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University study investigates northern lake emissions

Recent study by University researchers examines how natural carbon emissions affect climate models

By
Staff Writer
Tuesday, April 9, 2019

While most stories about greenhouse gas emissions focus on those from cars, planes and other forms of human consumption, carbon emissions from natural sources, while often neglected in the news, are also important to climate models.

Lakes in the northern regions of Canada, Alaska and Russia, also known as boreal lakes, are sources of naturally occurring greenhouse gas emissions. In a recent University study that could transform the current emissions models in the boreal lakes region, small satellites allowed a team of scientists to study the fluctuating water levels of small lakes across northern Canada and Alaska.

The team of researchers, led by Sarah Cooley, a PhD student in the Department of Earth, Environmental and Planetary Sciences at the University, studied the shoreline fluctuations in various regions using small satellites called CubeSats. The researchers explored the Canadian Shield, a previously understudied area that was thought to have relatively stable water levels. They found that the shoreline changes in these landscapes are surprisingly dynamic.

There is a universal decline in lakes’ areas over the summer season, spanning from late May to the end of August. Notably, there were many fluctuations in water levels in the Canadian Shield, an area with a rocky topography and many rivers.

The fieldwork for this research was based on the National Aeronautics and Space Administration’s Arctic-Boreal Vulnerability Experiment. Four main study areas were chosen for this project, with the intention of capturing a diverse set of geographic characteristics. The northern high latitudes contain millions of lakes that have never been studied, despite their role as important indicators of greenhouse gas emissions, said Laurence Smith, professor of geography at the University of California at Los Angeles. Researchers had never before been able to study fluctuations in lake area with both high resolution and high frequency, he added.

Cooley outlined two main goals for this research. “The first goal,” said Cooley, “was to use this new type of satellite known as CubeSats.” This relatively new technology has only been used for research in the last couple of years. Due to their small size, the CubeSats can take a picture of every part of Earth at three meter per pixel resolution.

The second goal was to study northern Canada and Alaska over a shorter time period than most previous research, since the lakes in this region have been losing area over the past fifty years.

The researchers were able to develop methods to analyze the large size of the data string produced by CubeSats imagery. An artificial intelligence device was created to filter over 25 terabytes of data and remove the unnecessary  information. The method involved “machine learning and computing software to take a massive data set and simplify it to accurate observations of the data,” Cooley said. With this new high-resolution technology, the researchers observed much finer changes in lake areas.

These results have two main implications. First, “the fluctuation in lake area will affect carbon dioxide and methane emission,” which is not taken into consideration by most current models, Cooley said. Second, machine learning makes it possible to analyze a large amount of CubeSats data efficiently. “Our ability to obverse the Earth at a higher resolution is orders of magnitude better than it has been previously,” she said.

Prior to this research, Cooley had studied the hydrology — water properties in relation to the environment — of the Arctic on a short time scale and “wanted to take this methodology and apply it to northern Canada and Alaska.”

In the future, these researchers hope to expand the scope of study to other parts of the Canadian Shield and are searching for new ways to incorporate CubeSats. “CubeSats are a powerful new tool in water resource management,” Smith said.

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