‘Massive disruption’: UK’s worst-case climate crisis scenarios revealed by scientists. Scientists say government must prepare for unlikely but ‘plausible’ 4C rise in temperature and a 2-metre rise in sea levels

Flooding in Wraysbury, England, last year. Photograph: Daniel Leal/AFP/Getty Images

by  Damian Carrington 

 

The worst-case impacts of the climate crisis for the UK have been laid bare by scientists, ranging from a scorching 4C rise in temperatures to a 2-metre rise in sea level. Another scenario sees a plunge of 6C in temperature after the collapse of key Atlantic Ocean currents, massively disrupting farming and energy needs.

The impacts, some of which are linked to climate tipping points, are seen as low probability but plausible. The researchers said the scenarios filled a gap in forecasting that had left the UK unprepared for extreme outcomes.

A second set of worst-case scenarios sets out the potential extent of extreme weather between now and the end of the century. These indicate that temperatures could soar in some months by up to 6C above average, while rainfall could be triple normal levels.

 

“The climate extremes we have mapped aren’t predictions, but they are plausible,” said Nigel Arnell, a University of Reading professor who led the study. “The UK has been planning without the tools to test against worst-case scenarios. We’ve now given decision-makers what they need to prepare for climate outcomes they hope never happen, but can’t afford to ignore.”

The probability of the extreme scenarios happening could not be calculated because of uncertainty about what action will be taken to tackle global heating and how the climate system will respond. Arnell said this made the analysis similar to national security risk assessments or the Bank of England’s stress tests for the financial system.

“You couldn’t have known what the probability of Russia invading Ukraine was, but you could have said this is what the consequences might be,” he added.

The worst-case scenarios could be used to inform the building of long-term infrastructure, such as new towns, nuclear power stations and urban drainage systems, Arnell said, adding that awareness of climate risks could speed the drive to cut fossil fuel emissions.

Published in the journal Earth’s Future, the analysis developed the worst-case scenarios using a combination of observed and historical experience, computer simulations and theory.

Global temperatures rising well above 4C by 2100 could happen if climate action collapses or if there are strong feedback loops such as the Amazon rainforest dying and releasing its enormous store of carbon. This would result in extreme and prolonged heatwaves and droughts hitting the UK in summer. Thousands of early deaths have already occurred in England in heatwaves with just a 1.3C increase in global temperatures.

Temperatures could also be driven up by about 0.75C if pollution from industry is sharply cut, the scientists said. This is because aerosol particles from burning coal and heavy fuels block sunlight from reaching the ground.

A major ocean current, the Atlantic meridional overturning circulation (Amoc) is weakening and losing stability because of global heating. It is one of the tipping points that most concerns scientists. A collapse beginning in 2030 would lead to 6C cooling in the UK.

“Agriculture would struggle enormously and water resources would be completely altered,” said Arnell. “Our heat and energy system would be completely caught out by changing winter energy demand. It wouldn’t happen overnight, but it would be massively disruptive.”

A collapse of even one part of Amoc, the sub-polar gyre, would reduce UK temperatures by 2.5C, the scientists said.

Flooding in southern Asia leaves 600 dead

Search and rescue operations are ongoing across Indonesia, Thailand, Malaysia and Sri Lanka, with hundreds still missing

 by Jessica Rawnsley

 

Torrential rains have triggered floods and landslides across parts of southern Asia, killing about 600 people.

Monsoon rain exacerbated by tropical storms caused some of the region's worst flooding in years, with millions affected in Indonesia, Malaysia, Thailand and Sri Lanka.

Intense rainfall began on the Indonesian island of Sumatra on Wednesday. "During the flood, everything was gone," a resident of Bireuen in Sumatra's Aceh province told Reuters news agency. "I wanted to save my clothes, but my house came down."

With hundreds still missing, the death toll is likely to rise. Thousands remain stranded, some awaiting rescue on rooftops.

 

As of Saturday more than 300 people had died in Indonesia and 160 in Thailand. There were also several deaths reported in Malaysia.

In Sri Lanka, which has been battered by Cyclone Ditwah, more than 130 people are dead and some 170 missing, officials said.

In Indonesia hundreds are still missing after heavy rains wreaked havoc on the island of Sumatra

An exceptionally rare tropical cyclone, named Cyclone Senyar, caused catastrophic landslides and flooding in Indonesia, with homes swept away and thousands of buildings submerged.

Indonesia's disaster agency said on Saturday that nearly 300 people were still missing after flooding devastated Sumatra.

"The current was very fast, in a matter of seconds it reached the streets, entered the houses," a resident in Aceh Province, Arini Amalia, told the BBC.

She and her grandmother raced to a relative's house on higher terrain. On returning the following day to retrieve some belongings, she said the flood had completely swallowed the house: "It's already sunk."

After waters rapidly rose in West Sumatra and submerged his home, Meri Osman said he was "swept away by the current" and clung onto a clothesline until he was rescued.

The bad weather has hampered rescue operations, and while tens of thousands of people have been evacuated, hundreds are still stranded, the Indonesian disaster agency said.

Tens of thousands of people have taken refuge in shelters in Thailand

In Thailand's southern Songkhla province, water rose 3m (10ft) and at least 145 people died in one of the worst floods in a decade.

Across the 10 provinces hit by flooding, more than 160 people have been killed, the government said on Saturday. More than 3.8 million people have been affected.

The city of Hat Yai experienced 335mm of rainfall in a single day, the heaviest in 300 years. As waters receded, officials recorded a sharp rise in the death toll.

At one hospital in Hat Yai, employees were forced to move bodies to refrigerated trucks after the morgue became overwhelmed, news agency AFP reported.

"We were stuck in the water for seven days and no agency came to help," Hat Yai resident Thanita Khiawhom told BBC Thai.

The government has promised relief measures, including compensation of up to two million baht ($62,000) for households that lost family members. 

Sri Lanka's government has declared a state of emergency and appealed for international assistance

In neighbouring Malaysia, the death toll is far lower, but the damage is just as devastating.

Flooding has wreaked havoc and left parts of northern Perlis state under water, with two people dead and tens of thousands forced into shelters.

Sri Lanka is also grappling with one of its worst weather disasters in recent years, and the government has declared a state of emergency.

More than 15,000 homes have been destroyed and some 78,000 people forced into temporary shelters, officials said. They added that about a third of the country was without electricity or running water.

Meteorologists have said the extreme weather in South East Asia may have been caused by the interaction of Typhoon Koto in the Philippines and the rare formation of Cyclone Senyar in the Malacca Strait.

The region's annual monsoon season, typically between June and September, often brings heavy rain.

Climate change has altered storm patterns, including the intensity and duration of the season, resulting in heavier rainfall, flash flooding and stronger winds.

Days of severe storms leave 18 dead as rising rivers threaten US south and midwest

 Severe storm causes flooding in Kentucky’s Casey county on Friday. Photograph: Ryan C Hermens/TNS/ZUMA Press Wire/REX/Shutterstock

Associated Press

 Power and gas shut off in regions as flooding worsens, threatening waterlogged and badly damaged communities 

 

After days of intense rain and wind killed at least 18 people in the US south and midwest, rivers rose and flooding worsened on Sunday in those regions, threatening waterlogged and badly damaged communities.

Utility companies scrambled to shut off power and gas from Texas to Ohio while cities closed roads and deployed sandbags to protect homes and businesses.

In Kentucky, downtown Frankfort, the state’s capital, was inundated.

“As long as I’ve been alive – and I’m 52 – this is the worst I’ve ever seen it,” said Wendy Quire, the general manager at the Brown Barrel restaurant.

As the swollen Kentucky river kept rising on Sunday, officials closed roads and turned off power and gas to businesses in the city built around it, Quire said. “The rain just won’t stop,” she said. “It’s been nonstop for days and days.”

 

The ongoing, global climate crisis is bringing heavier rainfall and related flood risks to most parts of the US, with the upper midwest and Ohio River valley among the regions most affected, according to Climate Central, an independent non-profit that researches weather patterns.

Forecasters warned that flooding could persist for days, as torrential rains lingered over many states, including Kentucky, Tennessee and Alabama. Tornadoes are possible in Alabama, Georgia and Florida, forecasters said.

The 18 reported deaths since the start of the storms on Wednesday included 10 in Tennessee. A nine-year-old boy in Kentucky was caught up in floodwaters while walking to catch his school bus. A five-year-old boy in Arkansas died after a tree fell on his family’s home and trapped him, police said. A 16-year-old volunteer firefighter in Missouri died in a crash while seeking to rescue people caught in the storm.

 

The National Weather Service (NWS) said on Sunday dozens of locations in multiple states were expected to reach a “major flood stage”, with extensive flooding of structures, roads, bridges and other critical infrastructure possible.

There were 521 domestic and international flights cancelled within the US, and more than 6,400 were delayed on Saturday, according to FlightAware.com. The website reported 74 cancellations and 478 delays of US flights early on Sunday.

The storms come after Donald Trump’s administration has cut jobs at NWS forecast offices, leaving half of them with vacancy rates of about 20%, or double the level of a decade ago.

Officials warned of flash flooding and tornadoes on Saturday across Arkansas, Mississippi, Tennessee and Kentucky. All of eastern Kentucky was under a flood watch through Sunday morning.

In north-central Kentucky, emergency officials ordered a mandatory evacuation for Falmouth and Butler, towns near the bend of the rising Licking river. Thirty years ago, the river reached a record 50ft (15 meters), resulting in five deaths and 1,000 homes destroyed.

The NWS said 5.06in (nearly 13 cm) of rain fell on Saturday in Jonesboro, Arkansas – making it the wettest day ever recorded in April in the city, dating back to 1893.

As of early Sunday, Memphis had received 14in (35cm) of rain since Wednesday, the NWS said. West Memphis, Arkansas, received 10in (25cm).

Forecasters attributed the violent weather to warm temperatures, an unstable atmosphere, strong winds and abundant moisture streaming from the Gulf.

In Dyersburg, Tennessee, dozens of people arrived on Saturday at a storm shelter near a public school in the rain, clutching blankets, pillows and other necessities.

Among them was George Manns, 77, who said he was in his apartment when he heard a tornado warning and decided to head to the shelter. Just days earlier the city was hit by a tornado that caused millions of dollars in damage.

“I grabbed all my stuff and came here,” said Mann, who brought a folding chair, two bags of toiletries, laptops, iPads and medications. “I don’t leave them in my apartment in case my apartment is destroyed. I have to make sure I have them with me.”

Guardian staff contributed reporting

 

 

Argentina flooding: 16 killed as two girls swept away by rising waters. Authorities warn more fatalities expected as a year’s worth of rain falls on Bahía Blanca in eight hours

Firefighters and volunteers help people out of flooded areas in Bahía Blanca, Argentina, on 8 March 2025. Photograph: Pablo Presti/EPA

 

Harriet Barber in Buenos Aires

 

 

Rescue teams in Argentina are searching for two girls, aged one and five, who were swept away by severe floods that ripped through Buenos Aires province, killing at least 16 people.

A year’s worth of rain fell on the city of Bahía Blanca and the town of Cerri on Friday, rapidly inundating neighbourhoods and destroying homes, bridges and roads. The rainfall – 400mm (15.7in) recorded in just eight hours – was more than twice the city’s previous record of 175mm (6.8in) set in 1930.

The sisters, Delfina and Pilar Hecker, were travelling with their parents when their car became trapped in the rising waters. According to reports, a truck driver, named as Rubén Zalazar, attempted to rescue the children before they were swept away. The body of 43-year-0ld Zalazar was found in a lagoon on Sunday.

 

At least 16 people have been declared dead by officials, with authorities saying there are “likely to be more”. In the latest press conference, Carlos Bianco, a minister in the Buenos Aires province, said at least 100 people were missing.

Authorities also said more than 1,000 people were evacuated over the weekend, while estimates suggest hundreds have been made homeless. Videos posted online showed neonatal nurses wading through knee-deep flood waters to rescue newborn babies.

“We looked at the street and saw a river. We saw cars, trucks, containers, everything floating by. You could hear store windows breaking, and see furniture being dragged by the current,” said Soledad Bengochea, 52, a resident. “In one car, we saw two people trapped. It was overwhelming and terrible. There are many people who have suffered.”

The national security minister, Patricia Bullrich, said the area had been “destroyed”, while Argentina’s president, Javier Milei, declared three days of national mourning.

But the government has also come under fire after it emerged the national emergency directorate – which provides disaster relief – was shuttered three days before the storm, with 485 employees dismissed or placed on leave. The decision comes as Milei’s administration conducts widespread cuts to state spending

The mayor, Federico Susbielles, said that the floods had caused millions in infrastructure damage. Agostina Bitti, a 34-year-old doctor, said there are “still houses under water”. “The entire city needs to be rebuilt,” she said.

Argentina’s economy ministry has pledged AR$10bn (US$9.2m at the official exchange rate) to help repair the damage and rebuild the city.

The Argentinian footballer Lionel Messi offered his condolences to the victims’ families, saying he wished them strength. Pope Francis, who has been hospitalised in Rome since 14 February, also sent a message to the victims. The Vatican press office said that the pontiff, who is also from Argentina, is holding those affected in his “thoughts and prayers”.

Extreme rainfall has become more common and more intense due to human-caused climate breakdown across most of the world, because warmer air can hold more water vapour.

 

Tempestades na Espanha deixam mais de 62 mortos

 

Região de Málaga também foi atingida

 

Autoridades da Espanha confirmaram nesta quarta-feira (30/01) que ao menos 62 pessoas morreram e várias estão desaparecidas após as enchentes  que atingiram a província de Valência. As inundações arrastaram carros, transformaram ruas de vilarejos em rios e interromperam o tráfego em linhas ferroviárias e rodovias.

Nesta terça-feira, chuvas torrenciais e inundações causaram estragos em várias partes do país, principalmente em uma ampla área do sul e do leste. Os maiores impactos foram registrados nas regiões costeiras mediterrâneas da Andaluzia, Múrcia e Valência.

Além das fortes chuvas, houve também queda de granizo e fortes rajadas de vento, segundo com o serviço meteorológico nacional Aemet. A agência previu que as tempestades devem continuar até esta quinta-feira

A força da água arrastou veículos e destroços pelas ruas de várias localidades. A polícia e os serviços de resgate usaram helicópteros para retirar pessoas de casas e carros. O governo da região de Valência pediu aos moradores que se desloquem para terrenos mais altos.

Inundações na Espanha transformaram ruas de vilarejos em rios e interromperam o tráfego em linhas ferroviárias e rodoviasFoto: JOSE JORDAN/AFP/Getty Images

 
 O transporte aéreo e ferroviário também foi afetado. Um trem de alta velocidade com quase 291 pessoas a bordo descarrilou perto de Málaga devido a um deslizamento de terra. A empresa ferroviária estatal Renfe informou que o acidente, porém, não deixou feridos.

 

Governo cria comitê de crise

O serviço de trens de alta velocidade e outras linhas de passageiros entre Valência e Madri foi interrompido. Aulas tiveram de ser canceladas em várias escolas e universidades. Mais de mil membros dos serviços de emergências da Espanha foram enviados para as áreas atingidas.

A tempestade já havia atingido Mallorca e outras Ilhas Baleares na segunda-feira, onde um alerta amarelo de tempestade ainda está em vigor para algumas áreas.

O governo da Espanha criou um comitê de crise para coordenar os esforços de resgate, que será presidido pelo primeiro-ministro, Pedro Sánchez.

Carros foram arrastados pela força das águas

 

A tempestade deve se mover para nordeste do país nesta quarta-feira, enquanto um alerta de clima severo permanece em vigor para uma grande parte da Espanha.

Tempestades após fortes secas

As tempestades que atingem a Espanha ocorrem após uma seca severa. Cientistas afirmam que o aumento dos episódios de clima extremo provavelmente está associado às mudanças climáticas. À medida que as temperaturas globais aumentam, o ar mais quente retém mais umidade, o que intensifica os níveis de precipitação.

Atividades humanas, como desenvolvimento urbano, desmatamento e infraestruturas inadequadas, também contribuem significativamente para os riscos de inundações.

rc/cn (AP, DPA, EFE)

 

The Morning: America’s flooding problem

 

Good morning. Today, my colleague Christopher Flavelle writes about how people are coping with increasing floods. We’re also covering early voting, sickle cell gene therapy and Hanoi, Vietnam. —David Leonhardt

In Plant City, Fla. Caitlin Ochs for The New York Times

 

 

Three views of the water

By Christopher Flavelle  I write about how we try to adapt to climate change.

 America has a flooding problem. When Hurricane Milton hit Florida, the images of inundation seemed shocking — but also weirdly normal: For what felt like the umpteenth time this year, entire communities were underwater. Since the 1990s, the cost of flood damage has roughly doubled each decade, according to one estimate. The federal government issued two disaster declarations for floods in 2000. So far this year, it has issued 66.

The reasons are no mystery. Global warming is making storms more severe because warmer air holds more water. At the same time, more Americans are moving to the coast and other flood-prone areas.

Those conflicting trends are forcing people to adapt. Advances in design, science and engineering — combined with a willingness to spend vast amounts of money — have allowed the United States and other wealthy countries to try new ideas for coping with water. In today’s newsletter, I’ll tell you about the three basic ways to deal with flooding.

1. Fight the water

The first strategy is to fight the water: Build walls to keep it out of your city, along with giant pumps and drains to remove whatever water gets in. Think of Holland, much of which would be underwater without a massive network of barriers, or Venice, which now relies on sea walls during high tide.

But thanks to climate change, this approach means ever-more-epic fortifications. After Hurricane Katrina, the federal government built a $14 billion, 350-mile defensive ring around New Orleans. The United States is also looking at building 12 movable sea barriers to protect New York Harbor from a storm surge, at an initial cost of $52 billion.

Even the beneficiaries aren’t always thrilled. A plan to build a six-mile-long, 20-foot-high sea wall around the coast of Miami prompted outrage: It would, after all, ruin the view. The plan was abandoned.

2. Live with it

The second approach is to accept that water will get in, so we should live with it. This entails elevating homes off the ground, as builders do in the Outer Banks or coastal Louisiana. It also means raising roads, power stations and other critical infrastructure — all at no small cost.

Another example of living with water is described in an excellent new piece from my colleague Rory Smith, who visited a coastal plain in southwest England that used to be farmland protected by a sea wall. Officials converted it into a marsh when they realized it was best just to open up flood barriers, turning the area into a giant sponge. Now, communities farther inland are less likely to flood.

Cities like Hoboken, N.J., have embraced this concept, building spaces designed to capture and hold storm water.

In Bradenton Beach, Fla. Callaghan O'Hare for The New York Times

 

 

 

3. Pack your bags

Sometimes those things don’t work. Then, and usually only then, communities resign themselves to simply leaving.

In 2016, the Obama administration provided $48 million to move Isle de Jean Charles, an island village of a few dozen families in Louisiana, away from the rising Gulf of Mexico. The single road to the mainland was frequently wrecked by storms, and, by common consensus, the community couldn’t be saved. It was the first climate-driven relocation project in the United States.

I visited Isle de Jean Charles to watch residents vote on where their new community should be built. Relocation — experts call it “managed retreat” — is about as hard as you might think. Few people are eager to leave, and there’s no guarantee that the community will remain intact.

Even so, the approach is becoming more common. Congress has passed millions of dollars to relocate Native American tribes, which often live on land dangerously vulnerable to flooding. Canada pushes some homeowners not to rebuild in the same place after a flood.

What now?

Behind those options is a puzzle: With so many tools available, why does flood damage in the United States (which cost more than $180 billion last year, according to one estimate) keep rising? I asked Chad Berginnis, head of the Association of State Floodplain Managers. “Two things,” he told me. “Irrationality and elections.”

People struggle to assess the danger when disasters are infrequent but incredibly costly, he said. And politicians realize they won’t become popular by raising people’s taxes to pay for colossal infrastructure projects.

With that in mind, Berginnis suggests a fourth option for flood protection: In especially high-risk areas, stop building new homes.

For more: I encourage you to read Rory’s article about how England surrendered farmland back to the water.

For more

• This summer, the U.S. government restricted building in flood plains.
• Last month, fueled by climate change, floods wreaked havoc across four continents.
• Real estate is booming in flood zones. Here’s why buyers risk it.
• Scientists are mapping landslide hazards in Alaska. Some homeowners don’t want to know.

 

Global heating ‘doubled’ chance of extreme rain in Europe in September

Residents wade through flood water after the Nysa Klodzka River flooded the town of Lewin Brzeski in south-west Poland on 19 September. Photograph: Beata Zawrzel/NurPhoto/Rex/Shutterstock

 
 

Planet-heating pollution doubled the chance of the extreme levels of rain that hammered central Europe in September, a study has found.

Researchers found global heating aggravated the four days of heavy rainfall that led to deadly floods in countries from Austria to Romania.

The rains were made at least 7% stronger by climate change, World Weather Attribution (WWA) found, which led to towns being hit with volumes of water that would have been half as likely to occur if humans had not heated the planet.

“The trend is clear,” said Bogdan Chojnicki, a climate scientist at Poznań University of Life Sciences, and co-author of the study. “If humans keep filling the atmosphere with fossil fuel emissions, the situation will be more severe.”

 

Storm Boris stalled over central Europe in mid-September and unleashed record-breaking amounts of rain upon Austria, the Czech Republic, Hungary, Poland, Romania and Slovakia. The heavy rains turned calm streams into wild rivers, triggering floods that wrecked homes and killed two dozen people.

The researchers said measures to adapt had lowered the death toll compared with similar floods that hit the region in 1997 and 2002. They called for better flood defences, warning systems and disaster-response plans, and warned against continuing to rebuild in flood-prone regions.

“These floods indicate just how costly climate change is becoming,” said Maja Vahlberg, technical adviser at the Red Cross Red Crescent Climate Centre, and co-author of the study. “Even with days of preparation, flood waters still devastated towns, destroyed thousands of homes and saw the European Union pledge €10bn in aid.”

Rapid attribution studies, which use established methods but are published before going through lengthy peer-review processes, examine how human influence affects extreme weather in the immediate aftermath of a disaster.

The scientists compared the rainfall recorded in central Europe over four days in September with amounts simulated for a world that is 1.3C cooler – the level of warming caused to date by burning fossil fuels and destroying nature. They attributed a “doubling in likelihood and a 7% increase in intensity” to human influence.

But the results are “conservative”, the scientists wrote, because the models do not explicitly model convection and so may underestimate rainfall. “We emphasise that the direction of change is very clear, but the rate is not.”

 

Physicists have shown that every degree celsius of warming allows the air to hold 7% more moisture, but whether it does so depends on the availability of water. The rains in central Europe were unleashed when cold air from the Arctic met warm, wet air from the Mediterranean and the Black Sea.

Warmer seas enhance the rainy part of the hydrological cycle, though the trend on parts of the land is towards drier conditions, said Miroslav Trnka, a climate scientist at the Global Change Research Institute, who was not involved in the study. When the conditions were right, he said, “you can have floods on steroids”.

Trnka compared the factors that result in extreme rainfall to playing the lottery. The increase in risk from global heating, he said, was like buying more lottery tickets, doing so over a longer period of time, and changing the rules so more combinations of numbers result in a win.

“If you bet long enough, you have a higher chance of a jackpot,” said Trnka.

The study found heavier four-day rainfall events would hit if the world heats 2C above preindustrial levels, with a further increase from today of about 5% in rainfall intensity and 50% in likelihood.

Other factors could increase this even more, such as the waviness of the jet stream, which some scientists suspect is increasingly trapping weather systems in one place as a result of global heating. A study published in Nature Scientific Reports on Monday projected that such blocking systems would increase under medium- and worst-case emissions scenarios.

Hayley Fowler, a climate scientist at Newcastle University, who was not involved in the study, said: “These large storms, cut off from the jet stream, are able to stagnate in one place and produce huge amounts of rainfall, fuelled by increased moisture and energy from oceans that are record-shatteringly hot.”

“These ‘blocked’ slow-moving storms are becoming more frequent and are projected to increase further with additional warming,” she added. “The question is not whether we need to adapt for more of these types of storm but can we.”

WWA described the week following Storm Boris as “hyperactive” because 12 disasters around the world triggered its criteria for analysis, more than in any week in the organisation’s history.

The study did not try to work out how much global heating had increased the destruction wreaked by the rains but the researchers said even minor increases in rainfall disproportionately increased damages.

“Almost everywhere in the world it is the case that a small increase in the rainfall leads to a similar order-of-magnitude increase in flooding,” said Friederike Otto, a climate scientist at Imperial College London’s Grantham Institute and co-author of the study. “But that leads to a much larger increase in the damages.”

 

Recordes de secas e cheias mais que dobram de 2014 a 2023 em relação aos dez anos anteriores no Brazil

 

Porto Alegre RS 2014

 

Levantamento do Serviço Geológico do Brasil leva em conta dados de mais de 700 estações no país

 

Leonardo Fuhrmann

São Paulo

As enchentes provocadas em Porto Alegre pelo transbordamento do lago Guaíba não são um problema isolado. O Serviço Geológico do Brasil (SGB) aponta, em levantamento feito para a Folha, que recordes de enchentes e secas foram bem mais comuns na última década do que em períodos anteriores.

A quantidade de recordes de cheias sofreu um aumento expressivo. De 2014 a 2023, somaram 314. Nos dez anos anteriores, eram 182.

A de secas atingiu 406 de 2014 a 2023, mais do que quatro vezes a soma da década anterior, de 92.

A base de número de estações permaneceu estável nos últimos 50 anos, segundo Artur Matos, coordenador do Sistemas de Alerta Hidrológico do SGB. Por isso, a fonte de comparação no período é praticamente a mesma.

Mas o sistema do SGB é bem mais antigo, com informações de mais de um século. Em Manaus, por exemplo, os levantamentos são feitos desde 1900.

 Leidemar Plazido, 29, (camiseta preta) retira pertences de sua casa, atingida pela inundação no bairro Sarandi, um dos mais afetados de Porto Alegre, para levar para a casa dos amigos Otavio Henrique, 25, e Katiane Dias, 31, que o acompanham e o abrigam - Bruno Santos - 22.mai.2024/Folhapress

 Na avaliação de Matos, os dados da última década são prova de que as mudanças climáticas estão provocando uma alteração nos regimes de chuvas do país, com estas últimas mais intensas e períodos mais longos de estiagem.

 

Além de um maior número de picos de enchente e de secas, os dez últimos anos ficaram marcados por quebras consecutivas desses recordes.

Os rios Taquari e Caí, no Rio Grande do Sul, por exemplo, bateram os três maiores recordes de cheia nos dois últimos anos. Em Uruguaiana (RS), o rio Uruguai teve uma de suas seis maiores cheias neste ano. No ano passado e em 2017 o rio também alcançou dois de seus maiores índices. O estado também teve uma estiagem recorde em 2021.

A situação se repete em outras regiões do Brasil.

A maior cheia do rio Amazonas foi em 2021 e 6 das suas 10 maiores cheias foram nos últimos dez anos. O rio teve sua pior seca em 2023. O rio Branco, que banha e dá nome à capital do Acre, registrou suas duas maiores cheias em 2023 e 2024. O Madeira, que em Porto Velho (RO), apresentou sua pior seca em 2023 e seis dos maiores recordes de baixa vazão nos últimos dez anos.

Fonte: Serviço Geológico do Brasil/Ministério de Minas e Energia
 

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Recordes de seca e cheia mais que dobram de 2014 a 2023 em relação aos dez anos anteriores - Jornal do Tocantins
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Recordes de seca e cheia mais que dobram de 2014 a 2023 em relação aos dez anos anteriores - Jornal do Tocantins
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Recordes de seca e cheia mais que dobram de 2014 a 2023 em relação aos dez anos anteriores - Jornal do Tocantins
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Fonte: Serviço Geológico do Brasil/Ministério de Minas e Energia

 

Matos afirma que o levantamento confirma uma ideia empírica que eles tinham de uma maior incidência dos recordes nos últimos anos e mostra uma tendência de mais secas e cheias. "Os dados apontam uma repetição de situações extremas, tanto de excesso como de falta de água", analisa.

Especialista em modelagem climática do Instituto Nacional de Pesquisas Espaciais (Inpe), Chou Sin Chan confirma que os fenômenos atuais fogem dos modelos climáticos tradicionais. Segundo ela, o desenvolvimento de novas equações meteorológicas têm sido um desafio para quem trabalha com previsões.

Para Chou, as mudanças climáticas estão por trás da alteração nos regimes de chuvas. O modelo atualmente aplicado pelo Inpe já leva em conta as projeções globais de concentração de monóxido de carbono e outros gases do efeito estufa em suas previsões. "A gente tem visto que as projeções que o Painel Intergovernamental sobre Mudanças Climáticas (IPCC) fez no início dos anos 2000 era bastante conservadora em relação à realidade que estamos vivendo", afirma.

O resultado é que, apesar de terem previstos fortes chuvas no Rio Grande do Sul, os levantamentos meteorológicos foram incapazes de apontar uma intensidade tão grande das chuvas e sua persistência ao longo do período.

Um dos motivos, segundo ela, foi a formação de uma massa de gases do efeito estufa que não permitiu que a frente fria seguisse para o Sudeste. Isso fez com que o período de chuvas na região se prolongasse além do previsto. "Lugares como o Rio e São Paulo, que geralmente são atingidos por frentes frias em abril e maio, tiveram calor e falta de chuvas ao longo destes dois meses", exemplifica.

 

Fonte: Serviço Geológico do Brasil 

 

Ela afirma que o obstáculo já causou outras enchentes nos últimos anos não só no Rio Grande do Sul e Santa Catarina, mas também no Uruguai e no norte da Argentina. "Esta situação tem provocado secas e recordes de calor no Sudeste, Centro-Oeste e até na Amazônia."

Outro desafio, de acordo com ela, tem sido prever chuvas muito intensas em uma região específica. É o caso das grandes chuvas que atingiram cidades da região serrana do Rio de Janeiro, como Teresópolis e Petrópolis, em 2011, 2022 e 2023. "As duas cidades ficam a menos de 100 quilômetros da capital fluminense, que não foi atingida pelas mesmas chuvas", afirma.

Pesquisador em Geociências do SGB, Marcus Suassuna aponta também para uma mudança no padrão das chuvas. "Muitas vezes, temos um recorde de chuva no meio de uma longa estiagem", diz. Segundo ele, a água cai em um mesmo lugar ou em um curto espaço de tempo, quando geralmente seria mais espalhada ao longo de uma estação.

 

Ele afirma que o problema é maior em regiões com pouca vegetação ou muito urbanizadas, onde o terreno é mais impermeabilizado. "Isto também acelera a velocidade com que a água das chuvas chegue aos rios, que não tem a capacidade de vazão daquele volume no mesmo ritmo."

Suassuna diz que a situação reforça a necessidade de aumentar a velocidade de informação e os pontos de monitoramento nas bacias hidrográficas, com atenção também para rios secundários que podem afetar bacias maiores ou grandes concentrações populacionais. Outros especialistas entrevistados pela Folha nas últimas semanas já haviam mencionado a necessidade de aprimoramento do sistema de alerta para evitar novas tragédias.

Vinculado ao Ministério das Minas e Energia, o SGB faz medições do volume das águas dos rios desde o início do século passado. Inicialmente, seus dados serviam fundamentalmente para a mineração, mas o monitoramento nas últimas décadas também passou a ser usado para a prevenção de eventos climáticos extremos.

Hoje, 75% do trabalho de monitoramento de bacias hidrográficas no país é feito pelo SGB. O Brasil conta com dados também do Instituto Nacional de Metereologia (Inmet), a Agência Nacional das Águas (ANA) e do Centro Nacional de Monitoramento e Alertas de Desastres Naturais (Cemaden).

Criado em 2011, o Cemaden é o único voltado diretamente para prevenção de eventos climáticos extremos, os demais produzem dados para a agropecuária e utilização de águas para o abastecimento de cidades e a geração de energia elétrica. Como foram criados para outras finalidades, esses monitoramentos não eram desenvolvidos para monitorar rios que provocam impactos em grandes concentrações populacionais