A number of scientists and members of think tanks are rejecting the popular consensus that humans are causing global warming and that carbon gas emissions pose a mounting threat to environmental stability.

Today, climatologists, economists, and free market advocates will gather in Time Square’s Marriott Marquis Hotel for the final session of a three-day conference challenging what its sponsor, the Heartland Institute, calls the “public hysteria and alarmism about man-made” global warming.

“We have no power to affect global climate change, which will take us in whatever direction it may take us,” a former business consultant, Christopher Monckton, said yesterday at the International Conference on Climate Change.

His remarks came shortly after a consortium of scientists released a report rebutting a U.N. panel’s recent assertions that carbon gas emissions are contributing to the earth’s current warming trend.

Far from being a product of human activity, this warming pattern is part of the climate’s natural ebb and flow, the report’s authors contend.

In their report, “Nature, Not Human Activity, Rules the Climate,” a group of American university professors also argues that computer modeling technology cannot accurately predict changes in the climate system.

They also write that popular anti-global-warming campaigns have become “unnecessary, costly, and disruptive for energy security,” as, in their opinion, carbon gas emissions pose a minimal threat to the climate.

Such assertions conflict with those of the U.N. Intergovernmental Panel on Climate Change, which has concluded that so-called greenhouse emissions are causing a rise in global temperatures and sea levels.

The panel’s conclusions became popularized in Vice President Gore’s 2006 documentary “An Inconvenient Truth,” which was cited in the Norwegian Nobel Committee’s 2007 decision to award him the Peace Prize.

At yesterday’s conference, scientists derided Mr. Gore’s film as a misleading work of fear-mongering “propaganda.”

“What is being exploited in these doomsday scenarios” about climate change “is the ignorance of science in the general public,” a former University of Winnipeg professor, Timothy Ball, said.

“It’s very appropriate that it got an Oscar from the land of make-believe.”

A spokeswoman for Mr. Gore, Kalee Kreider, dismissed those arguments as unfounded. “These groups try to obscure the scientific consensus that global warming is real,” she said in a statement yesterday.

“There will always be deniers — there are still people who don’t believe that we landed on the moon — but they really are on the fringe.”

The president of the Czech Republic, Vaclav Klaus, will be the keynote speaker this morning at the Heartland Institute’s conference.