Excerpts from 2015 essay Global Warming and Irrelevance of Science by Prof. Richard Lindzen.
In many fields, governments have a monopoly on the support of scientific research….
…, the powers that be invent the narrative independently of the views of even cooperating scientists. It is, in this sense, that the science becomes irrelevant. This was certainly the case in the first half of the twentieth century, where we just have to look at Lysenkoism  in the former Soviet Union, Social Darwinism, and Eugenics throughout the western world , as well as, in the 1960s, the unfounded demonization of DDT . Each phenomenon led to millions of deaths. And, in each case, the scientific community was essentially paralyzed, if not actually complicit. …
The implausibility or even outright silliness whereby global warming became global warming catastrophism (sometimes referred to as CAGW, catastrophic anthropogenic global warming) is so extensive that one hardly knows where to begin. …
The current issue of global warming/climate change is extreme in terms of the number of special interests that opportunistically have strong motivations for believing in the claims of catastrophe despite the lack of evidence. In no particular order, there are the
- Leftist economists for whom global warming represents a supreme example of market failure (as well as a wonderful opportunity to suggest correctives),
- UN apparatchiks for whom global warming is the route to global governance,
- Third world dictators who see guilt over global warming as providing a convenient claim on aid (ie, the transfer of wealth from the poor in rich countries to the wealthy in poor countries),
- Environmental activists who love any issue that has the capacity to frighten the gullible into making hefty contributions to their numerous NGOs,
- Crony capitalists who see the immense sums being made available for ‘sustainable’ energy,
- Government regulators for whom the control of a natural product of breathing is a dream come true,
- Newly minted billionaires who find the issue of ‘saving the planet’ appropriately suitable to their grandiose pretensions,
- Politicians who can fasten on to CAGW as a signature issue where they can act as demagogues without fear of contradiction from reality or complaint from the purported beneficiaries of their actions. (The wildly successful London run of “Yes, Prime Minister” dealt with this.) etc., etc.
All of the above special interests, quite naturally, join the chorus of advocates.