UMass Amherst to Study Changes in Arctic Rain/Snow Regimes

A group of students working with climate scientist Michael Retelle of Bates College on Linnevatnet (Lake Linne) in early spring on the Arctic island of Svalbard.
Students working with climate scientist Michael Retelle of Bates College on Linnevatnet (Lake Linne) in early spring on the Arctic island of Svalbard.

AMHERST, Mass. – Scientists know that the Arctic is warming faster than any other region, and this is associated with greatly reduced extent and seasonal persistence of sea-ice. Now a team of geoscientists has launched studies to investigate “a new hydrological regime” there, which means more rain than snow, especially in fall and spring, and possible increases in flash flooding, and earth moving over frozen ground on steep slopes with the risk of catastrophic slope failure.

Climate scientists Raymond Bradley, Distinguished Professor and director of the Climate System Research Center at the University of Massachusetts Amherst, and Michael Retelle at Bates College, Lewiston, Maine, say they suspect that recent conditions in the Arctic are unique in the last 1,000 years.

The two have received a three-year, $760,430 grant from the National Science Foundations’ Office of Polar Programs to support their research into newly emerging conditions on the island of Svalbard in the Norwegian Arctic. UMass Amherst will receive about $502,000 and Bates’ Retelle, an alumnus of the UMass Amherst geosciences program, will receive just over $258,000.

The researchers point out that changes such as more flash flooding and landslides can lead to a significant increase in the amount of sediment carried in rivers and streams, plus a change in their characteristic grain size, changes that are recorded by sediments deposited in lakes. They will study lake sediments in western Svalbard to identify the sedimentary signature of recent changes. They will then use this to reconstruct the long-term history of rainfall-related sedimentary events to determine when similar conditions may have prevailed in the past.

Bradley, an expert in using lake-bed sediment core samples to reconstruct past climate conditions, says, “We plan to use cores of lake sediments as a sort of tape recorder of how the climate and hydrology of the region have changed over time, to give us a long-term perspective on modern conditions. We expect future changes in climate will result in more rainfall and this may lead to additional flooding and landslides, creating dangerous conditions for communities in the Arctic. Svalbard has already started to see such changes, but other regions will likely be affected in the future as sea ice disappears and warmer conditions set in.”

As he explains, the type and amount of sediment transported to lakes carries with it information about weather and hydrological conditions in the lake watershed. The researchers plan to use sediment traps, micro-analytical techniques for high-resolution grain-size analysis, and to detect and measure single-year summer/winter deposits known as varves. They will also use scanning electron microscope image analysis to reconstruct rainfall-driven sedimentary events. They plan to obtain grain-size profiles using a laser particle-size analyzer to compare them with observed hydro-climatic events and other records.

In this way, they will be able to directly link high-magnitude rainfall events to sedimentary characteristics and apply that understanding to the long-term varved records, Retelle points out. “This will provide a unique perspective on the nature of recent sedimentary changes and provide insight into the effects of contemporary changes in climate on the hydrological regime of this region.”

Their results should have implications for other parts of the Arctic where sea ice is rapidly receding, the researchers add. The research will include contributions from a postdoctoral researcher, undergraduates from UMass Amherst and Bates College and a teacher from the Arctic Research Consortium of the United States Teachers and Researchers Exploring and Collaborating (PolarTREC) program. It allows U.S. teachers to spend three to six weeks in hands-on field research in polar regions so they then may incorporate Arctic earth science activities into their classes.

Retelle and Bradley say the work will also contribute to an important Arctic science initiative in Norway known as the Svalbard Integrated Arctic Earth Observing System, supported by that country’s Research Council.