Hudson Bay, Cape Churchill, Manitoba, Canada.
Global warming tends to crowd out other environmental threats, and with good reason — the warming we're baking into the atmosphere has the potential to utterly change the planet, and almost certainly for the worse. 2012 is already on track to be the warmest year on record, while global carbon emissions just keep rising. Will Rio+20 make a difference? It's hard to be hopeful given the repeated failure of the international community to agree to a global deal to reduce carbon emissions. Rio will likely focus more on spreading renewable energy and the green economy than on specific plans for carbon cuts, but nations will get another chance to negotiate at the annual U.N. climate summit in Qatar at the end of the year.