Because of global warming, the oceans are expected to rise. A large part of this is due to ice which is sitting on land in Greenland and Antarctica falling into the ocean.
My idea is to put a row of nuclear power plants on the coast of Greenland which will double as giant "snow machines" which, when the weather is cold enough, will shoot water from the ocean into the air so it will fall as snow over Greenland. This will not keep the world from warming, but it will keep the sea from rising.
A nuclear power plant basically just uses steam to turn a giant turbine connected to a generator. To double as a "snow machine", it would have to be adjustable to sometimes (i.e the right season and weather conditions) connect to a giant water pump instead. I'm picturing that it would pump the water up a giant tube about the height of a large skyscraper, where the skyscraper is maybe a mile offshore, so the salt in the water falls back into the ocean. Alternately, some of them could pump water from fresh water inland rivers where salt wouldn't be an issue.
The power from the nuclear power plants would be sent to both the US and Europe via giant underwater cables (is this possible?). The upside to this is that the nuclear power plants will be located far away from people, so the normal political opposition to building them would not be an issue.