Fifty Degrees Below - Kim Stanley Robinson [75]
“It makes sense to try to work on the trigger we’ve already identified,” Frank said.
Diane nodded. That meant the stalled downwelling of the thermohaline circulation, and she had already begun discussions with the UN and the IPCC broaching the possibility of overcoming the stall. “We’ll get a report on that later. Right now, what about carbon capture methods?”
Frank went down the list he had compiled.
1. freezing carbon dioxide extracted from coal-fired power plants and other industrial sources, and depositing the dry ice on the ocean floor near subduction zones or river deltas, where it would be buried,
2. injecting frozen CO2 into emptied oil wells or underground aquifers (a DOE project, tested by Canada and Norway already),
3. fertilizing oceans with iron to stimulate phytoplankton and absorb more CO2,
4. gathering agricultural wastes and dropping them to the ocean floor in giant weighted torpedoes,
5. gathering ag waste and converting it to ethanol for fuel,
6. growing biomass, both to burn in biofuels and to sequester carbon for the life of the plants (corn, poplar trees)
7. altering bacteria or other plant life to speed its carbon uptake, without triggering release of nitrous oxides that were more potent greenhouse gases than CO2 itself.
This last point was vexing all plans to stimulate carbon drawdown by biological means. “It’s the law of unintended consequences,” as one ecologist had put it to Frank. Now he explained to Diane and the others: “Say your iron spurs the growth of marine bacteria, drawing down carbon, but that includes the growth of types of bacteria that release nitrous oxides. And NOs are a much worse greenhouse gas than CO2. Also, a lot of the carbon in the ocean is fixed in dead diatom shells. Some marine bacteria feed on dead diatoms, and when they do, they free up that carbon, which had been fixed in carbonates that would have eventually become limestone. So is fertilizing the ocean with iron necessarily going to result in a net drawdown in greenhouse gases? Even in the short term it isn’t sure.”
“We need to be sure,” Diane said.
“That’s going to be hard, in this area anyway.”
In another meeting they discussed methods that had been proposed for direct climate alteration, including adding chemicals to jet fuel so that contrails would last longer and reflect more light back into space; seeding clouds; shooting dust into the upper atmosphere in imitation of volcanoes; and flying various sunscreens to high altitude. Again, because of the complexity of the various feedback mechanisms, and the importance of water vapor both in blocking incoming light and holding in outgoing heat, it was hard to predict what the result of any given action would be. No one had a good sense of how clouds might change in any given scenario.
“I don’t think we’re ready for anything like these projects,” Diane said. “We can’t be sure what effects we’ll get.”
At the time she said it, they were all looking at a slide from an NSF polar programs ecologist’s presentation. Both poles were heating up fast, but especially the Arctic; and the slide informed them that one-seventh of all the carbon on Earth was cached in biotic material frozen in the Arctic permafrost, which was rapidly melting. Once it was liquid again, bacterial action would start releasing some of that carbon into the atmosphere. “It could be more positive feedback, like the methane hydrates unfreezing on the continental shelves.”
“It’s the law of unintended consequences again.”
“Wouldn’t the tundra just turn into peat bogs?” Frank asked.
“Peat bogs are anoxic. Permafrost isn’t.”
“Ah.”
In a meeting the next day, a team from NOAA gave a presentation on what they had done to try to get a handle on the numbers involved in any potential scheme to intervene in the North