On his deathbed, French writer François Rabelais allegedly declared: “I go now in search of the Great Perhaps.” Rabelais was a man of science but in the 16th century, it was far too early for him to be an atheist. He had his doubts but didn’t want to risk expressing them in case he was about to meet his maker.

But Rabelais’ method of having it both ways has proven durable. Even today, it is a fairly common position. Many of us don’t actually believe the priests’ lurid tales of hell and damnation but we play the odds on the off-chance that they are telling the truth. Indeed, it’s a no-brainer: on the one hand, you have a few not particularly onerous tasks required of a religious person while on the other you have eternal punishment.

It is very much the same with climate change. The COP26 summit in Glasgow last week proposed a series of relatively mild measures to wean the world of fossil fuels (while replacing them and the jobs that went with them with renewable energy), curb deforestation and limit the release of methane into the atmosphere. World leaders accompanied these measures with gloom and doom warnings. If nothing is done, they said, an unprecedented calamity awakes the world. Moreover, it is “one minute to midnight”, to quote the summit’s host Boris Johnson.

What if indeed the dire scenarios scientists, environmental activists and Greta Thunberg’s kids are warning about will come to pass because we have not taken action?

There are plenty of conspiracy theories claiming that evil climate scientists have thought up global warming as a way to mooch off fat fellowships and grants. Donald Trump, the president of the leading industrial nation responsible for 15% of global CO2 emissions, has suggested that climate change was a Chinese hoax aimed to ruin the US economy. His administration pursued policies that seemed deliberately tailored to increase the US carbon dioxide emissions.

However, you don’t have to be an ignorant flat-earther, an oil company executive or a political hack in order to be skeptical about the conclusions of climate scientists or to doubt the necessity of disrupting the existing economy.

In fact, the warming of the atmosphere may be part of a natural cycle on earth. The planet began warming at the end of the last Ice Age and it has continued ever since; our activities have nothing to do with it and we can do little to prevent it. On the other hand, if we ever hope to reverse the warming of the atmosphere — the way modern agriculture has been able to produce enough food to feed eight billion mouths and avoid the mass starvation predicted by Thomas Malthus — we will surely need to speed up the global economy and technological progress, not meddle with them to slow them down.

Finally, there is a clever idea advanced back in 1974 by British environmentalist James Lovelock and American microbiologist Lynn Margulis called the Gaia Hypothesis. It suggests that the biosphere on Planet Earth resiliently maintains its own stability; whenever external shocks cause an imbalance, components of the biosphere naturally begin to act to restore the status quo. Thus, when the planet warms up, higher temperatures give rise to processes that ultimately will lead to its cooling, such as the spread of algae in the water or the growth of grasses and trees.

Which ones of these suppositions are true we do not know. What we do know for certain is that over the past 150 years we have released into the atmosphere around 2,400 gigatons of CO2.

Life on earth is based on carbon. Ever since the simplest microbes appeared on the planet some 3.5 billion years ago, living organisms have been dying and carbon has been deposited underground. It eventually turned into petroleum, natural gas and coal. But then, in a very short period of time in terms of the life of the planet humans have been able to dig up and release hundreds of millions years’ worth of buried carbon.

Since we first evolved — hairless and frozen during the last Ice Age — we have been burning fuel and releasing carbon into the atmosphere. Starting with wood and camel dung and graduating to hydrocarbons mined from the ground. This has been our earliest and most consistent pursuit, as well as our most important achievement — actually the only thing our civilization has been able to accomplish on a truly geological time scale. It will long outlive our buildings, roads and all other signs of our presence on the planet.

In doing so we have greatly increased the content of carbon dioxide in the air. In 1960, it comprised 0.032% in the atmosphere, but now it measures 0.045%. This may not seem like a big deal, but it represents a 40% increase in only a half-century.

More importantly, the CO2 level in the atmosphere had been effectively stable, at around 0.03%, for some 25-30 million years. Considering that we, homo sapiens, evolved only 300,000 years ago, our species have never consistently breathed the air with such a high concentration of carbon dioxide. We evolved and developed our civilization in a low CO2 environment.

Is it important? We tend to think of ourselves as masters of our own destiny but we are biological species like all other organisms on earth. We are the result of evolution, which takes place within the biosphere. The work of Dr. Margulis indicates that even minute changes in the biosphere can radically impact the evolution of simple organisms such as bacteria and viruses, and we now know that microbiome, the living fauna in larger organisms, are in turn active participants of their evolution, including the evolution of human beings.

In fact, whether or not CO2 in the atmosphere causes it to warm up, global warming may not be the only reason to worry about the burning of fossil fuels.