Instability in the global water cycle intensified floods, droughts and heat extremes in 2025, contributing to widespread humanitarian and economic impacts, according to a new report led by the Australian National University (ANU).
The 2025 Global Water Monitor Report states that continued warming is altering how water moves through the atmosphere, land and oceans, increasing the frequency and severity of water-related disasters. The international research team reports that such events caused nearly 5,000 deaths worldwide in 2025, displaced around eight million people and resulted in economic losses exceeding US$360m.
Led by Prof. Albert van Dijk from ANU’s Fenner School of Environment & Society, the report links these losses to floods, tropical cyclones, droughts and wildfires that interacted across water, food and energy systems.
“Changes to the water cycle are influencing the timing and location of disasters,” said Prof. van Dijk. “In 2025, floods, droughts and heat-related hazards repeatedly hit the same regions in quick succession, amplifying their combined impacts.”
The report highlights rapid transitions between wet and dry conditions, sometimes described as ‘climate whiplash’, which placed increasing pressure on ecosystems, infrastructure and water systems. One example cited was the Iberian Peninsula, where a wet spring drove vegetation growth before a sudden heatwave and flash drought dried soils and vegetation, contributing to severe wildfires in Spain and Portugal.
“The report documents how changes in atmospheric moisture, soil and groundwater conditions, river flows and surface water extent were closely associated with many of the year’s most damaging climate disasters,” said Prof. van Dijk.
Global land temperatures in 2025 were only slightly lower than the record set in 2024, with the past three years ranking as the hottest on record. Extreme heat remained a major driver of impacts, particularly in Europe, where prolonged summer heatwaves were linked to large numbers of heat-related deaths and increased wildfire activity.
“The close link between warming and the water cycle was evident in 2025, as growing instability saw unprecedented glacial lakes bursting their banks in the Himalayas following warm weather,” Prof. van Dijk said.
“A major tropical cyclone near the equator in Indonesia further highlighted that water-related hazards are emerging in regions where they were once rare.”
Flooding was widespread during the year, with global river flows and surface water extent above long-term averages. South and Southeast Asia were particularly affected by flooding linked to monsoon rainfall and tropical cyclones, while other regions, including Somalia, experienced rapidly developing drought conditions.
The report stresses that preparedness, including early warning systems and evacuation planning, remains critical as climate-related hazards intensify.
“The impact of a disaster depends on how well-prepared society is to manage them,” Prof. van Dijk said.
“In 2025, preparedness saved many lives, but there were failures and the fast-changing planet keeps throwing new surprises at us.”
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