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How climate change worsens heatwaves, droughts, wildfires and floods How climate change worsens heatwaves, droughts, wildfires and floods
(about 1 month later)
Parts of Greece are currently being hit by wildfires Much of Spain and southern Europe experienced very high temperatures in July and August 2023
Extreme weather is becoming more frequent and more intense in many places because of climate change.Extreme weather is becoming more frequent and more intense in many places because of climate change.
Scientists say this will continue whilst humans keep releasing planet-warming greenhouse gases.Scientists say this will continue whilst humans keep releasing planet-warming greenhouse gases.
Here are four ways climate change is linked to extreme weather.Here are four ways climate change is linked to extreme weather.
1. More fuel for wildfires 1. Hotter, longer heatwaves
Wildfires happen naturally in many parts of the world. It's difficult to know if climate change has caused a specific wildfire to spread because other factors like changes to land use are also relevant.
Greece is experiencing its worst July for wildfires on record, with fires hitting Rhodes and Corfu. Canada is also experiencing its worst wildfire season on record, with more than 25,000 acres (100,000 sq km) already burnt. This follows severe wildfires in Chile and Australia earlier in 2023.
Some regions - such as the western US - have seen an increase in the area burnt by wildfires in recent decades, but global wildfire trends are more complicated.
However, scientists say climate change is making the weather conditions needed for wildfires to spread more likely.
Extreme and long-lasting heat draws more and more moisture out of the ground and vegetation.
Dozens of people died and were evacuated in Chile as wildfires burned across the country
These tinder-dry conditions provide fuel for fires, which can spread at an incredible speed, particularly if winds are strong.
Scientists expect wildfires to become more frequent and intense in future due to the combined effects of land use and climate change.
Rhodes rescue flights under way as fires continue
How do wildfires start?
Millions under smoke advisory due to Canada fires
2. Hotter, longer heatwaves
Even a small increase to average temperatures makes a big difference.Even a small increase to average temperatures makes a big difference.
This is because the whole distribution of daily temperatures shifts to warmer levels, making hotter days more likely and more extreme.This is because the whole distribution of daily temperatures shifts to warmer levels, making hotter days more likely and more extreme.
Scientists use computer simulations to judge whether extreme weather events have been made more likely by warming caused by humans. Scientists use computer simulations to assess whether extreme weather events have been made more likely by warming caused by humans.
They say the intense heatwaves that hit southern Europe and the southern US and Mexico in July 2023 would have been "virtually impossible" without human-caused climate change, according to the World Weather Attribution network (WWA). For example, the intense heatwaves that hit southern Europe and the southern US and Mexico in July 2023 would have been "virtually impossible" without human-caused climate change, according to the World Weather Attribution network (WWA).
But these events are no longer rare, the WWA warns. If global warming reaches 2C above the pre-industrial period - before humans started burning fossil fuels at scale - these events are expected to happen every 2-5 years. But these events are no longer rare. If global warming reaches 2C above the pre-industrial period - before humans started burning fossil fuels at scale - these events are expected to happen every 2-5 years, the WWA warns.
In the UK, temperatures topped 40C for the first time on record in July 2022. This would have been "extremely unlikely" without climate change, the WWA says.In the UK, temperatures topped 40C for the first time on record in July 2022. This would have been "extremely unlikely" without climate change, the WWA says.
Why is it so hot in the UK?
Is the UK getting hotter?Is the UK getting hotter?
Life at 50 degreesLife at 50 degrees
Heatwaves are also becoming longer and more intense - including in the UK. As well as happening more frequently, heatwaves are becoming longer and more intense in many places, including the UK, where 2022 was the warmest year on record.
This can happen through "heat domes" - an area of high pressure where hot air is pushed down and trapped in place, causing temperatures to soar over large areas. This can happen as a result of "heat domes" - an area of high pressure where hot air is pushed down and trapped in place, causing temperatures to soar over large areas.
One theory suggests higher temperatures in the Arctic - which has warmed more than four times faster than the global average - are causing strong winds called the jet stream to slow, increasing the likelihood of heat domes.One theory suggests higher temperatures in the Arctic - which has warmed more than four times faster than the global average - are causing strong winds called the jet stream to slow, increasing the likelihood of heat domes.
3. Longer droughts 2. Longer droughts
Linking climate change and individual droughts can be difficult. The availability of water depends on more than just temperature and rainfall. Linking climate change with specific individual droughts can be difficult. The availability of water depends on more than just temperature and rainfall.
But longer and more intense heatwaves can worsen droughts by drying out soils. The air above then warms up faster, leading to more intense heat. But longer and more intense heatwaves can worsen droughts by drying out soils. This means the air above warms up more quickly, leading to more intense heat.
Increased demand for water from humans and farmers in hot weather puts even more stress on the water supply.Increased demand for water from humans and farmers in hot weather puts even more stress on the water supply.
In parts of East Africa, there were five failed rainy seasons in a row between 2020 and 2022, leaving more than 20 million people at risk of being dangerously short of food. In parts of East Africa, there were five failed rainy seasons in a row between 2020 and 2022, as the region suffered its worst drought for 40 years.
Climate change has made droughts like this more than 100 times more likely, according to the WWA. Climate change has made droughts like this at least 100 times more likely, according to the WWA.
Drought in Somalia - the country has suffered five failed rainy seasons in a row The East African drought hit agriculture and food security hard, displacing nearly 1.2 million people in Somalia alone, according to the World Meteorological Organisation.
3. More fuel for wildfires
Fires happen naturally in many parts of the world. It's difficult to know if climate change has caused a specific wildfire to spread because other factors are also relevant, like changes to the way land is used.
But climate change is making the "fire weather" conditions needed for their spread more likely, according to the UN's climate body, the IPCC.
Extreme and long-lasting heat draws more and more moisture out of the ground and vegetation.
These tinder-dry conditions provide fuel for fires, which can spread at an incredible speed, particularly if winds are strong.
Canada is experiencing its worst wildfire season on record, with over 160,000 sq km (40 million acres) already burnt.
Climate change more than doubled the likelihood of the extreme "fire weather" conditions in eastern Canada that allowed the fires to spread, according to the WWA.
There have also been severe wildfires in Greece, Chile and Australia in 2023.
Global fire trends are complicated because of changing land use, but many regions have seen increases in the area burnt by extreme wildfires in recent decades, including the western US and Canada.
Wildfires are projected to become more frequent and intense in future globally due to the the combined effects of land use and climate change, according to a recent report by the UN Environment Programme.
It suggested that the number of the most extreme fires may increase by up to 50% by 2100.
How do wildfires start?
Is climate change fuelling Canada's wildfires?
The numbers behind Canada's worst wildfire season
4. More extreme rain4. More extreme rain
The warmer it becomes, the more moisture the atmosphere can hold. For every 1C rise in average temperature, the atmosphere can hold about 7% more moisture.
This results in more droplets and heavier rainfall, sometimes in a shorter space of time and over a smaller area. This can result in more droplets and heavier rainfall, sometimes in a shorter space of time and over a smaller area.
In 2022, Pakistan experienced its wettest July and August on record, triggering devastating floods affecting more than 33 million people. It is "likely" that climate change played a role, according to the WWA, but natural weather patterns like the monsoon may have been involved too.In 2022, Pakistan experienced its wettest July and August on record, triggering devastating floods affecting more than 33 million people. It is "likely" that climate change played a role, according to the WWA, but natural weather patterns like the monsoon may have been involved too.
Extreme rainfall and flooding has also hit other regions, including West Africa between May and October 2022, and New Zealand in February 2023. Not all extreme rainfall events can be attributed to climate change, as other factors like natural variability or changes to land use can play a role. For example, climate change had a "limited" role in the heavy rainfall that hit the Emilia-Romagna region in northern Italy in May 2023, the WWA says.
Scientists cannot say for certain that they were caused by climate change, but the floods are consistent with the changes they expect in a warming world. But globally, the frequency and intensity of heavy rainfall events has increased over most land regions due to human activity, according to the IPCC.
And heavy precipitation will generally become more frequent and intense with further warming, the IPCC says.
A really simple guide to climate changeA really simple guide to climate change
How do we know climate change is caused by humans?How do we know climate change is caused by humans?
Greece Wildfires
Could powerful heatwaves and summer wildfires, which have devastated communities and displaced tourists in Greece, become the new normal in Europe?
Available now on BBC iPlayer (UK only)
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