A Wisconsin congressman is calling President Donald Trump "a moron" over a tweet that urged global warming to "come back fast" in the face of dangerous cold hitting the Midwest.

Hundreds of schools in the region cancelled classes through Wednesday, and the governors of Wisconsin and Michigan declared states of emergency amid wind chills as low as negative 60 degrees

Trump has frequently cast doubt on climate change, especially when cold weather hits. His tweet late Monday wondering "What the hell is going on with Global Warming" drew a quick response from Wisconsin Rep. Mark Pocan.

The Democrat responded by saying: "Only a moron would not understand global warming causes huge temperature swings."

Others also weighed in on Twitter, in replies to Trump's original post:

Northern Illinois University climate scientist Victor Gensini said the cold snap is "simply an extreme weather event" and doesn't represent the global trend toward a warming Earth. He noted the record heat currently in Australia.

The New York Times summed up the difference between climate and weather this way: Climate refers to how the atmosphere acts over a long period of time, while weather describes what’s happening on a much shorter time scale. Or, to use an analogy Trump might appreciate, weather is how much money you have in your pocket today, whereas climate is your net worth.