The media promoted alarmism, and discredited skeptics as being in the pay of big oil – while giving a free pass to Al Gore (a/k/a The Goracle), who made a movie based on an obvious lie then made millions selling carbon offsets.
Brit journalist Christopher Booker makes the claim that 2008 is the year “man-made global warming was disproved”. His three reasons are:
First, all over the world, temperatures have been dropping in a way wholly unpredicted by all those computer models which have been used as the main drivers of the scare.
Secondly, 2008 was the year when any pretence that there was a “scientific consensus” in favour of man-made global warming collapsed.
Thirdly, as banks collapsed and the global economy plunged into its worst recession for decades, harsh reality at last began to break in on those self-deluding dreams which have for so long possessed almost every politician in the western world.
While a good read Christopher Booker only hits around the edges of the AGW death sentence.
Australian scientist, and consultant to the Australian Greenhouse Office, David Evans makes a better more complete case:
From 1975 to 2001 the global temperature trended up. How do you empirically determine the cause of this global warming? It turns out we can learn a lot simply by observing where the warming occurred: each possible cause of global warming heats the atmosphere differently, heating some parts before others. The pattern of warming is the cause’s “signature”.
The signature of an increased greenhouse effect consists of two features: a hotspot about 10 km up in the atmosphere over the tropics, and a combination of broad stratospheric cooling and broad tropospheric warming. The signature of ozone depletion consists just of the second feature. These signatures are theoretically derived by the Intergovernmental Panel on Climate Change (IPCC), and are integral to our understanding of how the atmosphere works. 
We have been observing temperatures in the atmosphere for decades using radiosondes – weather balloons with thermometers that radio back the temperature as the balloon ascends through the atmosphere. The radiosonde measurements for 1979-1999 show broad stratospheric cooling and broad tropospheric warming, but they show no tropical hotspot. Not even a small one. 
Empirically, we therefore know that an increased greenhouse effect was not a significant cause of the recent global warming. (Either that or the signatures from the IPCC are wrong, so its climate models and predictions are rubbish anyway.)
Human carbon emissions were occurring at the time but the greenhouse effect did not increase. Therefore human carbon emissions did not increase the greenhouse effect, and did not cause global warming. So AGW is wrong, and carbon is innocent. Suspect exonerated – wrong signature.
Even the most simple-minded should comprehend that picture.
If the signature for the greenhouse effect includes X,Y and Z and only X and Z are present, whatever is going on isn’t the greenhouse effect.
Evans documents the machinations the warmists go through to ignore this fact, but there it is.
Evens, to my great amusement, takes The Goracle to task as well claiming he knew the new data (produced by new technology) about ice core samples and released in 2003 didn’t support his theory. So he used the old data instead.
To everyone but the enviro-whackos, that’s called a bald-faced lie.
Evans provides a timeline to demonstrate how the AGW myth gained favor with the media and general public:
Governments have spent over $50 billion on climate research since 1990, and we have not found any actual evidence for AGW. 
So if there is no evidence to support AGW, and the missing hotspot shows that AGW is wrong, why does most of the world still believe in AGW?
Part of the answer is that science changed direction after a large constituency of vested interests had invested in AGW. The old ice core data provided support from 1985, the IPCC was established by the UN in 1988 to look into human changes to climate, and the Kyoto Protocol was negotiated in 1997 to limit carbon emissions. By 1999 the western political class were doing something, the western media were rallying behind “saving the planet”, and scientists were being paid by governments to research the effects of human-caused global warming.
But then the evidence took science off in a different direction: the new ice core data in 2003, the missing hotspot in 2007, and the global temperature has stopped trending up since 2001 . Governments, the media, and many scientists did not notice.
The remainder of the answer for the current belief in AGW is darker and more political. An offbeat theory in the 1970s, AGW was adopted by a group of about 45 atmospheric modelers and physicists. That group dominated climate science journals, peer reviewed each others papers, and hindered competing ideas by underhand methods . AGW gained political support from proponents of nuclear power, and vice-president Gore appointed AGW supporters to science positions in the USA.
Damning charges to be sure, but believable to the sane among us.
The problem was exacerbated by a second one, government funding of research:
AGW grabbed control of climate funding in key western countries. Lack of diversity in science funding has been a major problem since government took over funding science in WWII. Science is like a courtroom – protagonists put forward their best cases, and out of the argument some truth emerges. But if only one side is funded and heard, then truth tends not to emerge. This happened in climate science, which is almost completely government funded and has been dominated by AGW for two decades. Skeptics are mainly scientists who are retired or who have moved on to other areas – their funding no longer depends on allegiance to AGW. The alarmists are full time, well funded, and hog the megaphone.
Evans then delves into the evidence presented as “proof” by AGW supporters and why it fails the test. However, near the end, he talks about the real problem we face.
Among non-scientists, AGW appeals strongly to two groups. Those who support big government love the idea of carbon regulations – if you control carbon emissions then you control most human activity. And those who like to feel morally superior to the bulk of their fellow citizens by virtue of a belief (the “warm inner glow” and moral vanity of the politically correct) are firmly attached to AGW. These groups are politically adept, are planning to spend your money and tell you how to eat, travel and how to live, and they are strenuously avoiding the evidence.
Too bad science has become all about the money on both sides. I guess the belief I used to have in the scientific debate was based on a myth.
It appears that science is just a tool and where it isn’t, you can’t distinguish it from the balderdash.
Al Gore, a leader of the scientific method? How low have we stooped?