Climate change to blame for Hurricane Maria's extreme rainfall

Climate change to blame for Hurricane Maria's extreme rainfall
Hurricane Maria near peak intensity, moving north towards Puerto Rico, on September 19, 2017. Credit: Naval Research Laboratory/NOAA.

Hurricane Maria dropped more rain on Puerto Rico than any storm to hit the island since 1956, a feat due mostly to the effects of human-caused climate warming, new research finds.

A new study analyzing Puerto Rico's history finds 2017's Maria had the highest average rainfall of the 129 storms to have struck the island in the past 60 years. A of Maria's magnitude is nearly five times more likely to form now than during the 1950s, an increase due largely to the effects of human-induced warming, according to the study's authors.

"What we found was that Maria's magnitude of peak precipitation is much more likely in the of 2017 when it happened versus the beginning of the record in 1950," said David Keellings, a geographer at the University of Alabama in Tuscaloosa and lead author of the new study in AGU's journal Geophysical Research Letters.

Previous studies have attributed Hurricane Harvey's record rainfall to climate change, but no one had yet looked in depth at rainfall from Maria, which struck Puerto Rico less than a month after Harvey devastated Houston and the Gulf Coast. Extreme rainfall during both storms caused unprecedented flooding that placed them among the top three costliest hurricanes on record (the other being Hurricane Katrina in 2005).

The new study adds to the growing body of evidence that human-caused warming is making like these more common, according to the authors.

Climate change to blame for Hurricane Maria's extreme rainfall
Comparison of lights at night in Puerto Rico before (top) and after (bottom) Hurricane Maria. Credit: NOAA.

"Some things that are changing over the long-term are associated with climate change—like the atmosphere getting warmer, sea surface temperatures increasing, and more moisture being available in the atmosphere—together they make something like Maria more likely in terms of its magnitude of precipitation," Keellings said.

Constructing a history of rain

José Javier Hernández Ayala, a climate researcher at Sonoma State University in California and co- author of the new study, is originally from Puerto Rico and his family was directly impacted by Hurricane Maria. After the storm, Hernández Ayala decided to team up with Keellings to see how unusual Maria was compared to previous storms that have struck the island.

The researchers analyzed rainfall from the 129 hurricanes that have struck Puerto Rico since 1956, the earliest year with records they could rely on. They found Hurricane Maria produced the largest maximum daily rainfall of those 129 storms: a whopping 1,029 millimeters (41 inches) of rain. That places Maria among the top 10 wettest hurricanes to ever have hit United States territory.

"Maria is more extreme in its precipitation than anything else that the island has ever seen," Keellings said. "I just didn't expect that it was going to be so much more than anything else that's happened in the last 60 years."

Climate change to blame for Hurricane Maria's extreme rainfall
Infrared satellite loop of Maria passing east of the Dominican Republic on September 21, after leaving Puerto Rico. Credit: NOAA.

Keellings and Hernández Ayala also wanted to know whether Maria's extreme rain was a result of natural climate variability or longer-term trends like human-induced warming. To do so, they analyzed the likelihood of an event like Maria happening in the 1950s versus today.

They found an extreme event like Maria was 4.85 times more likely to happen in the climate of 2017 than in 1956, and that change in probability can't be explained by natural climate cycles.

At the beginning of the observational record in the 1950s, a storm like Maria was likely to drop that much rain once every 300 years. But in 2017, that likelihood dropped to about once every 100 years, according to the study.

"Due to anthropogenic climate change it is now much more likely that we get these hurricanes that drop huge amounts of precipitation," Keellings said.

The findings show on hurricane precipitation has already started to become evident, according to Michael Wehner, a climate scientist at Lawrence Berkeley National Laboratory in Berkeley, California, who was not connected to the new study. Because so much of Maria's damage was due to flooding from the extreme amount of rain, it is safe to say that part of those damages were exacerbated by climate change, Wehner said.

"Extreme precipitation during tropical cyclones has been increased by climate change," he said. "Not all storms have a large amount of inland flooding, of freshwater flooding. But of those that do, the floods are increased to some extent by ."

Explore further

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More information: David Keellings et al, Extreme Rainfall Associated With Hurricane Maria Over Puerto Rico and Its Connections to Climate Variability and Change, Geophysical Research Letters (2019). DOI: 10.1029/2019GL082077
Journal information: Geophysical Research Letters

Citation: Climate change to blame for Hurricane Maria's extreme rainfall (2019, April 16) retrieved 16 October 2019 from
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Apr 16, 2019
''On the one hand we are ethically bound to the scientific method, in effect promising to tell the truth, the whole truth, and nothing but& which means that we must include all the doubts, caveats, ifs and buts. On the other hand, we are not just scientists, but human beings as well. And like most people, we'd like to see the world a better place, which in this context translates into our working to reduce the risk of potentially disastrous climate change. To do that we have to get some broad-based support, to capture the public's imagination. That, of course, entails getting loads of media coverage. So we have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have. This double ethical bind which we frequently find ourselves in cannot be solved by any formula. Each of us has to decide what the right balance is between being effective and being honest. I hope that means being both.''

Apr 16, 2019
What happened after 2018 tsunam and earthquake?

What happened after 2011 tsunam and earthquake?

What happened after 2004 tsunam and earthquake?

What happened 2017 september 7 Chiapas Mexico?

Apr 16, 2019
More complete nonsense from the alarmist fools.

Apr 16, 2019
"A storm of Maria's magnitude is nearly five times more likely to form now than during the 1950s"

Unsubstantiated nonsense.

Apr 16, 2019
What made it rain so heavy in 1956?

Apr 16, 2019
@ Whydening Gyre, a good question. Throughout history, events occurred like those we saw in PR a few years ago. Without the data of '57, we may have thought the 2017 storm was the worst ever to hit the island. I suspect conditions were just right (in '57) to provide lots of moisture in the atmosphere, which provided a rare event in PR's history, or so we would hope it is rare.

It is not so important that it has happened at this magnitude before. The real issue is frequency of such massive storms. With an increasing frequency of stronger and wetter hurricanes, one might ask why, rather than blow it off . If you can establish a trend never seen since the industrial revolution, it starts to look like an anthropomorphic effect.

Lot of naysayers out there. Most do not (or will not) understand climate change and its relation to human activities. When was the last time you saw a live passenger pigeon? Once numbering in the billions, we wiped them out. But this. too. is fake news......?

Apr 16, 2019
Sigh. Another study making spurious claims. Time for another debunking.

Hurricane Maria was the largest hurricane (Category 4) to hit Puerto Rico since the Category 5 San Felipe Segundo hurricane of 1928, which is outside the sample window the authors chose for rainfall measurements (1956). It isn't surprising that Maria had the highest rainfall since 1956. No other storm has compared in intensity to Maria since then. Hurricane Georges was "just" a Category 3 when it it in 1998, significantly less powerful than Maria.

They found an extreme event like Maria was 4.85 times more likely to happen in the climate of 2017 than in 1956

No they didn't. They used questionable methods to analyze a limited amount of data to divine that estimate. Global measures of total cyclone energy and tropical storm size and frequency show no discernible trend of "extreme events", but the authors "found" one in a limited spatial area with limited data.

Apr 16, 2019
Here are some links to show there is no measured evidence of an increase in "extreme weather events".

Global hurricane frequency:

Global tropical cyclone frequency:

Global tropical cyclone accumulated energy:

Cyclones and hurricanes from IPCC AR5 report, 2013:

Global precipitation anomalies from IPCC AR5 report, 2013:

Climate alarmists keep making the claim that extreme weather is increasing based solely on computer models. Measurements show otherwise.

Apr 16, 2019
According to government figures, there is a measurable increase in severity and frequency of winter storms since 1950. And that "Over the last 50 years, much of the U.S. has seen increases in prolonged periods of excessively high temperatures, heavy downpours, and in some regions, severe floods and droughts. "


All the nay-sayers should buy homes on the beaches so they can continue to deny climate change and sea level rise as they and their homes sink beneath the waves. We have people like this in N.J. Their trees are dying from saltwater intrusion but they deny it is from sea level rise. "Fake science" they call it - I call it in-your-face reality!

Apr 17, 2019
So the plan is to spend trillions of dollars redoing our whole energy system trying to stop climate change in order to save billions of dollars in damages?

I guess the Medieval Warming period wasn't really climate change since burning fossil fuels didn't cause it.

Apr 17, 2019 should ask its readers to vote if they think the article is biased.

Apr 17, 2019
Next year, 2020 the showdown begins between global warming represented by the CO2 belching fossil fuel industry and solar cooling represented by the sun with its noticeable lack of sunspots.

Global Warming vs. Solar Cooling: The Showdown Begins in 2020

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