Key facts
- 77% of extreme weather events studied were made more likely or severe by climate change.
- 8% of mapped events and trends were made less likely or less severe by climate change.
- Overall, 85% of events were likely influenced by human-caused climate change.
- NASA data from 2024 showed severe weather events at twice the 2003-2020 average.
- Average global surface temperature in 2025 was 1.44 degrees Celsius above preindustrial levels.
- A recent report linked rising temperatures to floods in Nepal and Tibet, killing over 1,300 people.
A growing body of scientific research continues to strengthen the connection between human-induced climate change and the increasing frequency and severity of extreme weather events globally. A 2004 study was among the first to link human-caused climate change to a specific event, the 2003 European heatwave, which resulted in over 70,000 deaths. This initial research spurred further investigation into these links.
A UK-based organization, Carbon Brief, has compiled and mapped over 900 studies covering nearly 1,000 extreme weather events and trends. Their analysis indicates that 77% of these events were made more likely or severe due to climate change, with some events being nearly impossible without human influence on global temperatures. Conversely, about 8% of the events were made less likely or severe by climate change, leading to an overall finding that 85% were likely influenced by human activity.
In 2025, NASA released new data from its GRACE satellite, highlighting a significant increase in the intensity of weather events such as droughts and floods over the preceding five years. The data showed that figures in 2024 had doubled the average seen between 2003 and 2020. NASA cited climate change as the most probable cause, although researchers noted that a longer dataset of over a decade would be needed to confirm this as a conclusive trend. Bailing Li, a co-researcher on the NASA study, stated that while direct causation cannot yet be proven, "other events suggest that (global) warming is the driving factor" and that the increasing number of extreme events is "certainly alarming."
Global temperatures have risen substantially over the past century due to the accumulation of human-produced greenhouse gases. In 2025, the average global surface temperature was approximately 1.44 degrees Celsius above the 1850–1900 preindustrial average. This warming has been linked to increases in the frequency and severity of many extreme weather events.
Most recently, scientists have connected industrial emissions to the warming of the Himalayan region, which contributed to devastating floods in Nepal and Tibet in August. A report by World Weather Attribution, involving two dozen international researchers, suggests that rising temperatures likely exacerbated the disaster by destabilizing ice and permafrost on mountain slopes. While acknowledging that the 2015 Nepal earthquake may have also played a role, the researchers indicated a "very strong linkage" between human-caused warming and the disaster. The report, which has not yet been peer-reviewed, could support Nepal's request for climate aid. The floods killed over 1,300 people, with thousands still missing and recovery efforts estimated to cost $5 billion. Researchers noted unusually warm temperatures in the days leading up to the disaster, reflecting high global temperatures that contributed to Earth's tied record for the hottest month in July and August. Scientists have also found that increased mercury levels at high elevations in the Himalayas, linked to fossil fuel burning, have exposed permafrost to more frequent above-freezing conditions, allowing water to seep into rock cracks and weaken them, according to mountain hydrologist Walter Immerzeel.