Cold weather doesn't mean global warming isn't happening

The wave of extreme cold affects millions of Americans and Canada has made it necessary to activate protocols to deal with it, on Friday in some parts of the country the temperature was recorded at -40. The province is experiencing extreme cold, leading to record power use, more emergency calls, flight disruptions.

For years, both casual observers and anti-scientific commentators have pointed to snowfall and low temperatures to question the scientific reality of human-induced climate change. Temperature records show that the Earth has warmed a little more than 1 degree Celsius (2 degrees Fahrenheit) since 1880.

Meteorologist Justin Shelley from Environment and Climate Change Canada says this intense cold will last a few more days. The Arctic air mass has settled over the province, causing temperatures to drop to -40s and wind chills to -50s. This is expected to continue over the weekend.

In Calgary, the temperature at night is expected to drop to -37 C and -38 C, and it won’t get warmer than -30 C during the day until at least Sunday.

If the temperature drops to -38 C at night, it would be similar to the lows in December 1996 and January 1997. The daytime high of -32 C would be the coldest since Dec. 28, 1968, when the high was -33.9 C.

However, short-term variations in a climate still occur, such as cold snaps, which consist of falls rapids in air temperature, resulting in several consecutive days of colder than average temperatures.

For example, This year the temperatures were above the normal average in some parts of the country, while in other parts of the world the temperatures rose seven degrees or more.

Despite climate change, winter still exists

Such situations exemplify how cold waves and global warming can coexist, in fact, they do: extreme cold is occurring on a smaller fraction of the global surface. In other words, what happens at the local level, or in short periods of time, is not necessarily representative of what happens at the national and global levels.

Another point to take into account is that the increase in average temperatures has not completely eradicated winter.

Therefore, it is still possible to experience a wide range of weather conditions, including extremes such as a week of high temperatures or a brief cold snap in April. In addition, variations in weather patterns caused by natural events, such as El Niño and La Niña, can influence outbreaks of cold air.

Although winter lingers, global climate change has made winters less harsh overall. This phenomenon is evident from the minimum temperature data during winter, as shown in the following graph.

During the period from 1910 to the 1980s, the land mass of the United States frequently experienced extreme cold during the winter, according to the National Centers for Environmental Information (NOAA).

However, since 1990, a proportion of the nation (generally no more than 10%) has experienced extremely cold winters, a sign that harsh American winters have become less widespread.

In short, yes, the Earth is warming up, but don't throw away your snow shovel or winter boots just yet. We will still have bouts of cold and ice even as global warming continues.

Understanding difference: Weather vs Climate

First, it’s important to know that weather and climate aren’t the same. Weather is what we experience in the short-term, like a cold day or week. Climate is the long-term pattern of weather. So, even if we have a cold spell, it doesn’t mean global warming isn’t happening.

Global warming is about the Earth getting hotter over a long time. The Intergovernmental Panel on Climate Change (IPCC) says the Earth’s average temperature has gone up about 1.18°C since the late 1800s. This is mostly because of things people do that release more carbon dioxide and other gases into the air.

Some studies suggest that global warming, which is causing Arctic ice to melt, might be making winters harsher in some places. As the ice melts, it can change wind patterns and lead to very cold weather in certain regions.

Climate change can cause extreme cold events in moderate latitudes. According to scientists, climate change disrupts the polar vortex, which can lead to colder winter weather.

Climate change is a long-term shift in weather patterns and temperatures. The Arctic is warming three times faster than the rest of the world. This is known as "Arctic Amplification". A study published in the Journal Science suggests that extreme cold weather events can be attributed to Arctic warming. Scientists found that heating in the Arctic disturbed the polar vortex, allowing colder winter weather to flow down to the US.

Is there global warming?

Undoubtedly. Global warming refers to an upward trend in global average temperatures. Federal agencies, universities, the most recent climate assessments, and research centres around the world have concluded that the Earth is warming. That conclusion is based on hard data, such as temperature measurements on land and water around the world for more than a century.

Over the course of a decade, cold spells can lead to colder-than-normal winter conditions at lower latitudes. At the same time, warm outbreaks at higher latitudes bring warmer-than-normal temperatures and occur simultaneously.

Global mean temperatures in 2020 were 1.76 degrees Fahrenheit (0.98 degrees Celsius) warmer than the 1901-2000 base period, according to researchers from the National Oceanic and Atmospheric Administration (NOAA). The world has just finished the hottest decade on record.

Polar vortex, an effect of global warming?

In recent years, several scientific studies have concluded that climate imbalance can cause this type of cold snap triggered by the polar vortex in North America.

The polar vortex is common during winter at the north pole. Normally, there is an airflow known as jet stream or 'jet stream' – that maintains low temperatures and wind in a given area. Due in large part to arctic amplification, the behaviour of the polar vortex has changed in recent decades. This, in turn, can influence the jet stream, short for "tropospheric polar jet stream." The jet stream is a fast-moving current of air found in the area of ​​the atmosphere where weather conditions occur and planes fly.

The fact that the North Pole is heating up twice as fast as the rest of the planet is affecting the jet stream and may destabilize the vortex.

Sometimes the vortex splits into more than one front and can move to areas further south. Splitting occurs naturally, but destabilizing air currents around the vortex could cause more splitting than usual.

Therefore, as the planet warms, the splitting and shifting of the polar vortex could become an increasingly frequent and extreme phenomenon, affecting not only Europe and the United States but also parts of the world.

This story was originally published on December 25, 2022, and has been updated as of January 13, 2024.

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