UVa scientists to study land use impact on climate change

University of Virginia scientists will lead a mapping and modeling project that could help answer an important question in climate change research: How does land use affect the planet's climate?

"There are global implications for every land use decision," said Deborah Lawrence, an environmental scientist at UVa. Most of these decisions are made in terms of economics; Lawrence said she wants to get the international community talking about the way those decisions - clearing forest to make way for agriculture or urban areas, for example - fit into the context of climate change.

"How do we use the land?" Lawrence said. "Let's consider the fact that it's going to affect the climate."

Land-cover change and climate are part of the same feedback loop, Lawrence said. Changes to Earth's surface, especially clearing forest, affect the reflectivity of the planet's surface and the water cycle, which can contribute to climate change and affect natural habitats, she said.

Switching to biofuels frequently is touted as a way to help slow climate change, but this could have unforeseen consequences, according to Lawrence. Increased reliance on biofuels could mean converting more land to farmland. That, as well as the additional food needed for an increasing population, could affect the global climate, she said.

Maintaining this delicate balance is what the project is all about. Lawrence and her team, which includes other UVa faculty and scientists from China, Russia and Canada, will use computer models devised by the National Center for Atmospheric Research to look for the right balance between forest, urban and agricultural land use. They also can see what happens in a variety of hypothetical situations, such as dedicating a large part of the remaining usable land to biofuel production.

"There's a cooling effect, but there's also a big carbon loss - is that offset by the cooling?" Lawrence said. "It gives us a window to look at a future world."

The model is extremely complex. It splits Earth's land surface into about 260,000 cells with sides 50 to 100 kilometers long. Each cell has different proportions of forested, bare, urban and agricultural land, which affect thousands of other variables, including reflectivity, water runoff and water cycled into the atmosphere. All of these things change when the land use inside a cell is altered.

Decisions on how to use millions of square miles of land can't be made by any one person or entity, but Lawrence said she hopes to give policymakers a starting point. They already talk about land use planning, she said, just not in the context of climate change. And although they're getting better at monitoring carbon dioxide buildup and its effect on climate, most policymakers don't think about the way land use connects to climate change.

"The issue is, for some reason, people are not dealing with the biosphere as much," Lawrence said. "There's always room to be thinking bigger."

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UVa scientists to study land use impact on climate change