If I were suddenly to be convinced that the human contribution to climate change is negligible, I know how I, as a progressive/liberal, would respond. I'd still be concerned about the impact of various kinds of pollution on human and environmental health (e.g., even if the air pollution in China wasn't contributing to climate change, it still kills hundreds of thousands of people every year and its reduction would remain a worthy goal). I'd still want laws in place restricting pollution sources rather than relying entirely on the free market to shut them down.
But I'd be happy to rely far more on market forces to produce more energy-efficient vehicles, and I'd remain confident that sustainable sources of energy such as solar, wind, and tide would increasingly compete with fossil fuels as the technology improves simply because sunlight, wind, and tide are essentially free and renewable (at least compared to fossil fuels) and don't have the drawbacks of nuclear waste storage and potential meltdowns at nuke plants. I'd also be much readier to take into account any economic hardship caused by anti-pollution laws when considering government policies.
I've noticed that denial of the overwhelming scientific consensus regarding the human causes of accelerated climate change is largely confined to (and almost universal among) political conservatives and particularly to those with a libertarian bent. I'd like to challenge any self-identified libertarian/conservative to imagine that they've been presented with evidence and arguments that thoroughly convince them that human activity is indeed a major factor accelerating climate change. Assume that without change in human activity the consequences will be felt within the next few decades in the form of such things as sea level rise engulfing large coastal and island areas with dense human populations, temperature rises in currently fertile areas such as the Great Plains that render them unsuitable for agriculture, melting ice caps at the poles, rapid extinction of numerous species and disruption of ecosystems, and the concomitant violence and turmoil as people vie for shrinking resources and habitable areas. What would be an appropriate response in the present that, while measurably reducing or changing the human activities that contribute to climate change, remains in accord with the core principles of libertarian/conservative thought?
My hypothesis is that there are, in fact, no effective responses to human causes of climate change consistent with libertarian principles, that without organized, concerted policies and efforts by governments and international organizations, there are no market mechanisms that would reliably reduce human impact on climate change. In the absence of a believable set of conservative ideas for effectively reducing the human contribution to climate change, the obvious conclusion is that the reasons for climate change denial among conservatives are entirely based in ideology- hence the skepticism towards the scientific consensus.
The motivation for the ludicrous assertions that academic scientists and research scientists employed by non-profit organizations are somehow motivated by access to personal gain through grants and government funding, rife among conservative media and internet pundits, becomes clear. If the world is in fact in a situation that requires concerted national and international efforts to avert impending environmental disaster, the fundamental assumptions of conservative and libertarian ideology are demonstrably inadequate to the task. The increasing rigidity of "conservative" thought in the last forty years renders it incapable of grappling with complexity when the market is simplistically seen as the default solution to any complex problem. Hence, conspiracy theory and irrationality form the response, since the alternative is recognizing the limitations of the ideology.