These kinds of dystopian weather events, happening often at the same time, are exactly what scientists have been warning about for decades. While extreme weather is a part of the natural cycle, the recent uptick in the ferocity and frequency of these extremes, scientists say, is evidence of an acceleration of climate impacts, some of which were underestimated by climate computer models.
"This is yet another example of where uncertainty is not our friend," says Michael Mann, distinguished professor of atmospheric science at Penn State. "As we learn more, we are finding that many climate change impacts, including these sorts of extreme weather events, are playing out faster and with greater magnitude than our models predicted."
On Wednesday NOAA released its latest State of the Climate Report, which finds that just during the month of August the U.S. was hit by four different billion-dollar disasters: two hurricanes, huge wildfires and an extraordinary Midwest derecho.
Just one such extreme event can strain emergency resources — a situation West Coast firefighters find themselves in now. However, in two dramatic cases this summer, the nation was hit simultaneously with concurrent catastrophes, some of which had no precedent in modern history. It's a concept scientists call compound events, and it is necessary to factor these confluences into future projections to properly estimate risk, response and resources.
In mid-August the West suffered through an extended heat wave which saw Death Valley surge to 130 degrees, the hottest temperature ever reliably measured on Earth. The tinderbox conditions caused by the heat, along with a rare lightning outbreak, sparked the first round of major wildfires in California this season, escalating into three of the four largest fires in state history. At about the same time a powerful derecho caused billions of dollars in damage in Iowa and Illinois, and Hurricane Laura plowed into the Gulf Coast of Louisiana as a Category 4 with 150 mph winds and 16 feet of storm surge.
Just three weeks later, and here we are again. This past weekend California experienced an even more intense heat wave, with the southern part of the state hitting 121 degrees west of the mountains for the first time in record-keeping history. Predictably, fires flared back up due to the severe heating and drying, and then went into overdrive as a wicked early-season cold front — which is also bringing heavy snow to the Rockies — brought a wind event through the mountains and valleys of the intermountain west.
In Washington state, an estimated 330,000 acres burned across the state on Monday, more than the total in each of the last 12 fire seasons. California has seen a record 2.3 million acres burn so far this year — more than 3 times the normal for an entire season (typically July through November), and 7 times the normal year to date.
If it were just this fire season, one could chalk the extremity up to mere coincidence. But scientists say this is part of an ongoing upward trend, made clear by the data and well understood by science.
"There is little doubt that we're witnessing an acceleration of fire activity in the West - be it in terms of burned area, number of large fires, fire growth, and of course direct and indirect impacts to people," explains Dr. John Abatzoglou, climate professor at the University of California Merced.
The acceleration has been dramatic. Fire season is now two to three months longer than it was just a few decades ago across much of the West. Since the 1970s, California has experienced a five-fold increase in annual burned area and an eight-fold increase in summer forest fire extent. At least 17 of California's top 20 largest wildfires have burned since 2000.
Increase in California areas burned by wildfires, 1975 to 2015. WILLIAMS, ABATZOGLOU ET AL., EARTH'S FUTURE
Abatzoglou makes clear that there are many factors — not just climate change — that contribute to the escalation of fire activity. These include the increased settlement of people in fire-prone lands and a legacy of fire suppression in many lower-elevation forests, which led to years of heavy growth of trees and brush.
"We can focus on the bad fortune of the lightning siege around the San Francisco Bay Area, or the multitude of stupid human tricks that materialized in large wildfires, but the confluence of long-term and short-term environmental factors set the table for the 2020 fire season," he said.
In other words, though climate change does not cause the heat waves or fires, it sets the stage so that when conditions are ripe, like the summer and fall of 2020, heat waves are more intense and fires burn more fiercely.
CLIMATE CENTRAL
This summer has been extremely hot and dry in the West. According to NOAA, Arizona, California, Colorado, Nevada, New Mexico and Utah each had their warmest August on record. Research has found that heat waves are now larger, getting more intense and lasting longer than decades ago. Specifically in California, extreme heat waves — like the ones of recent weeks — are now 3 to 4 degrees Fahrenheit warmer due to climate change. By 2080, that same study finds such heat waves will intensify by another 3 to 5 degrees.
This week's NOAA report also finds that the same general area in the West also experienced one of its driest Augusts on record. This short-term dry and hot pattern is mainly due to natural cycles in weather, and from season to season has the biggest impact on the amount of area burned because it determines how dry the forests and brush are.
"Across the Western U.S. forests, we find that climatic measures of fuel dryness explain about ¾ of the year-to-year variability in the burned area — highlighting that climate very strongly enables big fire seasons in warm-dry summers and inhibits widespread fire activity in cool-wet summers," explains Abatzoglou.
But over the long term, human-caused climate change has been gradually drying out the atmosphere and the fuel. "The observed changes in fuel dryness [plus the] number of days of high fire danger have been particularly stark in the American West over the past half-century," says Abatzoglou.
Since the 1970s the warm season in the West has heated up by 2 to 3 degrees Fahrenheit. This extra heat has increased the evaporation of moisture from the surface. While atmospheric moisture has also increased some, it has not increased nearly as fast as the temperature. That has caused a long-term "moisture deficit" and has accelerated the rate of foliage drying. This is part of the reason why, according to research, the West has entered into one of the worst megadroughts in the past 1,200 years.
A recent study, co-authored by Abatzoglou, found a direct link with nearly all of the increase in summer forest-fire area during the period from 1972–2018 driven by the increased moisture deficit. To illustrate just how impactful the moisture deficit is, right now, as unprecedented wildfires burn out of control, the deficit is at record low levels in the majority of the Western U.S.
Absurd atmospheric aridity (+ other factors) is enabling the ongoing fire outbreak – synchronized downslope winds… https://t.co/ohibdi2X5x— John Abatzoglou (@John Abatzoglou)1599605014.0
Another recent study from this spring found that the frequency of autumn days with extreme fire weather conditions has more than doubled since the 1980s, fueled by a combination of less rainfall and warmer temperatures.
But many scientists believe that there is more at play contributing to this extreme weather than simply the direct effects of warming and drying. One of those mechanisms is the indirect impacts of global warming on the most influential weather-maker on day-to-day conditions: the jet stream.
The speed and orientation of the jet stream — a river of fast-moving air currents in the atmosphere — determines the track, intensity and forward speed of most storm systems and also how cold or hot the weather is. The attributes of the jet stream at any given moment are determined largely by the placement of hot and cold air masses and the strength of the gradient between them. Because the Arctic has been warming at three times the rate of the rest of the globe, climate scientists know human-caused climate change is throwing the jet stream off-kilter. But how and to what extent is not totally understood.
A number of climate scientists believe that a warmer Arctic is slowing down the jet stream during certain times of year, resulting in a more wavy jet stream. As shown below, a wavy jet stream can catapult warm air northward into the Arctic and drive cold air far southward. This is exactly what happened during the catastrophic Midwest floods in 2019 and is also the kind of pattern we have right now, which is causing record low temperatures and extremely early season snow in the Rockies and Plains. A wavy jet stream is a normal part of nature, but climate change may be making it more amplified, resulting in more extremes.
"I think it's a triple whammy — heat and drought, which are favored by climate change, and the extra added ingredient is the slower, wavier jet stream," explains Mann. But he says the wavier jet stream isn't well resolved by current models, thus they underestimate the extremity of weather events enhanced by climate change.
As a result, when scientists dig into the causes of an extreme event, Mann says the studies underestimate the influence of human-caused climate change. "So if anything, climate attribution studies are likely to under-attribute the role that climate change is playing with these persistent extreme weather events," he said.
As for future fire seasons, Abatzoglou says we should expect extreme fires seasons like 2020's to become the rule rather than the exception.
"While the extent of the ongoing fire siege is beyond what most have seen in the West, the alignment of ingredients for such fire seasons is becoming more favorable as a result of climate change and land-use practices," he said. "We should expect, adapt, and prepare for similar years moving forward."
This story originally appeared in CBS News and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.
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According to weather records experts Christopher Burt, who wrote the comprehensive weather records book "Extreme Weather," and Maximiliano Herrera, who tweets under the Twitter handle Extreme Temperatures Around the World, the observation may be the hottest reliably recorded temperature in world history, breaking the 129.2 degrees Fahrenheit readings at Death Valley in 2013 and in Kuwait in 2016.
Cautions About the Record
Herrera and Burt are cautious about accepting the new record set at the Furnace Creek Visitor's Center in Death Valley. The measurement came in mid-August. But extreme high temperature records are much easier to set in July, which is the hottest month of summer. Also concerning was the fact that Sunday's temperatures at Furnace Creek showed some odd jumps during the day. (See the raw high-resolution data here by choosing a time up to six days in the past from the drop-down menu, then choosing "Decoded Data.")
However, there were some relevant wind direction changes at Furnace Creek that occurred during these temperature jumps, bolstering the idea that the temperature changes were real. The National Weather Service noted that transient high cirrus clouds may have played a role in the temperature changes. Further support for the 130 degrees Fahrenheit reading at Furnace Creek came from the nearby Stovepipe Wells site in Death Valley, which peaked at 125 degrees Fahrenheit on Sunday. That site, which lies in a cooler part of the valley and is 200 feet higher in elevation, is typically three to five degrees cooler than the Furnace Creek site.
The Greenland Ranch USWB weather shelter in Death Valley, California, site of the official world record extreme temperature of 134 degrees Fahrenheit on July 10, 1913. Photo is the oldest known photograph of the weather station (circa late 1910s to as late as 1921) and is looking west. NWS Las Vegas archives via Chris Burt
The Official World Record Will Remain 134°F
"If Sunday's observation passes an investigation (instrument calibration, etc.) then, yes, this a new reliably measured global extreme heat record," Burt wrote by email.
But the observation will not count as an official world record. In 2013, the World Meteorological Organization officially decertified the official all-time hottest temperature in world history, a 136.4 degrees Fahrenheit reading from Al Azizia, Libya, in 1923. (Burt was a member of the WMO team that made the determination.) After the abandonment of the Libya record, the official world record was given to a 134 degrees Fahrenheit measurement taken at Death Valley on July 10, 1913.
However, this record has been strongly disputed by Burt and Herrera.
"The old Death Valley record from July 1913 is 100% bogus (not just 99.9% such), as are all other temperature readings of 130 degrees Fahrenheit or higher from Africa in the past," Burt said.
Burt wrote a detailed 2016 blog post at Weather Underground challenging the 1913 record at Death Valley, explaining that official readings of 134, 130, and 131 degrees Fahrenheit taken on July 10, 12, and 13, 1913 were likely the result of an inexperienced observer. In order for the 1913 Death Valley record to be decertified, though, an official World Meteorological Organization investigation committee would have to be assembled to look into the matter, a years-long process for which there is currently no motivation.
The only other temperature of at least 130 degrees Fahrenheit officially recognized by the World Meteorological Organization is a 131-degree reading at Kebili, Tunisia, set July 7, 1931, which is considered to be Africa's hottest temperature.
Burt disputed this record: "I mentioned to the WMO about the Kebili temperature of 131 degrees Fahrenheit back in 2012, when asked what I thought the next hottest temperature in Africa (after Al Azzia) might be, since that was the only temperature over 130 degrees Fahrenheit that had an actual date attached to it. However, the Kebili 'record' is even more bogus than even the Al Azzia record, and I said so. Kebili is a relatively cool spot in Tunisia (an oasis) and never since the 1930s ever again recorded a maximum temperature above 118 degrees Fahrenheit. The WMO wanted something for their 'Africa' section at that time, and somehow the 131 degrees Fahrenheit made it into the database with no consideration of its validity whatsoever. Nowhere in Africa has any reliably observed temperature been measured above 126 degrees Fahrenheit."
A Weird Weather Day in California
Another argument supporting Sunday's 130 degrees Fahrenheit measurement at Death Valley was the unusual weather setup over California.
"I'm coming around to thinking that this 129.9° reading just might be for real," Burt said. "For one thing, the weather today in California has been unique. All kinds of strange local weather occurred. In fact, the folks at most of the state's National Weather Service offices are saying there has never been a day like today in recorded history in the state: all kinds of weird dynamics at work and the models just can't handle the details."
Yale Climate Connections contributor Bob Henson had these observations on Sunday's weird weather in California: "Among the strange developments over the weekend in California were a highly unusual round of pre-dawn thunderstorms in the Bay Area on Sunday, with only scant rain but profuse lightning that started multiple new wildfires. More than 4,800 lightning strikes were recorded in California on Saturday alone. Also on Saturday, a fire-based thunderstorm (pyrocumulonimbus) in Lassen County spawned what appear to be multiple fire whirls and 'fire tornados,' as indicated by radar and documented in photos and videos. The storm prompted what is apparently the first-ever NWS tornado warning related to pyrocumulonimbus. It will take further study to establish how many vortexes developed and how many might have been fire whirls (smaller-scale, shorter-lived spin-ups akin to dust devils) versus more unusual fire tornadoes, which extend up into a pyrocumulonimbus and which can generate surface winds of more than 100 mph.
"These events are related to an infusion of moisture from the tropical northeast Pacific, some of it from ex-Hurricane Elida, coupled with one of the strongest, hottest upper-level domes of high pressure ever recorded across the western United States in August. When such air is forced to descend, it warms up even more, which can lead to record-setting temperatures at the surface."
Reposted with permission from Yale Climate Connections.
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