Europe has the largest market for carbon permits in the world. The idea is, the more a company has to pay for permits to pollute, the greater incentive it has to reduce pollution. But the economic slowdown has greatly reduced the cost of permits.
An entrepreneur under contract with a native village in Canada dumped tons of iron in the Pacific to spark a plankton bloom that would capture carbon dioxide. That violated ocean treaties, and angered scientists who are studying that kind of geo-engineering.