The United States and China announced new goals for reducing their global warming pollution in the coming decades, with the U.S. ramping up its rate of decarbonization in five to 10 years and China promising that its carbon emissions will peak in the next 15 years. The announcements, which came at a multinational summit in Beijing Tuesday, made clear for the first time the commitments that the two biggest sources of greenhouse gases will make as part of the urgent United Nations negotiations. 

It is important to note that absolute scarcity doesn’t have to be on the horizon in any given resource category for this scenario to kick in. A lack of adequate supplies to meet the needs of a growing, ever more urbanized and industrialized global population is enough. Given the wave of extinctions that scientists are recording, some resources -- particular species of fish, animals, and trees, for example -- will become less abundant in the decades to come, and may even disappear altogether. 

More than three dozen national security officials, members of Congress and military leaders are warning of the threat climate change poses to U.S. national security, the latest in an indicator that U.S. intelligence and national security circles are increasingly worried about a warming planet. In a new bipartisan open letter, they stress the need for urgent action and call on both public and private support to address issues that included forced migration and the displacement of vulnerable communities, as well as the dangers related to food production during extreme weather events.

Aside from Mitt Romney's recent jab at Barack Obama's concern over global warming—and the president's tit-for-tat response—climate change has been largely under the radar in the campaign. But several groups, backed by hundreds of thousands of petitions, are trying to change that, at least for one night. Nine environmental organizations Friday delivered more than 160,000 petitions to Jim Lehrer urging him to ask a question about climate change during Wednesday's first presidential debate. 

The words global warming used to mean something. When the term became popular in the early 1990s, it sounded like something out of a science-fiction movie. Today, however, it is thrown around casually and most people seem to have forgotten its implications. (Similarly lost is the significance of April 22 — Earth Day; don’t pretend like you remember.) Of course, there are those dutiful citizens who are doing their best to combat global warming: refusing plastic bags at the bodega; driving under 60 mph with the windows up and the air-conditioner off; and buying recycled paper towels. But the actions of a few have next to no impact on global climate change.