The humiliation of President Emanuel Macron should be a cautionary tale for any world statesman or woman considering taking on the mantle of climate leadership.

The immediate cause of the protests? The carbon taxes on petrol and diesel that Macron had only recently touted as evidence of French leadership on mitigating climate change. As cars and barricades burned on the streets of Paris, Macron's climate policies also went up in smoke.

Watching Macron's climb-down, which was -- embarrassingly for him -- forced on him just at the time climate negotiations at COP24 in Katowice, Poland, were reaching their climax, I was reminded of the so-called "iron law" of climate politics identified by the American political scientist Roger Pielke Jr.

Professor Pielke's "iron law" was first proposed in his 2010 book "The Climate Fix," and it runs as follows: "When policies focused on economic growth confront policies focused on emissions reduction, it is economic growth that will win out every time."

It sounds cynical, but the iron law has never yet been broken, and Macron is just the latest world leader to learn this most obvious of lessons. Faced with a weakening domestic political position, erstwhile "climate chancellor" Angela Merkel has been forced to make concessions to the might of the German car industry and the country's powerful coal mining interests by watering down Germany's 2020 carbon targets.

What was especially damaging about the "gilet jaunes" protests was that they were clearly reflecting the demands of working people who -- while they may accept the science of climate change -- still feel that being forced to pay more for their fuel threatens their jobs and livelihoods in the immediate term.

Many see Emanuel Macron as "president of the rich," and his climate policies -- like organic food -- indulgence for those who can afford it. Climate mitigation now risks looking like an elite project: the conceit of the global Davos set, something for the Bill Gates's and Richard Bransons of this world.

Their anti-elite flavour puts the French protests in the same bracket as populist movements elsewhere. Indeed, the nationalist, anti-intellectual political trends of our age seem to be moving squarely against action on climate change -- at just the moment scientists have warned that the window to avoid drastic impacts later this century is rapidly closing.

Many of the leaders who have ridden the populist surge to power accordingly boast loudly about their skeptical view of climate science and their continued loyalty to coal, oil and gas. Think not just about Trump, but also President Bolsanaro in Brazil (who has vowed to resume deforesting the Amazon), Russia's Putin and numerous others.

Trump wears a miner's helmet at political rallies, and even sent his advisors to hold a side event at COP24 promoting coal. The Polish government -- led by the populist Law and Justice Party -- made no secret of its pro-coal agenda either, not least by hosting the UN climate talks in Katowice, an old-fashioned coal town where you can smell the scent of sulfur on the breeze.

To environmentalists this looks archaic, but it's actually smart politics: imagine being a coal miner -- or an oil refinery worker, or anyone that works in the fossil fuels that still account for 80% of the world's energy -- and being told that your job is killing the planet and destroying the lives of your grandchildren.

Of course you will vote for the populist who tells you that you are still a good person and that the job you are doing is worthwhile.

With the rise of Trump, and his stated determination to take the United States out of the Paris climate agreement, some hopefuls looked to the Chinese for carbon emissions leadership. But the "iron law" of climate policy applies as much in Beijing as Washington -- perhaps even more so.

President Xi Jinping is determined to keep the Communist Party's hegemonic grip on power in China, which depends in turn on maintaining the rapid growth that has led to the Chinese economic miracle.

Because coal is still the bedrock of the Chinese economy, promises by the Chinese leadership to peak and reduce coal consumption need to be looked at skeptically. Recent analysis has found over 250 gigawatts of new coal-fired power station capacity still being built in China.

No wonder neither Xi, nor Trump, nor even Macron or Merkel, even showed up for COP24 in Poland. The politics of climate change are such that leaders making grandiose carbon commitments on the world stage are likely to find their positions undermined rather than bolstered at home.

There is a way around the "iron law," but it means coming up with climate policies that defend and enhance the jobs and livelihoods of working people rather than undermining them.

The buzz-phrase for this is "just transition" -- an idea developed by the trade union movement which aims to make the transition to a low carbon economy fair on those who otherwise stand to lose out, especially workers in high carbon industries.

By embracing just transition, the climate progressives might yet face down the populist naysayers. Let's hope that the next world leader to embrace the climate agenda understands the need for political -- as well as environmental -- sustainability.