The Federal Advisory Committee Act imposes several ground rules for such panels, including that they meet in public, are subject to public records requests and include a representative membership.
The new working group would not be subject to any of those requirements.
While the plan is not finalised, NSC officials said they would take steps to assemble a group of researchers within the government. The group will not be tasked with scrutinising recent intelligence community assessments of climate change, according to officials familiar with the plan.
The National Security Council declined requests to comment on the matter.
Officials said that deputy national security adviser Charles Kupperman had said at the meeting that US President Donald Trump was upset that his Administration in November had issued the National Climate Assessment, which must be published regularly under federal law.
Kupperman added that congressional Democrats had seized upon the report, which is the product of more than a dozen agencies, to bolster their case for cutting carbon emissions as part of their Green New Deal.
Attendees at the session, which included acting interior secretary David Bernhardt and senior officials from throughout the government, debated how best to establish a group of researchers that could scrutinise recent federal climate reports.
More than one participant suggested that they might face a challenge establishing an independent outside panel that would question central findings of the National Climate Assessment and other landmark federal reports, said one official familiar with the discussion.
Happer, who headed an advocacy group called the CO2 Coalition before joining the Administration, has challenged the scientific consensus on climate change inside and outside of government.
Public records show the coalition, which describes its mission as informing policymakers and the public of the "important contribution made by carbon dioxide to our lives and the economy," has received money from far-right organisations and donors with fossil fuel interests.
In 2017, according to federal tax filings obtained by the Climate Investigations Centre, the group received US$170,000 from the Mercer Family Foundation and more than US$33,000 from the Charles Koch Institute.
One senior Administration official said the President was looking for "a mixture of opinions" and disputed the National Climate Assessment, a massive interagency report, in November that described intensifying climate change as a threat to the US.
"The President wants people to be able to decide for themselves," the aide said.
Several scientists, however, said the federal government's recent findings on climate change had received intense scrutiny from other researchers in the field before they became public.
Christopher Field, director of the Stanford Woods Institute who served on the National Academy of Sciences review panel for the scientific report that formed the basis of last year's climate assessment, said the committee met several times "to do a careful, page by page evaluation by the entire report."
"The whole review process is confrontational from the very get-go, but it's based in scientific credibility, in a traceable chain of evidence through publications," said Field, an earth system science and biology professor.
Trump officials had weighed the idea of conducting a "red team-blue team" exercise on climate change, an idea espoused by Scott Pruitt, who was then the chief of the Environmental Protection Agency, during the early months of the Administration. White House aides, including then-chief of staff John Kelly, blocked the idea, and at one point discussed whether to "ignore" the climate research being conducted by federal scientists.
Government researchers in a range of disciplines have identified climate change as a serious threat for the past two decades, under Republican and Democratic administrations.
In 2003, the Pentagon commissioned a report to examine how an abrupt change in climate would affect America's defence capabilities: Its authors concluded that it "should be elevated beyond a scientific debate to a US national security concern".
Last year, a military-funded study warned that sea level rise and other climate impacts could make more than a thousand low-lying islands in the Pacific Ocean "uninhabitable" by midcentury.
Just last month, the national intelligence director delivered a worldwide threat assessment that "climate hazards" including extreme weather, wildfires, droughts and acidifying oceans are worsening, "threatening infrastructure, health, and water and food security."
Judith Curry, a former Georgia Tech climate scientist whom Republicans have sought to testify on climate change because she often highlights the uncertainties that remain, said in an email that she backed the idea of an independent assessment of government climate reports as long as the participants reflected a range of perspectives and are not activists on either side of the debate.
But retired Rear Admiral David Titley, who served as oceanographer of the Navy and chief operating officer at the National Oceanic and Atmospheric Administration, said the new initiative could imperil national security by clouding "truthful assessments of the risks stemming from a changing climate".
He said: "I never thought I would live to see the day in the US where our own White House is attacking the very science agencies that can help the President understand and manage the climate risks to security of today and tomorrow."
Titley, who sits on the advisory board of the Centre for Climate and Security, a nonpartisan group focused on climate-related risks, added: "Such attacks are un-American."
Several experts questioned whether the White House's plan could undermine decades' worth of science pointing to a warming planet.
One federal climate scientist, who asked for anonymity to avoid possible retaliation, said agency researchers had pursued and published their research in the past two years without meaningful resistance.
Camilo Mora, a geographer and environmental professor at the University of Hawaii, said in an email that a single task force could not alter the findings of scientists across the globe.
"When it comes down to climate change, we are talking about thousands of independent papers, from everywhere, finding exactly the same thing: that the climate is changing, that we are doing it and that most often than not, the impacts are pretty bad," Mora said.
