The data came in last week, and as had been expected, 2015 was measured as the hottest year ever recorded — whether you ask NASA, NOAA, the Japanese Meteorological Agency, the UK's Hadley Centre, or Berkeley Earth — beating the previous record set only last year. A few days later, a gigantic blizzard smashed the eastern seaboard from New York to D.C., setting multiple snowfall and flooding records.
The press and climate scientists gave these their typical examination, and came to the usual conclusion. The temperature record was certainly caused by humanity's release of greenhouse gases, while a decent circumstantial case can be made that the blizzard was partly caused by climate change-induced disruptions in the Atlantic Meridional Overturning Circulation.
One traditional part of this routine was missing, however: the usual chorus of climate deniers and trolls nitpicking the data and/or loudly accusing the entirety of the scientific establishment of fraud. Some were still there, but they were notably quiet, particularly compared to previous denier frenzies like the "Climategate" mess. It demonstrates that climate denial really can be subdued — but not through argument, through demonstration and sheer social trench warfare.
But first, how can one tell whether denial is really fading? It's hard to know for sure, but the circumstantial case is fairly strong. Google Trends shows a marked decline in searches for "global warming hoax," (in blue below) somewhat but only partially offset by a slight rise in "climate change hoax" (in red). Though there was a huge spike during Climategate in late 2009, both measurements combined are far below where they were before that incident:
(Courtesy Google Trends)
Anecdotally, I notice substantially fewer denier trolls attacking me online than a couple years ago, and the denier blogs seem rather halfhearted and dispirited of late. The Republican Party is still committed to doing nothing about climate change, but has mostly retreated to weird evasive slogans like "I'm not a scientist" rather than full-throated denial.
Such a development rather goes against what was becoming the conventional wisdom in communications research. Several papers over the last couple years, particularly one by Brendan Nyhan in 2014, have found that it's basically impossible to talk somebody out of believing conspiracy theories. Argue against vaccine deniers on the scientific merits, talk about the risks of disease, or even present scary pictures of kids sick with rubella or mumps, and people are unmoved — or even double down on their beliefs.
But reasoned argument, citation of authority, or sheer fright aren't the only ways you might try to convince a vaccine denier. You could, to pick an extreme example, infect them and their entire family with a vaccine-preventable illness. That would be immoral to do on purpose, but it actually happened on accident to one woman and every one of her seven children, who all got whooping cough. Result: They got their shots.
Something similar has been happening with climate change, I suspect. For years and years now deniers like George Will have been cherry-picking the year 1998 (an unusually hot year due to a powerful El Niño) as evidence that there had been no warming since then. For the statistically literate, this was obvious garbage, but now it's irredeemable trash even on its own terms, with 2015 not only breaking the previous record (which was 2014, by the way) but setting the new record by the widest margin on record. Denial needs these sorts of faux-intellectual toeholds, and is palpably harmed when they are blown to smithereens.
The general discussion around whether extreme weather events can properly be attributed to climate change has also been notably more muted than before. The usual crowd of careerists who cynically nitpick such claims is barely to be seen. And typically a blizzard is prime time for deniers to pop up and flap their gums about how winter disproves climate change, but when temperature hits the mid-40s immediately after an extreme blizzard in January, it's a hard case to make.
All this doesn't mean that denial couldn't crop back up later, of course. Likely somebody will start whining about "no warming since 2015" inside of a year or two. But this shows that denial is not irreversible once it gains momentum. Reasoned argument doesn't generally move people's beliefs. But social pressure — some combination of argument, ridicule, and counter-mobilization, buttressed by undeniable empirical reality — just might.