We dump billions of tons of carbon pollution into the atmosphere each year. As a result, the concentration of carbon dioxide has increased by 40%. Excess carbon dioxide traps excess heat in the atmosphere. Excess heat causes extreme heat waves, droughts, and storms.

This year’s extreme weather follows last year’s. The last twelve months were the hottest on record for the United States. Texas saw its hottest and driest summer on record in 2011 by a wide margin, and research published recently shows that carbon pollution dramatically increased the probability of such extreme heat and drought. The data are in. This is what global warming looks like.