Bjorn Lomborg is director of the Copenhagen Consensus Center, and author of The Skeptical Environmentalist and Cool It.

Like the Kyoto Protocol before it, the drastically over-hyped Paris climate treaty has fallen victim to political and economic reality.

Now that President Donald Trump has officially pulled the United States from the accord, it is time to declare the entire Kyoto-Paris approach to global warming dead and buried. Instead of scrapping over the treaty's corpse, this is an opportunity to try a new, better and more efficient approach to solving global warming.

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Right now, the chances of anything so constructive seem slim. Rhetoric is overheated to the point of absurdity. Environmental campaigners condemn Mr. Trump for dooming the entire planet to a fiery Armageddon, yet claim rashly that the treaty could survive without the United States. It will not, and it should not.

The hyperbole and outrage can't hide the truth: even with the United States included, the treaty was not going to make much difference to global warming. Its grand rhetoric was never matched by the actual carbon-cutting promises within its pages. A lot was made of the treaty's fanciful pledge to keep global temperature rises as low as 1.5 C. But that would have been impossible in all realistic scenarios other than a devastating global recession.

The UN's own Framework Convention on Climate Change estimates that even if every country had made every single cut promised in the treaty to the fullest extent, CO2 emissions would only drop by 56 billion tons by 2030. Keeping temperature rises below 2 C – a less stringent goal even than the treaty promise of 1.5 C – requires a reduction of around 6,000 billion tons of CO2 emissions across the century.

So, even if Hillary Clinton had beaten Mr. Trump and had kept the United States in the treaty, and even if every single national leader on the planet (and their successors) had unflinchingly stood by every single treaty promise for year after year, regardless of economic downturn or political crisis, the Paris Treaty would have left 99 per cent of the problem in place.

Before Mr. Trump axed the treaty, many environmentalists quietly acknowledged this. They praised the agreement regardless, because of the political value of world leaders focusing on climate change and because they believed that much larger carbon-cutting promises would come later.

That foolhardy assumption flew in the face of history. As early as 1998, the Kyoto Protocol was sold to the world as the solution to climate change. Every honest analysis showed that its impact would be trivial. Backers claimed that it was just the beginning. Similar to Paris, the carbon-cutting treaty wasted energy and distracted attention from any effective solution to climate change.

The Kyoto-Paris approach fails politically and economically. Even if the Paris Treaty had survived for now, it would have faced a massive hurdle in three years, when rich countries needed to cough up $100-billion a year in "climate aid" to the developing world. That is 10 times more than donors have managed to put together in the past five years.

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And that's only a fraction of the price tag. Today's green solar and wind technology requires hundreds of billions of dollars in annual subsidies to achieve trivial temperature cuts. Trying to make significant cuts means shifting energy consumption from cheap fossil fuels to more expensive green energy. Even when done most effectively, this reduces economic growth.

We are told that green energy is becoming cheaper. But it can rarely compete with fossil fuels, and not at all when there isn't sun or wind, instead requiring expensive backup. That is why the little renewable energy that is effective will happen anyway, while most of the rest requires vast subsidies and achieves little. The International Energy Agency finds that wind provides 0.5 per cent of today's energy needs and solar PV, a minuscule 0.1 per cent. Even by 2040, if the Paris Treaty had kept going, after spending $3-trillion in direct subsidies, the IEA expected wind and solar to provide just 1.9 per cent and 1 per cent of global energy, respectively.

That is far from what is needed to transform our engine of development. To solve global warming, we need to invest far more into making green energy competitive. If solar and wind generation and storage were cheaper than fossil fuels, it wouldn't be necessary to force or subsidize anyone to stop burning coal and oil.

Research for Copenhagen Consensus shows a green energy R&D fund worth just 0.2 per cent of global GDP would dramatically increase the chance of a technological revolution. This would be significantly cheaper and much more effective than the Kyoto-Paris approach. Economists calculate returns to society of around $11 for every dollar invested.

A technology-led effort could advance not just solar and wind but all alternative-energy technologies. Encouraging world leaders would be far easier than strong-arming and bribing them into cutting growth – but it is also something that a smaller group of countries could pursue alone, and reap benefits. A carbon price might support such a policy, but climate-change policy must logically be technology-led.

The Kyoto-Paris approach has failed. Now is time to finally stop trying to make fossil fuels too expensive to use, and instead invest in the research needed to make green energy too cheap for the entire world to resist.