2021's weather disasters brought home the reality of climate change

Heat waves. Floods. Megadroughts. This year’s weather showed us that climate change is here—and deadly.

Published 7 Dec 2021, 14:04 GMT, Updated 10 Dec 2021, 10:19 GMT
canada-flood-mudslide
Members of the Canadian Forces fill sandbags to create a makeshift dike behind houses in Abbotsford, British Columbia, where last month's rainfall led to catastrophic floods.
Photograph by Darryl Dyck, The Canadian Press, Ap

From punishing heat in North America to record-breaking floods in Europe and Asia, this year’s weather showed us what it looks like to live in a world that has warmed by 1.1 degrees Celsius (2 degrees Fahrenheit) over the past century.

“Dangerous climate change is already here. That’s a harsh reality we need to recognise,” says Michael Wehner, an extreme weather researcher at the Lawrence Berkeley National Laboratory.

Extreme weather is already taking homes, businesses, and lives. Canada’s recent floods may be the most expensive in the country’s history, potentially costing an estimated $7.5 billion (£5.6 billion). The 18 weather disasters that hit the United States in 2021 together cost more than $100 billion (£75 billion), according to the most recent estimates.

In August, Wehner and other scientists on the Intergovernmental Panel on Climate Change published a report indicating they were now more confident than ever that climate change is influencing the world’s worst weather events, including these five.

Pacific Northwest heatwave 

Portland, OR residents cool off in a city relief center during June's historic, deadly heat wave. Climate change almost certainly made the heat worse.
Photograph by Nathan Howard, Getty Images

The Pacific Northwest and southwestern Canada—a region that supports some 13 million people is known for rainy, mild weather—experienced deadly heat this summer. Major cities such as Portland, Seattle, and Vancouver, where many residents lack air conditioning, saw historically high temperatures that surpassed 100°F (38°C).

The intense heat resulted from a weather phenomenon called a heat dome, in which an area of high pressure acts like a lid on a pot and keeps heat trapped over a specific region.

Research on the heatwave found that its intensity would have been “virtually impossible” without the planet-warming greenhouse gases that have been emitted into the atmosphere over the past 120 years. As a result of the heat, hundreds of people died in the region. One study published this summer concluded that more than a third of all heat-related deaths worldwide could be blamed on climate change. And it’s those already suffering the most—from lower incomes, poor health, or old age—who are most harmed by heat.

Plants and animals struggle to cope with extreme heat, too. In the Pacific Northwest, millions of marine animals died, as did many on land. Farmers saw berries roast on their vines.

Megadrought in the Western U.S. 

Houseboats on a drought-depleted Lake Oroville in Oroville, California on September 5, 2021. Much of California was gripped by excessive heat through the summer.
Photograph by Josh Edelson, AFP/Getty Images

In August, the U.S. declared a water shortage on the Colorado River—a first for the waterway. Lake Mead, one of the river’s most important reservoirs, dropped to historically low levels. While the declaration triggered water cuts to farmers in Arizona and parts of Nevada, with some 40 million people at least partially dependent on the river for water, future droughts could prompt more widespread water reductions.

A “megadrought” has been gripping the West since 2000. While the region would have likely experienced drought regardless of human influence, scientists say climate change is making it worse than it’s been in over 1,000 years.

Drought can create dangerous feedback loops. As the air warms, it sucks more moisture out of rivers, lakes, plants, and even the soil, which can in turn make the ground even hotter and drier.

And while the drought in the western U.S. was historic, climate change is likely to worsen drought around the world, with historically arid regions in Africa and the Middle East hit hardest.

Western wildfires

On August 30, firefighters with the Santa Clara fire unit try to protect structures on the Echo Summit, a mountainous part of California east of Sacramento. Intense heat and dried-out underbrush create conditions for larger, more frequent wildfires.

This year, California’s Dixie fire was the second largest in the state’s history. It burned half a million acres and some 400 homes, contributing to a string of busy fire seasons that have plagued the Western U.S.. North America wasn’t alone. Large wildfires broke out in Turkey, Greece—and perhaps most surprisingly—Siberian Russia.

When extreme heat and drought coincide, zapping the soil’s moisture and creating fields of dry vegetation, it only takes a small spark to ignite a deadly blaze. As climate change worsens heat and drought, it creates the conditions for larger and more frequent fires. In some parts of the West fire season now lasts all year.

Not only did the year’s wildfires immediately threaten homes and businesses, they also produced unhealthy air pollution and threatened endangered species, including California’s famed sequoia trees.

Extreme floods … everywhere 

Heavy rainfall resulting from a slow-moving low-pressure system over western Germany led to catastrophic damage and loss of life. Houses like the one shown here caved in after mudslides and sinkholes opened throughout the region.
Photograph by David Young, picture alliance/Getty Images

Canada, the U.S., Germany, China—extreme rainfall and the floods they triggered plagued the globe this year. In each of these places, the volume of precipitation was historic.

In British Columbia, 20 towns set rainfall records; Nashville saw its fourth wettest day ever; more rain fell on Central Park in a single hour than ever before in that timespan; German towns were inundated with more rain in two days than in a normal month; one day of rain in Zhengzhou, China, exceeded a year’s worth of average annual precipitation.

More intense rainstorms result from warming temperatures; for every 1°C (1.8°F) rise, the atmosphere can hold 7 percent more moisture. With more water at their disposal, storms have the potential to dump enough rain to cause flooding.

Many of this year’s floods brought to light how population centres and transit routes were engineered for a climate that may not prevail for much longer. For example, goods going to and from Asia stalled at Vancouver’s port, waylaid by floods. In major cities, underground train tunnels were swamped and streets turned into rivers.

Hurricane Ida: New Orleans to New York 

On August 29, a group of people walk through New Orleans' French District during Hurricane Ida. The Category 4 storm struck with winds of 150 mph. It was the strongest storm to hit Louisiana since the 1850s, and it caused widespread destruction as it moved east, eventually flooding New York City.
Photograph by Photo by Brandon Bell, Getty Images

Extreme rain is one major way climate change is making hurricanes worse. Hurricane Harvey, which struck Houston in 2017, was one of the most extreme examples of this. The storm dumped 60 inches of rain in some parts of Texas.

But it was Hurricane Ida that exemplified another dangerous trait of climate change-charged hurricanes: rapid intensification. This occurs when a hurricane’s winds increase by at least 35 mph in under 24 hours. Ida far surpassed that rate, growing by about 60 miles per hour in a day, from a Category 1 storm to a Category 4, its top winds clocking at 150 mph.

While Ida moved relatively quickly, scientists expect that future hurricanes on average will move more slowly over land, dumping more rain on a location and causing extreme flooding. Hurricane Harvey did just that over Houston; in 2020, Hurricane Sally stalled over Alabama. Researchers anticipate that future intense, rainy, sluggish storms will cause more destruction; as sea levels continue rising, deadly storm surges brought by hurricanes will worsen, too.

Only the beginning 

Scientists are still researching how climate change will influence winter weather, and they’re becoming increasingly confident that Arctic warming is producing harsher winter storms.

One recently published study found a possible link between the September Texas freeze and climate change, suggesting that the barrier between cold Arctic air and warm tropical air is becoming more unstable and that the polar vortex—the flow of air moving through the stratosphere—is becoming increasingly likely to deliver intense winter storms.

As one of the study's authors, Edward Maibach, an expert on climate change communication at George Mason University, says in an email, temperatures will continue to rise – and so extreme weather could continue to shape climate change beliefs.

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