1) Climate science represents a convergence of evidence

Why do so many scientists and scientific organizations accept that climate change is real, human-caused, and dangerous?

It's not because of any single line of evidence or any one prediction. Rather, says Shermer, "there is a convergence of evidence from multiple lines of inquiry — pollen, tree rings, ice cores, corals, glacial and polar ice-cap melt, sea-level rise, ecological shifts, carbon dioxide increases, the unprecedented rate of temperature increase — that all converge to a singular conclusion." Scientists call this sort of convergence of independent lines of evidence "consilience." Biologist E.O. Wilson wrote a very good book about it.

Climate denialists — indeed, most people — do not fully grasp the implications of consilience. The strength of consilience science does not issue from the validity of any one set of measurements or any one line of evidence. It's not vulnerable to wholesale refutation if anomalies are found in one data set or another. Even if individual lines of evidence are weak or uncertain, their convergence, the fact that many trails keep leading to the same place, can make consilience science strong.

And the convergence also makes consilience science fecund — it suggests and structures further research.

2) Climate "skepticism" does not
Writes Shermer:

For [climate] skeptics to overturn the consensus, they would need to find flaws with all the lines of supportive evidence and show a consistent convergence of evidence toward a different theory that explains the data. ... This they have not done.
I'm not sure the disengaged public understands this: Climate skepticism is not an alternative theory. The climate skeptic community is a hodgepodge, a farrago of theories and conspiracies that range all over the map, from sunspots to adjustments in particular temperature data sets to hoaxes by scientists greedy for grant money. There's no shared alternative framework, just a fixed certainty that the consensus must be wrong.

If the mainstream scientific consensus on anthropogenic climate change is wrong, then we'll need some other theory that makes sense of present-day changes and harmonizes with data from historical record. Climate skeptics have offered no such theory. Where climate change science is fecund, climate skepticism is moribund, merely destructive.