Team finds a better way to gauge the climate costs of land use change

Diana Yates at the University of Illinois News Bureau: Those making land use decisions to reduce the harmful effects of climate change have focused almost exclusively on greenhouse gases – analyzing, for example, how much carbon dioxide is released when a forest is cleared to grow crops. A new study in Nature Climate Change aims to present a more complete picture – to incorporate other characteristics of ecosystems that also influence climate.

“We know that forests store a lot of carbon and clearing a forest releases carbon dioxide into the atmosphere and contributes to climate change,” said University of Illinois postdoctoral researcher Kristina Anderson-Teixeira, who pioneered the new approach with plant biology and Energy Biosciences Institute professor Evan DeLucia. “But ecosystems provide other climate regulation services as well.”

The climate effects of a particular ecosystem also depend on its physical attributes, she said. One such attribute is its reflectivity, a quality climate scientists call albedo. ...Another factor that should be considered is an ecosystem’s ability to release heat through the evaporation of water. The more water available in an ecosystem, the more it cools itself by evapotranspiration or, as DeLucia puts it, “planetary sweating.”

...Scientists have known about biophysical effects for a long time, Anderson-Teixeira said. “But the challenge has been to incorporate them into a single metric that will help us design land-use policies that are going to help mitigate – and not exacerbate – climate change.”

...The researchers compiled data to calculate the “greenhouse gas value” of 18 “ecoregions” across North and South America, and also modeled the ecoregions’ biophysical characteristics. They looked at several types of forest, as well as grassland, tundra, tropical savanna and agricultural crops, such as soy, sugarcane, corn, miscanthus and switchgrass.

....The researchers found that biophysical attributes make a tropical rainforest even more valuable for protection against climate warming, but lessen the climate value of boreal (evergreen) forests in Canada....

Graphic by Kristina Anderson-Teixeira: Tropical rainforests have an even greater climate cooling impact when biophysical attributes, such as evapotranspiration, are included in calculations. Other ecoregions, such as boreal forests, have less climate cooling potential when biophysical attributes are also considered.