Study finds that carbon feedback in ecosystems may increase global warming

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A study published last month found that global warming may increase over the next half-century due to increased carbon feedback in ecosystems.

The study, published Jan. 29, focuses on measuring climate change and is part of an ongoing investigation spanning more than 25 years by researchers including John Harte, UC Berkeley environmental science, policy and management professor; Scott Saleska, associate professor of ecology and evolutionary biology at the University of Arizona; and Charlotte Levy, doctoral student at Cornell University.

The ongoing study, which began in 1989, monitored 10 30-square-meter plots of meadowland at Rocky Mountain Biological Laboratory in Colorado, focusing on four response variables that could be altered by climate change — the date of snowmelt, aboveground biomass of two vegetation forms, forbs and shrubs and levels of soil organic carbon. Five of these plots were heated with overhead infrared radiators, and five were control plots.

According to Harte, the biggest difficulties in the research process involved setting up the infrastructure, finding a good site, bringing in electricity to power the heaters and erecting the towers and cables from which the heaters are suspended.

150 undergraduate and graduate students worked on the project, maintaining and repairing automated monitoring equipment and conducting routine measurements every year, Harte said.

The results saw a large initial loss in the amount of soil organic carbon followed by a partial recovery. The decreasing soil organic carbon levels are of special interest to the researchers, as lost soil carbon means an increase in carbon in the atmosphere. There was also an increase in shrubs and a decrease in forbs, which means a net decrease in photosynthesis productivity.

“Professor Harte had the vision to establish three decades ago a ‘meadow warming’ experiment in the Colorado Rockies where he simulated a warmed climate with twice the carbon dioxide concentration of pre-industrial levels,” said Daniel Kammen, a UC Berkeley professor of energy, in an email. “This seemed far off then, but the world has continued to steadily increase greenhouse gas emissions, and we are fast approaching this level.”

Using a mathematical model, Harte and his co-researchers predicted that ecosystem responses to climate change could potentially make global warming much worse than what is currently predicted over the next 60 to 70 years.

Harte noted that previous models did not realistically take feedback from systems into account and underestimated the true effects of global warming, adding that his study helped provide a better idea of how to adequately measure climate change.

Harte said, however, that combating the possibility of increasing carbon levels for the next half-century requires implementing cleaner energy sources.

“We need to promote cleaner energy and more efficient use of energy,” Harte said. “Solar- and wind-powered energy plants need to be up and running.”

Contact Jessie Qian at [email protected].