In my mind, there is a question if even a massive reduction in use of fossil fuels can reverse climate change. With the unprecedented warming, the tundra is melting, releasing copious amounts of methane, which is a much stronger GHG than CO2. In addition, the warming ocean waters will cause the release of methyl hydrates, another strong GHG. These form a positive feedback which further increase global warming, releasing more GHGs. It may be time to bend over and kiss it good-bye.