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‘Global weirding': climate whiplash hitting world's biggest cities, study reveals

‘Global weirding': climate whiplash hitting world's biggest cities, study reveals

The Guardian12-03-2025

Climate whiplash is already hitting major cities around the world, bringing deadly swings between extreme wet and dry weather as the climate crisis intensifies, a report has revealed.
Dozens more cities, including Lucknow, Madrid and Riyadh have suffered a climate 'flip' in the last 20 years, switching from dry to wet extremes, or vice versa. The report analysed the 100 most populous cities, plus 12 selected ones, and found that 95% of them showed a distinct trend towards wetter or drier weather.
The changing climate of cities can hit citizens with worsened floods and droughts, destroy access to clean water, sanitation and food, displace communities and spread disease. Cities where the water infrastructure is already poor, such as Karachi and Khartoum, suffer the most.
Cities across the world are affected but the data shows some regional trends, with drying hitting Europe, the already-parched Arabian peninsula and much of the US, while cities in south and south-east Asia are experiencing bigger downpours.
The analysis illustrates the climate chaos being brought to urban areas by human-caused global heating. Too little or too much water is the cause of 90% of climate disasters. More than 4.4 billion people live in cities and the climate crisis was already known to be supercharging individual extreme weather disasters across the planet.
Rising temperatures, driven by fossil fuel pollution, can exacerbate both floods and droughts because warmer air can take up more water vapour. This means the air can suck more water from the ground during hot, dry periods but also release more intense downpours when the rains come.
'Our study shows that climate change is dramatically different around the world,' said Prof Katerina Michaelides, at the University of Bristol, UK. Her co-author, Prof Michael Singer at Cardiff University, described the pattern as 'global weirding'.
'Most places we looked at are changing in some way, but in ways that are not always predictable,' Singer said. 'And given that we're looking at the world's largest cities, there are really significant numbers of people involved.'
Coping with climate whiplash and flips in cities is extremely hard, said Michaelides. Many cities already face water supply, sewage and flood protection problems as their populations rapidly swell. But global heating supercharges this, with the often ageing infrastructure in rich nations designed for a climate that no longer exists, and more climate extremes making the establishment of much-needed infrastructure even harder in low income nations.
The researchers have worked in Nairobi, Kenya, one of the cities suffering climate whiplash. 'People were struggling with no water, failed crops, dead livestock, with drought really impacting their livelihoods and lives for multiple years,' Michaelides said. 'Then the next thing that happens is too much rain, and everything's flooded, they lose more livestock, the city infrastructure gets overwhelmed, water gets contaminated, and then people get sick.'
Sol Oyuela, executive director at NGO WaterAid, which commissioned the analysis, said: 'The threat of a global 'day zero' looms large – what happens when the 4 billion people already facing water scarcity reach that breaking point, and the food, health, energy, nature, economies, and security that depend on water are pushed to the brink?'
'Now is the time for urgent collective action, so communities can recover from disasters and be ready for whatever the future holds. This will make the world a safer place for all,' Oyuela said.
The savage wildfires in Los Angeles in January were an example of a single whiplash event, with a wet period spurring vegetation growth, which then fuelled the fires when hot and dry weather followed. Such events are increasing due to human-caused global heating.
The new analysis by Michaelides and Singer was much broader and examined the changes in wet and dry extremes over the past four decades in 112 major cities.
It found that 17 cities across the globe have been hit by climate whiplash, suffering more frequent extremes of both wet and dry conditions. The biggest whiplashes were seen in Hangzhou in China, the Indonesian megacity of Jakarta, and Dallas in Texas. Other whiplash cities include Baghdad, Bangkok, Melbourne and Nairobi. The rapid shift between wet and dry extremes makes it difficult for cities to prepare and recover, damaging lives and livelihoods.
The analysis also found that 24 cities have seen dramatic climate flips this century. The sharpest switches from wet to dry conditions have been in Cairo, Madrid and Riyadh, with Hong Kong and San Jose in California also in the top 10. Prolonged droughts can lead to water shortages, disrupted food supplies and electricity blackouts where hydropower is relied upon.
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The sharpest switches from dry to wet conditions were in Lucknow and Surat in India and in Nigeria's second city, Kano. Other cities with wet flips were Bogotá, Hong Kong and Tehran. Intense rains can cause flash floods, destroying homes and roads and spreading deadly waterborne diseases like cholera and dysentery when sanitation systems are overwhelmed.
The researchers also assessed the level of social vulnerability and quality of infrastructure in the cities. The cities with the biggest increases in climate hazards combined with the highest vulnerability – and therefore the places facing the greatest dangers – were Khartoum in Sudan, Faisalabad in Pakistan, and Amman in Jordan.
Karachi, also in Pakistan, ranked highly for vulnerability as well and is experiencing more wet extremes. Torrential rains in 2022 destroyed the family home of fisher Mohammad Yunis in Ibrahim Hyderi, a waterfront district in the city.
'We have spent many days and nights completely drenched in rain because we had no shelter,' he said. 'The weather affects everything. When it rains heavily, our children fall sick. But we don't have sufficient [clean] water. Our localities are breaking down. Houses near the drainage systems collapse due to floods. When floods come, walls fall apart. If we had enough money, we would not be living here.'
Even in the cities where the changes in climate were less stark, clear trends were seen in almost all of them. The places getting drier over the last 40 years included Paris, Los Angeles, Cape Town, and Rio de Janeiro. Many of those getting wetter are in south Asia, such as Mumbai, Lahore and Kabul.
The researchers also found 11 cities where the number of extreme wet or dry months had fallen in the last 20 years, including Nagoya in Japan, Lusaka in Zambia, and Guangzhou in China.
The overall results of the new study are consistent with the most recent report from the Intergovernmental Panel on Climate Change, which found there were both regions with increases in heavy rains and others with increases in drought, as well as some regions with increases in both, said Prof Sonia Seneviratne, at ETH Zurich in Switzerland, coordinating lead author of the IPCC chapter on weather and climate extreme events.
'A few tenths of a degree warmer and the life we know becomes increasingly at risk due to climate extremes such as heatwaves, droughts, and heavy rainfall,' she said.
Singer said: 'We hope our report can galvanise global attention on the challenges of climate change with respect to water. Perhaps it will lead to a more realistic conversation about supporting adaptation to climate change, with a sense of compassion and understanding of the challenges people are facing, rather than just saying, well, we can't afford it.'
Methodology
The researchers analysed the changing climate of cities using a standard index (SPEI) that combined precipitation with evaporation each month from 1983 to 2023. Index values above a widely-used threshold were categorised as extreme.
To assess changes over the four decades, the data was split into two 21-year periods. The cities that experienced at least 12 months more of one type of extreme climate (wet or dry) and at least 12 months less of the other type of extreme climate in the second 21-year period were classed as having a climate flip. The cities that had at least five months more of both extreme wet and extreme dry in the second period were classed as having developed climate whiplash. The overall wetting or drying trends were determined from all 42 years of data.
The population data used to determine the 100 most populous cities was based on population density, not the administrative boundaries of the city, and therefore are a truer reflection of the city's size. Social vulnerability was measured using the standard Human Development Index and the water and waste infrastructure data was taken from a global dataset published in 2022.

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‘Blackouts can happen anywhere': how power systems worldwide can collapse
‘Blackouts can happen anywhere': how power systems worldwide can collapse

The Guardian

time02-05-2025

  • The Guardian

‘Blackouts can happen anywhere': how power systems worldwide can collapse

Europe's biggest blackout in over 20 years on the Iberian peninsula unleashed hours of chaos for people in Spain, Portugal and parts of France earlier this week. But in the aftermath it has raised a common question for governments across the continent: could the same happen here? Europe's political leaders and energy system operators have given assurances that such blackouts are extraordinarily rare, and that European power grids are some of the most stable in the world. Yet energy experts have warned that although wide-scale blackouts may be rare, no grid is infallible. Prof Jianzhong Wu, the head of the school of engineering at Cardiff University, told the Guardian blackouts 'can happen anywhere'. 'Despite today's high standards of reliability, low-probability but high-impact blackout events can still happen. These networks are not designed to be completely blackout-free because achieving such a level of reliability would require investment far beyond what is economically feasible,' he said. Charmalee Jayamaha, a senior manager at the UK government-backed Energy Systems Catapult, said: 'No system can be 100% resilient,' so risks 'need to be balanced with our willingness to pay to reduce them'. If no power system is bulletproof, then what are the risks that could trigger a catastrophic blackout in any country? Here we look at the top reasons a power system might collapse. Major power system collapses are frequently due to factors that are difficult to foresee or control. Extreme weather events and natural disasters present a clear risk because storms, heatwaves and earthquakes can lead to devastating damage to critical national infrastructure. Lightning strikes and solar flares have also been known to damage vital equipment such as substations and power lines, which are crucial to maintaining the stability of the grid. Early reports suggested that Spain's blackout had been caused by a 'rare atmospheric phenomenon' due to a sudden change in temperature, which may have destabilised the grid. But the grid operator, Red Eléctrica, later dismissed the theory. Most outages due to natural disasters are easier to identify. In the US state of Texas, a series of three winter storms in early 2021 caused windfarms and gas power plants to freeze over, leaving 4.5m homes and businesses without power, some for several days. The risk of these events is on the rise as the climate crisis increases the frequency and severity of extreme weather events. Some blackouts are entirely human-made. Jayamaha said geopolitical factors and cyber-attacks had the potential to cause 'major interruptions' to the grid. Human error could also play a role. After the Iberian blackout many questioned whether malevolent state actors had taken aim at the grid. However, Red Eléctrica was quick to insist there was no sign of an attack and later ruled the theory out. Still, the risk of a cyber-attack on power grid infrastructure is 'not science fiction', according to the Dutch cybersecurity expert Dave Maasland. He told the Dutch press that 'attacks on power supplies are possible and have already caused disruptions in the past'. He pointed to Russia's attacks on Ukraine's power system in 2015 and 2016, and a failed attempt after its invasion in 2022. In the most simple terms, a blackout is caused when the power system stops working: this can be due to an unexpected mechanical glitch involving power lines, substations or other grid infrastructure – or a more complex problem with how the system runs. Sign up to Business Today Get set for the working day – we'll point you to all the business news and analysis you need every morning after newsletter promotion A key concern to emerge after Spain's blackout is the role that renewable energy may have played in the system collapse. Without a clear explanation for the outage it is too soon to comment, experts have said. What we know so far is that Spain's electricity system suffered two major generation losses in the solar-rich south-west of the country within seconds, which may have destabilised the grid connection between Spain and France, and ultimately led to a full loss of power across the energy system. The initial trigger remains under investigation. It is true that a renewables-rich grid is more difficult to run than one powered by fossil fuels. This is because the grid was originally designed with big coal, gas and nuclear power plants in mind. These plants feature spinning turbines that create inertia on the system, which helps to maintain the grid's frequency at about 50Hz. Wind and solar farms do not create inertia on the grid, meaning that at times of high renewables output it can be more difficult to keep the frequency steady if there is a sudden loss of power. A significant fluctuation in frequency can cause generators to automatically disconnect, leading to a collapse of the system. Jayamaha said the shift to renewables would require grid companies to invest in grid-stabilising technologies. 'The electricity grid is undergoing unprecedented change as we reduce our reliance on fossil fuels and move to solutions that are cheaper, better, and cleaner. This creates different resilience challenges that need to be managed,' she said. 'Resilience is no longer just about having enough spare megawatts you can simply switch on – but about the right mix of technologies and system capabilities to operate a grid with a lot more renewables.' Kate Mulvany, a principal consultant at Cornwall Insight, said that in the UK, a key part of that effort had been the development of new balancing and system management tools, 'particularly the integration of grid-scale batteries, which play a vital role in maintaining stability'. 'The electricity system in GB is among the most reliable in the world. So, while a major blackout will always be possible, the extensive safeguards in place make it extremely unlikely,' she said. In many cases, the risk factors outlined above can coincide, meaning relatively common or innocuous events can compound to create a cascading failure that leads to catastrophe. These 'black swan' events are nearly impossible to anticipate – meaning grid operators are under pressure to prepare for the unexpected. 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Flood and drought exposure ‘ramping up for world's most populated cities'
Flood and drought exposure ‘ramping up for world's most populated cities'

The Independent

time12-03-2025

  • The Independent

Flood and drought exposure ‘ramping up for world's most populated cities'

The world's 100 most populated cities are becoming increasingly exposed to floods and droughts, new research has found. Charity WaterAid has warned that 90% of all climate disasters are driven by too much or too little water, and that weather-related disasters have increased by 400% in the last 50 years. Its study, developed with academics from University of Bristol and Cardiff University, compared each city's social and water infrastructure vulnerabilities – such as poverty and waste systems – alongside more than 40 years worth of new data on climate hazards. With this, the researchers identify which cities and communities worldwide could be the most vulnerable to extreme climate changes and the least equipped to handle them. The analysis, released on Wednesday, found that 17% of the cities studied are experiencing 'climate whiplash', where both droughts and floods are intensifying. It also showed that 20% of the cities have seen a major flip, previously experiencing one extreme and now increasingly facing the other. For example, southern Asian cities are now shifting toward a more extreme wet climate, becoming increasingly flood-prone, whereas European cities are flipping towards a more extreme dry climate. London, Madrid and Paris are among those that have seen this drying trend over the last four decades, according to the study, which warned that the region could face more frequent and long-lasting droughts as a consequence. Meanwhile, Colombo in Sri Lanka, and Faisalabad and Lahore in Pakistan are seeing the most dramatic flip from historically dry conditions to becoming severely flood-prone. Overall, the report said cities across Africa and Asia are emerging as the most at-risk of extreme climate shifts, causing devastating impacts on access to clean water for urban communities on the front line of global warming. But WaterAid said that the increased exposure to floods and drought globally is putting major pressure on vital water access and sanitation systems, making it harder for communities and economies to prepare for, recover from, and adapt to climate change. The charity is urging the British Government to upholds its foreign aid commitments and its current international climate finance commitments and invest a third of its adaptation budget in water action. It also called on the Foreign Office to launch an international water security strategy and feature action on the water crisis across all areas of foreign policy. Tim Wainwright, WaterAid UK's chief executive, said: 'This research comes at a pivotal time, as we're seeing a sweep of global aid cuts, which could leave basic human rights hanging in the balance. 'Floods and droughts are stripping away people's foundation of survival – water. 'But with a reliable supply of clean water, communities can recover from disasters, stay healthy, and be ready for whatever the future holds. It all starts with clean water.' The charity is working with partners globally to tackle the impacts of climate change on water, with solutions like harvesting rainwater, monitoring water levels and installing toilets designed to withstand floods. But the organisation urged global decision makers to prioritise and invest in key solutions that strengthen community resilience against extreme weather. Mr Wainwright said: 'We urge the UK to show leadership and maintain its influential role in tackling global climate and health challenges – essential to creating a secure world free from poverty.' Professor Katerina Michaelides, lead scientist from University of Bristol, said: 'The findings from our study illustrate just how differently and dramatically climate change is expressing around the globe – there is no one-size-fits-all. 'A deeper understanding of localized climate hazards can support more intelligent and bespoke planning in major cities.' Professor Michael Singer, lead scientist from Cardiff University, added: 'One interesting outcome of this study is how many of the climate hazard trends appear to spread over broad regions, suggesting that there may be significant adaptation challenges to new hazard regimes, but also regional opportunities for collaboration between nations to become more resilient to climate change in urban centres.'

‘Global weirding': climate whiplash hitting world's biggest cities, study reveals
‘Global weirding': climate whiplash hitting world's biggest cities, study reveals

The Guardian

time12-03-2025

  • The Guardian

‘Global weirding': climate whiplash hitting world's biggest cities, study reveals

Climate whiplash is already hitting major cities around the world, bringing deadly swings between extreme wet and dry weather as the climate crisis intensifies, a report has revealed. Dozens more cities, including Lucknow, Madrid and Riyadh have suffered a climate 'flip' in the last 20 years, switching from dry to wet extremes, or vice versa. The report analysed the 100 most populous cities, plus 12 selected ones, and found that 95% of them showed a distinct trend towards wetter or drier weather. The changing climate of cities can hit citizens with worsened floods and droughts, destroy access to clean water, sanitation and food, displace communities and spread disease. Cities where the water infrastructure is already poor, such as Karachi and Khartoum, suffer the most. Cities across the world are affected but the data shows some regional trends, with drying hitting Europe, the already-parched Arabian peninsula and much of the US, while cities in south and south-east Asia are experiencing bigger downpours. The analysis illustrates the climate chaos being brought to urban areas by human-caused global heating. Too little or too much water is the cause of 90% of climate disasters. More than 4.4 billion people live in cities and the climate crisis was already known to be supercharging individual extreme weather disasters across the planet. Rising temperatures, driven by fossil fuel pollution, can exacerbate both floods and droughts because warmer air can take up more water vapour. This means the air can suck more water from the ground during hot, dry periods but also release more intense downpours when the rains come. 'Our study shows that climate change is dramatically different around the world,' said Prof Katerina Michaelides, at the University of Bristol, UK. Her co-author, Prof Michael Singer at Cardiff University, described the pattern as 'global weirding'. 'Most places we looked at are changing in some way, but in ways that are not always predictable,' Singer said. 'And given that we're looking at the world's largest cities, there are really significant numbers of people involved.' Coping with climate whiplash and flips in cities is extremely hard, said Michaelides. Many cities already face water supply, sewage and flood protection problems as their populations rapidly swell. But global heating supercharges this, with the often ageing infrastructure in rich nations designed for a climate that no longer exists, and more climate extremes making the establishment of much-needed infrastructure even harder in low income nations. The researchers have worked in Nairobi, Kenya, one of the cities suffering climate whiplash. 'People were struggling with no water, failed crops, dead livestock, with drought really impacting their livelihoods and lives for multiple years,' Michaelides said. 'Then the next thing that happens is too much rain, and everything's flooded, they lose more livestock, the city infrastructure gets overwhelmed, water gets contaminated, and then people get sick.' Sol Oyuela, executive director at NGO WaterAid, which commissioned the analysis, said: 'The threat of a global 'day zero' looms large – what happens when the 4 billion people already facing water scarcity reach that breaking point, and the food, health, energy, nature, economies, and security that depend on water are pushed to the brink?' 'Now is the time for urgent collective action, so communities can recover from disasters and be ready for whatever the future holds. This will make the world a safer place for all,' Oyuela said. The savage wildfires in Los Angeles in January were an example of a single whiplash event, with a wet period spurring vegetation growth, which then fuelled the fires when hot and dry weather followed. Such events are increasing due to human-caused global heating. The new analysis by Michaelides and Singer was much broader and examined the changes in wet and dry extremes over the past four decades in 112 major cities. It found that 17 cities across the globe have been hit by climate whiplash, suffering more frequent extremes of both wet and dry conditions. The biggest whiplashes were seen in Hangzhou in China, the Indonesian megacity of Jakarta, and Dallas in Texas. Other whiplash cities include Baghdad, Bangkok, Melbourne and Nairobi. The rapid shift between wet and dry extremes makes it difficult for cities to prepare and recover, damaging lives and livelihoods. The analysis also found that 24 cities have seen dramatic climate flips this century. The sharpest switches from wet to dry conditions have been in Cairo, Madrid and Riyadh, with Hong Kong and San Jose in California also in the top 10. Prolonged droughts can lead to water shortages, disrupted food supplies and electricity blackouts where hydropower is relied upon. Sign up to Down to Earth The planet's most important stories. Get all the week's environment news - the good, the bad and the essential after newsletter promotion The sharpest switches from dry to wet conditions were in Lucknow and Surat in India and in Nigeria's second city, Kano. Other cities with wet flips were Bogotá, Hong Kong and Tehran. Intense rains can cause flash floods, destroying homes and roads and spreading deadly waterborne diseases like cholera and dysentery when sanitation systems are overwhelmed. The researchers also assessed the level of social vulnerability and quality of infrastructure in the cities. The cities with the biggest increases in climate hazards combined with the highest vulnerability – and therefore the places facing the greatest dangers – were Khartoum in Sudan, Faisalabad in Pakistan, and Amman in Jordan. Karachi, also in Pakistan, ranked highly for vulnerability as well and is experiencing more wet extremes. Torrential rains in 2022 destroyed the family home of fisher Mohammad Yunis in Ibrahim Hyderi, a waterfront district in the city. 'We have spent many days and nights completely drenched in rain because we had no shelter,' he said. 'The weather affects everything. When it rains heavily, our children fall sick. But we don't have sufficient [clean] water. Our localities are breaking down. Houses near the drainage systems collapse due to floods. When floods come, walls fall apart. If we had enough money, we would not be living here.' Even in the cities where the changes in climate were less stark, clear trends were seen in almost all of them. The places getting drier over the last 40 years included Paris, Los Angeles, Cape Town, and Rio de Janeiro. Many of those getting wetter are in south Asia, such as Mumbai, Lahore and Kabul. The researchers also found 11 cities where the number of extreme wet or dry months had fallen in the last 20 years, including Nagoya in Japan, Lusaka in Zambia, and Guangzhou in China. The overall results of the new study are consistent with the most recent report from the Intergovernmental Panel on Climate Change, which found there were both regions with increases in heavy rains and others with increases in drought, as well as some regions with increases in both, said Prof Sonia Seneviratne, at ETH Zurich in Switzerland, coordinating lead author of the IPCC chapter on weather and climate extreme events. 'A few tenths of a degree warmer and the life we know becomes increasingly at risk due to climate extremes such as heatwaves, droughts, and heavy rainfall,' she said. Singer said: 'We hope our report can galvanise global attention on the challenges of climate change with respect to water. Perhaps it will lead to a more realistic conversation about supporting adaptation to climate change, with a sense of compassion and understanding of the challenges people are facing, rather than just saying, well, we can't afford it.' Methodology The researchers analysed the changing climate of cities using a standard index (SPEI) that combined precipitation with evaporation each month from 1983 to 2023. Index values above a widely-used threshold were categorised as extreme. To assess changes over the four decades, the data was split into two 21-year periods. The cities that experienced at least 12 months more of one type of extreme climate (wet or dry) and at least 12 months less of the other type of extreme climate in the second 21-year period were classed as having a climate flip. The cities that had at least five months more of both extreme wet and extreme dry in the second period were classed as having developed climate whiplash. The overall wetting or drying trends were determined from all 42 years of data. The population data used to determine the 100 most populous cities was based on population density, not the administrative boundaries of the city, and therefore are a truer reflection of the city's size. Social vulnerability was measured using the standard Human Development Index and the water and waste infrastructure data was taken from a global dataset published in 2022.

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