In late 2018, Washington Post environmental writer Chris Mooney began noticing a small but recurring theme in scientific studies about climate change: Most places on the planet had gotten warmer on average over the preceding century, but some had become hotter than others. Prolonged warming had changed these local ecosystems for the worse, indicating that climate change wasn’t just an abstract future threat but an ongoing one.

Mooney began talking up the idea with his editor, Trish Wilson, and soon a series of articles, photos, videos and graphics was born. Eventually, the effort to document places on the planet that had experienced above-average warming involved 53 people in The Post’s newsroom.

On Monday, a panel of judges awarded the series the Pulitzer Prize, journalism’s highest honor. The project, dubbed “2C: Beyond the Limit” for the benchmark two-degree Celsius temperature rise, won for explanatory journalism.

The Post also had three finalists in this year’s awards, which recognized work published in 2019.

Post sports columnist Sally Jenkins was a finalist in the commentary category for columns about the U.S. women’s soccer team’s World Cup title and LeBron James’ comments about China, among others. A series detailing the extent of the pharmaceutical industry’s massive distribution of opioid drugs — and the deadly addiction crisis that resulted — was a finalist in public-service reporting. And The Post’s extensive coverage of shootings in El Paso, Tex., and Dayton, Ohio, over one bloody weekend in August was a finalist in the breaking-news category.

The New York Times led all news organizations on Monday by winning three Pulitzers: for articles about abusive financial practices in New York City’s taxicab industry (in the investigative reporting category); for a series about assassinations by members of Russia’s intelligence services (international reporting); and for writer Nikole Hannah-Jones’s essay about slavery and history, as part of the Times’ “1619 Project” commemorating the 400th anniversary of the arrival of the first African slaves to colonial America (commentary).

ProPublica, the nonprofit investigative news organization, shared the public-­service award in partnership with the Anchorage Daily News for stories about the absence of law enforcement in dozens of rural Alaskan villages. The organization also won a second Pulitzer in national reporting for articles about breakdowns, accidents and neglect in the U.S. Navy’s 7th Fleet.

The New Yorker magazine also won two Pulitzers — Barry Blitt, for editorial cartooning, and Ben Taub in feature writing for his story about a former prisoner at the U.S. prison at Guantánamo Bay in Cuba.

The 2020 prizes were the first to recognize audio journalism; the winner in that category was “This American Life,” the long-running public-radio program hosted by Ira Glass.

This year’s prizes were also the first during Donald Trump’s presidency in which no news organization was recognized for its reporting about Trump’s policies, finances or business practices.

The Pulitzer announcement by Columbia University’s journalism school was delayed for two weeks this year because of complications from the coronavirus shutdown, including travel restrictions on judging panels. The pandemic has also made the traditional newsroom celebrations of the awards impossible, because journalists across the country are now working remotely. A luncheon honoring the winners, typically held a month after the awards are announced, appears to be in jeopardy this year, too.

Mooney sparked The Post’s “2C” project when he noticed a key detail in climate studies of Puerto Rico and the Mojave Desert: These locations were heating up much faster than the global average, to disastrous effect. The studies suggested that rising temperatures are an uneven phenomena, affecting some parts of the world more than others.

Mooney, whose byline appeared on five of the 10 stories submitted for the Pulitzer, said his reading of the studies gave him “the sense that there was a common theme, where regions that were seeing unusually high levels of warming were seeing some type of bizarre or dramatic ecosystem upheaval.”

By collecting and studying multiple sets of temperature data from around the world stretching back to the late 1800s (a task spearheaded by staffer John Muyskens), Post reporters found that roughly 10 percent of the planet has already warmed by ­at least 2 degrees Celsius, or 3.6 degrees Fahrenheit. Climate scientists have warned that a two-degree rise for the entire planet could result in cataclysmic conditions.

Mooney and other Post journalists traveled to a dozen hot spots — Australia, Siberia, Qatar and Angola, among them — to report on what warming conditions had wrought. Among the stories were those by reporter Darryl Fears, who documented the destruction of Tasmania’s extensive kelp forests because of ocean warming, and Steven Mufson, who reported on Qatar’s air conditioning of outdoor spaces amid unbearable heat.

Some the stories had compelling backstories of their own. Photographer Michael Robinson Chavez spent two days in an open 15-foot boat to reach a remote part of eastern Russia; reporter Juliet Eilperin traveled in the luggage compartment of a small plane to get to a lake in Alaska.

The project included an online tool that enabled readers to search the temperature data The Post had collected to show how much regions of the world had warmed over more than 120 years, including more than 3,000 counties in the United States.

The series involved reporters, editors, copy editors, graphic specialists, designers, videographers and photographers. The project “makes clear how urgent this matter is,” said Martin Baron, The Post’s editor. “People’s lives and livelihoods are disappearing. It’s not our job to make policy or recommendations about what to do about it, but [this work] does serve as a warning.”

Among other journalism winners were the Seattle Times, for national reporting for exposing the extent of design flaws and the lack of regulatory oversight of Boeing’s 737 Max jet, and the Louisville Courier-Journal, which won in the breaking-news category for its reporting about a flurry of pardons by outgoing Gov. Matt Bevin (R) in his final days in office.

The Baltimore Sun won the local reporting prize for stories that revealed that the city’s former mayor, Catherine Pugh, made deals on behalf of the city with organizations that purchased mass quantities of a children’s book she wrote.

The breaking-news photography award went to the staff of Reuters, for its portfolio documenting protests in Hong Kong. Photographers from the Associated Press won the feature photography award for their work about daily life in Kashmir, the disputed territory between India and Pakistan.

Christopher Knight, the Los Angeles Times art critic, won in the criticism category. Knight had been a three-time finalist for his work.

And in editorial writing, Jeffery Gerritt of the tiny Palestine Herald-Press in Texas won for his editorials about medical neglect of inmates in Texas county jails before they were ever convicted.

The awards come amid increasingly troubled news for the news industry. Advertising and subscriptions have been declining at most news organizations for years, but the coronavirus has been a near-knockout punch for many. Several of the winners, such as the Los Angeles Times and Baltimore Sun, have recently announced layoffs, pay cuts or furloughs. News of the first-ever Pulitzer won by the tiny Herald-Press came just three days after it said it would cut back its print edition to three days per week to save money.

Pulitzer winners receive $15,000, except in the public-service category, in which the award is a gold medal.