For me it is clear that the extreme weather in the US is caused by global warming and CO2 emissions and other factors.
John Holdren, President Obama’s science adviser, says in the video: “If you’ve been hearing that extreme cold spells like the one that we’re having in the United States now disprove global warming, don’t believe it.”
From the Guardian: “Just 90 companies caused two-thirds of man-made global warming emissions: Chevron, Exxon and BP among companies most responsible for climate change since dawn of industrial age. We know who’s profiting from emissions—let’s bill them. Shell, BP, ExxonMobil and Chevron are some of the 90 entities discovered in a recently published research that contribute to most of the world’s emissions.”