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How much is climate change to blame for weird winter weather?

What, exactly, is causing the type of strange seasonality that sees buds bursting from branches in February, and us going from parkas to pullovers in a matter of hours?
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Walking along a snow-covered trail, tree branches shine with a fresh coating of ice, a Christmas card version of deep winter. But there is something off in these woods. A closer inspection of the branches reveals small green buds bursting from the branches — spring cocooned in crystal.

Tricking the internal clock of many species into believing spring has sprung has become more and more common across parts of the province. We humans, going from parkas to pullovers in a matter of hours, are also experiencing the bewildering mystery of modern weather. 

But what, exactly, is causing the type of strange seasonality not seen decades ago?

Climate change is the easy answer, but there’s more to it.  

In Ontario, spring blooming species begin “waking up” anywhere from mid-March to mid-May. But the intense freezing and warming cycles characterizing recent winter weather have caused confusion for many types of flora, with spring blooms greening branches before the end of February. 

The phenomenon is not unique to Ontario. Across the U.S., key plant species have begun flowering, lining wintery streets with bright bursts of colour. Cherry blossoms found in the heart of Washington DC are a distinct symbol of spring in the American capital, and 2023 could break a three-decade record for early blooming, according to the National Park Service. Farther north, New York is experiencing its warmest winter on record with spring conditions arriving 32 days earlier than normal, the earliest onset of spring in the city in 40 years since records were kept. 

In Canada's capital, the nation's iconic Rideau Canal Skateway in Ottawa failed to open for the first time in its 53-year history due to warm weather. Many conservation areas across southern Ontario remained closed for ice fishing and other activities this winter for the same reason.

Tragically, the warm weather has cost lives. The OPP had to remind snowmobilers at the end of January that going out on lakes across parts of Ontario, an annual tradition for thousands, was simply too dangerous this year. 

“Right now, we’ve not had a deep freeze, like some very cold nights, that gets you that ice thickness. So, although it appears that there’s ice in most places, it’s been unpredictable, and it makes the conditions very poor,” Const. Aaron Coulter warned, after a Toronto man survived an underwater ordeal on Six Mile Lake in Muskoka.

Sadly, another man involved in the incident who could not be saved was later found by an underwater search and rescue team.

Days later, a little to the north, a 29-year-old snowmobiler went through the thin ice on Oastler Lake and died. 

“It’s just not safe,” Coulter told local media. 

The warm winter weather is being blamed by the OPP for multiple snowmobiling accidents. 

"The weather, as you are well aware, has been up and down and what may appear to be a fully thick, frozen lake or river could change pretty rapidly with the mild weather," Sgt. Paul Beaton, who co-ordinates the OPP's snowmobile program, told the CBC.

“This is far and away the mildest winter we've seen in the last decade,” said Robert McLeman, a professor in the department of geography and environmental studies at Wilfrid Laurier University and a member of the Waterloo Climate Institute. “We've looked at historical weather records and it's pretty clear this is going to be one of the wildest and craziest winters in a long time.”

The unusual weather, even in this era of climate change, has left many questioning what’s causing it. Climate change is certainly impacting our weather and ecological systems, but winters like this have led many to wonder just how much.

To understand how climate change affects day-to-day temperature and precipitation, the difference between weather and climate has to be untangled. 

Weather is the short-term temperature and precipitation that we see on a day-to-day and week-to-week basis. The daily highs and lows and accumulation of snow, rain and ice are the day’s weather. An area’s climate on the other hand is determined by long-term trends identified in average weather conditions, such as temperature, precipitation and the prevalence of specific weather events, including extreme weather, over a period of time. Climate trends are often looked at over 30 years or longer. 

“The example I use is a hockey goalie,” McLeman said. “The performance of a hockey goaltender in any game can vary from one game to the next. But if you look at their performance over the course of a season or multiple seasons, you get a better indicator of what their average performance is. The season would be the average (climate) and an individual hockey game would be the weather.”

There is no doubt climate change is happening. Since 1981, the global rate of warming has been approximately 0.18 degrees per decade, more than twice the rate of the century prior. A study that used artificial intelligence to predict warming timelines conducted by researchers at Stanford University and Colorado State University, concluded that the 1.5-degree threshold recognized as a tipping point for climatic disaster by experts across the globe, will likely be surpassed within the next decade. Other scientists agree that, globally, a two or even three degree increase is more likely, with the current carbon emissions trajectory.

Alarmingly, compared to planetary changes, southern Ontario is warming at twice the rate of the global average. Local geographies play a huge role in temperature variations. One of the key influences on climates around the world is the oceans and their patterns. These giant bodies of water absorb heat, but they warm and cool much slower than surrounding land. During the summer months, cool breezes will flow across the water and onto coastal areas. In the winter, the water stays warm for longer, supplying heat to the surrounding landscape. Proximity to a large water body helps to moderate climate. Ontario is an inland landmass, so the climate is much less impacted by ocean temperatures and much of the heat is absorbed by the land. 

“Canada is a large continent with a large land area,” McLeman said. “So especially areas away from the ocean are going to warm up faster than areas that are closer to the ocean or oceans themselves.”

The Great Lakes act in a similar way, but being much smaller do not have the mass to modify temperatures on the same scale as oceans. 

Along with dramatic temperature changes this winter, southern Ontario has also seen drastic variations in precipitation. The winter began with large amounts of snowfall across the province in December. Then it all but disappeared, and before the end of the month, Toronto set a record when the thermometer just before the new year reached 13C. The balmy temperatures continued through most of January, and on Feb. 14 and 15, two more records were broken when the weather hit 9C, then almost 14C. 

Mixed in between the spring weather, winter storms have also blown in during this bizarre season.

In late January, residents across southern Ontario were warned to brace for a severe winter storm that saw two-to-three centimetres of snow fall per hour and wind gusts of up to 60 kilometres. 

These brief winter storm events will become more common as the climate continues to warm. The phenomenon, called lake effect snow, only occurs in a few places around the world next to large water bodies like the Great Lakes.

When cold air blows across a warm body of water, picking up evaporation and moisture as it goes along, the warmer air rises into the atmosphere where it cools and condenses, falling as snow. As the climate warms, the Great Lakes will hold onto their heat longer, causing more of these weather events. 

“We've seen that this winter has been quite infamous for all the snow that [Buffalo] has been getting,” McLeman said. “And that's because the winds that hit Buffalo have been blowing across the entire length of Lake Erie so they picked up a lot of moisture from the lake and then it all gets dumped on Buffalo.”

Similar effects can be seen in the Georgian Bay area as winds cross Lake Huron.

Despite an overall warming climate, extreme cold is still common. In January 2022, eastern Ontario and much of Quebec saw unusually low temperatures, the lowest recorded since the early 2000s. This prompts skeptics to claim climate change is not as severe a threat as scientists warn. There are explanations for dramatic changes in temperature from year to year.

Looking at 20-year temperature data, there are peaks and troughs every couple of years representing highs and lows. Regardless of the overall trend — which shows increasing temperatures due to climate change — these variations will continue to occur due to two processes known as El Niño and La Niña, which happen approximately every two to seven years, but do not occur regularly (El Niño generally occurs more frequently than La Niña). 

During El Niño, trade winds, which are the permanent east to west prevailing winds across the world’s equatorial region, weaken, causing warm water to be pushed back east toward the west coast of the Americas. The warmer waters cause the Pacific jet stream (the air above) to shift farther south leaving parts of Canada and the northern United States warmer and drier than normal. 

“During an El Niño period, places that are warm become cooler, places that are wet become drier, and vice versa, places that are drier become wetter,” McLeman explained. “For example, during an El Niño year, you might have drought or dry conditions or fires in the Amazon forest area, which is normally a wet tropical rainforest. And conversely, areas that might normally be dry get more precipitation than usual.”

The El Niño phenomenon is one explanation for the peaks, or warmer winters, that can be seen on climate graphs.

La Niña has the opposite effect. Trade winds become stronger pushing the warm water toward Asia while west of North America, cold water moves north, cooling the jet stream above as it also shifts north leading to colder, wetter winters across Canada. La Niña is responsible for many of the dips we see in winter temperatures over a few years. 

“When La Niña comes, it's sort of the climate trying to correct itself and it goes past normal, it goes the other direction,” McLeman said, explaining why it is difficult to distinguish which particular weather events can be attributed to climate change. But it is clear the average temperature is increasing, which has the potential to cause more drastic winter temperatures and storms in years to come. 

“As the average goes up, what that means is, what today seems very cold compared to average, is not as cold as a cold period was 50 years ago, because the average is changing,” he said. “And similarly, a summer that might be hotter than average today is even hotter than a summer that was hotter than average years ago because the whole baseline is changing.”

Rachel Morgan is a federally funded Local Journalism Initiative reporter at The Pointer