People haven't just made the planet hotter. We've changed the way it rains.

·8 min read

You probably noticed a lot of weird weather in 2021.

From record-breaking deluges and tropical storms to drought-stricken landscapes that erupted in wildfire, the nation seemed to lurch from one weather-related disaster to the next.

You’re forgiven if you dismiss these events as unrelated, albeit unfortunate, phenomena. But they actually share a common bond – they’re all part of a new climate reality where supersized rainfalls and lengthening droughts have become the norm.

Blame global warming.

Related video: UN report gives 'code red for humanity' on climate change

Rising temperatures don’t just make the planet hotter. They’ve also knocked longstanding precipitation patterns off balance by altering how much water cycles between earth and sky.

Yes, there have always been erratic weather patterns, but now the heaviest downpours and droughts are growing more extreme, USA TODAY revealed in its recent yearlong project, Downpour.

Check out how a summer of extreme weather reveals a stunning shift in the way rain falls.

That trend started almost imperceptibly in the late 20th century, as the accumulation of earth-warming greenhouse gases reached critical levels in the atmosphere.

Now, decades later, those changes are nearly impossible to ignore.

East of the Rockies, more rain is falling, and it’s coming in more intense bursts. In the West, people are waiting longer to see any rain at all.

“They’re all interconnected to the impact that climate change is having on these persistent weather extremes,” said Michael Mann, a climatologist at Penn State University and author of the book "The New Climate War."

“It’s not a contradiction to have huge floods, unprecedented floods and unprecedented heat waves and droughts at the same time.”

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READ: How a summer of extreme weather reveals a stunning shift in the way rain falls in America.

See how rainfall has changed in your community.

The majority of Americans have experienced first-hand the impacts of these shifting precipitation patterns.

Take this past summer alone. In just over one week in June:

- A deluge dropped 7 inches of rain in Detroit, swamping highways and stranding motorists.

- At least 136 daily rainfall records were set during storms across five states along the Mississippi River.

- Tropical Storm Claudette soaked a swath of the South, flooding homes in Louisiana and in Alabama, where it dropped up to 8 inches of rain and claimed 14 lives.

- Meanwhile, the drought-stricken West grappled with soaring temperatures that shattered century-old records, prompted heat warnings and ultimately killed more than 200 people.

A dozen states, including Iowa, Ohio and Rhode Island, saw five of their 10 wettest years in history over the past two decades.

Michigan experienced six since 2008 alone.

At the opposite extreme, eight states – including five in the West – had at least three record-dry years in the same time period. That’s double what would be expected based on historical patterns.

Want to see what’s happening near you? Here’s our searchable database.

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READ: See how precipitation has changed in your community

Learn more about the science behind the changing rainfall trend

Some climate scientists said greenhouse gases like carbon dioxide and methane are to blame.

These gases trap heat and cause The Earth to warm. This warming raises temperatures, of course. But it also hastens evaporation and pulls more moisture into the air. More moisture means more water than can fall in the form of rain and snow.

At the same time, some scientists say rising temperatures have altered the summertime movement of the jet stream that transports moisture across the country. Weather systems that used to hustle along get stalled more often now, dumping more rain in one place.

The combination of a wetter atmosphere and a slower jet stream has been blamed for fueling the intensity of many of the storms that flooded dozens of communities and killed more than 100 people in 2021.

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READ: Our warming climate is having a dramatic impact on precipitation. What does the data tell us about your state?

The uptick in intense rainfalls threatens hundreds of U.S. sewer systems

As states rack up records for rainfall, flooding, droughts and wildfire, it’s becoming clear our country was built for the climate of the past.

Roads, bridges, sewer systems and entire communities that decades ago seemed safe from fire and flood now lie within one or both danger zones.

Take any one of the nearly 730 U.S. communities with a so-called “combined sewage overflow” system.

These antiquated networks of underground pipes combine rainwater, snowmelt and toilet waste into the same system. In normal conditions, the water gets treated before it’s discharged.

But during heavy rains, the systems can’t handle the extra water. And, by design, they discharge everything – even untreated waste –into rivers, lakes and even back into people’s homes.

They altogether spilled 850 billion gallons of raw sewage into the open waters in 2004 alone, the last time the federal government estimated it.

But now the warming planet is producing heavier and more frequent storms in the same regions of the country with these systems – the Midwest, Mid-Atlantic, and Northeast. Even communities that have upgraded their sewers can’t handle some of these deluges.

Detroit, for example, has already spent $1.4 billion to fix its combined sewer system. But the city discharged nearly 5 billion gallons of sewage-tainted water during the last week in June when damaging storms swept across Michigan.

"The infrastructure in this country was built for the climate of the 20th century,” Detroit Mayor Mike Duggan said shortly afterward. “It was not built for what we have today.”

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READ: Climate change brings a perfect storm of raw sewage and rainfall in cities that can least afford it

What does climate change sound like in states like Michigan?

To help explain the impact of precipitation changes, USA TODAY turned to Full Sail University in Winter Park, Florida. Faculty members at the music and recording school agreed to compose original music for several states based on more than a century of precipitation data.

Michigan, which has experienced six of its wettest years on record since 2008, is among the states for which the faculty members composed music.

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READ: What if you could hear climate change? Listen to music based on a century of rainfall data

Heavier rains contribute to an outsized share of the fertilizer runoff poisoning the Gulf of Mexico

Supersized rainfall events fueled by climate change have wreaked havoc last year on communities like Detroit, New York City and Waverly, Tennessee.

But deep inside rural America, these deluges exacerbate a more insidious problem with an even wider reach.

Rain falling on fertilized farmland can wash excess nutrients from crops into rivers, lakes and oceans, where spur algae growth that sucks up oxygen and chokes out life. It’s the phenomenon responsible for toxic algae blooms and the massive dead zone growing in the Gulf of Mexico.

And the problem is only getting worse with climate change.

An exclusive data analysis by USA TODAY and Midwest Center for Investigative Reporting found that the kinds of extreme rainfall events made more common by a warming planet cause three times as much fertilizer runoff than other rain events and contribute to an outsized share of it in the waterways.

The findings mirror a larger study conducted by University of Iowa researchers that found heavy rain across the Mississippi River Basin also contributed to one-third of the nitrogen that flushed into the Gulf of Mexico.

Among the most striking consequences of fertilizer runoff, the Gulf’s dead zone spans the coasts of Louisiana and Texas and has rendered uninhabitable some 6,330 square miles of water, according to recent measurements by the National Oceanic and Atmospheric Administration.

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READ: Excess fertilizer washed from Midwestern fields is slowly poisoning the Gulf of Mexico

A deadly combination of wildfires followed by heavy rainfalls threatens the West

Meanwhile, decades of rising temperatures and more intense wildfires have turned parts of the American West into a nearly impervious landscape where even one downpour can trigger deadly, post-fire debris flows, commonly called mudslides.

These once-infrequent events now threaten an area nearly twice the size of the entire state of Connecticut. Some 6.5 million acres across Arizona, California, Colorado, Nevada, New Mexico, Idaho, Utah, Oregon and Washington are in harm’s way. That’s double the size of the hazard from just three years ago.

In the past four years alone, the fast-moving flows have damaged and destroyed hundreds of homes, closed major transportation routes across at least three states and caused more than $550 million in property damage. Close to 170 people have been injured and 28 people died since 2018.

For years, local, state and federal officials invested in more pressing threats, like the wildfires that lay the groundwork for these debris flows. Now, possibly hundreds of thousands of Americans face a risk they may not even realize. And by the time they find out, it may be too late.

“Everyone told me that there was no way anyone could have known this was going to happen,” said Colorado Brown, who lost four family members in the debris flow that hit Poudre Canyon, Colorado, in July.

“I just, I really wish that there was a better way to see these things coming.”

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READ: Deadly mudslides threaten more Americans as heavy rains loom over scorched lands

This article originally appeared on USA TODAY: Climate change: We didn't just made Earth hotter. We altered the rain.