Heatwave in U.S.: From Coast to Coast, Millions Affected

Heat Wave

A widespread heatwave has begun across the contiguous U.S., with at least 35 million people likely to see temperatures reach or exceed 100°F by the end of the week. Heat alerts are in place across at least 16 states in the south, midwest and western U.S.

Media reports said:

The hot weather, which comes courtesy of another heat dome building across the U.S. Southwest, Rockies and then sliding into the western Plains, will only aggravate drought conditions and worsen many of the western wildfires.

The heat will be noteworthy not so much for its severity as it will be for its expansiveness, with temperatures in the 90s to low triple-digits stretching from Washington and Oregon to the East Coast at times.

Temperatures will be especially heightened on Monday across Idaho and portions of Montana, where excessive heat warnings are in effect.

Forecast highs in northeastern Montana and northern Wyoming, an area of the country that so far this summer has seen more 100-degree days than Dallas, Texas, are once again into the triple digits.

Some locations in eastern Montana could reach 110 degrees on Monday and Tuesday.

As an area of high pressure in the upper levels of the atmosphere, colloquially known as a heat dome, spins and intensifies over the Rockies through midweek, it’s likely to continue pushing heat and some humidity to the north.

A ribbon of heat is stretching from the Pacific Northwest — where large wildfires are already burning — eastward across the Intermountain West and northern Rockies, and then into the Midwest, Ohio Valley, and Mid-Atlantic states.

Cities including Omaha, Des Moines, Minneapolis, Oklahoma City, Dallas and Shreveport, Louisiana, are also under heat advisories, with some regions placed in excessive heat watches, for extreme heat that may not peak until midweek in the Midwest in particular.

Highs in Minneapolis, on Tuesday and Wednesday are forecast to be in the mid-to-upper 90s on Tuesday and Wednesday. “Extreme heat and humidity will significantly increase the potential for heat related illnesses,” the Weather Service warned.

Overnight lows are not forecast to drop below the mid-70s in the Twin Cities, heightening public health risks by depriving the body of an opportunity to rest and cool down.

Scientists concluded that the Pacific Northwest heat wave, which broke all-time heat records in dozens of locations including Seattle and Portland at 108°F and 115°F, respectively was so severe it was “virtually impossible” in the absence of global warming.

This event will be at least the fifth distinct heat wave the U.S. will have seen so far this summer.

The latest heatwave comes after the U.S. saw its hottest June on record, featuring an unprecedented heat wave in the Pacific Northwest as well as extreme heat in the Southwest.

Is Something Missing?

That heat event, plus other events that have taken place around the world this summer, have some climate scientists questioning whether their computer models are missing something fundamental, since extreme events seem to be outpacing predictions in some parts of the world.

The heat has combined with drought conditions across the West to yield perilous wildfire risks, and more than 80 large blazes are currently burning, with more than 20,000 personnel deployed to fight the flames.

And according to a new study published in Nature, “record-shattering” temperatures are going to become two to seven times more frequent than in the last 30 years.

In the Pacific Northwest, an excessive heat warning remained in place in southwestern Idaho until midnight on Monday, with the National Weather Service warning of “dangerously hot” temperatures set to reach 106F (41.1C).

Idaho has 23 active wildfires, the most of any state, which have so far burned over 192,000 acres.

The Pacific Northwest has suffered hundreds of fatalities during an extended heatwave last month, as the extreme heat caused power cables to melt and roads to buckle in Seattle this summer.

In South Dakota, St Louis, Missouri, and parts of Washington state, heat indexes could reach more than 110F.

The extended high ridge is causing concern among firefighters battling the more than 80 major wildfires currently burning across the western United States.

By Wednesday, the Central US states of Kansas and Nebraska will experience the highest temperatures in the nation, up to 20 degrees above average, the National Weather Service reported.

In Louisiana, a heat advisory is already in place for almost the entire state, as well parts of Oklahoma, Tennessee and Mississippi.

In Texas, the power grid operator said demand would reach a record high over the next week as homes and businesses crank up their air conditioners to battle the heat wave.

Houston reached 97F (36C) on Monday, and is expected to reach the 90s every day between July 22 and August 2.

The state’s power grid failed during a deadly winter storm in February, leaving millions of people without power.

According to the US National Ocean Service, a heat dome occurs when ridges of high pressure become lodged in the Earth’s atmosphere, trapping mountains of warm air beneath them.

In explaining what causes the heat domes, scientists from the National Ocean Service found the main cause was a “strong change in ocean temperatures from west to east in the tropical Pacific Ocean during the preceding winter”.

The new study, published on Monday in Nature, found that if current greenhouse gas (GHG) emissions continue, heat waves could become 21 times more likely by 2050.

Even after dozens of national record-breaking temperatures in 2021, report co-author Erich Fischer, a climate scientist at ETH Zurich, said: “We haven’t seen anything close to the most intense heat waves possible under today’s climate, let alone the ones we expect to see in the coming decades”.

Chances of ‘Record-Shattering’ Heatwaves to Soar

“Record-shattering” events similar to North America’s recent deadly heatwave could soar in the coming years if little is done to tackle rapidly rising greenhouse gas emissions, a new study says.

The research finds that similar record-shattering heatwaves could become between two and seven times more likely across the world by 2050, when compared to the last three decades, if greenhouse gas emissions rise extremely quickly.

And such events could become up to 21 times more likely by 2080 if little is done to tackle rising emissions, the study says.

However, taking rapid action on greenhouse gas emissions could stem much of the expected increases in record-shattering heat, the scientists add.

The findings come just months before world leaders are due to meet for a major global climate summit in Glasgow. The talks are seen as crucial for getting the world on track to meeting its aspirational goal of limiting global heating to 1.5C above pre-industrial levels.

“We need to prepare for more record heat events that shatter previous record temperatures by large margins,” Dr Erich Fischer, a senior scientist at ETH Zurich and lead author of the study, published in the journal Nature Climate Changetold The Independent.

“This is yet another piece in the puzzle that demonstrates that, in order to reduce the risk of such record-shattering heat, greenhouse gas emissions need to be reduced very rapidly.”

Last month’s record-breaking North American heatwave stunned climate scientists.

The event saw Canada set a new temperature high of 49.6C (121F) – more than 4C above the previous record of 45C (113F). Parts of the US including Seattle and Portland also saw temperatures that were several degrees above previous records.

The new research uses climate models to assess how the probability of such “record-shattering” events occurring anywhere in the world is likely to change in the coming decades.

The researchers looked at the probability of such events occurring under a range of future scenarios.

This included a future scenario where GHG emissions are extremely high (known as “RCP8.5”) and a scenario where temperature rise is successfully limited to well below 2C (known as “RCP2.6”). Limiting global heating to well below 2C is the goal set by countries under the Paris Agreement.

The research finds that, under a scenario of very high GHG emissions, week-long heat events that break records by three or more standard deviations will be come between two and seven times more likely in the period 2021-2050 and three to 21 times more likely in the period 2051-2080, when compared to the last three decades.

In the second half of the 21st century, record-shattering heat events could occur every six to 37 years somewhere in the northern midlatitudes, the research adds.

The “hotspot areas” for record-shattering heatwaves are likely to include densely populated areas such as the eastern US, central Europe, eastern Asia and parts of South America and Africa, the scientists say.

Though heatwaves will continue to get more extreme in the coming decades, rapid action to slash the rate of GHG emissions could prevent much of the expected increases in the second half of the 21st century, said Dr Fischer.

“If we are able to stabilize temperatures at 2C, we should expect to see less such record-shattering events after a couple of decades,” said Dr Fischer.

“The heatwaves would still be there but we would not expect them to break records by those margins.”

The new research shows that the world is likely to see more “unprecedented events” as the climate warms, said Dr Scott Power, a senior scientist at the Australian government’s Bureau of Meteorology, who was not involved in the research.

“The new study further highlights that reducing global greenhouse gas emissions can moderate the likelihood of record shattering,” he told The Independent.

“Unprecedented events like these could, in some instances, push ecosystems and societies beyond their ability to cope.

Dr Vikki Thompson, a senior research associate at the University of Bristol, added that it is worth noting that the world currently has targets in place to avoid the very high greenhouse gas emissions expected under the RCP8.5 scenario.

“The good news is that we can prevent the worst case shown in this study – we are already on target to be below it and further reductions in emissions will reduce the risk of unprecedented extremes further,” she said.

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