College Station, Tex.-Fertilizer and other nitrogen sources, which have taken the blame for creating dead zones in the Gulf of Mexico and other large water bodies, actually may be a factor in reducing greenhouse gases, according to a team of international scientists. Thirty experts from institutions around the world under the direction of Texas A&M University Distinguished Professor of Oceanography and Atmospheric Sciences Robert Duce have concluded that human-caused atmospheric nitrogen compounds, which are carried by wind and deposited into the ocean, increase production of marine plant life, which causes carbon dioxide to be drawn from the atmosphere into the ocean. This process removes about 10 percent of the human-caused carbon dioxide in the atmosphere, potentially reducing the climate warming, according to the team’s paper, which is published in the current issue of the journal Science. The human-caused nitrogen fertilization of the ocean removes some of the most important greenhouse gas – carbon dioxide – from the atmosphere, Duce emphasized. However, he cautioned, this gain is offset by the nitrogen compound nitrous oxide that also forms in the ocean due to the nitrogen fertilization and is re-emitted into the atmosphere. Nitrous oxide is a powerful greenhouse gas itself – about 300 times that of carbon dioxide – thus canceling out about two-thirds of the apparent gain from the carbon dioxide removal, he explained. However, he continued, “The whole system is so complex that we’re still rather unsure about what some of the other impacts might be within the ocean. Still, if you don’t consider the impact of human-caused nitrogen when trying to model climate change, you’re missing a possibly significant part of the overall carbon cycle as well as the nitrogen cycle. Nitrogen deposition is potentially a very important factor in the climate change issue.”
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