DETROIT — It’s a question on many blue lips this week, as the Midwest braced for below-zero temperatures for its daily high on Wednesday: How can global warming be true when it’s so cold?

Even President Donald Trump, in a tweet late Tuesday, seemed to question the coexistence of climate change and an arctic chill over much of the U.S.

“In the beautiful Midwest, windchill temperatures are reaching minus 60 degrees, the coldest ever recorded. In coming days, expected to get even colder. People can’t last outside even for minutes. What the hell is going on with Global Waming? Please come back fast, we need you!,” Trump tweeted.

As climate scientists constantly stress, weather does not equal climate.

“Weather is day to day, week to week, and climate is the long-term average of all the weather that occurs over a long period of time, like decades,” said David Easterling, a climate scientist with the National Oceanic and Atmospheric Administration’s Center for Environmental Information in Asheville, N.C.

A commuter braves the wind and snow in frigid weather, Wednesday, Jan. 30, 2019, in Cincinnati. The extreme cold and record-breaking temperatures are crawling into a swath of states spanning from North Dakota to Missouri and into Ohio after a powerful snowstorm pounded the region earlier this week. (AP Photo/John Minchillo)

Commuters braves the wind and snow in frigid weather, Wednesday, Jan. 30, 2019, in Cincinnati. The extreme cold and record-breaking temperatures are crawling into a swath of states spanning from North Dakota to Missouri and into Ohio after a powerful snowstorm pounded the region earlier this week. (AP Photo/John Minchillo)

Commuters braves the wind and snow in frigid weather, Wednesday, Jan. 30, 2019, in Cincinnati. The extreme cold and record-breaking temperatures are crawling into a swath of states spanning from North Dakota to Missouri and into Ohio after a powerful snowstorm pounded the region earlier this week. (AP Photo/John Minchillo)



Commuters braves the wind and snow in frigid weather, Wednesday, Jan. 30, 2019, in Cincinnati. The extreme cold and record-breaking temperatures are crawling into a swath of states spanning from North Dakota to Missouri and into Ohio after a powerful snowstorm pounded the region earlier this week. (AP Photo/John Minchillo)

Commuters braves the wind and snow in frigid weather, Wednesday, Jan. 30, 2019, in Cincinnati. The extreme cold and record-breaking temperatures are crawling into a swath of states spanning from North Dakota to Missouri and into Ohio after a powerful snowstorm pounded the region earlier this week. (AP Photo/John Minchillo)

Chicago's lakefront is covered with ice on Wednesday, Jan. 30, 2019. Temperatures are plummeting in Chicago as officials warn against venturing out into the dangerously cold weather. (AP Photo/Teresa Crawford)



The wind blows a balloon horizontal as a runner bundled against the cold jogs past Wescott Station Antiques in St. Paul, Minn. during below-zero temperatures on Tuesday, Jan. 29, 2019. Wind chills were approaching minus 40 degrees. (Scott Takushi/Pioneer Press via AP)

Evan Roberts is covered in frost while jogging across the Stone Arch Bridge Tuesday, Jan. 29, 2019, In Minneapolis. Extreme cold and record-breaking temperatures are crawling into parts of the Midwest after a powerful snowstorm pounded the region, and forecasters warn that the frigid weather could be life-threatening. Roberts, who is originally from New Zealand, said he will take tomorrow off from running outside and run inside on a treadmill. (David Joles/Star Tribune via AP)

Water vapor rises above St. Anthony Falls on the Mississippi River as the Stone Arch Bridge is obscured, seen from the Third Ave. Bridge Tuesday, Jan. 29, 2019, In Minneapolis. Extreme cold and record-breaking temperatures are crawling into parts of the Midwest after a powerful snowstorm pounded the region, and forecasters warn that the frigid weather could be life-threatening. (David Joles/Star Tribune via AP)



Carman Diego Lopez inspects and works on rail cars at the Metra Western Avenue Yard, Tuesday, Jan. 29, 2019, in Chicago. Forecasters warn that the frigid weather Tuesday will get worse and could be life-threatening. The extreme cold and record-breaking temperatures are crawling into a swath of states spanning from North Dakota to Missouri and into Ohio after a powerful snowstorm pounded the region earlier this week. (AP Photo/Kiichiro Sato)

A worker clears snow from a train at the Metra Western Avenue Yard, Tuesday, Jan. 29, 2019, in Chicago. The extreme cold and record-breaking temperatures are crawling into a swath of states spanning from North Dakota to Missouri and into Ohio after a powerful snowstorm pounded the region earlier this week. (AP Photo/Kiichiro Sato)

Scott Ward clears the snow from his car parked in front of his home in Davenport, Iowa, Monday, Jan. 28, 2019. (Kevin E. Schmidt/Quad City Times via AP)



A plow removes snow along West Wisconsin Avenue at North 8th Street in Milwaukee on Monday, Jan. 28, 2019. Heavy snow and gusting winds created blizzard-like conditions Monday across parts of the Midwest, prompting officials to close hundreds of schools, courthouses and businesses as forecasters warn that dangerously cold weather is right behind the snowstorm. (Mike De Sisti/Milwaukee Journal-Sentinel via AP)

“You’re always going to have these occasional cold-air outbreaks, but we’ve been having fewer of them over the last few decades.”

Added John Allen, a meteorologist and climate scientist at Central Michigan University, “The way to think about this is kind of like what you had for breakfast each day, as compared to what you usually have eaten for breakfast over your entire life. So we could be in a a warming trend and still experience a cold winter, or cold day.”

It’s important to remember that climate change is a global phenomenon, while weather is a local experience, Easterling said. The global atmosphere is always trying to find a temperature balance — meaning when it’s bitterly cold in Michigan or elsewhere, nearly invariably it is unusually warm in some other part of the world.And, sure enough, as we get our polar vortex on, Fairbanks, Alaska — less than 200 miles from the Arctic Circle — had a high temperature of 24 degrees on Tuesday, well above its typical January average high temperature of 2 degrees.

“Just because it’s cool here in North America doesn’t mean this is true for other places in the world,” Allen said. “Australia is currently experiencing all-time record temperatures — exceeding 115 F — and extended heat waves. These are the features of a warming world, and it’s important to take the whole Earth into account — not just our local area.

“The evidence for a warming climate is long term and extremely strong, so hence a cold day means little for that overall pattern.”

The concern with climate change is that human activities such as fossil fuel-burning are putting so-called greenhouse gases such as carbon dioxide into the atmosphere to an extent that heat that typically escapes is held in place, causing temperatures to rise globally over the long term. The four warmest years on historical record, in terms of overall global average temperatures, were the last four years, Easterling said. NASA and NOAA climate data shows the 20 warmest years on record have all occurred since 1995.

There’s even emerging evidence that climate change may make these frigid dips of arctic air down into the U.S. more possible.

“In the past there was a very strong gradient of cold air at the poles and warmer air south of the poles. That gradient kept the cold where it is, just like a strong temperature gradient in a lake keeps warm water at the surface and colder water below,” said Donald Scavia, professor emeritus of environment and sustainability at the University of Michigan.

“As the poles are warming faster than the rest of the planet, that gradient weakens, allowing the cold air currents to dip south.”

While the global conditions contributing to climate change continue — as Trump’s skepticism on the phenomenon signals the U.S. will not be playing a leading role on the topic as it has previously — at least the polar vortex is skipping town later this week. Saturday’s high temperature in Detroit is forecast to be a relatively balmy 31 degrees.

———

©2019 Detroit Free Press

Visit the Detroit Free Press at www.freep.com

Distributed by Tribune Content Agency, LLC.