Why snow, colder weather conditions don't debunk climate change

With a seeming rise in the occurrence of snow days, blizzards and icy travel, the common belief that climate change isn’t happening comes as no surprise.

Prior to New Year’s Day in 2018, President Donald Trump tweeted a statement suggesting that the record-breaking frigid temperatures forecast on New Year’s Eve proved that global warming isn’t a valid concern.

However, the United States makes up only about 2 percent of the entire Earth’s surface area.

Scientists stress that locally wintry weather conditions are not indicators of changes in climate, and weather conditions in one part of the world are not representative of what’s occurring globally.

“It’s like saying, 'if everyone around me is wealthy, then poverty is not a problem,'” Peter Frumhoff, the Union of Concerned Scientists science and policy director and chief climate scientist, told CNN.

Scientists point to hard data, including temperature measurements on land and water taken over several decades, which points to an upwards trend in global temperatures, otherwise known as global warming.

“We know that right now, we’ve had three years – 2016, 2015 and 2014 – which were the hottest on record since 1880,” said Brenda Ekwurzel, climate science director and senior climate scientist for the Union of Concerned Scientists.

NASA reported that 16 of the 17 warmest years on record all happened since 2001.

“Global warming is definitely happening,” Ekwurzel added.

Extreme winter weather and climate change

A popular question seems to be that if global warming is occurring, why do winters seem unusually harsh?

Understanding the distinct difference between weather and climate helps to answer that question.

"Weather refers to the conditions in the atmosphere over a short period of time, whereas climate refers to trends in atmospheric patterns over a much longer timescale," said Dr. John Fleming, a climate scientist with the Center for Biological Diversity.

“This is well expressed as an analogy: weather is like your mood, whereas climate is like your personality,” he said.

“This is why it is possible to have unusually cold weather across much of the U.S. [during] winter, while observing that globally, surface temperatures have been steadily rising,” he added.

Much of the continental United States may be unusually cold during winter, but temperatures for most of the rest of the world are well above average. (Map from the University of Maine Climate Change Institute)

Despite the fact that the Earth is becoming steadily warmer, frigid conditions continue to occur during winter at higher elevations or throughout the year in higher altitudes.

Factors that play a role in both regional and global weather conditions include ocean pattern, upper winds, the extent of Arctic sea ice melting, seasons and the shifting shape of the jet stream, which is an atmospheric highway located at the level at which jets cruise.

Research has shown that these factors can actually contribute to an increase in extreme weather conditions, including more intense heat waves, heavier precipitation and increasing snowfall.

“Some research suggests that a warming Arctic is producing a weaker, less stable jet stream that allows frigid Arctic air to dip south,” said Fleming.

Ice cover in the Arctic appears to be shrinking faster, compared with the previous 1,500-year period, according to the 2017 Arctic Report Card.

“It indicates how the effects of warmer global temperatures can reverberate through our climate system and across the globe,” he added.

A series of publications have concluded that a cold wave during winter that could have crossed the U.S in about five days can now last 14 days, according to Ekwurzel.

“It’s slow, and if you’re sitting there with cold, Arctic air blasting down the continental U.S. for 14 days, you can imagine the extreme cold temperatures we could reach,” she said.

“We’d freeze the Great Lakes, icing forms, you’re freezing citrus crops; it’s really disastrous,” she added.

Climate change is most rapidly occurring in the far northern latitudes, according to AccuWeather Senior Meteorologist Brett Anderson.

"Despite the potential increase in extremes, average winter temperatures are still expected to continue to trend warmer over the next several decades across the majority of the Northern Hemisphere," Anderson said.