With their win of control of the U.S. House of Representatives, Democrats will now have the numbers to put climate change issues back on the congressional agenda.

But the Republicans reinforced their firewall against any legislative efforts in the Senate by gaining at least two new members with poor records on confronting the climate crisis. That bolsters the power of Majority Leader Mitch McConnell of Kentucky to block any measures unfavorable to the fossil fuel industries.

In the states, a pair of ballot initiatives that would have cut climate pollution—in Colorado and Washington—appeared to be headed for defeat after heavy spending by fossil fuel interests that opposed them. But some incoming governors have pledged more aggressive support for clean energy.

And in one House race after another, Republicans who have been out of step with the prevailing scientific consensus on climate change were replaced by Democrats committed to taking action.

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Back in the majority on House committees, Democrats will at least be able to turn a spotlight on the problem by using hearings to bring public attention to communities pummeled by storms, droughts, floods and wildfires, and wielding subpoena power to investigate President Donald Trump's climate policy rollbacks and retreat from responsibility.

In all, it's a mixed message, and the midterm election results highlight the steep challenges that remain at a time when the world's scientists, and most national governments, are emphasizing the need for more rapid action on climate change.

House Minority Leader Nancy Pelosi, in line to regain the House speakership, has promised to revive the select committee on climate change that the GOP eliminated when it seized control of the House in 2010. The purpose would be to "prepare the way with evidence" for energy conservation and other climate change mitigation legislation, Pelosi told The New York Times.

Nancy Pelosi, currently the House minority leader, is in line to regain the speakership and has promised to revive the select committee on climate change that the GOP eliminated when it seized control of the House in 2010. Credit: Zach Gibson/Getty Images

Tiernan Sittenfeld, senior vice president for government affairs for the League of Conservation Voters, said the election results amounted to a rejection of "the most anti-environmental U.S. House of Representatives in our nation's history."

"Since 2009, the extreme Republican leadership of the U.S. House has put corporate polluters ahead of people and their communities time and again," Sittenfeld said. "For the last two years they have aided and abetted the most anti-environmental president ever. But now voters have clearly called for change, supporting candidates who campaigned on protecting people and our environment—and rejecting those who gave only lip service to the urgent threat of climate change."

But voters delivered a mixed verdict on their appetite for action to rein in fossil fuels. Voters in Colorado rejected a ballot initiative that would have put new restrictions on fracking. Washington, one of the few states where Democrats control most statewide offices, was on track to reject an initiative for the nation's first carbon fee—following a record $30 million campaign by the oil industry to defeat it. Voters in Nevada approved an initiative to boost renewable energy to 50 percent of the state's electricity by 2030, but Arizona voters rejected a similar initiative.

Michigan's Gretchen Whitmer and several other Democratic governor's race winners are vocal supporters of renewable energy. Credit: Bill Pugliano/Getty Images

Clean energy champions captured several governorships—Jared Polis in Colorado, Gretchen Whitmer in Michigan, and J.B. Pritzker in Illinois all have embraced commitments to 100 percent renewable energy. Polis had opposed the ballot measure to restrict drilling operations in the state, where oil revenues are important to the state and local governments.

Florida, the state with the largest population at risk from sea level rise, in a region pummeled by extreme storms in the past two years, elected as its next governor former U.S. Rep. Ron DeSantis, who had insisted "I am not a global warming person." DeSantis, with a pro-environmental voting record of 2 percent by the League of Conservation Voters tally, will succeed Gov. Rick Scott, who had put global warming on the back burner for the last eight years and is now poised to go to the Senate. Republicans picked up that Senate seat when Scott defeated the incumbent Democrat, Sen. Bill Nelson.

The Senate also gains a hardline opponent of climate action in Rep. Kevin Cramer, who defeated Democratic Sen. Heidi Heitkamp in North Dakota. Representing the No. 2 oil-producing state behind Texas, Heitkamp routinely broke from Democratic colleagues on environmental votes. But she sought funding for carbon capture technology and voted to preserve rules protecting wildlife and reining in methane emissions from oil and gas operations. Cramer served as an energy adviser to Trump during the 2016 campaign and was a key architect of the president's agenda to expand production of fossil fuels and eliminate environmental protections. He did not record a single pro-environmental vote last year, according to the League of Conservation Voters.

Voters Booted Climate Science Deniers—and Some Moderates

While adding to their numbers in the House, mainly by defeating staunch foes of climate action, Democrats also forced out Republicans who had staked out more moderate positions on climate change. At least a dozen of the 45 GOP members of the Climate Solutions Caucus were defeated, including its co-founder, Rep. Carlos Curbelo of Florida, author of the only bipartisan carbon pricing legislation introduced in the last Congress. Many of those who lost, including Curbelo, were vulnerable at the outset. But foes of climate action seized on the results as a rebuke of efforts to forge bipartisan consensus. The main goal of the caucus has been to build support for a carbon tax.

"So much for trying to attract so-called 'moderate' voters by embracing the climate alarmist agenda," scoffed former Congressman Tim Huelskamp, president of the Heartland Institute, which disputes the science of climate change and opposes actions to address the problem.

The Democratic victors in many races, however, won over voters with the argument that the best prescription for climate action would be to put the House back in the hands of Democrats. Debbie Mucarsel-Powell, the Democratic nonprofit fundraiser and development consultant who won Curbelo's South Florida seat, argued that Republicans had done nothing to protect the state's treasured coast and reefs. Up the coast in Virginia, Navy veteran and nuclear engineer Elaine Luria defeated another Climate Solutions Caucus member, Republican Rep. Scott Taylor, with an argument that he paid only lip service on environmental protection issues vital to the future of Virginia Beach and Norfolk.

Debbie Mucarsel-Powell, a development consultant who argued for protecting Florida's coast and reefs, defeated Republican Rep. Carlos Curbelo, a co-founder of the House Climate Solutions Caucus. Curbelo had won support from some environmental groups that wanted to encourage bipartisan efforts on climate and environment issues. Credits: Tom Williams/CQ Roll Call via Getty Images

Mark Reynolds, executive director of the advocacy group Citizens Climate Lobby, which worked to organize the Climate Solutions Caucus, praised Curbelo for his leadership but said his departure would not be the end of the caucus. Under Democratic control, Reynolds said there is "great potential" to advance bipartisan legislation to price carbon. "We're confident other Republicans will step up to lead, and the existing and potential members are invested in continuing bipartisan work on climate," Reynolds said. "To paraphrase Mark Twain, reports of the death of the Climate Solutions Caucus are greatly exaggerated."

Many of the House's climate science deniers were swept out of office, including Rep. John Culberson (R-Texas), Rep. Jason Lewis (R-Minn.), and Rep. Claire Tenney (R-N.Y.). In Iowa, a state where farmers have been buffeted both by weather and by Trump's energy and trade policies, voters sent home Reps. Rod Blum and David Young, replacing them with two women with backgrounds as advocates of defending and expanding clean energy in Iowa. Iowa's sole remaining climate-denying GOP congressman, Steve King, held on to his seat for a ninth term, although his opponent, J.D. Scholten, came within four points of victory in a district that Trump won by 27 points.

New Leadership and a New Direction for House Committees

Rep. Dana Rohrabacher (R-Calif.), another strident climate denier who was seeking chairmanship of the House Science Committee if the GOP maintained control of the House, appeared headed for defeat after 30 years in Congress. Instead, the top Democrat on that committee, Rep. Eddie Bernice Johnson (D-Texas), said she plans to steer a new direction for the committee if the Democratic leadership affirms her as chair. For the past five years, under the leadership of Rep. Lamar Smith (R-Texas), the committee has served as a platform for the fossil fuel industry's battles against scientists.

Johnson said she would pursue an agenda that addresses "the challenge of climate change, starting with acknowledging it is real, seeking to understand what climate science is telling us, and working to understand the ways we can mitigate it." She also said she wanted to restore the credibility of the committee "as a place where science is respected and recognized as a crucial input to good policymaking."

Under Republican Rep. Lamar Smith (right), the House Science Committee served as a platform for the fossil fuel industry's battle against science. Democratic Rep. Eddie Bernice Johnson, a fellow Texan, plans to steer it in a different direction if she is affirmed as its next chair. Credit: Tom Williams/CQ Roll Call via Getty Images

Under Democratic control, the House Science Committee could well become the arena for scrutiny of the Trump administration's controversial moves against science, including efforts to restrict the scientific research used by federal agencies in rulemaking and the elimination of experts from federal agency science advisory boards. One issue that could lead to hearings is industry funding of a study used to underpin the Environmental Protection Agency's decision to weaken truck pollution standards; Johnson and her colleagues on the Science Committee called for an EPA inspector general's investigation of the matter several weeks ago.

The House Energy and Commerce Committee, with a long history as a powerful oversight committee, is likely to unleash its investigators on the Trump administration's environmental and energy agencies, sniffing for evidence of waste, conflicts of interest and abuse. Rep. Frank Pallone (D-N.J.), who is in line to take over as chair of the Energy and Commerce Committee, said holding the Trump administration accountable will be part of his agenda.

"One of our main priorities would be strengthening the economy and creating more good-paying jobs by rebuilding America through investments in green energy and drinking water infrastructure," he said in a statement before the election. "We would also focus on the need to address climate change by looking at its impacts on our communities and economy, and by holding the Trump Administration accountable for dangerous policies that only make it worse."

"We also have serious concerns with how Trump's EPA has consistently sided with the special interests over people's health and the environment, and we will look to restore the environmental protections that have been gutted over the last two years," Pallone said.

Scientists and Other Candidates Talked About Climate Change

In a year that saw a record number of scientists running for Congress—more than a dozen—at least eight will be joining the House. Two are Democrats who unseated Republican incumbents in the Chicago area: Sean Casten, an engineer who spent 17 years in the energy efficiency business and has pledged to make climate change a priority, and Lauren Underwood, a nurse and public policy expert. Chrissy Houlahan, an engineer and former science teacher who blasted the Trump administration for appointing climate deniers to key regulatory positions, took Pennsylvania's recently redrawn 6th Congressional District outside of Philadelphia.

In Florida, Scott declared victory over Nelson, a three-term senator who had called Florida, with its tidal street flooding and sea level rise and damage from powerful hurricanes, "ground zero" for climate change. The Associated Press reported the race appeared to be headed to a mandatory recount.

Aliki Moncrief, executive director of Florida Conservation Voters, called the losses for Nelson and Tallahassee Mayor Andrew Gillum, who was running for governor, "pretty disappointing."

Despite the elevated climate concerns in Florida, she said, "when it came to choosing candidates, concerns about climate ... didn't overcome entrenched partisanship." The results mean cities and other local governments will have to continue to "lead the way," which will be made easier as the costs of clean energy fall.

In Iowa, where farmers have struggled with extreme weather and Trump's trade and energy policies, Democrats defeated two congressmen who denied climate science. Abby Finkenauer, a 29-year-old state legislator, unseated Republican Rep. Rod Blum. Credits: Lauren Justice for The Washington Post via Getty Images; Scott Olson/Getty Images

In Iowa, where renewable energy and the massive farm economy are top issues, Democrats unseated two Republican climate skeptics in races that drew hundreds of thousands of dollars from conservation groups.

The incendiary conservative Rep. Steve King beat back a strong challenge from Democrat J.D. Scholten, who had made climate change a campaign issue by stressing the threat it poses to the state's agriculture industry. But two other seats flipped to Democrats who had also been talking about climate change on the campaign trail.

State Rep. Abby Finkenauer defeated Republican incumbent Rod Blum, who was ensnared in an ethics investigation and labeled one of the most vulnerable members of Congress. Finkenauer, at 29, who won by nearly 5 percentage points, will become one of the youngest people to serve in the House. Businesswoman Cindy Axne also narrowly defeated Iowa Republican David Young for another House seat. Vice President Mike Pence had campaigned for Young last month, and Trump had urged Iowans to support Young at a recent rally.

Rhea Suh, president of the Natural Resources Defense Council, said the election results gave the House a mandate to hold the Trump administration accountable.

"The American people have stood up to Trump," she said. "We've rejected his reckless assault on the environment, public health and our children's future. And we've empowered the House to hold him to account for putting polluter profits first and putting the rest of us at risk. Now it's on the House to carry out the people's will."

Top image: Photo illustration based by photo by Win McNamee of Getty Images