El Niño cycle has a big effect on a major greenhouse gas
Nitrous oxide is commonly associated with laughing gas — the pleasantly benign vapor that puts patients at ease in the dentist’s chair. But outside the dentist’s office, the gas plays a serious role in the planet’s warming climate. After carbon dioxide and methane, nitrous oxide is the third-largest contributor of greenhouse-gas emissions to the atmosphere. The colorless gas is also the top culprit in the depletion of ozone — the layer of the atmosphere that protects Earth from the sun’s ultraviolet radiation. The majority of nitrous oxide emissions arise naturally from soil, where microbes break down nitrogen, releasing nitrous oxide as a byproduct. However, human activities such as farming, and the use of fertilizer, in particular, have increased nitrous oxide emissions over the last 35 years — a rise that has contributed to the overall warming of the planet. Now scientists in MIT’s Center for Global Change Science have developed...