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Extreme weather: What is it and how is it connected to climate change? Extreme weather: What is it and how is it connected to climate change?
(25 days later)
People around the globe are experiencing dramatic heatwaves, deadly floods and wildfires as a result of climate change. People around the globe are experiencing more intense heatwaves, deadly floods and wildfires as a result of climate change.
The UK and parts of Europe have seen temperatures of above 40C this month, leading to transport disruption and water shortages.
Emissions caused by the burning of fossil fuels have been trapping heat in the atmosphere since the start of the industrial era. This extra heat isn't evenly distributed across the globe, and bursts out extreme weather events.
Unless global emissions are cut, this cycle will continue.Unless global emissions are cut, this cycle will continue.
A really simple guide to climate change
How do we know climate change is caused by humans?
Dozens of bushfires as heat grips Australia's east
Here are four ways climate change is changing the weather.Here are four ways climate change is changing the weather.
1. Hotter, longer heatwaves1. Hotter, longer heatwaves
To understand the impact of small changes to average temperatures, think of them as a bell curve with extreme cold and hot at either end, and the bulk of temperatures in the middle.To understand the impact of small changes to average temperatures, think of them as a bell curve with extreme cold and hot at either end, and the bulk of temperatures in the middle.
A small shift in the centre means more of the curve touches the extremes - and so heatwaves become more frequent and extreme.A small shift in the centre means more of the curve touches the extremes - and so heatwaves become more frequent and extreme.
Temperatures in the UK topped 40C for the first time on 19 July. Temperatures in the UK topped 40C for the first time on record, in July last year, leading to transport disruption and water shortage.
The Met Office estimates that the extreme heat seen during the most recent heatwave is ten times more likely now because of climate change. And things could worsen. The Met Office estimates the extreme heat is ten times more likely now because of climate change. And things could worsen.
"In a few decades this might actually be a quite a cool summer," says Professor Friederike Otto, a climate scientist at Imperial College London."In a few decades this might actually be a quite a cool summer," says Professor Friederike Otto, a climate scientist at Imperial College London.
The Met Office has also pointed out that heatwaves are not just hotter: They're also lasting longer. Warm spells have more than doubled in length in the past 50 years.The Met Office has also pointed out that heatwaves are not just hotter: They're also lasting longer. Warm spells have more than doubled in length in the past 50 years.
Why is it so hot in the UK?Why is it so hot in the UK?
Is the UK getting hotter?Is the UK getting hotter?
Heatwaves can be made longer and more intense by another weather phenomenon - a heat dome.Heatwaves can be made longer and more intense by another weather phenomenon - a heat dome.
In an area of high pressure, hot air is pushed down and trapped in place, causing temperatures to soar over an entire continent.In an area of high pressure, hot air is pushed down and trapped in place, causing temperatures to soar over an entire continent.
When a storm distorts the jet stream, which is made of currents of fast-flowing air, it is a bit like yanking a skipping rope at one end and seeing the ripples move along it.When a storm distorts the jet stream, which is made of currents of fast-flowing air, it is a bit like yanking a skipping rope at one end and seeing the ripples move along it.
These waves cause everything to slow drastically and weather systems can become stuck over the same areas for days on end - as was seen in India earlier this year. These waves cause everything to slow drastically and weather systems can become stuck over the same areas for days on end.
India and Pakistan have already faced five successive heatwaves this year, with Jacobabad, in Pakistan, registering 49C at one point in May. India and Pakistan faced successive heatwaves, with Jacobabad, in Pakistan, registering 49C at one point in May.
In the Southern Hemisphere, Argentina, Uruguay, Paraguay and Brazil all saw an historic heatwave in January - many areas reported their hottest day on record.
In the same month, Onslow in Western Australia hit 50.7C, the joint-highest temperature ever reliably recorded in the Southern Hemisphere.In the same month, Onslow in Western Australia hit 50.7C, the joint-highest temperature ever reliably recorded in the Southern Hemisphere.
Last year, North America was also hit by long heatwaves. The western Canadian town of Lytton burnt down when temperatures hit 49.6C, breaking the previous record by almost 5C.
Such an intense heatwave would have been virtually impossible without climate change, says the World Weather Attribution network, a collaboration between international climate scientists.
One theory suggests higher temperatures in the Arctic are causing the jet stream to slow, increasing the likelihood of heat domes.One theory suggests higher temperatures in the Arctic are causing the jet stream to slow, increasing the likelihood of heat domes.
The Arctic is also warming more than four times faster than the global average in recent decades. In June 2020, average temperatures in Siberia were up to 10°C above normal, reaching a new record of 38°C in the Arctic circle. This triggered devastating wildfires and sea ice loss.
The World Weather Attribution network (WWA), a collaboration between international climate scientist, concluded this was "almost impossible" without climate change.
Scientists warn 2023 could be even warmer, as a climate phenomenon called La Niña - which has been suppressing global temperatures - has come to an end.
Life at 50 degreesLife at 50 degrees
How do El Niño and La Niña change the weather?
2. More persistent droughts2. More persistent droughts
As heatwaves become more intense and longer, droughts can also worsen. Making a direct link between climate change and individual drought events is challenging. A number of factors influence water availability, not just temperature and precipitation.
But as heatwaves become more intense and longer, droughts are likely to worsen.
Less rain falls between heatwaves, so ground moisture and water supplies run dry more quickly. This means the ground takes less time to heat up, warming the air above and leading to more intense heat.Less rain falls between heatwaves, so ground moisture and water supplies run dry more quickly. This means the ground takes less time to heat up, warming the air above and leading to more intense heat.
Drought in Somalia - the country has suffered three failed rainy seasons in a rowDrought in Somalia - the country has suffered three failed rainy seasons in a row
Demand for water from humans and farming puts even more stress on water supply, adding to shortages.Demand for water from humans and farming puts even more stress on water supply, adding to shortages.
3. More fuel for wildfires3. More fuel for wildfires
Wildfires can be sparked by direct human involvement - but natural factors can also play a huge part.Wildfires can be sparked by direct human involvement - but natural factors can also play a huge part.
The cycle of extreme and long-lasting heat caused by climate change draws more and more moisture out of the ground and vegetation.The cycle of extreme and long-lasting heat caused by climate change 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.These tinder-dry conditions provide fuel for fires, which can spread at an incredible speed.
A firefighting aircraft tackling a wildfire in Slovenia in March Earlier this year the Chilean government put three regions on high alert for forest fires amid weeks of high temperatures.
The Northern Hemisphere's wildfire season begun early in some areas, due to lack of rainfall and unseasonable warmth, and has worsened through July. Dozens of people have died and been evacuated in Chile as wildfires burn across the country
Most recently severe wildfires have been reported in France, Spain, Portugal, Greece, Croatia and Albania - with thousands of residents evacuated and several hundreds reported to have died. In Australia, New South Wales is experiencing its worst fires since the 2019/20 "Black Summer" - as strong winds and scorching temperatures drive the fires' rapid spread.
More than 10,000 residents and tourists have been evacuated in France since the start of July Last summer, France, Spain, Portugal, Greece, Croatia and Albania experienced severe wildfires - with thousands of residents evacuated and several hundreds reported to have died.
In Canada last summer, heatwaves led to fires which developed so rapidly and explosively that they created their own weather system, forming pyrocumulonimbus clouds. These colossal clouds then produced lightning, igniting more fires. More than 10,000 residents and tourists were evacuated in France during the 2022 wildfires
The frequency of large wildfires has increased dramatically in recent decades. In 2021, Canada experienced heatwaves that led to fires which developed so rapidly and explosively that they created their own weather system, forming pyrocumulonimbus clouds. These colossal clouds then produced lightning, igniting more fires.
Compared with the 1970s, fires larger than 10,000 acres (40 sq km) are now seven times more common in western America, according to Climate Central, an independent organisation of scientists and journalists.Compared with the 1970s, fires larger than 10,000 acres (40 sq km) are now seven times more common in western America, according to Climate Central, an independent organisation of scientists and journalists.
Then and now: The burning issue of wildfiresThen and now: The burning issue of wildfires
How do wildfires start?How do wildfires start?
4. More extreme rainfall events4. More extreme rainfall events
In the usual weather cycle, hot weather creates moisture and water vapour in the air, which turns into droplets to create rain.In the usual weather cycle, hot weather creates moisture and water vapour in the air, which turns into droplets to create rain.
The warmer it becomes, however, the more vapour there is in the atmosphere. This results in more droplets and heavier rainfall, sometimes in a shorter space of time and over a smaller area.The warmer it becomes, however, the more vapour there is in the atmosphere. This results in more droplets and heavier rainfall, sometimes in a shorter space of time and over a smaller area.
Already this year, floods have hit Spain and also parts of eastern Australia. In a period of just six days Brisbane saw almost 80% of its annual rainfall, while Sydney recorded more than its average annual rainfall in little over three months. In 2022 floods hit Spain and also parts of eastern Australia. In a period of just six days Brisbane saw almost 80% of its annual rainfall, while Sydney recorded more than its average annual rainfall in little over three months.
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Watch: Record-breaking floods hit Spain’s east coastWatch: Record-breaking floods hit Spain’s east coast
Watch: Record-breaking floods hit Spain’s east coastWatch: Record-breaking floods hit Spain’s east coast
These rainfall events are connected to the effects of climate change elsewhere, according to Peter Gleick, a water specialist from the US National Academy of Sciences.These rainfall events are connected to the effects of climate change elsewhere, according to Peter Gleick, a water specialist from the US National Academy of Sciences.
"When areas of drought grow, like in Siberia and western US, that water falls elsewhere, in a smaller area, worsening flooding," he says. "When areas of drought grow, like in Siberia and western US, that water falls elsewhere, in a smaller area, worsening flooding," he said.
The weather across the globe will always be highly variable - but climate change is making those variations more extreme.The weather across the globe will always be highly variable - but climate change is making those variations more extreme.
And the challenge now is not only limiting the further impact people have on the atmosphere but also adapting to and tackling the extremes we are already facing.And the challenge now is not only limiting the further impact people have on the atmosphere but also adapting to and tackling the extremes we are already facing.
Related TopicsRelated Topics
FloodsFloods
DroughtDrought
WildfiresWildfires
Climate changeClimate change
Severe weatherSevere weather
HeatwavesHeatwaves