How does climate change affect the strength and frequency of floods, droughts, hurricanes, and tornadoes?
Earth’s lower atmosphere is becoming warmer and moister as a result of human-caused greenhouse gas emissions. This gives the potential for more energy for storms and certain extreme weather events. Consistent with theoretical expectations, the types of events most closely related to temperature, such as heatwaves and extremely hot days, are becoming more likely. Heavy rainfall and snowfall events (which increase the risk of flooding) are also generally becoming more frequent.
As Earth’s climate has warmed, more frequent and more intense weather events have both been observed around the world. Scientists typically identify these weather events as “extreme” if they are unlike 90% or 95% of similar weather events that happened before in the same region. Many factors contribute to any individual extreme weather event—including patterns of natural climate variability, such as El Niño and La Niña, which shift rainfall patterns and contribute to drought or heavy rainfall (for la Nina) in many tropical and subtropical land areas. However, studies can show whether the warming climate made an event more severe or more likely to happen.
A warming climate can intensify heatwaves by raising the chances of very hot days and nights, so temperatures during a heatwave become hotter than they would be in a cooler climate. Warmer conditions also increase evaporation on land, which can worsen drought and create conditions more prone to wildfire and a longer wildfire season. A warming atmosphere is also associated with heavier precipitation events (rain and snowstorms) through increases in the air’s capacity to hold moisture.
Earth’s warmer and moister atmosphere and warmer oceans make it likely that the strongest hurricanes will be more intense, produce more rainfall, affect new areas, and possibly be larger and longer-lived. This is supported by observational evidence from the North Atlantic and by numerous studies that attribute changes in temperature and weather patterns to human-induced climate change. In addition, sea level rise (see Question 14) increases the amount of seawater that is pushed on to shore during coastal storms, which, along with more rainfall produced by the storms, can result in more destructive storm surges and flooding. While global warming is likely making hurricanes more intense, the change in the number of hurricanes each year is quite uncertain. This remains a subject of ongoing research.
Some conditions favourable for strong thunderstorms that spawn tornadoes are expected to increase with warming, but uncertainty exists in other factors that affect tornado formation, such as changes in the vertical and horizontal variations of winds.
Page last updated: July 2026
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