On July 7, Mike Flannigan, a scientist at the University of Alberta, stared at satellite imagery on his computer as one wildfire after another ignited across British Columbia during the course of the unusually hot day.
Like much of the Western U.S. this summer, British Columbia has been under the influence of a broad area of high pressure in the atmosphere, which inhibits storm systems that could bring beneficial rainfall, and favors hotter and drier weather than average.
In total, 140 wildfires began on that one day, setting what may be a new record, Flannigan said in an interview.
That warm and dry weather pattern has proven to be remarkably resilient as the province’s wildfire woes have worsened to the point where the 2017 fire season — which isn’t over yet — is already the second largest on record there, burning about 1.4 million acres through Monday.
In Canada, Flannigan said, the area burned each year has doubled since the 1970s, despite improvements in fire management.
“This is due to human caused climate change. I can’t be more direct than that.”
“This is due to human caused climate change,” he said. “I can’t be more direct than that.”
It’s not just British Columbia that’s suffering this summer either. Across the globe, it’s as if summer weather is on steroids, with searing heat waves, deadly flash floods, and massive fires affecting many areas. Scientists say that we’d better get used to it, thanks in part to global warming.
A new normal
Events during the past few months show how warming temperatures combined with natural climate variability are tipping the odds in favor of extreme weather that can cause damage around the world.
Studies have tied the increasing number of large fires in parts of Canada and the U.S. to global warming. In fact, the level of fire activity across the boreal forests, which stretch from Alaska to Canada and around the top of the world to Scandinavia and Russia, is unprecedented in the past 10,000 years, according to a study published in 2013.
Wildfires haven’t just been confined to the far north this year either. In the U.S., 5.9 million acres have burned in fires so far in 2017, mainly across the West, which is 1.9 million acres above the past decade’s annual average amount. As of Monday morning, firefighters were battling 11 large blazes in California alone, with additional large fires burning in Idaho, Montana, Nevada, Oregon, Washington, and Wyoming.
A wet winter followed by a dry, hot summer has provided the perfect set up for a blockbuster fire season in much of the West. The winter fostered the growth of vegetation that is now serving as fuel for the fires.
There is still some uncertainty in attributing wildfire trends to-date to human-caused climate change, although climate models are in agreement that fire activity will increase in a warming climate.
A forthcoming federal climate assessment leaked to the New York Times on Monday, for example, found “medium confidence for a human-caused climate change contribution to increased forest fire activity in Alaska in recent decades, but low confidence for a detectable human climate change contribution in the western United States based on existing studies.” It did, however, note the expectation for more wildfires in future decades.
Valerie Trouet, an associate professor in the tree-ring lab at the University of Arizona in Tucson, said the West is facing a “perfect storm for extreme fire.”
“One, there is a combination of wet winters and dry summers,” she said in an interview.
“Two is the overall warming temperatures on top of that, which makes firefighting more difficult, which makes fires stay hotter” and burn longer, Trouet said.
“Another factor that comes into play is the fact that we’ve been putting out fires for a century or more so there is a very dense fuel load so that when a fire lights it’s going to get very big, very fast.”
Trouet is also investigating changing jet stream patterns to see how they may be related to wildfire patterns, particularly in southern Europe, which has been ablaze this summer, with deadly consequences.
“A lot of the extreme weather that we’re seeing is also related to a wavier jet stream that is a side effect of climate change,” she said, since there are now longer, more persistent weather patterns that can cause more extreme events to fester.
She acknowledged that scientists don’t yet know what may be driving this shift, but mounting evidence shows that it’s taking place.
Trouet is far from an outlier in thinking that something odd is going on with the jet stream, which plays a dominant role in steering weather systems around the globe. Flannigan, too, cited jet stream shifts as playing a role in igniting fires in some areas, including parts of Canada, while suppressing them in others.
“Expect more of this,” he said. For example, high pressure ridges — like the one above British Columbia now — have long been known to be conducive to fire, but “they’re becoming stronger and they’re staying longer.”
In other words, weather phenomena are tending to arrive and persist for an unusually long period of time, like an unwelcome houseguest that just won’t leave.
Michael Mann, the director of the Earth System Science Center at Penn State University, has been studying stuck weather patterns.
“A number of recent extreme summer weather phenomena such as the 2003 European heat wave, 2010 Moscow fires/Pakistan floods, 2011 Texas/Oklahoma heat wave & drought, 2015 California wildfires (and more recent events we are currently looking at) were associated with this phenomenon,” Mann said in an email.
Although other factors come into play, he said, “We do think this is a contributor to the increasing number of highly persistent extreme weather events over the past two decades.”
Fires and record heat
The wildfires this year have occurred in concert with, and sometimes even helped to offset, summer heat waves.
Ironically, it was the smoke from the fires in British Columbia that blotted out enough sunshine in Seattle and Portland to keep some all-time high temperature records from being broken during an intense heat wave during the first week of August. Even so, Seattle reached a peak temperature of 94 degrees Fahrenheit, and Portland, unaccustomed to severe heat waves, stewed in a smoky, hazy 105-degree day on Aug. 3.
Around the world, signs of a planet with a worsening fever are widespread. While natural weather variability still plays a dominant role in day-to-day conditions, climate change is tipping the balance in favor of certain types of climate extremes over time, with none more closely linked to warming than heat waves. While each heat wave has its own distinct mix of causes, the sheer number of events and records that have fallen so far this summer is noteworthy.
Right now, in parts of Europe, a severe and prolonged heat wave, nicknamed “Lucifer,” has gripped the continent. Spain, France, Serbia, Romania, and Croatia are all seeing temperatures soar into the 110s Fahrenheit. It will take time to determine how many people died as a result, but at least two fatalities have been directly attributed to it so far.
While summers tend to be hot in parts of Spain and southern Europe, this heat wave has been exceptional in terms of its high temperatures and long duration.
According to the Associated Press, train routes had to be canceled in southern Serbia after tracks warped from the heat. The heat and dry weather has caused officials to implement water conservation measures in Rome, including shutting down famous fountains in Vatican City.
A June heat wave contributed to a deadly wildfire in Portugal that killed upwards of 60 people while injuring more than 200. Heat and fires also affected Spain, France, and Switzerland during that period, among other countries.
Climate scientists have yet to study many of the specific extreme events underway around the world, but the July heat prompted an investigation from an international team specializing in a form of climate detective work known as extreme event attribution.
The researchers from England, France, Switzerland, and the U.S., found that climate change made the intensity and frequency of such extreme heat at least twice as likely to occur in Belgium, at least four times as likely in France, Switzerland, the Netherlands, and central England, and at least 10 times as likely as Portugal and Spain.
On July 21, Shanghai, China, which is the most populated city in the world with 24 million residents, set a record for its hottest day since record-keeping began there in 1872. The high temperature on that day was 105.6 degrees Fahrenheit, or 40.9 degrees Celsius, and it fits with a pattern of hotter weather in that city.
Other exceptional heat records have been set this spring and summer across the globe, partly as a consequence of rising global average temperatures in response to increasing amounts of greenhouse gases, such as carbon dioxide, in the atmosphere.
In May, the western Pakistani town of Turbat hit a stifling 53.5-degree Celsius high temperature, which was a whopping 128.3 degrees Fahrenheit. This tied the all-time highest temperature for Pakistan, and came close to tying the world record for hottest temperature on record, set in Mitribah, Kuwait, in 2016.
According to Weather Underground, Spain, France, Belgium, the Netherlands, Ireland, Norway, Germany, and Austria all set or tied national monthly temperature records for the month of May when a late-month heat wave set in. This included a high temperature of 90 degrees Fahrenheit in Tinnsjø, Norway on May 27.
Alaska also set high temperature records this summer, and given climate trends in the state, these are worrisome ones for local residents under whom the ground is literally shifting as permafrost melts, releasing long-trapped greenhouse gases and further warming the climate.
Barrow, Alaska, on the northern tip of the state above the Arctic Circle, had its warmest July on record, and at least three locations in central Alaska had their warmest month of any month this past July.
Even normally hot places have been unusually hot. Take Death Valley, California, for example, which has the reputation for being one of the hottest spots in the U.S. In July, Death Valley set the record for not only its hottest month, but the hottest month on record for any location worldwide. The average temperature for the month of July was 107.4 degrees Fahrenheit.
To get an average monthly temperature that high, you need some extraordinary heat, and Death Valley had that in spades. The temperature never fell below 89 degrees Fahrenheit all month, and one night the low temperature was 103 degrees. (But at least it was a dry heat, right?)
Like many of the other heat waves detailed here, the Death Valley record occurred as a result of a large area of high pressure, which is sometimes referred to as a heat dome, sitting over the region for an extended period of time. Some studies have shown that certain weather patterns associated with contortions of the jet stream are linked to such extremes and influenced by climate change.
“We often think of climate change as a distant issue, one that only matters to future generations,” said Katharine Hayhoe, a climate researcher at Texas Tech University. “Yet many of us are already experiencing its impacts here and now, as human-induced climate change interacts with, and exacerbates, natural patterns such as the heat and heavy downpours that already characterize our summers.”
On Aug. 6, stationary thunderstorms flooded the low-lying city of New Orleans, dumping up to 10 inches of rain on parts of the city in just a few hours time. This rain overwhelmed the city’s pumping system that is designed to move water out of city streets and into Lake Ponchartrain, turning streets into rivers and flooding many homes and businesses.
According to Nola.com, the pumps are designed to handle an inch of rain in the first hour, and a half an inch of rain during subsequent hours, but the storms dropped far more than that.
Like extreme heat, precipitation extremes have also been tied to climate change, since warming air and sea temperatures serve to increase the supply of moisture available for storm systems. More precipitation is now falling in heavier bursts in parts of the world, testing infrastructure such as the 24 pumps in New Orleans.
“We do have climate change, which means warmer oceans, always now potentially providing a greater source of moisture to enhance rain events by 5 to 20 percent, and with extremes even higher,” said Kevin Trenberth, a climate researcher at the National Center for Atmospheric Research in Boulder, Colorado. “New Orleans may be a case in point, like the Louisiana floods a year ago,” he said in an email.
There have been some cool spots of note, too. Much of Germany and western Russia have had a remarkably cool summer so far. And the Arctic, which is normally dominating climate headlines for its rapid sea ice loss at this time of year, has been flirting with all-time low sea ice levels but running unusually cold and cloudy for this time of year.
A series of storms is set to sweep across the Arctic Ocean in coming days, dumping snow on sea ice, potentially averting another all-time record low sea ice extent in September.
It’s worth considering that the summer of 2017 offers a glimpse into our climate future — which looks even more challenging depending how much countries succeed in cutting greenhouse gas emissions.
In April, researchers reported that by midcentury, what is considered extreme heat now will be commonplace in much of the world.
In other words, Death Valley, here we come.