On Thursday, the Environmental Protection Agency (EPA) is set to repeal the legal framework that empowers it to regulate greenhouse gas emissions.

“President Trump and Secretary Lee Zeldin will officially rescind the 2009 Obama-era endangered status designation,” said White House Press Secretary Caroline Leavitt during a press briefing on Tuesday. “This marks the largest deregulatory initiative in American history, projected to save Americans $1.3 trillion from regulatory burdens.”

The EPA’s 2009 decision, known as the Endangered Findings, identifies greenhouse gases such as carbon dioxide and methane as key contributors to global warming, which poses risks to public health and welfare. This finding is crucial for establishing regulations under the Clean Air Act. It also underpins mandatory emissions reporting for fossil fuel companies, among other regulations.

If upheld against anticipated legal challenges from environmental groups, this measure could dismantle a majority of U.S. policies aimed at mitigating climate pollution.

Details of the rule that revokes this certification have not yet been released. However, in a draft rule issued in August, the EPA proposed eliminating all greenhouse gas emissions standards for vehicles. Leavitt indicated that this deregulation would lower the prices of cars, SUVs, and trucks, hinting that the final version might also reduce vehicle emissions requirements.

Additional climate regulations may also face repeal: In June, EPA Administrator Lee Zeldin proposed a rule to revoke carbon dioxide standards for power plants. The EPA is also re-evaluating other policies linked to endangerment findings, including methane regulation, a potent greenhouse gas.

In a briefing last month prior to the EPA’s announcement, Manish Bapna, President and CEO of the Natural Resources Defense Council, labeled the expected repeal as “the largest assault on federal authority to combat the climate crisis in U.S. history.”

“From the devastating floods in Texas and North Carolina to the catastrophic fires around Los Angeles and the unprecedented heat waves every summer, more individuals are experiencing the consequences of human-induced disasters,” Bapna remarked. “A ruling negating endangered studies would represent a complete denial of these incidents and the reality of climate change.”

Conversely, the Heartland Institute, a conservative think tank, commended the impending regulatory changes.

“The Obama administration’s assertion that carbon dioxide endangers human health is scientifically flawed and is pure political maneuvering,” claims the think tank’s president, James Taylor.

The endangerment study conducted during President Barack Obama’s first term is now under scrutiny, with the EPA stating that it “improperly analyzes the scientific record” and that its scientific basis is overly pessimistic and unsubstantiated.

In a preliminary draft of the rule, the EPA argued that the endangerment study amplifies the risk of heat waves, overpredicts warming trends, and overlooks the benefits of increased carbon emissions, such as enhanced plant growth. Many scientific organizations refute these claims.

The agency has also noted that court rulings since 2009, like West Virginia v. EPA, have already curtailed its ability to regulate greenhouse gases. This Supreme Court decision stated that the EPA lacks broad authority to transition energy production from coal to cleaner alternatives.

Much of the discussion surrounding the interim rule is based on a contentious report ordered by Energy Secretary Chris Wright. Recently, a judge determined that Wright and the Department of Energy violated transparency laws in creating and managing the working group involved.

It remains unclear whether the final rule will maintain the same rationale or modify its justification based on public feedback.

Scientific organizations opposing the EPA’s draft rule concentrated on a DOE report suggesting that rising carbon dioxide levels could promote a “greening” effect. The report also indicated that discernible trends in extreme weather events are lacking, complicating the attribution of such events to climate change due to various factors, including “natural climate variability and data limitations.”

The American Geophysical Union, a leading scientific association, stated: The report presented ‘inaccurate and selective’ data.

“Human actions are altering the climate more rapidly than ever, leading to severe impacts on individuals and the ecosystems we depend on,” the union added, highlighting that greenhouse gas emissions are at their highest levels in the past 800,000 years.

“Climate change is a direct catalyst for rising global temperatures, heat waves, sea level rise, ocean acidification, and is intensifying extreme weather events such as hurricanes, floods, wildfires, and droughts.”

The National Academies of Sciences, Engineering, and Medicine published their report on the endangerment findings, concluding that the findings remain accurate and have stood the test of time.

Additionally, a collective of 85 climate scientists released a report claiming that previous rebuttals to DOE reports illustrate a pervasive issue of misrepresentation, failing to meet appropriate standards for informing policy decisions.

According to Copernicus, the European Union’s climate monitoring service, last year was the third warmest on record. The last 11 years have marked the warmest period in modern recorded history.

During President Donald Trump’s administration, the EPA aggressively rolled back numerous environmental protections. Zeldin previously promised in a Wall Street Journal editorial that he was “putting a dagger into the heart of the religion of climate change.”

However, reversing the endangered status is likely to instigate a significant legal confrontation.

The Natural Resources Defense Council has vowed to battle the EPA “every step of the way.” David Doniger, an attorney with the agency, asserted that defending the rule change in court would be “impossible” given the overwhelming evidence indicating that greenhouse gas pollution is exacerbating climate change and intensifying disasters like wildfires, floods, and heat waves.