How might this fit into a warming world

Climate is the standard for conditions over decades, not the weather that occurs over a single day, week, or even year. Winters in Boston have warmed by about 3 degrees Fahrenheit on average over the past 50 years, analyzes of National Weather Service data showed.

Greenhouse gases, mainly by burning fossil fuelstrap heat, which warms the Earth’s surface. The conventional understanding of climate change is that heat then creates All — winter, spring, summer and autumn; oceans, forests, cities and grasslands – a little warmer.

However, some climate scientists have argued in recent years that this may be too basic an understanding when it comes to the highly complex global climate system. While it’s true that winters are getting warmer over the long term, we shouldn’t be surprised by a few weeks of very cold air or heavy snowfall, climate scientists said.

“Our view of global warming is too simplistic,” said Judah Cohen, an MIT climate scientist who has studied the relationship between extreme winter weather and climate change. “Simply saying that climate change will only lead to ever warmer winters and less snowfall doesn’t reflect everything that’s going on. »

Cohen’s research observed that the cold air mass circulating over the Arctic, known as the polar vortex, is weakening and stretching more frequently. When this happens, very cold air from the Arctic is pushed south toward the continental United States.

Emerging scientific work by Cohen and others suggests that this phenomenon may be occurring more often due to climate change, particularly because of how quickly the Arctic is warming.

The Arctic is warming twice as fast as the global average. According to Cohen, warming and melting sea ice could cause the polar vortex to weaken and stretch, which would then allow very cold air to enter the continental United States. The science is still emerging, in part because climate change models have not been able to reliably reproduce the phenomenon.

Mid-to-late January is typically the coldest time of year in Boston. Temperatures typically range between 22 and 36 degrees Fahrenheit, according to the National Weather Service. Data shows that Tuesday’s temperatures, reaching 19 degrees, were just below the “normal” temperature range for January 21 in Boston.

The coldest January temperatures so far this month are still – even with the big blast of Arctic air – slightly above normal.

In a typical January, the coldest nighttime temperatures would be about 3 degrees, according to a Globe analysis of national weather data. So far this month, the coldest nighttime temperatures are averaging around 13 degrees.

Looking at the planet as a whole, certain areas Temperatures are colder than usual and some are warmer right now, said Jared Rennie, a research meteorologist with the National Oceanic and Atmospheric Administration. Climate change probably means fewer cold days on average, Rennie said, but that doesn’t mean it won’t happen.

“To put it bluntly, this cold outbreak does not challenge global warming,” Rennie said.

Globe staff Ken Mahan contributed to this report.

Erin Douglas can be contacted at [email protected]. Follow her @erinmdouglas23.