Carolyn Kaster/ASSOCIATED PRESS A tree art installation made up of individual trees and hydrangeas is arranged in front of the U.S. Capitol on April 22, 2018, to celebrate Earth Day.

“Today we turn the page on this committee from climate change denial to climate action,” he said.

In an opening statement, Rep. Raúl Grijalva (D-Ariz.), the committee chairman, called climate change the “most urgent and pressing challenges of our time.”

The House Committee on Natural Resources kicked off a full month of climate-related discussions with a hearing Wednesday examining how climate change is affecting communities around the country. (Compare that to a hearing the Republican-led committee held in July to assess “ innovative and alternative uses of coal .”)

The playing field is now different, with Democrats having won back control of the U.S. House in November. And on Wednesday, climate change was front and center on Capitol Hill.

That hearing was part of a yearslong, GOP-led effort to downplay, dismiss and turn a blind eye to the threat the planet now faces. Republicans in the U.S. are one of the only major parties in the developed world that challenge the scientific consensus on climate change. During the four years after 2014 that the GOP controlled both chambers of Congress, Democrats found themselves largely handcuffed, unable to move the needle on climate policy.

“I sincerely hope that someday soon, the committee on science will cease lecturing and harassing scientists and instead return to listening and supporting them,” she said.

In her opening statement that day, Rep. Eddie Bernice Johnson of Texas, then the ranking Democrat on the committee, said theories floated by her colleagues on the right had become “punchlines on late-night television.”

Smith, one of Washington’s most vocal deniers of climate science, stacked the witness panel with prominent climate skeptics. Over the course of two hours, he challenged the credibility of Science magazine, one of the world’s most respected science publications, and accused climate scientists ― as he often did ― of manipulating data to push personal agendas.

In March 2017, then-Rep. Lamar Smith (R-Texas) convened a hearing of the House Committee on Science, Space and Technology to “examine the scientific method and process as it relates to climate change .” What transpired wasn’t a thoughtful discussion about how to tackle the urgent, irrefutable crisis, but a drawn-out hearing questioning whether humans are even the primary cause.

No more climate denialism. No more evasions. @HouseDemocrats are in charge. Led by @RepRaulGrijalva , the Natural Resources Committee will hold the first Congressional hearings on climate change in a decade starting on Wednesday, Feb 6th. It's time to #ActOnClimate . pic.twitter.com/L39R1W0RQ9

Simultaneously, a subcommittee of the Energy and Commerce Committee held a hearing on the environmental and economic effects of global climate change. It was the committee’s first hearing on climate in six years.

Rep. Paul Tonko (D-N.Y.), chairman of the Subcommittee on Environment and Climate Change, compared the climate fight to the space race

“There’s no question we have reached this generation’s Sputnik moment,” he said.

As the committees met, NASA and the National Oceanic and Atmospheric Administration released their annual global temperature analysis, which found that 2018 was the fourth-hottest year in 139 years of record-keeping.

Democrats on the Science, Space and Technology Committee, which is now chaired by Johnson, will continue pushing the party’s climate agenda next week when it hosts a hearing on the current state of climate science.

Kate Marvel, a climate scientist at Columbia University and NASA’s Goddard Institute for Space Studies, said it is long overdue that the climate crisis receives the attention it deserves in Washington, D.C.

“These hearings should have basically taken place before I was born,” she said. “Given that they didn’t, I think the second best time for them to happen is now.”

Marvel added that she finds it “deeply sad” it took Democrats flipping the House to make this happen.

“Political differences aside, we all live on this planet,” she said. “We are all going to be impacted by climate change, if we haven’t already.”

In some Democratic circles, the conversation has already shifted far beyond grappling with the scientific realities of climate change. Late last year, a new cadre of left-wing Democrats, spurred on by protests, began championing a so-called Green New Deal aimed at eradicating poverty with a massive federal stimulus plan to dramatically scale back fossil fuel use and rapidly deploy clean energy infrastructure over the next decade.

Rep. Alexandria Ocasio-Cortez (D-N.Y.) and Sen. Ed Markey (D-Mass.) are expected to unveil a Green New Deal resolution later this week that would set guidelines for legislation to get the United States to 100 percent carbon-free electricity.

Katharine Hayhoe, director of the Climate Science Center at Texas Tech University, told HuffPost she is encouraged to see that upcoming hearings will dive into, among other things, the federal government’s National Climate Assessment. Hayhoe is a co-author of that report, which was issued late last year by 13 federal agencies. It concluded the United States has already warmed on average 1.8 degrees Fahrenheit over the past century, and without drastic cuts in greenhouse gas emissions, it will warm at least 3 more degrees ― and perhaps as much as 9 degrees or more ― by 2100.

“The whole purpose of that federal document is to inform sound decision-making,” Hayhoe said.

That assessment followed a dire United Nations report warning world governments that they must cut global emissions in half over the next 12 years to avoid warming of 2.3 degrees Fahrenheit, beyond which climate change is forecast to cause a cataclysmic $54 trillion in damages.

It is yet to be seen if the slew of hearings will surface details about future climate legislation.

“We need to move quickly into conversations about solutions,” said Greg Carlock, the researcher at the think tank Data for Progress who authored the first major blueprint for a Green New Deal back in September. “I would hope these hearings move very quickly into the solutions phase.”

North Carolina Gov. Roy Cooper (D) and Massachusetts Gov. Charlie Baker (R) were among the witnesses to testify at the House Natural Resources Committee’s hearing. Both said the science is clear on climate change and that their states are already feeling the effects. And they voiced support for federal legislation to promote cuts in greenhouse gas emissions.

“We believe it’s essential for the federal government to create a target with respect to emission reductions that can vary by state or region,” Baker said. “In our state’s experience, setting an aggressive target for reducing greenhouse gas emissions provides the foundation for clean energy policy, sends a clear message to industry and enables long-range planning.”

In the face of sobering climate forecasts, President Donald Trump and his team have worked to boost domestic fossil-fuel production, rolled back environmental regulations and dismissed warnings that the planet is barreling toward catastrophic climate change. Trump made no mention of climate change in Tuesday’s State of the Union address but declared that his administration “unleashed a revolution in American energy.”

“The United States is now the No. 1 producer of oil and natural gas anywhere in the world,” he said to applause. “And now, for the first time in 65 years, we are a net exporter of energy.”

This article has been updated with comments from Wednesday’s hearings.