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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.
Here are four ways climate change is linked to extreme weather.
1. Hotter, longer heatwaves
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.
Scientists use computer simulations to judge whether extreme weather events have been made more likely by warming caused by humans.
For example, a record-breaking heatwave across Spain, Portugal and northwest Africa in April was made at least 100 times more likely by climate change, according to the World Weather Attribution network (WWA).
Temperatures which topped 40C in the UK for the first time on record in July 2022 would have been “extremely unlikely” without climate change, the WWA says.
Heatwaves are also becoming longer and more intense – including in the UK.
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.
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 and increasing the likelihood of heat domes.
2. Longer droughts
Linking climate change and individual droughts can be difficult. The availability of water is not just down to 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.
Demand for water from humans and farming in hot weather puts even more stress on the water supply.
In parts of East Africa, an ongoing drought has left more than 20 million people at risk of being dangerously short of food. Climate change made this drought more than 100 times more likely, according to the WWA.
3. More fuel for wildfires
Wildfires happen naturally in many parts of the world. It’s difficult to know if climate change has caused a wildfire because other factors like changes to land use can be involved.
Some regions – such as the western US – have seen an increase in the area burnt by wildfires, but global wildfire trends are complex.
However, scientists say climate change is making the weather conditions needed for wildfires more likely.
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.
Alberta in Canada has seen “unprecedented” wildfires, forcing nearly 30,000 people to leave their homes. This follows severe wildfires in Chile and Australia earlier in 2023.
Scientists expect wildfires to become more frequent and intense in future due to the combined effects of land use and climate change.
4. More extreme rain
The warmer it becomes, the more moisture the atmosphere can hold.
This results 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.
Extreme rainfall and flooding has also hit other regions, including West Africa between May and October 2022, and New Zealand in February 2023.
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.
