Ocean geoengineering scheme aces its first field test
https://www.science.org/content/article/ocean-geoengineering-scheme-aces-its-first-field-test
By Paul Voosen, Science.
Excerpt: Alkaline lime powder spread in Florida estuary drew down carbon and reduced acidification. The balmy, shallow waters of Apalachicola Bay, off Florida’s panhandle, supply about 10% of U.S. oysters. But the industry has declined in recent years, in part because the bay is warming and its waters are acidifying because of rising carbon dioxide (CO2) levels. ...state officials encouraged climate scientists to perform an unusual experiment to see whether they could reverse the changes in the water. In May, at an Apalachicola estuary, the researchers injected some 2000 liters of seawater enriched with lime, an alkaline powder and a primary ingredient in cement that’s derived from chalk or limestone. They showed it neutralized some of the acidity and, in the process, drew CO2 out of the atmosphere. ...as CO2 continues to rise and geoengineering a climate solution grows more tempting, ocean liming has a key advantage over other geoengineering proposals, such as schemes to release sunlight-reflecting particles in the atmosphere. “Altering the chemistry of seawater is much more controllable than throwing particles in the air,” McGillis says. Particles can stay in the stratosphere for months or years. Ocean additives tend to only last a month before being diluted and dispersed, he says. “There’s much greater control if it goes south.”...