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How climate change worsens heatwaves, droughts, wildfires and floods How climate change worsens heatwaves, droughts, wildfires and floods
(5 months later)
Parts of northern Libya were hit by devastating flooding after extreme rainfall caused two dams to collapse Climate change is the most likely explanation for why Dubai has been experiencing increasingly heavy rainfall events, a new study says.
Extreme weather is becoming more frequent and more intense in many places around the world because of climate change. Here are four ways that climate change is linked to extreme weather.
Here are four ways climate change is linked to extreme weather. 1. More extreme rain
1. Hotter, longer heatwaves For every 1C rise in average temperature, the atmosphere can hold about 7% more moisture.
Even a small increase to average temperatures makes a big difference. This can result in more droplets and heavier rainfall, sometimes in a shorter space of time and over a smaller area.
This is because the whole distribution of daily temperatures shifts to warmer levels, making hotter days more likely and more extreme. Scientists assess whether individual extreme weather events can be attributed to climate change by taking account of natural and human causes.
Scientists use computer simulations to assess whether extreme weather events have been made more likely by warming caused by humans. In the case of the intense rainfall which fell in Dubai, the United Arab Emirates (UAE) and Oman in April 2024, it was difficult to conclude exactly how much of a role climate change played. That's because heavy rain in this region is rare, giving scientists fewer historical comparisons.
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 types of events have become 10-40% heavier, and climate change is the most likely explanation, according to the World Weather Attribution (WWA) group.
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 two to five years, the WWA warns. In the same month, extreme flooding hit parts of East Africa.
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. It's too early to say exactly what role climate change played in that event. But heavy rainfall in the same region in October and November 2023 was worsened by a combination of climate change and a natural weather phenomenon known as the Indian Ocean Dipole, the WWA found.
As well as happening more frequently, heatwaves are becoming longer and more intense in many places, including the UK. In September 2023, northern Libya was hit by deadly flooding.
This can happen as a result of heat domes, which are areas of high pressure where hot air is pushed down and trapped in place, causing temperatures to soar over large areas. The mayor of Derna in northern Libya suggested as many as 20,000 may have been killed as a result of the flooding
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. The heavy rainfall was made up to 50 times more likely by climate change, and years of political instability hampered efforts to prepare for such events.
Globally, heavy rainfall events have become more frequent and intense over most land regions due to human activity, according to the UN's climate body, the IPCC.
This pattern will continue with further warming, the IPCC says.
2. Hotter, longer heatwaves
Even a small increase to average temperatures makes a big difference to heat extremes.
The distribution of daily temperatures shifts to warmer levels, making hotter days more likely and more intense.
In early April 2024, temperatures in Mali hit 48.5C during an extreme heatwave across the Sahel region of Africa, which has been linked to increased hospitalisations and deaths.
This level of heat would not have been possible without human-caused climate change, the WWA found, and will become more common as the world continues to warm.
In the UK, temperatures topped 40C for the first time on record in July 2022, causing extensive disruption across the country. This would have been extremely unlikely without climate change, the WWA says.
Heatwaves are also becoming longer in many places, including the UK.
This can happen as a result of heat domes, which are areas of high pressure where hot air is pushed down and trapped, causing temperatures to soar over large areas.
One theory suggests that higher temperatures in the Arctic - which has warmed nearly four times faster than the global average - are causing strong winds called the jet stream to slow, increasing the likelihood of heat domes.
Is the UK getting hotter?Is the UK getting hotter?
Life at 50 degreesLife at 50 degrees
2. Longer droughts 3. Longer droughts
Linking climate change with specific 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.
But longer and more intense heatwaves can worsen droughts by drying out soil. This makes the air above warm up more quickly, leading to more intense heat. The availability of water depends on more than just temperature and rainfall, with natural weather systems also playing a key role. This was the case with drought in southern Africa in early 2024.
Increased demand for water from humans, especially farmers, in hot weather puts even more stress on the water supply. But heatwaves fuelled by climate change can worsen droughts by drying out soil. This makes the air above warm up more quickly, leading to more intense heat.
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. During periods of hot weather, increased demand for water, especially from farmers, 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, as the region suffered its worst drought for 40 years. This displaced 1.2 million people in Somalia alone.
Climate change has made droughts like this at least 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.
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. And human-caused warming was also the main driver of the Amazon rainforest's worst drought in at least half a century in the second half of 2023.
3. More fuel for wildfires 4. 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, such as changing land use. Fires happen naturally in many parts of the world. It's difficult to know if climate change has caused or worsened a specific wildfire because other factors are also relevant, such as changing land use.
But climate change is making the weather conditions needed for wildfires to spread more likely, according to the UN's climate body, the IPCC. But climate change is making the weather conditions needed for wildfires to spread more likely, the IPCC says.
Extreme and long-lasting heat draws more and more moisture out of the ground and vegetation. Extreme, long-lasting heat draws more moisture out of soils and vegetation.
These tinder-dry conditions provide fuel for fires, which can spread at an incredible speed, particularly if winds are strong.These tinder-dry conditions provide fuel for fires, which can spread at an incredible speed, particularly if winds are strong.
Rising temperatures may also increase the likelihood of lightning in the world's northernmost forests, increasing the risk of fires. Canada experienced by far its its worst wildfire season on record in 2023.
Canada experienced by far its its worst wildfire season on record in 2023, with around 18 million hectares (45 million acres) burned. Canada experienced by far its worst wildfire year on record in 2023
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. Climate change more than doubled the likelihood of the extreme "fire weather" conditions in eastern Canada in May and June 2023, which helped fires to spread, the WWA says.
Extreme wildfires are projected to become more frequent and intense in future across the globe, according to a recent report by the UN Environment Programme (UNEP). This is due to the the combined effects of shifting land use and climate change Rising temperatures may also increase the likelihood of lightning in the world's northernmost forests, triggering fires.
The number of the most extreme fires may rise by as much as 50% by 2100, UNEP suggests. Extreme wildfires are projected to become more frequent and intense in future globally, according to the UN Environment Programme (UNEP). This is due to the the combined effects of shifting land use and climate change.
The number of the most extreme fires may rise by up to 50% by 2100, UNEP suggests.
How do wildfires start?How do wildfires start?
4. More extreme rain
For every 1C rise in average temperature, the atmosphere can hold about 7% more moisture.
This can result in more droplets and heavier rainfall, sometimes in a shorter space of time and over a smaller area.
Parts of northern Libya were hit by devastating floods in September as a result of extreme rainfall and two major dam collapses. The heavy rainfall was made as much as 50 times more likely by climate change, according to the WWA.
The destruction was exacerbated by social and political instability in the country, which hampered efforts to adequately prepare for and respond to such storms - for example by maintaining dams.
Not all extreme rainfall events can be attributed to climate change, as other factors including changes to land use can play a role. For example, the WWA says that climate change only had a "limited" role in the heavy rainfall that hit northern Italy in May 2023.
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.
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