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The air at ground level was still last December when Elizabeth Burakowski and Bob Evans, a U.S. Forest Service tower-climbing trainer, prepared to ascend a tower in Durham. But, up 100 feet the wind was blowing. Their task was to place an albedometer鈥攁n instrument that measures 鈥渁lbedo鈥� or how much radiation reflects off of a surface鈥攐n a boom to extend out over the forest canopy.

For Burakowski climbing is all in day鈥檚 work as she earns her doctorate in Earth and environmental science in the interdisciplinary Natural Resources and Earth System Science (NRESS) Ph.D. program at 91制片厂.

鈥淲e understand that recent winter warming trends are linked to greenhouse gases, but over the long term we still don鈥檛 know yet what impact the change in surface albedo has had on winter temperature,鈥� Burakowski says. 鈥淚 aim to answer this question in my dissertation.鈥�

In 2008, Burakowski, working with her adviser Cameron Wake of the Institute for the Study of Earth, Oceans, and Space, conducted the most rigorous analysis to date of wintertime climate data in the northeastern U.S. from 1965 to 2005. Their findings, which were published in the peer-reviewed Journal of Geophysical Research-Atmosphere, showed that the region鈥檚 signature wintertime conditions are disappearing at an ever-increasing rate.

The warming trend of the past 40 years in the northeast coincides with a period during which global and northern hemisphere surface air temperature increases are driven primarily by enhanced levels of manmade greenhouse gases in the atmosphere. The period also has seen a significant decline in the extent of Arctic sea ice. The 11 warmest years in the global instrumental temperature record (since 1850) have occurred since 1995.

Surface albedo 鈥� an absorbing topic

Burakowski鈥檚 doctoral study will be the first to measure the albedo of the New Hampshire landscape in winter and is part of the NH EPSCoR 鈥淓cosystems and Society鈥� research project.

Why is it important in New Hampshire and the region to understand surface albedo in winter?

鈥淚n New Hampshire the decrease in surface albedo can amplify a small amount of global warming. This results in even greater regional warming,鈥� says Research Associate Professor Cameron Wake. When a little warming removes snow cover, the sun shines on the darker surface, which absorbs more energy, warms up faster, enhances warming, and melts more snow. 鈥淚t sets up a vicious cycle for much warmer winters,鈥� Wake explains.

To understand climate change in our region and elsewhere, scientists need to tease out the role of surface albedo. Burakowski鈥檚 research is an important beginning.

鈥淭oday, New Hampshire is the second most forested state in the U.S. with nearly 80 percent forest cover, which is typical for New England,鈥� Burakowski says. 鈥淣ow imagine the New England landscape over 100 years ago, deforested to make way for sheep pasture, fuel homes, and support a booming lumber and paper mill industry. In 1870, as a result of land clearing, New Hampshire鈥檚 forest cover dropped to below 50 percent.鈥�

A snow-covered field has a very high albedo, reflecting most of the sun鈥檚 energy back out to space, leaving very little energy to be re-emitted as heat. The dark forest canopies that have regrown since 1870 now absorb much of the sun鈥檚 energy and help to warm the landscape.

鈥淚t鈥檚 not unlike choosing to wear a white t-shirt on a sunny day,鈥� Burakowski says. 鈥淎 white t-shirt, like a snow-covered field, reflects solar energy to keep you cool. While a dark t-shirt, like a forest canopy, absorbs solar energy and increases surface temperature. Deforestation is like putting a white t-shirt over the landscape, and reforestation is like putting a black t-shirt over it.鈥�

Globally averaged, notes Burakowski, changes in land use have resulted in cooling over the period 1850 to present due to sustained deforestation over much of the Northern Hemisphere. But this is not the case in the northeastern U.S. where forests have been regrowing since the late 1800s. This region has likely experienced warming due to changes in land use.

Building a baseline measure

Burakowski plans to build a baseline measure to understand the effect of land use on albedo in New England. She鈥檒l do this using many tools including satellite imagery, tower and field placement of albedometers, and snow data gathered by a group of 18 鈥渃itizen scientists.鈥� It鈥檚 a long-term project, and eventually, she even hopes to equip her volunteers with infrared temperature guns to evaluate how changes in albedo affect temperature. Finally, using computer models, she鈥檒l recreate historical levels and project future ones.

Burakowski鈥檚 volunteers are all self-proclaimed weather nuts and members of the Community Collaborative Rain Hail and Snow Network (CoCoRAHs). They tend to be pretty plain spoken.

As for the snow this past winter, citizen-scientist Midge Eliassen says simply, 鈥淚t was rotten.鈥�

Nonetheless, everyday this winter at solar noon, Eliassen trudged outdoors to measure the snow or lack thereof. Then using a metal tube, she鈥檇 take a snow core, cap the tube听and weigh it on a scale.

鈥淭hey鈥檝e got a calculation to figure out how dense the snow is. It makes a difference in the albedo readings,鈥� says Eliassen, who is also a longtime water monitor for the Lake Sunapee Protective Association. 鈥淔or example, now I understand the difference in the reflectivity of a conifer versus a deciduous tree canopy. I never knew about albedo until this study.鈥�

Elizabeth Burakowski鈥檚 research is funded by NH EPSCoR鈥檚 鈥淓cosystems and Society鈥� project, an award from the National Science Foundation鈥檚 Experimental Program to Stimulate Competitive Research (NSF# EPS-1101245). .

Written by Carrie Sherman