In seeking to prevent environmental breakdown, what counts above all is not the new things we do, but the old things we stop doing. Renewable power, for instance, is useful in preventing climate chaos only to the extent that it displaces fossil fuels. Unfortunately, new technologies do not always lead automatically to the destruction of old ones. In the UK, for example, building new offshore wind power has been cheaper than building new gas plants since 2017. But the wholesale disinvestment from fossil fuels you might have expected is yet to happen. Since the UN climate summit last November, the government has commissioned one new oil and gas field, and reportedly plans to license six more. It has overridden the Welsh government to insist on the extension of the Aberpergwm coalmine. Similar permissions have been granted in most rich nations, even before Russia’s invasion of Ukraine. Why? Politics. Fossil fuel companies need spend just a fraction of their income on lobbying – funding politicians and their parties, buying the services of thinktanks and public relations agencies, using advertising to greenwash their credentials – to impede the energy transition and defend their investments. Fossil fuels will become stranded assets only when governments insist that they be left in the ground. Yet, somehow, a major strand of thinking in rich nations continues to ignore this obvious truth. The latest example is the economist Oded Galor’s much-praised new book, The Journey of Humanity. Galor argues that the driving forces of human development override setbacks such as wars, pandemics and depressions to deliver ever-increasing prosperity and welfare. They will, he believes, continue to propel a “relentless march of humanity” towards an “even more bountiful future”. While the book makes some interesting points, you might have imagined that climate and ecological breakdown, as they present the greatest threat to the optimism that he professes, would be covered in depth. But while he acknowledges their importance, his treatment is remarkably brief, even glib. The only source he cites in support of his main contention on the issue is Bill Gates, whose techno-utopianism and political naivety are notorious among environmentalists. Instead of detailed analysis, I found handwaving and magical thinking. Galor claims, without providing the necessary evidence, that “the power of innovation accompanied by fertility decline” may allow us to avoid a difficult choice between economic growth and environmental protection. He asserts that a decline in fertility will buy us the time we need to develop unspecified “revolutionary technologies” that will one day rescue us from the climate crisis. So, rather than encouraging countries to adopt “clean energy technologies and environmental regulations”, we should instead help them further to reduce fertility. Just a few problems. While the decline in population growth rates is real enough, it comes far too late to deliver the salvation that Galor anticipates. The most optimistic of current projections, which assumes the deployment of all the measures Galor recommends, sees global population peaking in 2064, then declining to a little higher than today’s level by 2100. But already, as the current devastating heatwave in India and Pakistan suggests, the conditions required to sustain human life in some parts of the world are at grave risk, while some Earth systems could be approaching their tipping points. If they pass these critical thresholds, and this triggers a cascade of change, the living planet could flip into a state that is largely uninhabitable. There’s likely to be no return from this on any human timescale. The long arc of human history for which Galor claims to have developed a “unified theory” is a mere instant of Earth systems’ time. He also fails to establish a connection between fertility rates and fossil fuel use. There are plenty of countries whose low fertility rates are accompanied by very high fossil fuel consumption: Canada, for instance, has a fertility rate of just 1.5 children for every woman of childbearing age, Russia 1.6, and the US, Australia, China and the UK 1.7. We already possess the technologies required to avoid catastrophe. What’s missing is the political will to deploy them at sufficient speed, and to shutter the legacy industries with which they compete. A few days before his book was published in the UK, the UN Office for Disaster Risk Reduction warned that irrational optimism and a misperception of risk greatly exacerbate our exposure to disaster. The timing was coincidental, but it stands as a direct riposte to his claims. Groundless optimism could be seen as one of the “cultural traits” that, Galor says, help determine the journey of humanity. It leads us not to his “even more bountiful future”, but to a different place altogether. His is the latest in a line of books by professional optimists – Gates, Steven Pinker, Matt Ridley – who have failed to grasp the nature of either Earth systems or the political economy that bears upon them. These men are not climate deniers; they are politics deniers. They appear to believe that the transformations necessary to prevent systemic collapse can happen without political pressure or political change. Understandably, the media loves them. Nothing fundamental needs to change, we can sit and wait for technological and demographic shifts and everything will work out in the end. A simple story with a happy ending, telling power what it wants to hear, this is the Disney version of environmental science. If we leave these issues to “the market” and other supposedly automatic processes, we can see what will happen. This week, the Guardian is publishing the results of its carbon bomb research. New oil and gas projects, if not stopped, will push global temperatures beyond the limits to which governments claim to have committed us, and are likely to drive Earth systems past their tipping points. In other words, only a radical break from business as usual will prevent planetary disaster. This requires the mass mobilisation of citizens to demand that their governments stop these projects and keep fossil fuels in the ground. How do we know such protests work? Because if they didn’t, our government would not be planning to ban them. Politics, which means seeking to change the decisions made in our name, is all that stand between us and catastrophe. This is why I see the politics deniers as more dangerous now than the climate deniers. We need optimism, and there could be some grounds for it, but it must be rooted in political and environmental reality. Fairytales are a threat to life on Earth. George Monbiot is a Guardian columnist