Darn. It looks like one promising theory for geoengineering won't work.
When the Coast Guard research vessel John P. Tully churned across the North Pacific in the summer of 2008, scientists on board discovered an anomaly on a microscopic scale. Tiny ocean plants called phytoplankton were blooming like crazy.
By sheer luck, the ship was sailing through an event that temporarily turned the North Pacific Ocean into a colossal lab experiment. The findings – published Tuesday by a Canada-U.S. team led by University of Victoria oceanographer Roberta Hamme – have dashed a hopeful theory: that sprinkling iron into oceans to stimulate phytoplankton growth might reverse the effects of global warming.
[. . .]
The free-floating, single-celled plants – the foundation of the marine food chain – absorb carbon dioxide (CO2) when they die, effectively creating a carbon sink in the ocean depths. Based on that knowledge, scientists have suggested that seeding key regions of the ocean with iron could offset carbon dioxide in the atmosphere.
But the phytoplankton bloom in 2008 had only a modest impact on CO2 levels, Prof. Hamme concluded.
Earth’s oceans naturally absorb about two petagrams of carbon annually – compared to the estimated 6.5 petagrams of carbon released each year by fossil fuel consumption. (A petagram is one of those mind-numbing measurements that has too many zeros to really grasp – 15 in all.) The huge plankton bloom barely nudged the meter – Prof. Hamme estimates it absorbed 0.01 petagrams of carbon.
“It tells us the amount of iron we would have to put into the ocean would just be gigantic, and it disappeared so fast, you’d have to keep putting it in over and over again,” she said in an interview.