Planet Earth . Picture: SUPPLIED
Planet Earth . Picture: SUPPLIED

I once knew a libertarian economist who had nothing but scorn and loathing for what he called "the climate change business" — by which he meant all the scientists, NGOs and other "alarmists" apparently making money out of scaring people that the world was about to end.

Giving the market complete free rein, without even a faint clank of government regulation, was the way to enduring happiness and prosperity. "Let’s privatise the air," he’d say, only half joking.

Just two decades later, it has become pretty much obvious to most concerned citizens of the planet that climate change is real and that we have, in fact, probably played a big part in it.

A graph in The Economist this week showing the average temperature increase on the Earth’s surface between 1850 and 2018 is perhaps the most sobering indication of the trouble the planet is in. As the magazine notes, only climate models that take human activity into account go any way to explaining rising temperatures.

The main culprit is carbon, which we have been digging from the earth in the form of fossil fuels and spewing with gusto into the atmosphere. The knock-on effect is simple: the Earth warms up, and places where once crops could be grown become deserts. Sea levels rise, making more places uninhabitable.

For anyone under the age of, say 40, the future looks … uninhabitable. Hence the explosion of climate activism among young people.

For the little it’s worth, my libertarian friend has admitted that "we might have got it wrong". When a libertarian changes tack, it’s time to listen.