More than 100 world leaders have been meeting in Copenhagen for the final stretch of the biggest international global warming negotiations in history.
|Delegates, including world leaders, at the climate change conference in Copenhagen, have been locked in dispute amid boycotts and squabbling over conventions [AFP]
However, the conference has been rocked by deep divisions between rich and poor countries over emissions targets and how much financial aid to provide for developing countries dealing with global warming.
Despite the gravitas and worldwide media attention, however, the public is still stuck on a very basic question: Is global warming real; and if it is, have humans caused it?
Ideology fuels much of the popular debate - liberals say it is real, while conservatives say it is not.
But in the scientific community, the consensus is nearly unanimous. Nearly all of the world's scientists say decades of careful study show that climate change is, indeed, a fact, and that it has been driven by human activity.
The Intergovernmental Panel on Climate Change (IPCC) - a scientific body comprised of thousands of scientists from around the world - says the average temperature of the Earth's near-surface air and oceans has been increasing because of higher concentrations of greenhouse gases caused by deforestation and fossil-fuel burning.
The increase in global temperature is expected to melt glaciers and sea ice, raise sea levels, increase the intensity of storms, damage agriculture, and contribute to the extinction of many species.
"The climate is changing, it's changing unidirectionally, it's changing fast, and it's changing irreversibly," says Atiq Rahman, a prominent Bangladeshi scientist who has worked with the IPCC.
"So that is how severe the crisis is."
But the dissenters - a small yet vocal group - say such views are alarmist. They do not believe global warming is a threat and, even if it is happening, do not believe humans have caused it.
Many of the sceptics are lobbyists for oil and gas interests, or free-market economics advocates who believe any efforts to regulate greenhouse gases will be a financial disaster.
"'Global warming' is not a global crisis. It is a global scientific fraud," Lord Christopher Monckton, a business consultant and high-profile climate sceptic, told the Heartland International Conference on Climate Change in March. The Heartland Institute is a non-profit research group which promotes free-market ideas.
Many of the most prominent climate sceptics are not climatologists themselves. Steve Milloy, who runs the popular website Junk Science, has ties with the oil, tobacco and pharmaceutical industries. Craig Idso, the founder of the Center for the Study of Carbon Dioxide and Global Change in Tempe, Arizona, is a geographer partially funded by energy interests.
And Lord Monckton is a business consultant in the UK who studied classics and journalism at university.
The scientists at Real Climate, the blog written by some of the world's most prominent climatologists, have described the writings of sceptics such as Monckton as "cuckoo eggs in a nest ... only designed to look real enough to fool onlookers and crowd out the real science".
But a few of the sceptics are scientists, including the eminent physicist Freeman Dyson. He says Al Gore, the former US vice-president, and prominent climate scientist James Hansen, the head of the NASA Goddard Institute for Space Studies in New York, rely too much on computer-generated climate models and suspect science to predict global warming's havoc.
The sceptics appeared to gain momentum, at least in the media, late last month after a series of unseemly emails were stolen from the Climate Research Unit at the University of East Anglia in the UK.
Sceptics held up the emails as a smoking gun, saying the exchanges showed that top climate scientists withheld information and manipulated data. But the scientists who wrote those emails - and the colleagues who trust their work - have said they are being misrepresented for ideological reasons.
"This is a collision between science and politics, frankly," says James White, a paleo-climatologist who leads the Institute of Arctic and Alpine Research (Instaar) at the University of Colorado at Boulder.
"If there was collusion among scientists to make up something this big, it would have to go well beyond this group. It's like trying to claim we didn't go to the moon."
The scandal may have eroded the public's trust, at least in the US.
|Have scientists relied too heavily on computer simulations of weather patterns? [AFP]
A recent CNN/Opinion Research Corporation poll showed that only 45 per cent of Americans believe that human activity, such as emissions from cars and heavy industry, has caused global warming.
Globally, the economic crisis has supplanted climate change as a major problem: A recent Nielson/Oxford University survey of 27,000 Internet users in 54 countries showed that only 37 per cent were "very concerned" about global warming.
The fury over ClimateGate, as the email scandal at the Climate Research Unit was dubbed, forced director Phil Jones to step down pending an investigation. The science community insisted that the CRU data was only one piece of a rigorously researched body of evidence that essentially showed the same conclusion - that the Earth was warming. But the criticism continued and even exploded into death threats against climatologists.
"It's a sad commentary on the times we live in," said Jerry Meehl, a climatologist at the National Center for Atmospheric Research in Boulder, Colorado.
"I think there are a lot of angry, indignant people out there, and it doesn't take much to get them to react in that way to almost any issue if they think they sense a conspiracy that tweaks their almost constant sense of outrage and paranoia."
Because the climate change debate has become so politicised and polarised, the real challenge has become communicating something as complicated as the climate system to people who do not have a background in science, Meehl says.
"But when information is presented in a factual way, emphasising that 'do you believe in global warming' is the wrong question - because it's a matter of evidence, not belief - there is usually a great appreciation of a clear explanation without political spin," Meehl says.
"I always present climate change as a science issue, not a political issue."
The National Ocean and Atmospheric Administration also devoted a page on its site to explaining why the earth is warming and why humans are causing it. (http://www.ncdc.noaa.gov/indicators/)
Jim White of Instaar says today's climatologists are fighting major interests such as the oil and gas industries in much the same way physicians were fighting the tobacco lobby in the 1960s.
The evidence that nicotine caused lung diseases such as cancer was overwhelming, but the tobacco industry's strategy was to discredit scientists as "uncertain and greedy and full of junk science," White said.
"That's what climate scientists are up against today."