It’s basically career suicide to spend any time at all trying to disprove anything in climate science. Who’s gonna fund you? Exxon Mobile?
So the climate scientists have carte blanche to provide data and analysis with little fear of critical pushback.
Prestigious science academies and ad hoc expert committees deliver reports that say (or imply), first, that meaningful trends can be identified, and, second, that the rates and magnitudes of temperature increase observed are ipso facto unusual or dangerous.
“To compare late 20th century warming with earlier geological warm events requires the use of local proxy data, because no global temperature statistics are available prior to the 20th century. One of the best such datasets that extends over an adequate period of time is the oxygen isotope record from the Greenland ice core already referred to (Grootes et al, 1993; Davis and Bohling, 2001). These data show a ~1500 year warming-cooling cycle of 1 - 2°C magnitude. This cyclicity is probably of solar origin (Bond et al, 2001; Singer and Avery, 2006), and the late 20th century warming period represents a peak within it (Figure 10). Consistent with this, Solanki et al (2004) have shown that the activity of the sun has been building since the end of the Little Ice Age in the late 19th century, and that over the last 60 years it has been at its strongest since the early Holocene, c. 8000 ybp. In turn, Svensmark (2007, and other papers) has identified a possible mechanism whereby solar activity affects cosmic ray influx which in turn controls the cloud formation that acts as one of the Earth’s main thermostats.
The Greenland ice core data also reveal typical rates of temperature change of up to 2.5°C/century for periods of cooling and warming of decadal to centennial time span (Figure 11).
In Greenland, then, the late 20th century warming proceeded at unalarming rates to reach a peak that was probably cooler than were the preceding Minoan, Mediaeval and Roman warm periods. And at the other pole, in Antarctica, similar ice core evidence shows that late 20th century temperature was up to 5°C cooler than temperature highs associated with geologically recent interglacial periods (Watanabe et al, 2003). Therefore, the magnitude of the late 20th century warming, and its rate of change, both fall well within known natural limits. In addition, the late 20th century warming that is widely attributed to human greenhouse emissions is of similar rate and magnitude to an earlier natural warming between 1905 and 1940; in relationship to which, it has been shown that the warmest decade of the last 1250 years in the European Alps was the 1940s rather than the 1990s (Buntgen et al, 2006).
The IPCC’s (2001, p 97) prescient diagnosis therefore remains true today:
The fact that the global mean temperature has increased since the late 19th century and that other trends have been observed does not necessarily mean that an anthropogenic effect on the climate system has been identified. Climate has always varied on all time-scales, so the observed change may be natural. A more detailed analysis is required to provide evidence of a human impact. “"
But who’s gonna dispute any of that said analysis? Basically it's the Big Labowski meme, "You're not wrong, you're just a dick," because at the end of the day, being ecologically aware, and trying to minimize human's environmental footprint is still a noble cause and will still effect our grandchildren even if the end result is only cleaner air, cleaner water, and less trash in our communities.