That's the question that upsets both sides. Catastrophists don't want to hear it because it suggests something worked. Skeptics do not want to hear it because it suggests that investments have been used for something. Then no one sets it up. And the debate goes in circles.

Let us start with the gross figures of investments — those swallowed up from Paris, verifiable sources by source. Global investments in clean energy reached $2,200 billion in 2025, twice as much as in fossil fuels as in 2015. Over the ten years after Paris, aggregate global investment in renewables alone exceeds $4 trillion, according to Bloomberg. In Europe, climate investment reached €498 billion in 2023, up 98% since 2015. In France, low-carbon investments — public and private, transport, energy and construction — passed the 100 billion mark in 2023 according to the Treasury Directorate-General.

It is on this mountain of money that those who conclude to fail rely on. But Jean-Pierre Favennec, a geopolitics energy specialist, recalls a physical reality that the general public debate systematically ignores. On the basis of the work of historian Jean-Baptiste Fressoz, he set the framework: "There is no realenergy transition. There is an ever-increasing need for energy, and the various sources of energy add more than they replace." His example is devastating of simplicity: "It has long been said that coal has replaced wood. But in reality, wood consumption has continued to increase, if only because wood was needed to support coal mines."

This is why emissions continue to increase despite investments. It is not that renewables do not work. Global energy demand is growing faster than it is decarbonized. Jean-Pierre Favennec assured him: "We are facing a constant increase in energy needs through theplanet. The world population is growing. The level of individual wealth is increasing. All this leads to a steady increase in energy demand." Forty years ago, world oil consumption was around 70 million barrels a day. Today it is well over 100 million.

But Jean-Pierre Favennec — who is neither a catastrophist nor a climate-scepticist — also says the thing that neither of them wants to hear: "Without the development of renewable energies, the increase in fossil energy consumption would probably be even greater."

It's a reality. And the IEA data quantify it. Since 2019, the deployment of five clean technologies — solar, wind, nuclear, electric vehicles, pumps,heat— avoids 3 billion tonnes of CO2 per year, or 7% of global annual emissions. Without this deployment, emissions growth between 2019 and 2023 would have been three times greater. The cost of solar has fallen by 90% since 2010. The 55% terrestrial wind. 93% battery storage. These are not projections. These are market facts.

On the warming trajectory, the result is perhaps the most eloquent of all. By 2015, the world was rising to +3.6°C by 2100. The latest climate action tracker projections bring this figure to +2.6°C. One degree less. Concretely: at +2.6 °C, the planet would experience an additional 57 days of extreme heat per year compared to today. At +4 °C, that would be 114 days. The difference between these two figures is exactly what the billions invested since Paris have begun to produce.

François de Rugy formulates the question of the counterfactual with a sharpness that the summer stands usually forbid: "Already, this means that the efforts made have not been made for nothing. We are still in a time of transition, we are still in a time when global emissions are increasing. But the most advanced countries have managed to decouple their economic growth from the growth of their greenhouse gas emissions."

The share of fossils remains at 81%: failure or statistical trap?

This is Bjørn Lomborg's shocking argument at dinners: fossil fuels accounted for 82.6% of the global energy mix in 2006. By 2023, they still weighed 81.1%. Fifteen years, thousands of billions, and the needle almost didn't move.

Jean-Pierre Favennec does not dispute the figure. He changed the reading: "The slight decline in the share of fossil fuels in the global energy mix is nevertheless an encouraging sign. This gain in reducing the share of fossil fuels is still significant, as most countries are moving far away." The complete picture: 5-6% hydraulic, 3-4% nuclear, 3-5% solar and wind. Small figures in absolute terms — but representing billions of tons of emissions avoided each year out of a constant increase in total consumption.

The true reading of the 81% figure is therefore not "nothing has changed". It's "demand grew so fast that own gains were not enough to reduce the relative share of fossils." These are two very different statements. Confounding them — deliberately or not — is exactly the Lomborg method: an exact figure, a misleading conclusion. Real results, ambitions still out of reach

These results are real. They're not enough. No contradiction in that — just the discomfort of a reality that resists simple narratives.

Absolute emissions continue to grow. Global energy demand, driven by billions of people who legitimately aspire to a better standard of living, increases faster than the capacity of renewables to decarbonize it. The Institute of the Economy for Climate Change estimates that €842 billion a year would be needed in the EU to meet the 2030 targets — compared to €498 billion invested today. Globally, BloombergNEF estimates the need at $4,800 billion annually for a zero net scenario — three times the current level.

Jean-Pierre Favennec temperes without minimizing: "The figure of 4,800 billion dollars is indeed very high, but it is not completely out of proportion with the investments made each year in the energy sector" — which already reach about 4 000 billion from all sources. But it raises a constraint that the major climate plans are slamming: "What questions me more is not so much the amount of investment — even if it is colossal — than the space needed to install these infrastructures." The areas required for global solar and wind farms are a physical and territorial challenge that the zero net scenarios rarely mention in their public communication.

UNEP's 2025 emissions gap report is non-appealable: with onlypolitical The current trajectory leads to +2.8 °C. With full implementation of national commitments, at +2.3-2.5 °C. The new contributions submitted at the end of 2025 barely moved the needle.

François de Rugy points out the contradiction that undermines the descending discourses: "How can you finance massive investments, whether it be companies, individuals or the state, and simulate economic decline? I don't know how."

What this debate reveals about us

The question "Did the billions invested help anything?" has an answer. It's double, uncomfortable, and that's exactly why we're avoiding it.

Yes, they served. A degree less on the trajectory. Three billion tons avoided each year. Solar has become the cheapest energy in human history. The rate of growth of emissions divided by five since Paris.

No, they weren't enough. The shows are breaking records. The investment gap remains abyssal. National commitments do not meet the Paris targets.

These two truths coexist. Neither side wants to admit it — because both need a simple answer to exist. François de Rugy expresses it with a rare frankness in politics: "If we value the results obtained, it is a motivation to continue — while if we spend our time saying that it is nothing, we nourish the discourse of those who say that there is nothing to do. "

One last point of method — perhaps the most important. IEA "avoided" emission figures are themselves based on a counterfactual. It is a solid estimate, not a certainty engraved in marble. The key variable: what would have been burned in the absence of investment? More coal, more gas, or nuclear? The answer moves the final result considerably. To say this does not weaken the argument — on the contrary. This is what distinguishes him from Bjørn Lomborg's speech: to assume uncertainty where it exists, rather than conceal it behind statistics sorted on the part.

So the next time someone tells you that "everything is better so the transition is useless" — ask her what would have happened without her. And the next time someone tells you that "every empire so nothing worked" — ask him exactly the same question. In both cases, you will have achieved more for the quality of the climate debate than all the editorials written under the heat this summer.