Why do people believe these conspiring men? Because it happens to fit their pre-existing notions or opinions on climate, economy, religion, or plays to their benefit in terms of vested interest (e.g., oil industry).
The bottom line is that the scientific community has near unanimous consensus on the topic of climate change. By the way, what proportion of scientists would it take to constitute a consensus? 50.1%, 60%. 75%, 80%, 90%, 95%, 98%, 99%, 100%?
I think that we can all agree that reaching a 100% consensus on any scientific theory is nigh unto unattainable, but was exactly what was discovered in a study carried out in 2004, and consensus has continued to strengthen since then.
In 2004, a study by the well-resepcted UC San Diego sociologist Naomi Oreskes was published Science, America's most prestigious scientific journal (http://leisureguy.wordpress.com/2007/09/04/the-scientific-consensus-on-global-warming/). Results described in that study showed that NONE of the 982 peer-reviewed scientific papers on the topic of climate change published between 1993 and 2003 disputed the conclusion of anthropogenic climate change.
Other studies have claimed to show disputations and lack of consensus among scientists regarding anthropogenic climate change. For example, a paper titled "Scientific Consensus on Global Warming" was published in the latter 2000s http://ruby.fgcu.edu/courses/twimberley/EnviroPol/ScientificConsensusOnGlobalWarming.pdf.
Be advised that the formatting and layout of these kinds of papers are intended to make them appear to be credible sources of information, but they are not comparable to peer-reviewed publications in professional scientific journals.
Back to the Heartland Institute paper...it reported moderate agreement on some topics, but significant disagreement on others. There are, however, several points of concern related to this report and others like it. The most important concern is that this report cannot be considered verifiable scientific information since it was never subjected to peer-review and was not published in a reputable scientific journal. Another note of concern is the source of the paper itself. It is a product of "The Heartland Institute". Investigative research into public records shows that this institute and others like it are engaged in carrying out an active campaign to cloud the public's perception of well-documented scientific conclusions regarding climate change. If you have questions about this I strongly recommend that you take a look at the book "Merchants of Doubt" by Naomi Oreskes (http://www.merchantsofdoubt.org/)
You can also read more about the oil-backed Heartland Institute at this site: http://www.desmogblog.com/heartland-institute.
Getting back to the original point of the posting. There is clearly near unanimous consensus among climate scientists (98%+) that climate change is happening and more than 90% confident (IPCC report, 2007) that the current trend of global warming is being driven mainly by anthropogenic forcing factors, including greenhouse gas emissions and land-use changes, among other activities.
So what does scientific lack of consensus on verifiable scientific observations on this topic look like? It looks like this:
(Figure courtesy of NASA http://earthobservatory.nasa.gov/IOTD/view.php?id=80167&src=share#.UQK6EDpBexI.facebook)
Every year, groups of climatologists working independently in the USA, Great Britain, Japan, and other locations around the world, collect temperature data and generate average annual observed temperatures. They can then plot their data onto one graph, as shown above, and see where differences and variations among their results are. If there is any lack of consensus it is that some data show slightly warmer temperatures some years, while others show slightly cooler ones, but within a range of acceptable statistical variability, all the data produce the same long-term trends. In other words - consensus.
Similar work is done by climatologists investigating causes (also referred to as climate forcing factors), and they also nearly universally conclude that without human-produced effects, we would not currently be experiencing a warming trend. Instead we would be experiencing a gradual cooling trend.
So whenever you hear someone parroting some out of date or completely unsupportable fallacy that there is no scientific consensus on anthropogenic climate change, ask them about their source of information. It will inevitably originate in some non-scientific think tank or media outlet that clearly has an agenda that benefits if people do not understand that there is scientific consensus on climate change and that we had better get busy doing something about mitigating the effects of climate change.
That's all for today. Cheers!