A new Gallup poll shows that compared to three years ago, twice as many Americans believe that global warming’s consequences are exaggerated.
And in just the last year, there has been an increase in skepticism from 41% to 48%.
The chart below shows a number of trends. Skepticism about global warming was generally low in 1997, when the polling started, before climate change was getting regular news coverage, either fact or opinion based.
In fact, the level of skepticism did not change much with the increasing coverage of climate change in the wake of An Inconvenient Truth, increasingly publicized consensus among the vast majority of climate scientists that global warming was real, human caused and potentially devastating, the Third Assessment Report from the Intergovernmental Panel on Climate Change  (IPCC) in 2001, or even the Nobel prize winning Fourth IPCC Assessment Report in 2007. So, we could assume that roughly 30% of the skeptics are not going to be persuaded by science. They have their opinion and they are sticking to it.
There is a nice little spike in skepticism just after the 2004 election, a point at which the move from climate change as a scientific issue to climate change as a partisan issue began to really take hold. But then Hurricane Katrina happened in the summer of 2005 and even some of the new skeptics began to see a connection between the voracity of the hurricane and our changing climate. Skepticism fell.
So what has happened more recently to increase the skepticism to such high levels? Not much to do with the science which continues to be conclusive. Just last week, the UK’s National Weather Service, the Met Office  asserted that there are ‘clear fingerprints’  of human caused climate change in over 100 recent studies of sea ice, rainfall and global temperature.
This concept of global temperature is key and not well understood by the lay person. Both the Colbert Report  and the Daily Show  ran segments spoofing people’s (and Fox News’s) inability to understand that just because it is cold and snowing in Washington, D.C. doesn’t mean that there aren’t record high temperatures in Australia or Southern Africa. In fact, despite a snowy winter in the northeast, NASA reports that, globally, 2009 was the second warmest year since 1880 . And despite 2008 being the coolest year of the decade due to a strong La Nina effect in the Pacific, the last decade was the warmest on record.
NASA explained it this way in a January press release:
The near-record global temperatures of 2009 occurred despite an unseasonably cool December in much of North America. High air pressures from the Arctic decreased the east-west flow of the jet stream, while increasing its tendency to blow from north to south. The result was an unusual effect that caused frigid air from the Arctic to rush into North America and warmer mid-latitude air to shift toward the north. This left North America cooler than normal, while the Arctic was warmer than normal.
“The contiguous 48 states cover only 1.5 percent of the world area, so the United States’ temperature does not affect the global temperature much,” Hansen said.
But does anyone know or care about global temperatures when they’re freezing their tail off in New Jersey? When shoveling out your driveway for the umpteenth time, it’s hard to even care that Maine and Vancouver have been snowless. For many, the data being used to assess global warming is what they can see out their own window. And the Gallup polling in March 2009 and March 2010 would reflect this method of formulating an opinion about climate change; following both of those cool winters in the U.S. skepticism increased. As Stephen Colbert would say, we may be turning into a nation of peek-a-boo-ologists.
There are a number of other factors that also seem to be driving the increasing skepticism about climate change; partisanship, money and so-called scandal.
Observe the sharp spike in skepticism following the 2008 election when passing a greenhouse gas emissions reduction bill became a major component of the Obama administration’s agenda, making it a major target of the Republican agenda. Climate change went from being a national issue that was embraced by members of both parties to a partisan issue with one side chanting “drill, baby, drill” and defining itself in opposition to anything and everything that the other side supports.
For Republicans, “the new political expediency is to be a global warming skeptic,” said Marc Morano, executive editor of the skeptic clearinghouse website ClimateDepot.com and a former aide to outspoken skeptic Sen. James M. Inhofe (R-Okla.). - Los Angeles Times 
Then there are recent errors in research and stolen emails that are easily misunderstood. Atmospheric Sciences professor Andrew Dressler of Texas A & M University explained in an Op/Ed in the Houston Chronicle last week why relying on these ‘scandals’ to formulate an opinion about the reality of climate change is foolish.
In recent months, e-mails stolen from the University of East Anglia’s Climatic Research Unit in the United Kingdom and errors in one of the Intergovernmental Panel on Climate Change’s reports have caused a flurry of questions about the validity of climate change science.
These issues have led several states, including Texas, to challenge the Environmental Protection Agency’s finding that heat-trapping gases like carbon dioxide (also known as greenhouse gases) are a threat to human health. However, Texas’ challenge to the EPA’s endangerment finding on carbon dioxide contains very little science. Texas Attorney General Greg Abbott admitted that the state did not consult any climate scientists, including the many here in the state, before putting together the challenge to the EPA. Instead, the footnotes in the document reveal that the state relied mainly on British newspaper articles to make its case.
Contrary to what one might read in newspapers, the science of climate change is strong… - Houston Chronicle 
As he goes on to explain, the climate is definitely changing, human activity definitely causes heat trapping gases and those heat trapping gases are the cause of the changing climate. It should be simple, but it is not.
Finally, and perhaps most impacting, there is the money being poured into creating a so-called debate over whether climate change is real, human caused and dangerous. Greenpeace reports  that from 1998 – 2006,. ExxonMobil put over $2.2 million into just one denier think tank. From 1998 – 2005, the company spent $16 million  with denier lobby groups and think tanks. BP spent $8 million in just 8 months in 2009 lobbying against climate legislation. The Heritage Foundation , which tried to use the 2008 La Nina cooling to cast doubts on the reality of climate change, received $50,000 from ExxonMobil that year, and another denier think tank, Atlas Economic Research, received $100,000.
As the tobacco companies can attest, pour enough money into a marketing campaign and you can get people to do just about anything. Even spend their hard earned money on a product that will kill them.
All of these factors have played a role in increasing the level of skepticism about climate change. What they haven’t done is changed the scientific conclusions that climate change is real, human caused and poses a great danger. And they haven’t solved the problem of what we are going to do about that.