Changes in temperature and precipitation have already impacted the amount of nitrogen introduced into U.S. waterways, according to new research from a team of three Carnegie ecologists published this week in Environmental Science & Technology.
Nitrogen from agriculture and other human activities washes into waterways, which, in excess, creates a dangerous phenomenon called eutrophication. This can lead to toxin-producing algal blooms or low-oxygen dead zones called hypoxia. Over the past several summers, dead zones and algal blooms in lake and coastal regions across the United States have received extensive news coverage.
Carnegie’s Anna Michalak and her team have spent several years studying the effects of nitrogen runoff and how expected changes in precipitation patterns due to climate change could lead to greater risks to water quality.
But their efforts so far have focused on making predictions of the future. Now, with Tristan Ballard, they looked backward to analyze long-term trends in nitrogen runoff going back to the 1980s.
“We wanted to see whether we could find evidence in the historical record of changes in temperature and precipitation affecting the amount of nitrogen that gets into watersheds in the contiguous U.S.,” said lead author Ballard. “Our findings could improve our modeling of future risks and guide management efforts.”
They found that climate was a key factor in how much nitrogen ended up in the water system, with warming springtime temperatures and accompanying storms having a direct impact on nitrogen runoff.
Read more at Carnegie Institution for Science