By Maggie Astor

MOUNT PLEASANT, S.C. — From a couch on the back deck of a dockside restaurant, the Beatles playing in the background and a breeze blowing off the water, Joe Cunningham gestured to Shem Creek.

“This could be the reality here, of oil rigs and oil spills off the beach,” Mr. Cunningham said. “An oil spill could just decimate the area, and all of a sudden instead of people coming to Charleston, South Carolina, they high-tail it down to Florida or somewhere else.”

Offshore drilling might not captivate voters in most parts of the country, but it did here. For months, Mr. Cunningham called for the restoration of a federal ban as his Republican opponent, Katie Arrington, talked about immigration and warned that a vote for him would be a vote for Nancy Pelosi’s “San Francisco values.” And in November, Mr. Cunningham, 36, defeated Ms. Arrington in a House district that last elected a Democrat four years before he was born.

It was one of the biggest upsets of the midterms, and it turned on an ideal issue for a candidate who, before he became a lawyer, was an ocean engineer.

“‘We believe in science’ — that line always drew applause,” he said in an interview. “I think it’s a sad state of affairs when you have to actually say that. Imagine someone saying that about any other subject, like, ‘I believe in history’ — topics that are proven with evidence and facts and numbers.”

Mr. Cunningham is one of at least 11 freshman representatives with a background in science, medicine or technology. Eight of them are Democrats, and they are some of the first victors of a trend that began soon after President Trump was elected: Alarmed by inaction on climate change and the administration’s marginalization of experts, many more scientists have been entering politics.

“There is this growing consensus among the scientific community that they need to go beyond advocacy and signing polite letters and actually get involved in electoral politics,” said Shaughnessy Naughton, a chemist and the president of 314 Action, a two-year-old organization that supports candidates with scientific and medical backgrounds. The group — which raised $4 million for the 2018 elections — trained about 1,500 prospective candidates and supported the eight winning Democrats, as well as Senator Jacky Rosen and more than 30 successful state-level candidates. (While members of any party can attend trainings, the group doesn’t endorse Republicans for federal offices because, Ms. Naughton said, “we can’t justify supporting Republicans when the G.O.P. platform is aligned against scientific consensus on issues like climate change.”)

Elaine Luria, an engineer who operated nuclear reactors in the Navy, flipped Virginia’s Second Congressional District, which had been represented by a Republican for 16 of the last 20 years. Kim Schrier, a pediatrician, won Washington’s Eighth District, which had never elected a Democrat. Sean Casten, a biochemist, defeated a six-term Republican incumbent in the Sixth District of Illinois. T.J. Cox, a chemical engineer, won in California; Chrissy Houlahan, also an engineer, in Pennsylvania; Lauren Underwood, a registered nurse, in Illinois; and Jeff Van Drew, a dentist, in New Jersey.

At least three Republicans with science or medical backgrounds, and starkly different views, also won House seats: Mark Green of Tennessee, a former Army physician; Kevin Hern of Oklahoma, a businessman with a degree in aerospace engineering; and John Joyce of Pennsylvania, a dermatologist.

In several of the districts that flipped, science was at the very center of the campaign. 314 Action spent $500,000 on advertising in Mr. Cunningham’s race, hammering the offshore drilling issue, and it was largely based on that issue that Mr. Cunningham received endorsements from several local Republican officials. The same issue resonated in coastal Virginia, where Ms. Luria said she “did not meet a single person on the campaign trail, regardless of political affiliation, who wants offshore drilling off of our coast.”

For Mr. Casten — a former cancer researcher with degrees in molecular biology, biochemistry and biochemical engineering — the big issue involved Sterigenics, a company that sterilizes medical equipment at a facility in Willowbrook, Ill. The plant uses a carcinogenic chemical called ethylene oxide, and a Department of Health and Human Services report released in August found a high risk of cancer in nearby communities. (Sterigenics said the report had “purposefully relied upon a worst-case scenario for assessing risk.”)

The report became a liability for the incumbent Republican, Peter Roskam, who had received campaign contributions from the American Chemistry Council. The council and Sterigenics had been lobbying the E.P.A. for several years not to classify ethylene oxide as a known human carcinogen, and Mr. Roskam — whose spokeswoman declined to make him available for an interview — had supported legislation to put industry representatives on the E.P.A. boards that make such decisions.

Now that they are in Washington, the Democratic scientists-turned-representatives face a new challenge. Many of them said that, beyond addressing climate change and other science-related issues, they wanted to bring a more scientific mind-set to Congress.

For the last six years, the House Committee on Science, Space and Technology was led by Lamar Smith, a Texas Republican with no scientific background. Under him, the committee investigated the debunked idea that global warming had “paused,” subpoenaed organizations whose research affirmed the reality of climate change, and promoted rules that reduced the number of scientists and increased the number of industry representatives on E.P.A. advisory panels. At times, committee members showed a basic lack of scientific knowledge: During a hearing in 2014, Steve Stockman, another Texas Republican, said it was nonsensical to think melting glaciers and ice sheets would increase sea levels because glasses don’t overflow when the ice cubes in them melt.

Mr. Smith has now retired, and four other Republicans on the committee were not re-elected. The new chairwoman, Eddie Bernice Johnson, a Texas Democrat and former psychiatric nurse, is the first person with a scientific background to hold that position since the 1990s. Ms. Johnson said in an interview that she had invited the new scientists to join, though committee assignments may not be finalized for several weeks.

But the old dynamics are not going to disappear.

There will continue to be tension even with some of the scientists on the other side of the aisle: Mr. Hern, the aerospace engineer elected in Oklahoma, has questioned whether human activity is the primary cause of climate change, and Mr. Green, the doctor from Tennessee, repeated the debunked claim that vaccines can cause autism. (He later backtracked, telling HuffPost that children should be vaccinated.) They, too, feel their experience gives them a more authoritative voice and, in Mr. Hern’s words, “an understanding of many of the issues that others might not have.”

Representative Don Beyer of Virginia, a Democrat on the science committee, acknowledged that eight people could not “change the entire culture.” But, he said, they could change Congress’s perspective.

“So often, our perspective of politicians is lawyers and people with the gift of gab,” Mr. Beyer said. “Now we’re getting people that have a deep knowledge of mathematics and physics and chemistry and biology, and that’s a really important perspective in an increasingly scientific world.”

Mr. Cunningham is already preparing a bill that would ban drilling off the Atlantic coast for 10 years. Mr. Beyer and Bill Foster — an Illinois Democrat and physicist who is the only member of Congress with a doctorate in a scientific field — described several other legislative priorities for the committee, including more oversight of the E.P.A. and other science-related government bodies; regulation of developing technologies like human genetic engineering, artificial intelligence, cryptocurrencies and mobile payments; and, of course, measures to combat climate change. One of the first may be carbon pricing legislation — which would charge corporations for their carbon emissions — because unlike more aggressive measures, Mr. Foster said he believed that might get through the Republican-led Senate.

Mr. Foster said he believed Mr. Casten would be particularly helpful on carbon pricing. With experience in both biochemistry and business, Mr. Casten can “really talk about the nuts and bolts about what it means,” he said, “and how different industry sectors will react to that, and how that’s going to affect the carbon footprint of different industries, in a quantitative way.”

Ultimately, that sort of subject expertise, more than the Sisyphean task of changing the congressional approach to science, may be the new members’ most immediate contribution.

While talking about Ms. Luria, a nuclear engineer, Mr. Foster recalled the congressional discussion of the Iran nuclear agreement, which included a page describing the technical changes Iran needed to make to its reactor cores to ensure that the reactors could not produce large quantities of weapons-grade plutonium.

“Democrats and Republicans were coming to me in this period saying, ‘Bill, what does this mean and how should I vote on it?’” he said. “With Elaine there, at least that will cut my workload in half. We’ll have two competent members who can talk about reactor cores.”

Read in The New York Times.