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New data from Nasa has revealed a dramatic rise in the intensity of weather events such as droughts and floods over the past five years.
The study shows that such extreme events are becoming more frequent, longer-lasting and more severe, with last year’s figures reaching twice that of the 2003-2020 average.
The steepness of the rise was not foreseen. The researchers say they are amazed and alarmed by the latest figures from the watchful eye of Nasa’s Grace satellite, which tracks environmental changes in the planet. They say climate change is the most likely cause of the apparent trend, even though the intensity of extremes appears to have soared even faster than global temperatures.
A Met Office expert said increases in extremes have long been predicted but are now being seen in reality. He warned that people were unprepared for such weather events, which would be outside previous experience.
The data is not yet peer-reviewed, and researchers said they would need another 10 or more years to confirm to conclusively call it a trend. The data has been co-produced by Dr Bailing Li, from the Hydrological Sciences Laboratory of Nasa’s Goddard Space Flight Center – affiliated with the University of Maryland’s Earth System Science Interdisciplinary Center, who told the Guardian: “We can’t prove causation yet – we would need a much longer dataset. It’s difficult to pinpoint exactly what’s happening here, but other events suggest that (global) warming is the driving factor. We are seeing more and more extreme events round the world, so this is certainly alarming.”
Her colleague Dr Matthew Rodell, chief of hydrologic sciences at Goddard, also counselled caution over the latest data, but admitted that he too was worried about the apparent acceleration of a trend in destructive events. “It’s certainly scary,” he said.
The earlier part of the Nasa time series was published in Nature Water in 2023. The researchers used a mathematical formula to calculate the total effect of a weather event in terms of severity measured by the total area affected, the duration of the event and how wet or dry it was. The paper warned that disturbance to the water system would be one of the most significant consequences of the climate crisis.
The paper noted that the intensity of extremes was strongly correlated with global mean temperature, more so than with El Niño, the influential ocean current, or other climate indicators, suggesting that continued warming of the planet will cause more frequent, more severe, and longer and/or larger droughts and floods.
The Nasa researchers produced the updated statistics at the request of the Oxford-based research organisation Global Water Intelligence, whose head, Christopher Gasson, said water companies were in the firing line of climate change – facing too much water or too little water – or both.
He said most water companies were completely unprepared to cope with the changes under way. “This is extremely scary,” he said. “The industry needs to attract investment on a massive scale.”
Prof Richard Betts, head of climate change impacts at the Met Office and Exeter University, said of the Nasa report: “This is a stark reminder that a hotter planet means more severe floods and droughts. This has long been predicted, but is now being seen in reality.
“The world isn’t prepared for the changes in intense rainfall and drought that are now occurring. All around the world people have built their ways of living around the weather that they and their forebears were used to, which leaves them vulnerable to more frequent and severe extremes that are outside past experience. As well as urgently ramping up efforts to reduce emissions to halt global warming, we need to catch up on adaptation to live better with the changes that are already happening.”
A recent report by the charity WaterAid said extreme fluctuations between floods and droughts were devastating millions of lives, with many major cities experiencing “whiplash” events from drought to flood or heat to cold – or vice versa.
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The Royal Meteorological Society warned that such sudden transitions from one extreme to the other caused more harm than the individual events alone, affecting agriculture, infrastructure, biodiversity and human health.
Their report said: “Rising temperatures are disrupting key drivers such as the jet stream and the polar vortex, changing our weather patterns.”
Asher Minns, from the Tyndall Centre for Climate Change Research at the University of East Anglia, said that their own unpublished UK-based studies also showed more intensification of both droughts and floods as well as abrupt shifts between extreme wet and dry conditions – called hydroclimatic whiplash events.
Meanwhile, the World Meteorological Organization’s latest report calculates an 80% chance that at least one of the next five years will top 2024 as the warmest year on record.
It says global temperatures are set to continue to increase over the next five years, increasing climate risks and impacts on societies, economies, and sustainable development.
The unpredictability of extreme events revealed in the new data is likely to alarm the insurance industry, which bases current premiums on previous trend data. This could have widespread effects across entire economies.
