1. Intimidation of climate researchers. IPCC leading scientist Michael Mann has been subjected to more of this than most. As author of the 1998 paper which showed the "Hockey Stick" graph of global surface temperatures for the past 1000 years - a graph made famous in Al Gore's "An Inconvenient Truth" - professor Mann has been determined by the denialists as perhaps the most important single person to discredit in the eyes of the public. But he's only one among a number of climate scientists who receive death threats, threats to their families, and other intimidations, as detailed in this article from Physics Today. When billions in corporate profits are at stake, how far will they go? The tactics are "chilling", in the words of professor B. Santer. I myself have been threatened, for exposing denialism I have personally witnessed. This kind of behavior is a disgrace to any civilized people that purport to value honesty.
2. Deluging climate researchers with "Freedom of Information" demands for vast quantities of documents and emails. The Freedom of Information Act was created as a means for citizens to demand openness from their government. It was not intended as a harrassment tool to be used on good scientists. Scientists already provide in their published papers the description of their methods, calculations, assumptions, background science, and reasoning towards their conclusions. They must - or their paper would not make it past journal referees. Incredibly, such people as ex-coal CEO Steve McIntyre of climateaudit.org who has led this kind of intimidation, and yet when pressed on what he will do with it, admits that he's not qualified to pass judgement on the information itself (!). How can they get away with this? - the laws, in many jurisdictions, (such as Texas) make this easy, so that "fishing expeditions" can be undertaken with impunity, even when there is no search warrant, no evidence whatsoever of wrong-doing. Why would these FOI demands be made? Forcing scientists to assemble the documents takes large amounts of time away from their research, delaying policy change decisions which may result from that research. And, of course, motivating the more timid to perhaps halt further research which may make them a target.
3. Claiming the "science isn't settled". The denialists, of course, arrogate to themselves the decision on what is the definition of "settled". This provides an unlimited time period for further quarterly profits. The truth is - the science has been "settled" - in that humans have been convicted as the primary culprit in global warming (indeed, the only culprit) for ~25+ years now. That is quite long enough, together with the prospects of devastating long term consequences for civilization, to have motivated global priorities to reverse CO2 emissions. They take advantage of the layman's ignorance of science to imply that because studies are still being done and that important processes are still poorly modelled and understood, that we shouldn't "rush" to any policy decisions. The point is this: the answer on the fundamental question - is anthropogenic CO2 the major cause of global warming and ocean acidification? - IS settled, the answer is yes!. As long as better numerical predictions and more refined climate modelling can be accomplished, there will always be a proper place for more scientific studies. Science is never going to be "done". It's not like building a bridge, which is "done" at some point. Related: "Research shows that laypeople and the (popular) media tend to view all scientific viewpoints as equally valid and, therefore, give too much credence to the minority claims, even if the actual weight of evidence is heavily against them. As a result, they may frame global warming as scientifically controversial, when it is only politically controversial" (from Physics Today). The late Stanford climatologist and IPCC key contributor Dr. Stephen Schneider pointed out (32 minutes into this lecture) that he repeatedly told the media that the IPCC's conclusion that global warming was human-caused was not at all based on the "hockey stick", but instead on the many "fingerprints" (observational patterns in global warming which can only be produced by man-made greenhouse gases), and not once would the media actually print this fact.
4. Claiming it may take a number of papers back and forth before we know the truth, so it's premature to indict humans in climate change. While that can indeed be true in many situations in science, here this rationalization gives a blank check for further foot-dragging, while simultaneously allowing the denialist to posture as the true believers in healthy skepticism and being fair to "other views". Since one may always claim that the climate "skeptics" side probably have another paper in the future which will finally refute the climate "alarmists" (even when there is no evidence for such papers) this excuse is good for unlimited delay and denial. I've had this excuse laid on me - 20 years after conviction on human-caused climate change was strong enough to rightfully insist on strong changes to human civilizations' "business as usual". What it shows is that the people making this claim have not read the journal science , have refused to look at the published point-by-point indictments showing how devastating are the flaws and junk science contained in the denialist writings. Or worse - they have an agenda to promote.
5. Most insufferable of all, for me personally, is seeing junk science and red herring "science" offered up to students while refusing to acknowledge the message - the message - contained in the wording, the tone, the juxtaposition of irrelevant and misleading points, in their delivery.... The message is delivered implicitly, leaving a backdoor of plausible deniability while still being very intent on delivering the message. That message is - you can't trust those climate scientists; they hide data, they claim it's our fault when we don't KNOW that... oh those unscrupulous climate scientists and their ulterior motives! All the while refusing to read the actual journal papers, refusing to read the actual science, giving carte-blanche credibility, with zero fact checking, to denialist misrepresentations. Giving carte-blanche credibility to "climategate" (2,3), to the urban heat island myth, to the "Greenland may be GAINING ice" myth, to the temperature leads CO2 myth, to the medieval warming myth, etc., and worse. I've seen this personally, delivered with all the moral posturing of being an unbiased paragon of honest scientific skepticism and "climate expertise", while being anything but. Is it any wonder why such a growing number of non-science students have a vague cynicism towards science - something rare when I was a student decades ago?
6. When shown you are wrong - Ignore it. Pretend it never happened. Move on to the next denial, the next point of attack. Never give good science and good scientists their due. When honesty is the foremost value to be honored, when "the truth above all else" is the #1 priority, inside a persons psyche - the honorable thing to do is to admit when you've wronged scientists, and when you have been wrong in your claims and your behavior. Openly, candidly, with a full apology to those you've hurt. Have we seen this among climate denialists? No. They simply pretend that the direct correspondence, the research, the papers debunking their claims... all of it, never happened. They put on blinders to their past and continue looking for more opportunities to engage in the tactics described here. An example was an attempt to re-ignite the "climategate" affair (and its debunking) just before the 2011 Durban, South Africa conference to reach accords on how to handle climate change (which pretty much ended in failure, just like Copenhagen 2 years earlier). That's just one example. I've seen it everywhere. I regard it as one of the defining characteristics of climate denialism.
7. If you can't find enough supporters for your pro-oil rally - rent them! Amazing but true, as homeless people were rounded up and exploited for low cost, and bussed to join a pro-fracking rally. Not the first time this has happened.
8. Continually resurrect "Climate Zombies" - climate denial claims which have been thoroughly debunked, but still keep appearing in blogs, op/ed's, re-tweets, and in front of Congress. This is the hallmark of denialism vs honest skepticism. Denialists never acknowledge the debunkings. They judge it's safe to do so, because the vast majority of people will never go to the places the debunkings have been shown. Especially those buried in wonky intimidating journal papers. And, that judgement has pretty much been an effective one, judging by the frequency that I and others continually get re-confronted with these. I've given up wasting my time on re-debunking - I mostly just link anyone interested to the best sites for these debunkings. Here, and here most concisely. I do update these debunkings as new evidence is published.
9. Lie, lie, lie. This tactic happens everywhere. If you dress them up in print with proper fonts, and dress up the liars with proper attire and decorum on camera, the gullible will take it at face value. Or at the very least, give it equal credibility, thereby advancing the football halfway to the goal of accepting the Lies, with no real work necessary. A good example is the "32,000 scientists have signed a petition repudiating the existence of human-caused global warming" lie. One of the claimed signers of this petition - is me! Yes, I'm on their list. No, of course I didn't sign it. Probably name-harvesting of scientists from the web, is my guess. More on this particular outright lie here.