Healthy, undisturbed soil sinks carbon, storing what’s generated when plants and other living things decompose so it doesn’t get released as a planet-warming greenhouse gas.
But a new study out of UC Riverside suggests nitrogen pollution from cars and trucks and power plants might make soil release that carbon in Southern California and other similarly dry places – worsening, rather than helping to fight, climate change.
Dryland ecosystems like ours cover roughly 45% of land on Earth. They also store 33% of the carbon found in the top layer of soil worldwide. So if nitrogen pollution is making the carbon stored in these soils vulnerable, that definitely rings some alarm bells, said Peter Homyak, an environmental sciences professor at UC Riverside who co-authored the study.
The findings offer new motivation, then, to speed the transition away from fossil fuels and cut back on nitrogen-rich fertilizer if we want to slow global warming that’s already creating climate refugees due to worsening heat waves, droughts, floods and wildfires.
“Our study highlights once again how nitrogen pollution can affect even the non-living environment around us, beyond the well-established detrimental effects of air pollution on us humans,” said Johann Püspök of Austria, who started the study while he was Homyak’s student at UC Riverside. “So, getting a grip on air pollution and fertilizer overuse is still an important task.”
In places that get more regular rain and snow, other studies have shown that adding nitrogen to soil can increase carbon storage. Nitrogen fuels plant growth, which captures carbon and draws it down into the soil. It also helps slow decomposition of whatever is in the soil.
That’s not what happened when Püspök’s team analyzed nitrogen-enriched soil across Southern California, which has some of the worse nitrogen pollution levels in the world.
They took samples from areas at Irvine Ranch National Landmark in Orange County, Sky Oaks…
Read the full article here
