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Study: Human-Altered Ecosystems Emit Greenhouse Gases

sorting recycling at landfill
(Photo by Christina Estes - KJZZ)
Trash delivered to the Phoenix transfer station at 27th Avenue and Lower Buckeye Road.

A new greenhouse gas study found the Earth’s land surface actually contributes to the warming global climate, counter to what scientists previously believed.

The study is the first to calculate the global balance of carbon dioxide, methane and nitrous oxide. It looked at only “biogenic” greenhouse gases, which come from plants, animals and microbes. “For the past few decades the land surface has been acting as a net sink of carbon dioxide from the atmosphere,” said Deborah Huntzinger, an assistant professor of climate sciences at Northern Arizona University and coauthor of the study. “In a sense it’s mitigating the influence of human actions. But what we found with this study is that when you also consider biogenic sources of methane and nitrous oxide, the terrestrial biosphere is a contributor to climate change.” 

The study found these biogenic emissions have risen since the Industrial Revolution, due to agriculture, sewage, landfills and other human activities. As a result, Huntzinger said, ecosystems contribute to climate change, instead of slowing it down.

Southern Asia is the largest contributor of these gases, likely because of fertilizer on crop fields.

News Science
Melissa grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert. She has a B.S. in Environmental Science from the University of Arizona and an M.FA. in Creative Writing and Environment from Iowa State University.