NEW YORK -- These are tough times to be a skeptic about global warming.
Two years ago, an international United Nations panel concluded with near certainty that human activity plays a role in the planet's rising temperatures. And now, the new U.S. administration has vowed to spearhead international efforts to reduce greenhouse-gas emissions.
But more than 600 people gathered in New York City this week at the International Conference on Climate Change say they are up to the challenge.
Joseph Bast, president of the Heartland Institute, which organized the conference, argues that the extent and causes of global warming are far from proven. The goal of the gathering, he tells RFE/RL, is to provide a forum to challenge people like former U.S. Vice President Al Gore with a healthy dose of skepticism.
"We think we have a great story to tell that more and more prominent scientists are coming out saying global warming is not a crisis, that the question of what causes it and how extensive it's going to be are wide open in the scientific community," Bast said.
"And that message is not effectively reaching enough people," he adds. "So, by holding an event like this we hope that we can get the attention of more people and eventually have an effect on public policy."
There is a special urgency at this year's gathering. Governments around the world are working on plans to further tax greenhouse-gas emissions, while U.S. President Barack Obama has proposed to roll greenhouse-gas emissions back to their 1990s levels. 'Vehicle For Government Intervention'
But many conference participants say those efforts are misguided. Those who acknowledge global warming is happening say the Earth is going through a natural, periodic cycle, with industrial activity contributing very little to the process.
By the ideology which uses or misuses it -- it has gradually turned into the most efficient vehicle for advocating extensive government intervention into all fields of life and for suppressing human freedom and economic prosperity.
The Heartland Institute bills itself as a free-market think tank. Until 2006, the Chicago-based group received money from oil giant Exxon Mobil, although that has now stopped. The institute has not shied away from taking up other controversial causes. For example, it also seeks to decrease high taxes on cigarettes and curbs on smokers.
The keynote speech was delivered by Czech President Vaclav Klaus, who has become well-known for his opinions on the issue. Speaking to students at Columbia University a day later, he reaffirmed his vocal opposition to the concept that global warming is man-made.
"The problem is not global warming," Klaus said. "By the ideology which uses or misuses it -- it has gradually turned into the most efficient vehicle for advocating extensive government intervention into all fields of life and for suppressing human freedom and economic prosperity."'An Overstated Truth'?
Al Gore has won worldwide acclaim for his environmental activities and especially for raising awareness about climate change with the film "An Inconvenient Truth." In 2007 he won the Nobel Peace Prize along with the UN panel for his climate-change-awareness activities.
Bast of the Heartland Institute argues that although Gore is the most prominent spokesman for the man-made climate-change cause, his arguments lie "way outside the mainstream scientific community."
Czech President Vaclav Klaus is a well-known skeptic of climate change.
"Very few qualified scientists would say that Al Gore and what he says in his film is accurate. He grossly overstates the possibility of sea-level rise for example," Bast says.
"There's simply no peer-reviewed scientific literature that would justify predictions of a 20-foot [6-meter] rise in sea level, and yet that's very prominent in his film."
Dr. Howard MacCabee, an oncologist in California and a conference participant, says that even very liberal estimates show that industrial pollution by itself has negligible or little effect on global warming.
"Human contribution is small, probably not zero, and it's small compared to these other factors which we cannot change. We cannot change the sun, we cannot change [the sun's] multidecadal oscillations, we can't change ocean currents, we can't stop El Nino," MacCabee says.
"El Nino was the biggest spike on the temperature for the past 40 years. That was in 1998 and the hottest year in our recent history was the 1998, the year of El Nino, which has nothing to do with CO2 [carbon dioxide]," he adds.
For now, the conference participants seem to be losing the argument.
A recent opinion poll in the United States showed that 58 percent of respondents believe climate change is at least partly caused by humans. But another poll, by the Pew Research Center, indicates that in these times of economic turmoil, addressing climate change is not a top priority for many Americans.