March 2023

More and stronger extreme weather events

This article is part of our series focused on the causes and consequences of a warming planet.

sky with cloudsExtreme weather events typically don’t happen very often. However, more and stronger extreme weather events are consistent with what scientists expect from a warming planet. These events are becoming more frequent and severe around the world. Extreme weather events include heatwaves, droughts, wildfires, extreme rainfall, winter precipitation, hurricanes, floods, and other events.

Examples of extreme weather events in 2022 include Hurricane Ian, extreme warming in British Columbia and the state of Washington, flooding that covered one-third of the country of Pakistan, droughts and wildfires across Western US, and many other places on the planet.

Perhaps the most impactful of these is the additional heat. This additional heat causes more heat waves. A heat wave is generally considered a string of continuous days with daily maximum temperature above a certain level, such as five consecutive days with daily high temperatures above 95ยบ F. The worldwide number of local record-breaking temperature extremes is now much higher than would be expected in a climate with no long-term warming. Because nights are warming faster than days, the evenings do not provide the ability to cool, making heat waves even more of a threat. In the US, heat waves have become more frequent and intense, especially in the West. Cold spells have become less frequent and intense across the nation.

The US Southwest is expected to become hotter and drier. The probability of mega-droughts lasting decades is increasing. These periods may be punctuated by high rainfall events called "atmospheric rivers" where currents of moisture laden air come off the Pacific Ocean and drop their precipitation on California. This type of event happened during the California Gold Rush in the mid-19th Century when much of the Central Valley was flooded.

Heavy downpours have increased nationally, especially over the last three to five decades, with the largest increases in the Midwest and Northeast. The frequency and intensity of heavy precipitation events are expected to continue to increase in the future. Heavy downpours that currently occur about once every 20 years are projected to occur two to five times more often by 2100.

Some extreme weather events are more closely linked to a warming planet than others. For example, EPA (Environmental Protection Agency) reports that scientists have high confidence that recent heat waves, droughts and extreme rainfall will continue in the future and become more frequent and intense. Scientists are less confident about events like tornadoes.

Whether a warming planet causes more Atlantic Hurricanes is uncertain. But science shows that a warming planet increases the rise in intensity of hurricanes when over water, increases the hurricane’s rate of rainfall, and may even slow the movement of hurricanes.

These extreme weather events will impact agricultural production around the world. Weather variability within and between years will make agricultural production more variable. Midwestern farmers will experience this variability in both the production and sale price of their commodities.

See the Ag Decision Maker website for more from this series.

Don Hofstrand, retired extension agricultural business specialist,
Reviewed by Dr. Eugene Takle, retired professor emeritus Iowa State University


Don Hofstrand

retired extension agricultural business specialist
View more from this author
Reviewed by

Dr. Eugene Takle

retired professor emeritus Iowa State University