Trees are nature's tool for pulling carbon dioxide out of the air, but there aren't enough trees in the world to suck up all the CO2 humans are putting there. That's why researchers are pushing to create artificial leaves to help fight climate change.
The annual report included for the first time an estimate of the additional carbon dioxide emissions attributed to traffic congestion. It could help further visualize a largely invisible pollution problem.
The recent announcement that the Chicago Climate Exchange will soon cease its carbon trading system saddened some environmentalists. At one point, members did a fair bit of business, voluntarily buying and selling carbon emissions, metric tons of CO2, as commodities.