Battling air pollution may contribute to climate change by impacting soil carbon storage

Decades-old policies aimed at improving air quality may also be accelerating global climate change, warns a recent study published in the journal Ecology.

For generations, nitrogen pollution in the air has worked its way into ecosystems in a process called deposition, leading to greater carbon stores in soils around the world (among many other consequences). Since the 1970s, however, rates of nitrogen deposition have fallen as multinational agreements targeting air pollution took effect. Now, nearly 30 years of data from a long-running nitrogen deposition experiment in Michigan suggest that the improvements in air quality are rapidly reversing carbon gains in soils.

With less nitrogen pollution coming from the atmosphere, soil microbial activity is picking up, ramping up decomposition and decreasing the amount of carbon retained and stored in soils. This reduction in soils' capacity to serve as carbon sinks could compromise efforts to mitigate climate warming, say the authors, especially if similar patterns are repeated in forest systems across the planet.