“Climate change increases the frequency of extreme weather events.”

The evidence of observed changes in extremes and their attribution to human influence (including greenhouse gas and aerosol emissions and land-use changes) has strengthened since AR5, in particular for extreme precipitation, droughts, tropical cyclones and compound extremes (including dry/hot events and fire weather). Some recent hot extreme events would have been extremely unlikely to occur without human influence on the climate system. The probability of compound events has likely increased in the past due to human-induced climate change and will likely continue to increase with further global warming.

It is an established fact that human-induced greenhouse gas emissions have led to an increased frequency and/or intensity of some weather and climate extremes since pre-industrial time, in particular for temperature extremes. Evidence of observed changes in extremes and their attribution to human influence (including greenhouse gas and aerosol emissions and land-use changes) has strengthened since AR5, in particular for extreme precipitation, droughts, tropical cyclones and compound extremes (including dry/hot events and fire weather). Regional changes in the intensity and frequency of climate extremes generally scale with global warming. New evidence strengthens the conclusion from the IPCC Special Report on Global Warming of 1.5°C (SR1.5) that even relatively small incremental increases in global warming (+0.5°C) cause statistically significant changes in extremes on the global scale and for large regions (high confidence).

As Earth's climate changes, it is impacting extreme weather across the planet. Record-breaking heat waves on land and in the ocean, drenching rains, severe droughts, and more powerful hurricanes have all been linked to climate change. Because a warmer atmosphere can hold more moisture, it can produce heavier rainfall events. At the same time, warming can worsen droughts by increasing evaporation. These changes are increasing the frequency and intensity of some extreme weather events.

The frequency and intensity of severe storms has increased. This trend will likely continue as the effects of climate change become more pronounced. The amount of precipitation falling in the heaviest 1% of storms increased by 42% in the Midwest and 55% in the Northeast from 1958 through 2016. Heavier storms are projected to increase in frequency at a faster rate than storms that are less intense.

One of the most visible consequences of a warming world is an increase in the intensity and frequency of extreme weather events. The National Climate Assessment finds that the number of heat waves, heavy downpours, and major hurricanes has increased in the United States, and the strength of these events has increased, too. Climate change is expected to worsen the frequency, intensity, and impacts of some types of extreme weather events.

Scientists say extreme weather events like these are becoming more frequent and severe due to climate change. Communicating the link between climate change and extreme weather is crucial because it helps people understand that today's events are not just random. Research has shown that human-caused climate change has increased the likelihood or severity of many types of extreme weather, especially heat waves and heavy rainfall events.

With increasing global surface temperatures the possibility of more droughts and increased intensity of storms will likely occur. As more water vapor is evaporated into the atmosphere it becomes fuel for more powerful storms to develop. This in turn can cause more extreme weather events, including more intense hurricanes and more frequent heavy rainfall events that can lead to flooding.

A major driver of increased costs of extreme weather is the increase in population and material wealth over the last several decades. The intensification of extreme weather events due to climate change is also playing a role in increasing losses. Since 1980, the number and cost of disasters have increased over time, which is partially due to increased exposure and vulnerability, but also reflects changes in some types of extreme weather events influenced by climate change.

Extreme weather and climate events, such as heat waves, cyclones, and floods, are an expression of climate variability. These events and events influenced by climate change are increasing in frequency and intensity in many regions. Growing evidence attributes an increasing proportion of these extreme events to anthropogenic climate change, particularly heat extremes and heavy precipitation events.

Across the globe, extreme weather is becoming the new normal… From season to season and year to year, weather events that were once rare occurrences are now increasingly commonplace. Human activity is causing rapid changes to our global climate that are contributing to extreme weather conditions. Though it is difficult to determine with certainty whether climate change caused any specific weather event, scientists say that global warming will make storms like this one more common.

As the global climate warms, we expect (and are beginning to observe) changes in the frequency, intensity, and duration of extreme heat events, heavy rainfall, and some types of drought. While not every kind of extreme weather is increasing everywhere, the odds of many extremes have shifted toward more frequent or more intense events as a result of human-caused warming. It is still possible to have cold outbreaks and other extremes that seem to contradict warming, but these occur against a background trend of rising temperatures and changing statistics of extremes.

Scientists are detecting a stronger link between the planet’s warming and its changing weather patterns. And the trajectory is clear — hotter heat waves, drier droughts and stronger storms. A warming Earth creates conditions that fuel dangerous hurricanes and floods, and research suggests that we’ll see stronger hurricanes as the planet heats up.

We need to examine long-term data to understand how climate change is affecting weather extremes such as rainfall patterns, droughts, hurricanes and heatwaves. The US EPA notes an increase in the ACE index since the 1990s, although this is compared to several decades of very low intensity during the 1970s and 1980s. Cyclone intensity may have increased, but it is hard to say conclusively, given improvements in measurement records over time. For some types of extremes, such as hurricanes in the United States, the evidence for long-term increases in frequency is still mixed and subject to large uncertainties.

This latest iteration of the interactive map includes more than 600 studies, covering almost 750 extreme weather events and trends. Across all these cases, 74% were made more likely or severe because of climate change. This includes multiple cases where scientists found that an extreme was virtually impossible without human influence on global temperatures. Around 9% of the events and trends in the map were made less likely or severe by climate change. In the remaining 17% of cases, the studies either found no human influence (10%) or they were inconclusive (7%), often due to insufficient data.

Climate change is not necessarily increasing the overall number of hurricanes, but research indicates it is increasing the proportion of storms that reach the most intense levels (Categories 4 and 5) and the amount of rainfall they produce. Some studies suggest that while frequency of tropical cyclones globally may decrease or remain unchanged, the frequency of the strongest storms and of extreme rainfall associated with them is likely to increase in a warming climate.

Many of the extreme weather events we are experiencing around the world are made more likely and more intense because of human-caused climate change. This includes more frequent and intense heatwaves, heavy rainfall events and some types of flooding. However, not every type of extreme weather shows the same clear signal. For example, there is lower confidence about observed global trends in tornadoes and hail, and for some regions in droughts and tropical cyclone frequency.

While there is strong evidence that global warming has increased the frequency and intensity of some types of extreme weather (such as heatwaves and heavy rainfall), it is not accurate to state that all extreme weather events are increasing everywhere. Some types of extremes show little or no long-term trend, and a few (such as very cold temperature extremes) have decreased in frequency as the climate has warmed. Any claim that global warming is causing more extreme weather must be nuanced and specific about which types of extremes and which regions are being discussed.

Many people believe that global warming is causing more frequent and severe weather events. However, the empirical evidence for a significant increase in most types of extreme weather on a global scale is not compelling. For example, there is little evidence of long-term increases in hurricane frequency, tornadic activity, or drought globally, and some metrics show decreases. Where changes are observed, such as in heat waves and heavy precipitation in some regions, natural variability and changes in observation practices complicate attribution to greenhouse gas–driven climate change.