Yes, climate change is making hurricanes worse

Three things make very bad storms like Irma and Harvey worse:

1. Warming ocean temperatures

2. Rising sea levels

3. Extreme rainfall

Here’s how:

1. Warming ocean temperatures

Hurricanes thrive over warm water and strengthen in intensity. NASA says tropical storms “are like giant engines that use warm, moist air as fuel.”

Adalberto Roque/AFP/Getty Images

Global ocean temperatures have climbed about 1.5 degrees Fahrenheit higher than their average temperature for most of the 20th century.

Ricardo Arduengo/AFP/Getty Images

Global ocean temperatures

NOAA, 1992-2017

2. Rising sea levels

Global sea levels have risen 3.4 inches since 1993. That doesn’t seem like much, but the pace at which they are rising is accelerating.

Sean Rayford/Getty Images

By the end of the 21st century, scientists expect seas to rise by as much as 4 feet – enough to swamp many coastal areas, especially during big storms.

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Sea height variation

NASA, 1993 - 2017

3. Extreme rainfall

Flooding, not wind, is often the greatest threat from a hurricane. Harvey dumped a record 51 inches of rainfall as it sat over Texas and Louisiana.

Richard Bouhet/AFP/Getty Images

The frequency of two-day heavy rain events – defined as one that occurs, on average, only every five years – has been increasing in recent decades.

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Two-day heavy rain events

US Global Change Research Program, 1900-2015

According to the most recent National Climate Assessment in 2014, the intensity, frequency and duration of North Atlantic hurricanes have increased since the early 1980s.

Martin Bureau/AFP/Getty Images

You can say, ‘I don't believe in climate change,’ but the planet is warming, humans are responsible, and the risks are becoming increasingly serious and even dangerous.

Katharine Hayhoe

Director of the Climate Science Center at Texas Tech University