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Time Magazine
3 days ago
- Climate
- Time Magazine
Why ‘Hundred-Year' Weather Events Are Happening More Than Once Every 100 Years
Climate change is leading not only to droughts, wildfires, and extreme weather. It's also leading to oxymorons—at least when it comes to what are known as hundred-year storms, floods, and other events. Long-term weather forecasting—the kind that predicts conditions months or even years or decades in advance—is all about probabilities, factoring together not only current conditions and trends, but the historical record. An area that has seen floods in the past when the spring was unusually rainy or tropical storms were unusually fierce, is likely to see them again if the same conditions recur. Ditto the likelihood of severe storms when the atmosphere is holding a lot of moisture and the oceans are atypically warm. Environmental scientists have gotten so good at reading weather history that they can characterize some severe storms or floods as likely to occur in a given area only once in 100 years—or even 500 years or a thousand years. That's where the oxymoron comes in. As climate change leads to greater meteorological volatility, the one in 100—or 500 or 1,000—year events are occurring twice or three times or more in those windows. Since 1999, there have been nine storms along the North Carolina coast that qualify as hundred or thousand year events. From 2015 to 2019, one suburb of St. Louis experienced three major floods, two of which met the criteria for hundred-year events. One study by the Montreal-based carbon removal project Deep Sky calculates that the frequency of deadly hurricanes has jumped 300%, with 100-year storms now forecast to occur once every 25 years. Climate change is also redefining what qualifies as one of these rare and intense events. 'In April, an extreme rainfall event hit the Mississippi Valley, including Arkansas, Mississippi, Kentucky, and Tennessee,' says climate scientist Andrew Pershing, chief program officer at Climate Central, an advocacy and communications group. 'Some of our colleagues at the World Weather Attribution group did a study and calculated that it was a 100-year event based on today's climate, but without climate change it would have been more like a 500-year event.' Making those kinds of calculations can take some doing—and a fair bit of data modeling—because climate unfolds over the course of millennia and modern weather and climate records barely go back a century. 'Scientists first look at 30 years of data, 50 years of data and figure out how frequently these events occur,' says Pershing. 'The challenge is that when you do that you're using data from the past when it was around two degrees cooler than it is now. When you start to do the calculations for today's climate, you find that events that you might expect to happen once every hundred years might happen once every 20 years.' The math here gets a little simpler. By definition, a hundred-year storm has a 1% likelihood of occurring in any one year; for a 500-year storm it's 0.2%; for a thousand years it's 0.1%. But every year the probability clock starts anew; if the 1% longshot comes in and a hundred-year storm occurs on the Carolina coast in 2025, that same area would typically have the same 1% chance in 2026—but climate change is making the likelihood even higher. 'It's not like you can calendar one of these events and say you're cool for another 100 years,' says Pershing. Driving the more frequent events is what Pershing describes as a 'thirstier' atmosphere, one that is hotter and thus capable of holding more moisture. 'We have a supercharged water cycle and that means that when you get a rain event it has a better chance of being a bigger event than it used to be,' says Pershing. Some of those bigger events could be coming soon—in the form of hurricanes. On May 22, the National Oceanic and Atmospheric Administration (NOAA) released its projections for storm severity in the 2025 Atlantic hurricane season, which runs from June 1 to November 30. NOAA did not attempt to predict 100- or 500- or thousand-year events, but it does see trouble looming. The agency projects a 60% chance of an above-average hurricane season, a 30% chance of an average season, and just a 10% chance of below average. Across the six hurricane months, NOAA predicts 13 to 19 named storms—with winds of 39 mph or higher—up to 10 of which will likely develop into hurricanes with winds of 74 mph or more. Up to five of those could be major hurricanes—category 3, 4, or 5, with winds of 111 mph or more. And the impact could extend far beyond the coastal regions that are usually hardest hit. 'As we witnessed last year with significant inland flooding from hurricanes Helene [in September] and Debby [in August], the impacts of hurricanes can reach far beyond coastal communities,' said acting NOAA administrator Laura Grimm in a statement. Things could get dicey not only in the Atlantic, but in the Pacific as well. Already, tropical storm Alvin is forming off the southwest coast of Mexico, two weeks ahead of the start of the eastern Pacific hurricane season. In addition to hurricanes, floods, and storms, heat waves, droughts, and wildfires can be projected out over centuries. 'A hotter atmosphere can hold more water, but if you squeeze that moisture out over a mountain range like what happens in the west, then you end up with a much drier air mass,' says Pershing. 'The atmosphere then wants to suck the moisture out of the ground and so droughts get more severe.' There's no easy fix for a feverish atmosphere. In the short run, adaptation—dikes and levees to protect flood-prone cities, relocating residences away from eroding coasts—can help. In the longer run, shutting off the greenhouse emissions that created the problem in the first place is the best and most sustainable bet for limiting hundred-year storms to their hundred-year timelines. 'We have to quit fossil fuels as fast as we can,' says Pershing. 'This will give the climate a chance to stabilize and us a chance to adjust.'
Straits Times
3 days ago
- Science
- Straits Times
Extreme heat waves are getting longer and hitting the tropics hardest: Study
Indonesia and Singapore have both recorded an additional 99 extreme heat days since May 2024. ST PHOTO: BRIAN TEO Four billion people experienced at least 30 additional days of extreme temperatures over the past year as a result of climate change, with nations in the tropics the most severely impacted, according to a study released on May 30. Indonesia and Singapore have both recorded an additional 99 extreme heat days since May 2024 when compared to a scenario that stripped out the impacts of global warming, researchers from London-based World Weather Attribution, US non-profit Climate Central, and the Red Cross Climate Centre found. Barbados, Haiti and a number of other Caribbean and Pacific island states and territories each had more than 120 extra hot days. Scientists defined extreme heat days as instances when daily temperatures were above 90 per cent of the historical average for a given location, aiming to gain better insight into conditions experienced locally rather than by making comparisons to worldwide averages. Last year (2024) was the hottest ever recorded, and the period studied in the report covered several severe heat waves, including in the southwest US last June, across southern Europe the following month, and through central Asia in March 2025. Periods of extreme heat disproportionately impact vulnerable populations, including older adults, low-income communities and pregnant people, the study said. There are frequently also negative effects on agricultural productivity, water availability and energy infrastructure. Of the 247 countries and territories analysed in the study, those with the highest number of additional extreme heat days were overwhelmingly in regions closest to the equator. 'Temperatures are less variable in the tropics than in the mid-latitudes, which means that the climate change trend is emerging more clearly in tropical regions,' said Dr Clair Barnes, a research associate at Imperial College London and member of the World Weather Attribution group. That means those regions will more likely experience extreme heat, she said. The World Weather Attribution group is an international scientific collaboration focused on finding out to what degree climate change is to blame for extreme weather events. Extreme heat has one of the strongest links to climate change. Small island states are among the most exposed to and least prepared for climate risks, and saw the starkest increase in extreme heat days during the period studied. That's because 'the oceans surrounding them tend to hold heat for a long time, keeping temperatures higher in what would previously have been cooler months,' Dr Barnes said. BLOOMBERG Find out more about climate change and how it could affect you on the ST microsite here.
Japan Times
01-05-2025
- Climate
- Japan Times
South Korea's deadly fires made twice as likely by climate change, researchers say
South Korea's worst ever wildfires in March were made twice as likely as a result of climate change and such disasters could become even more frequent if temperatures continue to rise, scientists said on Thursday. Fires in the country's southeast blazed for nearly a week, killing 32 people and destroying around 5,000 buildings before they were brought under control in late March. The fires burned through 104,000 hectares of land, making them nearly four times more extensive than South Korea's previous worst fire season 25 years ago. The hot, dry and windy conditions were made twice as likely and 15% more intense as a result of climate change, a team of 15 researchers with the World Weather Attribution group said after combining observational data with climate modelling. South Korea normally experiences cold dry winters and rapid increases in temperature in March and April, making it vulnerable to fires at that time of year, said June-Yi Lee of the Research Center for Climate Sciences at Pusan National University. This year, average temperatures from March 22 to 26 were 10 degrees Celsius higher than usual in the southeast, and patterns of low and high pressure to the north and south generated the powerful winds that helped the fire spread, she told a briefing. "This year, the size of the impact was very extreme ... because of the dry weather, the heat and the high temperatures — a perfect storm of conditions," she said. The weather that drove the fires could become even more common if global warming continues on its current trajectory and rises another 1.3 degrees by 2100. "The models project on average a further increase of about 5% in intensity and a further doubling of the likelihood of similarly extreme events," said Clair Barnes of the Centre for Environmental Policy at Imperial College London (ICL). The blazes also raised concerns that South Korea's extensive tree planting program since the 1970s had made the country more fire-prone, and forest management needs to adjust to meet the challenges of extreme heat, said Theo Keeping at ICL's Leverhulme Centre for Wildfires. "Once a wildfire event is extreme enough, it can't be put out with drops from planes and helicopters or from spraying water from the ground ... so we need to manage risk before these events happen," he said.
Yahoo
30-04-2025
- Climate
- Yahoo
South Korea's deadly fires made twice as likely by climate change, researchers say
By David Stanway SINGAPORE (Reuters) -South Korea's worst ever wildfires in March were made twice as likely as a result of climate change and such disasters could become even more frequent if temperatures continue to rise, scientists said on Thursday. Fires in the country's southeast blazed for nearly a week, killing 32 people and destroying around 5,000 buildings before they were brought under control in late March. The fires burned through 104,000 hectares (257,000 acres) of land, making them nearly four times more extensive than South Korea's previous worst fire season 25 years ago. The hot, dry and windy conditions were made twice as likely and 15% more intense as a result of climate change, a team of 15 researchers with the World Weather Attribution group said after combining observational data with climate modelling. South Korea normally experiences cold dry winters and rapid increases in temperature in March and April, making it vulnerable to fires at that time of year, said June-Yi Lee of the Research Center for Climate Sciences at Pusan National University. This year, average temperatures from March 22-26 were 10 degrees Celsius higher than usual in the southeast, and patterns of low and high pressure to the north and south generated the powerful winds that helped the fire spread, she told a briefing. "This year, the size of the impact was very extreme … because of the dry weather, the heat and the high temperatures - a perfect storm of conditions," she said. The weather that drove the fires could become even more common if global warming continues on its current trajectory and rises another 1.3 degrees by 2100. "The models project on average a further increase of about 5% in intensity and a further doubling of the likelihood of similarly extreme events," said Clair Barnes of the Centre for Environmental Policy at Imperial College London (ICL). The blazes also raised concerns that South Korea's extensive tree planting programme since the 1970s had made the country more fire-prone, and forest management needs to adjust to meet the challenges of extreme heat, said Theo Keeping at ICL's Leverhulme Centre for Wildfires. "Once a wildfire event is extreme enough, it can't be put out with drops from planes and helicopters or from spraying water from the ground … so we need to manage risk before these events happen," he said.
Reuters
30-04-2025
- Climate
- Reuters
South Korea's deadly fires made twice as likely by climate change, researchers say
SINGAPORE, May 1 (Reuters) - South Korea's worst ever wildfires in March were made twice as likely as a result of climate change and such disasters could become even more frequent if temperatures continue to rise, scientists said on Thursday. Fires in the country's southeast blazed for nearly a week, killing 32 people and destroying around 5,000 buildings before they were brought under control in late March. The fires burned through 104,000 hectares (257,000 acres) of land, making them nearly four times more extensive than South Korea's previous worst fire season 25 years ago. The hot, dry and windy conditions were made twice as likely and 15% more intense as a result of climate change, a team of 15 researchers with the World Weather Attribution group said after combining observational data with climate modelling. South Korea normally experiences cold dry winters and rapid increases in temperature in March and April, making it vulnerable to fires at that time of year, said June-Yi Lee of the Research Center for Climate Sciences at Pusan National University. This year, average temperatures from March 22-26 were 10 degrees Celsius higher than usual in the southeast, and patterns of low and high pressure to the north and south generated the powerful winds that helped the fire spread, she told a briefing. "This year, the size of the impact was very extreme … because of the dry weather, the heat and the high temperatures - a perfect storm of conditions," she said. The weather that drove the fires could become even more common if global warming continues on its current trajectory and rises another 1.3 degrees by 2100. "The models project on average a further increase of about 5% in intensity and a further doubling of the likelihood of similarly extreme events," said Clair Barnes of the Centre for Environmental Policy at Imperial College London (ICL). The blazes also raised concerns that South Korea's extensive tree planting programme since the 1970s had made the country more fire-prone, and forest management needs to adjust to meet the challenges of extreme heat, said Theo Keeping at ICL's Leverhulme Centre for Wildfires. "Once a wildfire event is extreme enough, it can't be put out with drops from planes and helicopters or from spraying water from the ground … so we need to manage risk before these events happen," he said.
