Terrestrial biosphere contributing to warming climate

Field at sunset

NAU assistant professor Deborah Huntzinger and a group of researchers have analyzed the net balance of three greenhouse gases, comparing amounts of gases released into the atmosphere with carbon dioxide absorbed by land and seas.

The article published this week in Nature, detailed findings from the first study of its kind: evaluating releases of methane and nitrous oxide into the atmosphere and subtracting the terrestrial uptake of carbon dioxide.

Biogenic fluxes were measured, which include natural processes of gas emissions from soil and wetlands, as well as increased emissions from human activities, primarily agricultural-based practices like fertilization. Data from burning of fossil fuels were not included in the study.

The researchers used greenhouse gas data from 2001 to 2010 and compared it to information from pre-industrial-era emissions, enabling the team to explain changes created by human activity.

Southern Asia, with 90 percent of the world’s rice fields and the prolific use of nitrogen fertilizer, represented the most significant net climate warming effect from biogenic emissions. The terrestrial uptake of carbon dioxide in North America and northern Asia was equal or greater than the human-caused biogenic emissions of methane and nitrous oxide, leading the researchers to suggest those regions have a small but significant role in mitigating climate warming.

The findings suggest that worldwide, human activities are profoundly affecting the land biosphere, making them a contributor to changes in climate. The information could inform policy makers working to mitigate global warming, especially in regions with large-scale agricultural activity.