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Climate crisis is driving heatwaves and wildfires. Here's how [1]

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Date: 2022-07-21

Brutal heat waves are gripping both Europe and the United States this week and are forecast to dump searing temperatures on much of China into late August.

In addition to temperatures spiking above 40 Celsius (104 Fahrenheit), wildfires are raging across southern Europe with evacuations in towns in Italy and Greece.

The searing heat is part of a global pattern of rising temperatures, attributed by scientists to human activity.

Climate change makes heat waves hotter and more frequent. This is the case for most land regions, and has been confirmed by the UN’s global panel of climate scientists (IPCC).

Greenhouse gas emissions from human activities have heated the planet by about 1.2 Celsius since pre-industrial times. That warmer baseline means higher temperatures can be reached during extreme heat events.

“Every heatwave that what we are experiencing today has been made hotter and more frequent because of climate change,” said Friederike Otto, a climate scientist at Imperial College London, who also co-leads the World Weather Attribution research collaboration.

Firefighters try to control a wildfire in Louchats, France, on July 17. Thibaud Moritz/AFP/Getty Images A firefighter battles a blaze in the suburb of Pallini, east of Athens, Greece, on July 20. Panayotis Tzamaros/NurPhoto/Getty Images Residents of the neighborhood of Las Llanadas, on the Spanish island of Tenerife, rush to evacuate their animals from the area on July 23. Andres Gutierrez/Anadolu Agency/Getty Images Firefighters spray flame retardant in Hostens, France, on July 22. Benoit Tessier/Reuters Police officers and locals attempt to extinguish a wildfire burning in the village of Vatera, Greece, on July 23. Elias Marcou/Reuters Burned areas are seen on Mont Saint-Michel de Brasparts in Saint-Rivoal, France, on July 22. Sevrette J/ANDBZ/Abaca/Sipa USA Residents of the Greek village of Vrisa wait to evacuate the area on July 24. Anthi Pazianou/AFP/Getty Images Firefighting vehicles are ablaze during a wildfire outside Brasparts, France, on July 19. Loic Venance/AFP/Getty Images This aerial photo shows burnt olive trees and fields in Megara, Greece, on July 20. Aris Oikonomou/AFP/Getty Images A local resident fights a fire with a shovel in Tabara, Spain, on July 19. Bernat Armangue/AP A wildfire burns atop a mountain in the northern suburbs of Athens on July 19. Chine Nouvelle/SIPA/Shutterstock Helicopters drop water above a fire in Avila, Spain, on July 18. Pablo Blazquez Dominguez/Getty Images Firefighters take a break in Catalonia, Spain, on July 17. Eric Renom/NurPhoto/Getty Images A fire engine is driven through El Pont de Vilomara, Spain, on July 18. Albert Gea/Reuters A wildfire burns forest near the Portuguese village of Memoria on July 12. Paulo Cunha/EPA-EFE/Shutterstock Burnt-out cars are seen in central Portugal on July 14. Octavio Passos/Getty Images This aerial photo shows destruction in a residential area following a large blaze in London on July 20. Leon Neal/Getty Images Firefighters work in Avila on July 18. Pablo Blazquez Dominguez/Getty Images A firefighter and a member of Spain's Civil Guard watch a fire in Zamora, Spain, on July 18. Isabel Infantes/Reuters An airplane takes part in firefighting operations in Portugal on July 14. Octavio Passos/Getty Images Burnt cars and trees are seen at a campsite in southwest France on July 19. Clement Viala/infobassin/ABA/Shutterstock Firefighters attempt to control a fire in the French communes of Landiras and Guillos on July 13. Thibaud Moritz/AFP/Getty Images Firefighters work in Rebolo, Portugal, on July 14. Armando Franca/AP A local resident tries to stop flames from reaching houses in Figueiras, Portugal, on July 12. Joao Henriques/AP A cloud of smoke rises from the Dune of Pilat, in the Arcachon basin of southwest France, on July 13. Thibaud Moritz/AFP/Getty Images A firefighter looks on during firefighting operations in Espite, Portugal, on July 13. Pedro Rocha/AFP/Getty Images A wildfire burns through vegetation in Landiras, France, on July 13. Laurent Theillet/AFP/Getty Images People rest after being evacuated from a campsite in western France on July 13. Thibaud Moritz/AFP/Getty Images People look at plumes of smoke caused by a wildfire in Malaga, Spain, on July 15. Hannah McKay/Reuters People take pictures of firefighting aircraft flying over La Teste-de-Buch, France, on July 14. Thibaud Moritz/AFP/Getty Images Firefighters set a backfire to a plot of land to prevent a wildfire from spreading further in Louchats, France, on July 17. Thibaud Moritz/AFP/Getty Images Residents watch as a column of smoke emerges from a fire in A Pobra do Brollón, Spain, on July 17. Eliseo Trigo/EPA-EFE/Shutterstock Residents of Alhaurín el Grande, Spain, were evacuated because of a fire in the Sierra de Mijas mountain range on July 15. Alex Zea/Europa Press/Getty Images A firefighter tackles the flames surrounding Portugal's Ancede village on July 15. Hugo Delgado/EPA-EFE/Shutterstock In pictures: Wildfires in Europe Prev Next

But other conditions affect heatwaves too. In Europe, atmospheric circulation is an important factor.

A study in the journal Nature this month found that heatwaves in Europe have increased three-to-four times faster than in other northern mid-latitudes such as the United States. The authors linked this to changes in the jet stream – a fast west-to-east air current in the northern hemisphere.

To find out exactly how much climate change affected a specific heat wave, scientists conduct “attribution studies.” Since 2004, more than 400 such studies have been done for extreme weather events, including heat, floods and drought – calculating how much of a role climate change played in each.

This involves simulating the modern climate hundreds of times and comparing it to simulations of a climate without human-caused greenhouse gas emissions.

For example, scientists with World Weather Attribution determined that a record-breaking heat wave in western Europe in June 2019 was 100 times more likely to occur now in France and the Netherlands than if humans had not changed the climate.

Heatwaves will still get worse

Global warming is already driving extreme heat events.

“On average on land, heat extremes that would have happened once every 10 years without human influence on the climate are now three times more frequent,” said ETH Zurich climate scientist Sonia Seneviratne.

Temperatures will only cease rising if humans stop adding greenhouse gases to the atmosphere. Until then, heatwaves are set to worsen. A failure to tackle climate change would see heat extremes escalate even more dangerously.

Countries agreed under the global 2015 Paris Agreement to cut emissions fast enough to limit global warming to 2°C, and aim for 1.5°C, to avoid its most dangerous impacts. Current policies would not cut emissions fast enough to meet either goal.

A heat wave that occurred once per decade in the pre-industrial era would happen 4.1 times a decade at 1.5°C of warming, and 5.6 times at 2°C, the IPCC says.

Letting warming pass 1.5°C means that most years “will be affected by hot extremes in the future,” Seneviratne said.

Climate change drives wildfires

Climate change increases hot and dry conditions that help fires spread faster, burn longer and rage more intensely.

In the Mediterranean, that has contributed to the fire season starting earlier and burning more land. Last year, more than half a million hectares burned in the European Union, making it the bloc’s second-worst forest fire season on record after 2017.

Hotter weather also saps moisture from vegetation, turning it into dry fuel that helps fires to spread.

“The hotter, drier conditions right now, it just makes [fires] far more dangerous,” Copernicus senior scientist Mark Parrington said.

Countries such as Portugal and Greece experience fires most summers, and have infrastructure to try to manage them – though both have received emergency EU help this summer. But hotter temperatures are also pushing wildfires into regions not used to them, and thus less prepared to cope.

Forest management and ignition sources are also important factors. In Europe, more than nine out of 10 fires are ignited by human activities, like arson, disposable barbeques, electricity lines, or littered glass, according to EU data. But the climate crisis typically creates conditions that make the impacts of these fires much worse.

Countries, including Spain, face the challenge of shrinking populations in rural areas, as people move to cities, leaving smaller workforces to clear vegetation and avoid “fuel” for forest fires building up.

Some actions can help to limit severe blazes, such as setting controlled fires that mimic the low-intensity fires in natural ecosystem cycles, or introducing gaps within forests to stop blazes rapidly spreading over large areas.

But scientists concur that without steep cuts to the greenhouse gases causing climate change, heat waves, wildfires, flooding and drought will significantly worsen.

“When we look back on the current fire season in one or two decades’ time, it will probably seem mild by comparison,” said Victor Resco de Dios, professor of forest engineering at Spain’s Lleida University.

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[1] Url: https://www.cnn.com/2022/07/21/world/climate-heat-wave-wildfires-weather-explainer-intl/index.html

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