WORLD leaders are at the United Nations this week, at the invitation of Secretary General Ban Ki-moon, to “champion an ambitious vision anchored in action that will enable a meaningful global agreement” on climate change next year.

But if history is any guide, the dialogue is unlikely to produce the ramped-up response we need to address the many threats we face from the unrelenting buildup of greenhouse gases in the atmosphere. Government leaders have gathered multiple times over the past several decades to address climate change, most recently in 2009 in Copenhagen, where negotiators tried, but failed, to “seal the deal” with a new commitment to reduce emissions.

Five years later, given the difficult geopolitics, there is little to show for it. Perhaps the world community should take a different approach before the next round of talks, in Paris in December 2015, ends with another Copenhagen-style outcome with minimal results.

Smart people in the 20th century thought we could tackle climate change with a treaty in which the world’s nations agreed to “targets and timetables” for reducing emissions. These reductions would be implemented by top-down, national mandates and government support for clean energy technologies. But 22 years after the original climate agreement, emissions continue to rise and threats of significant harm loom larger.

As one of those who, as an official at the Environmental Protection Agency, negotiated that first United Nations treaty in 1992, I believe we need to shift gears and try something new. Relying on national governments alone to deliver results is not enough, as the last two decades have shown. The real action on climate change around the world is coming from governors, mayors, corporate chief executives and community leaders. They are the ones best positioned to make change happen on the ground. Accordingly, we need to move from a top-down strategy to a bottom-up approach.

Mayors in Barcelona, Melbourne and the Brazilian city of Curitiba, for instance, are trying to expand public transportation. New York City’s former mayor Michael R. Bloomberg worked with pipeline companies to increase natural gas access so residents could shift from dirty fuel oil furnaces to cheaper and cleaner natural gas ones.

British Columbia and Quebec have introduced cap-and-trade programs that put a price on greenhouse gas emissions, making it more expensive to pollute and encouraging innovation. California has done the same thing. So have nine states in the Northeast and the Mid-Atlantic.

In Connecticut, where I served as commissioner of energy and environmental protection, Gov. Dannel P. Malloy, a Democrat, has begun a “green bank” that uses limited government money to leverage vastly increased flows of private capital for clean energy projects.

These efforts show that the quest for a clean energy future can be pursued in a serious, cost-effective and bipartisan manner without the impetus or imprimatur of national governments.

Leaders in many industries have also stepped up, seeing sustainability as good for their bottom line. Unilever’s food divisions, for instance, have encouraged their supplier-farmers to adopt efficiency advances and lower-carbon production methods. Dow Chemical has developed a filtration system that reduces the energy used to purify water by 30 percent. Alcoa has helped Boeing and Ford achieve better fuel efficiency by reducing the weight of their planes and cars.

These corporate successes and many more should be highlighted when world leaders gather in Paris to negotiate the next round of climate commitments.

More fundamentally, why not invite leaders from states, provinces, cities and companies to join representatives of national governments in signing the anticipated 2015 climate change agreement? Sure, the focus of international relations for hundreds of years has been on nation-states, but there is no reason this has to be so. We should recalibrate our approach to engage local, regional and corporate leaders, especially on issues like climate change that require broad-based public support if we are to succeed.

And while we’re at it, let’s shift away from the top-down way that the federal government subsidizes clean energy innovations, which relies on picking winners and assisting chosen industries and technologies. Instead, let’s promote a financing approach in which the government works to engage the private sector in delivering clean energy projects.

This can be done with green banks and bonds and other private-sector clean energy finance mechanisms that could drastically increase the flow of capital into energy efficiency and renewable power. A private-market emphasis offers the prospect of not just more money and better projects, but also competition to lower costs.

Conceding that the present approach isn’t working will be hard for some. But let’s hope this week’s gathering starts us down a new path.