Mr. Hulot is not alone among environmentalists in denouncing the hypocrisy and inadequacy of government action on climate change. The Paris accords are “a fraud, really, a fake,” said climate activist James Hansen in 2015. “There is no action, just promises.”

Three years later, Mr. Hansen’s words look prescient. Even ostensibly committed countries like Germany and France are on course to miss the voluntary 2020 targets they announced to such fanfare in 2015. The Climate Action Tracker estimates that only Morocco and Gambia are on a “Paris agreement compatible” path.

The climate-change movement is stuck, even after a scorching summer elevated the issue across much of the Northern Hemisphere. It is powerful enough to command lip service from politicians, but too weak to impose the policies it says are needed to prevent catastrophic change.

Many environmentalists fail to grasp that the real problem isn’t skepticism that the climate is changing, or even that human activity is a leading cause of the change. Millions worry about climate change and believe human activity is in large part responsible. But they do not believe that the climate movement has the answers for the problems it describes. Green policy blunders, like support for ethanol in the U.S. and knee-jerk opposition to nuclear power, erode confidence that environmental activists—who too often have an anticapitalist, Malthusian and technophobic view of the world—can be trusted, to as they often say, to “save the planet.”

For center-right politicians and people who support both free markets and a healthy environment, the status quo is also a problem. In the U.S. and abroad, market-friendly politicians cannot embrace the stagnant, statist and rent-seeking policies often proposed by environmentalists. Yet neither do they wish to turn a blind eye to a consequential problem that voters care about.

The world needs a green movement that can command more than lip service from politicians. Such a movement would be tech-positive, pro-science and pro-growth, recognizing that capitalism can deliver technological and social changes that offer humanity’s best hope of a greener and cooler future. A realistic green movement would not only embrace zero-carbon nuclear power as part of the solution to the climate problem; it would embrace the broader potential of the information revolution to raise living standards around the world while reducing humanity’s carbon footprint.

One example would be the promotion of telework and other changes to the way people commute. The daily trek of hundreds of millions of commuters around the world is a major contributor to world-wide emissions. Commuting’s pernicious influence will grow as developing countries continue to urbanize. Promoting telework—substituting the movement of data for the movement of people and cars—will bend the carbon curve even as it saves time and money. The shift to autonomous cars can have a similar impact and reduce the number of vehicles on the road.

Videoconferencing is already making inroads in the business world. Instead of $100 billion boondoggles like California’s struggling high-speed rail project, policy makers should encourage the development and deployment of this technology—reducing emissions and saving taxpayer dollars.

A smarter green movement also would embrace the development and use of genetically modified organisms in agriculture. Tweaking the genes of specific crops can raise yields while shrinking humanity’s carbon footprint. A field of “tweaked” soybeans that need little or no fertilizer or pesticides is the real killer app for solar power. Human ingenuity plus sunlight can dramatically reduce the need for fertilizer and pesticides with all the greenhouse-gas emissions and other environmental damage they entail.