We have seen record-breaking temperatures in major cities across the United States this month -- just one more indication that we are experiencing the increasingly devastating impacts of climate change and need to alter our course immediately. One important step would be to reject the Keystone XL pipeline which will pump dirty tar sands across the heartland of the United States. Tar sands oil is the dirtiest, most carbon-intensive fossil fuels on the planet. Stopping Keystone XL will indeed be a big step against the tar sands. Demand that President Obama show climate leadership by signing this petition calling for the rejection of Keystone XL.