extreme heat

Faster disaster: climate change fuels ‘flash droughts’, intense downpours and storms

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Andrew King, The University of Melbourne and Andrew Dowdy, The University of Melbourne

The run of extreme weather events around the world seems to be never-ending. After the northern summer of extreme heat and disastrous fires, we’ve seen more exceptional autumn weather over Europe with record-breaking heat in the UK.

Meanwhile, record-breaking rain and intense flash floods struck Greece before the same storm devastated Libya, with thousands dead.

Almost 20% of Africa is estimated to be in drought, and drought conditions are returning to parts of Australia. To top it off, we’ve seen several hurricanes intensify unusually quickly in the Atlantic.

We know climate change underpins some of the more extreme weather we’re seeing. But is it also pushing these extreme events to happen faster?

The answer? Generally, yes. Here’s how.

Flash droughts

We usually think of droughts as slowly evolving extreme events which take months to form.

But that’s no longer a given. We’ve seen some recent droughts develop unexpectedly quickly, giving rise to the phrase “flash drought”.

How does this happen? It’s when a lack of rainfall in a region combines with high temperatures and sunny conditions with low humidity. When these conditions are in place, it increases how much moisture the atmosphere is trying to pull from the land through evaporation. The end result: faster drying-out of the ground.

Flash droughts tend to be short, so they don’t tend to cause the major water shortages or dry river beds we’ve seen during long droughts in parts of Australia and South Africa, for example. But they can cause real problems for farmers. Farmers in parts of eastern Australia are already grappling with the sudden return of drought after three years of rainy La Niña conditions.

As we continue to warm the planet, we’ll see more flash droughts and more intense ones. That’s because dry conditions will more often coincide with higher temperatures as relative humidity falls across many land regions.

Flash floods and extreme rainfall

Climate change can cause increased rainfall variability. Some parts of the world will get a lot wetter, on average, while others will get drier, increasing the variation in rainfall between different regions. For Australia, most locations are generally expected to have intensified downpours of rain, as well as intensified droughts. So we might be saying more often “it doesn’t rain, it pours!”.

We’re seeing exceptionally extreme rainfall in many recent events. The recent floods that submerged villages in Greece came from a sudden downpour of over 500 millimetres in a single day. Hong Kong was hit last week by the heaviest rains in 140 years, flooding subway stations and turning streets into rivers.

But why does it happen so quickly?

Sudden extreme rains fall when we have very moist air coupled with a weather system that forces air to rise.

We’ve long known human-caused climate change is increasing how much moisture the air can hold generally, rising by about 7% per degree of global warming. That means storms now have the potential to hold and dump more water.

Notably, the impact of climate change on rain-bearing weather systems can vary by region, which makes the picture more complicated. That means, for instance, climate change may lead to more extreme rain in some places, while other places may only see an intensification in really short extreme rain events and not for longer timescales.

We can safely say, though, that in most parts of the world, we’re seeing more intense storms and sudden extreme rainfall. Sudden dumps of rain drive flash floods.

More moisture in the air helps fuel more intense convection, where warm air masses rise and form clouds. In turn, this can trigger efficient, quick and intense dumps of rain from thunderstorms.

These short-duration rain events can be much larger than you’d expect from the 7% increase in moisture per degree of warming.

Flash cyclones? Hurricanes are intensifying faster

Last month, Hurricane Idalia caused major flooding in Florida. As we write, Hurricane Lee is approaching the US.

Both tropical storms had something odd about them – unusually rapid intensification. That is, they got much stronger in a short period of time.

Usually, this process might increase wind speeds by about 50 kilometres per hour over a 24-hour period for a hurricane – also known as tropical cyclones and typhoons. But Lee’s wind speeds increased by 129km/h over that period. US meteorological expert Marshall Shepherd has dubbed the phenomenon “hyperintensification”, which could put major population centres at risk.

Rapidly intensifying tropical cyclones are strong and can be very hazardous, but they aren’t very common. To trigger them, you need a combination of very high sea surface temperatures, moist air and wind speeds that don’t change much with height.

While still uncommon, rapid intensification is potentially getting more frequent as we heat the planet. This is because oceans have taken up so much of the heat and there’s more moisture in the air. There’s much more still to learn here.

Australia’s El Niño summer in a warming world

Spring and summer in Australia are likely to be warmer and drier than usual. This is due to the El Niño climate cycle predicted for the Pacific Ocean. If, as predicted, we also get a positive Indian Ocean Dipole event, this can heighten the hotter, drier weather brought by El Niño. After three wet La Niña years, this is likely to be a marked shift.

If it arrives as expected, El Niño would lower the risk of tropical cyclones for northern Australia and reduce chances of heavy rain across most of the continent.

But for farmers, it may help trigger flash droughts. Prevailing warm and dry conditions may rapidly dry the land and reduce crop yields and slow livestock growth.

Drier surfaces coupled with grass growth from the wet years could worsen fire risk. Grass can dry out much faster than shrubs or trees, and grass fires can start and spread very rapidly.

Climate change loads the dice for extreme weather. And as we’re now seeing, these extremes aren’t just more intense – they can happen remarkably fast. The Conversation

Andrew King, Senior Lecturer in Climate Science, The University of Melbourne and Andrew Dowdy, Principal Research Scientist, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Continue ReadingFaster disaster: climate change fuels ‘flash droughts’, intense downpours and storms

Summer 2023 was the hottest on record – yes, it’s climate change, but don’t call it ‘the new normal’

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Kansas City’s baseball stadium ran misters to cool people off in heat near 100 degrees on June 28, 2023.
AP Photo/Charlie Riedel

Scott Denning, Colorado State University

Summer 2023 has been the hottest on record by a huge margin. Hundreds of millions of people suffered as heat waves cooked Europe, Japan, Texas and the Southwestern U.S. Phoenix hit 110 degrees Fahrenheit (43 degrees Celsius) for a record 54 days, including a 31-day streak in July. Large parts of Canada were on fire. Lahaina, Hawaii, burned to the ground.

As an atmospheric scientist, I get asked at least once a week if the wild weather we’ve been having is “caused” by climate change. This question reflects a misunderstanding of the difference between weather and climate.

Consider this analogy from the world of sports: Suppose a baseball player is having a great season, and his batting average is twice what it was last year. If he hits a ball out of the park on Tuesday, we don’t ask whether he got that hit because his batting average has risen. His average has gone up because of the hits, not the other way around. Perhaps the Tuesday homer resulted from a fat pitch, or the wind breaking just right, or because he was well rested that day. But if his batting average has doubled since last season, we might reasonably ask if he’s on steroids.

Unprecedented heat and downpours and drought and wildfires aren’t “caused by climate change” – they are climate change.

The rise in frequency and intensity of extreme events is by definition a change in the climate, just as an increase in the frequency of base hits causes a better’s average to rise.

And as in the baseball analogy, we should ask tough questions about the underlying cause. While El Niño is a contributor to the extreme heat this year, that warm event has only just begun. The steroids fueling extreme weather are the heat-trapping gases from burning coal, oil and gas for energy around the world.

Nothing ‘normal’ about it

A lot of commentary uses the framing of a “new normal,” as if our climate has undergone a step change to a new state. This is deeply misleading and downplays the danger. The unspoken implication of “new normal” is that the change is past and we can adjust to it as we did to the “old normal.”

Unfortunately, warming won’t stop this year or next. The changes will get worse until we stop putting more carbon dioxide and other greenhouse gases into the atmosphere than the planet can remove.

The excess carbon dioxide humans have put into the atmosphere raises the temperature – permanently, as far as human history is concerned. Carbon dioxide lingers in the atmosphere for a long time, so long that the carbon dioxide from a gallon of gasoline I burn today will still be warming the climate in thousands of years.

That warming increases evaporation from the planet’s surface, putting more moisture into the atmosphere to fall as rain and snow. Locally intense rainfall has more water vapor to work with in a warmer world, so big storms drop more rain, causing dangerous floods and mudslides like the ones we saw in Vermont, California, India and other places around the world this year.

By the same token, anybody who’s ever watered the lawn or a garden knows that in hot weather, plants and soils need more water. A hotter world also has more droughts and drying that can lead to wildfires.

So, what can we do about it?

Not every kind of bad weather is associated with burning carbon. There’s scant evidence that hailstorms or tornadoes or blizzards are on the increase, for example. But if summer 2023 shows us anything, it’s that the extremes that are caused by fossil fuels are uncomfortable at best and often dangerous.

Without drastic emission cuts, the direct cost of flooding has been projected to rise to more than US$14 trillion per year by the end of the century and sea-level rise to produce billions of refugees. By one estimate, unmitigated climate change could reduce per capita income by nearly a quarter by the end of the century globally and even more in the Global South if future adaptation is similar to what it’s been in the past. The potential social and political consequences of economic collapse on such a scale are incalculable.

Fortunately, it’s quite clear how to stop making the problem worse: Re-engineer the world economy so that it no longer runs on carbon combustion. This is a big ask, for sure, but there are affordable alternatives.

Clean energy is already cheaper than old-fashioned combustion in most of the world. Solar and wind power are now about half the price of coal- and gas-fired power. New methods for transmitting and storing power and balancing supply and demand to eliminate the need for fossil fuel electricity generation are coming online around the world.

In 2022, taxpayers spent about $7 trillion subsidizing oil and gas purchases and paying for damage they caused. All that money can go to better uses. For example, the International Energy Agency has estimated the world would need to spend about $4 trillion a year by 2030 on clean energy to cut global emissions to net zero by midcentury, considered necessary to keep global warming in check.

Just as the summer of 2023 was among the hottest in thousands of years, 2024 will likely be hotter still. El Niño is strengthening, and this weather phenomenon has a history of heating up the planet. We will probably look back at recent years as among the coolest of the 21st century.The Conversation

Scott Denning, Professor of Atmospheric Science, Colorado State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Continue ReadingSummer 2023 was the hottest on record – yes, it’s climate change, but don’t call it ‘the new normal’

US Billboard Campaign Blasts Fossil Fuel Giants for Causing Extreme Heat

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A billboard in Austin, Texas shows a U.S. map with high temperatures across the nation.
 (Photo: Fossil Free Media)

Original article by ULIA CONLEY republished from Common Dreams under Creative Commons (CC BY-NC-ND 3.0). 

“From Alaska to Maui, our communities are struggling to survive the rapidly worsening impacts of the climate crisis, all the while, Big Oil is raking in billions at our expense.”

As about 111 million people in nearly two dozen states continued to face heat advisories, with temperatures reaching as high at 115°F in some cities, the nonprofit media lab Fossil Free Media unveiled a multicity campaign with one simple goal: ensuring that all Americans understand that the intense heatwaves across much of the country this summer have not been a natural phenomenon, but the result of continued fossil fuel extraction.

Starting Thursday drivers along stretches of highway in Phoenix, Arizona; Austin, Texas; and Fresno, California will pass by prominent billboards displaying a map of record-breaking temperatures that have been recorded across the U.S. this summer.

Fresno drivers will be reminded of a 109°F day in their city while those in Phoenix will see 117°F plastered over their hometown on the map, accompanied by the words, “Brought to you by Big Oil” and ThankYouBigOil.com.

That website redirects to Fossil Free Media’s (FFM) Stop the Oil Profiteering (STOP) project, where visitors can read about the estimated cost of climate-related disasters such as hurricanes, extreme heat, and wildfires—over $600 billion from 2016-20 alone—and the 5,000 people killed by such events in that same time period.

“The fossil fuel industry has known for decades that their products are fueling climate change and extreme weather, yet they have failed to act,” reads the website. “Instead, major oil and gas companies continue to invest billions into new projects that lock in decades more fossil fuel extraction while our communities take the heat… literally.”

Jamie Henn, director of the organization, said on social media that the public “needs to understand that this summer’s brutal heatwave was brought to you by Big Oil.”

The World Weather Attribution said last month that the heatwaves experienced by people across the U.S. and Europe in July would have been “virtually impossible” without the climate crisis, which scientists have for years said is being fueled by heat-trapping emissions from oil, gas, and coal extraction.

The organization also reported this week that wildfires in eastern Canada in recent weeks were made twice as likely by the climate emergency, which as STOP said, has created “tinderbox conditions” by making droughts longer and more intense.

“From Alaska to Maui, our communities are struggling to survive the rapidly worsening impacts of the climate crisis, all the while, Big Oil is raking in billions at our expense,” said Cassidy DiPaola, spokesperson for FFM and STOP. “There’s no denying that this summer’s brutal heatwaves are being fueled by the same Big Oil companies who are spreading climate disinformation and blocking much needed climate progress.”

More than 100 people in the U.S. have died of heat-related causes so far this year, and weather experts have continued to report high temperatures throughout August after July set a world record for the hottest month in recorded history.

Jennifer Falcon, a resident of Austin, told FFM that the climate crisis has emerged as an economic justice issue in her community as Texas broke its all-time record for power consumption last month, with people across the state struggling to stay cool.

“Texans are paying 800% more to cool their homes during the extreme heat that blankets our state,” she said. “This means choosing between food on the table or cooling your home to mitigate health impacts from the sweltering heat while Big Oil profits.”

As millions of people in the U.S. faced sweltering temperatures this summer—raising the risk of heat-related illness and even severe contact burns—ExxonMobil reported $7.9 billion in profits, its second-highest profit margin for a second quarter in over a decade.

Along with the billboards, STOP unveiled an ad showcasing the Big Oil’s link to the climate extremes Americans are increasingly at risk of facing.

“Record heatwaves? You can thank Big Oil for that,” said STOP. “Deadly wildfires? Yep, that’s Big Oil. Catastrophic storms? Smog-covered cities? You guessed it—Big Oil.”

The group is one of several scheduled to lead a March to End Fossil Fuels in New York City on September 17, with the rally being held as the United Nations holds a Climate Ambition Summit.

Aimed at pressuring U.S. President Joe Biden to declare a climate emergency, Fossil Free Media said the march is expected to be “the largest climate action since before the pandemic.”

Original article by ULIA CONLEY republished from Common Dreams under Creative Commons (CC BY-NC-ND 3.0). 

Continue ReadingUS Billboard Campaign Blasts Fossil Fuel Giants for Causing Extreme Heat

Extreme heat warnings in effect in 28 states across US

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https://www.theguardian.com/environment/2022/jul/21/extreme-heat-warnings-advisories-28-states

100 million Americans are enduring searing temperatures as Biden declines to announce a climate emergency

The National Weather Service has warned that extreme heat will affect more than 100 million people in the US this week, with triple-digit temperatures in some states and broken temperature records in many areas across the country.

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Heat warnings and advisories have been put in place for 28 states, with central and southern states facing the brunt of the scorching heat.

Some parts of Oklahoma reached 115F (46C) this week, while the Dallas area hit 109F (42C).

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Continue ReadingExtreme heat warnings in effect in 28 states across US