Chlorine gas was used by both sides during World War I but was banned by the Geneva Protocol, along with the use of other poison gases, after the end of the war.

CNN: Al Qaeda's track record with chemical weapons

He is now representing a new coalition, "All Risk, No Reward, " which opposes Keystone XL. It goes after the additional greenhouse gases but also showcases the damage causes by spills to Americans in the heartland.

CNN: Oil, money and politics; EPA snags Keystone XL pipeline

After climbing relentlessly to reach 781 megatonnes last year, Canada's emissions of gases linked to climate change will start to fall within three years, he promised.

ECONOMIST: Trying again on emissions policy

The earth, after all, may be going through one of its warming phases whether we release greenhouse gases or not.

FORBES: Global Food Wars

California, after all, only accounts for about 2% of the world's output of greenhouse gases.

ECONOMIST: Going deeper green

While the aircraft has flown before, this was the first flight for it after being loaded up with eleven different scientific instruments, which will be used to examine trace gases, aerosols, and dynamics of the upper troposphere and lower stratosphere.

ENGADGET: NASA's unmanned Global Hawk completes key test flight