First, it was the debunking of the Mann “hockey stick” graph, showing clear evidence the global climate was getting warmer. Then, once the data sets and proxies were examined, the 'evidence' of such warming evaporated, shown to be selective deletion of data and proxies that, if included, would have shown little, if any warming.
Next, solar physicists and paleoclimatologists showed a direct correlation between sunspot cycles and changes in global temperatures. (We must remember, though, that correlation does not imply causality. Instead, it merely means there's some kind of connection between the two.)
Then, claims that 1998 was the warmest year on record turned out to be erroneous. Instead, the warmest year was way back in 1934. And 1998 was instead a turning point, where global temperatures started falling.
And then, Al Gore's prediction that the arctic ice would be gone in less than 5 years has been turned on its head because satellite photos and ground observations show the arctic ice is growing, as are glaciers that have, until recently, been shrinking.
Now there's yet another slap in the face of the AGW faithful, one they will have a tough time ignoring:
Pre-industrial CO2 levels were about the same level as they are today. Not lower. Not higher. But the same.
By now you must be asking yourself “How can that be? They said the CO2 levels were higher today than anytime in recorder history!”
The answer? They lied.
It hasn't necessarily a pre-meditated act, but some of the collected data was ignored or factored out as “noise” even though it was anything but. This skews the results to achieve a preconceived idea of what the data should show.
How many failed predictions, discredited assumptions and evidence of incorrect data are required before an idea loses credibility?
Most people don’t know that thousands of direct measures of atmospheric CO2 were made beginning in 1812. Scientists took the readings with calibrated instruments and precise measurements as the work of Ernst-Georg Beck has thoroughly documented. Guy Stewart Callendar was an earlier visitor to these records. He rejected most of the records including 69% of the 19th century records and only selected certain records that established the pre-industrial level as 280 ppm.
[Looking at graph in the article] [i]t is clear how only low readings were chosen. Also notice how the slope and trend is changed compared to the entire record.
In other words, only the data supporting the hypothesis that CO2 levels were lower in the past was included, meaning data was selected to fit the hypothesis rather than the other way around.
According to acceptable scientific method, one is supposed to collect data through observation and experimentation, and then generate a hypothesis based upon those observations and data. Then one tests the hypothesis by making further observations and design experimental studies to test the hypothesis. If the observations and tests do not match with the hypothesis, then it is time to go over the observations and data again, then modify the hypothesis, then retest the hypothesis. This is done until the hypothesis matches the observed phenomenon. The testing and results should also be reproducible by others. But when it comes to anthropogenic global warming, far too many proponents appear to be forcing the data to match the hypothesis in order to prove that they are right and everyone else is wrong. In many cases results are not reproducible by others, meaning either the data is suspect or the the hypothesis put forward is erroneous, or worse, fraudulent.
Regardless, somehow we're supposed to take action and spend our money based upon suspiciously derived theories with little or no basis in fact? I don't think so.