To say the results of the US election cast a pall over climate negotiations in Marrakech is like saying Indonesian forest fires make Singapore a little hazy. In the appropriately named Blue Zone of the conference venue, participants went through the motions of formal talks and side events, while private huddles dwelled on the new shocking reality of a US President-elect who has pledged to withdraw the United States from the historic Paris Agreement, which concluded last year and which has already entered into force.

Implementation of that agreement was the theme of COP22 (short for the 22nd Conference of the Parties to the climate convention), with banners around the city of Marrakech proclaiming “A Time for Action.” Not surprisingly, a theme of post-election conversations there was how US action on climate change could be continued even with the prospect of a dramatic reversal in policy at the federal level. And while such a reversal would have enormous and in many ways irreversible impacts, the outlook for action by others is not entirely gloomy.

One element of hope was provided by the potential of state and local governments to continue efforts supported by most American citizens to reduce emissions and adapt to the impacts of climate change already underway. Many are pinning their hopes on the example of California, with its leading-edge cap-and-trade system. Canadians reminded colleagues from south of the border that until recently, provinces such as Quebec and Ontario—which are linking up with California’s emissions trading scheme—were far out in front of Canada’s federal climate policy.

In his speech to COP22 delegates a week after the election, US Secretary of State John Kerry highlighted the efforts of coastal city mayors to address “sunny day floods” as a non-partisan recognition of the reality of rising sea levels. Secretary Kerry also stressed the role of the private sector in meeting US emission reduction goals. He asserted that market forces would continue to bring down emissions by prompting investments in renewable energy in the United States and other countries.

Hope lies in action by these subnational authorities and by the private sector to reduce global emissions and promote adaptation; discussions in Marrakech suggest that similar hope extends to conserving tropical forests.

 As co-author Jonah Busch and I detail in our new book, Why Forests? Why Now?, conserving tropical forests offers a solution to climate change that is vastly under-appreciated. We don’t need to try and invent an expensive new carbon capture and storage technology; we already have one that is economical and proven—tropical forests. And we cannot achieve our Paris climate objectives without them.

Not only is the clearing and burning of forests a major source of greenhouse gases, but standing forests offer the only safe and natural technology for pulling carbon out of the atmosphere.  As our synthesis of published research shows, halting tropical deforestation and allowing damaged forests to grow back could be equivalent to somewhere between one-quarter and one-third of current annual global emissions.

But despite recognition of the importance of forests in the Paris Agreement and in the mitigation plans of dozens of nations, reducing the rate of forest loss has so far proven elusive in most tropical countries. In Marrakech, discussion of the potential for action on forests focused on initiatives at the subnational (or “jurisdictional”) level.

For example, Governor Victor Manuel Noriega Reategui of San Martin, Peru spoke at a side event of his ambition for jurisdictions in the Amazon region to establish a “brand” as a source of sustainably-produced goods. And on a panel at the Indonesia Pavilion, Governor Awang Farouk Ishak elaborated on his vision for sustainable development in East Kalimantan embodied in a recently announced “Green Growth Compact” in the province.

Not coincidentally, these two jurisdictions are among 19 developing country members of the Governors Climate and Forests Task Force—established by Governor Arnold Schwarzenegger of California in 2008—that in 2014 offered to reduce deforestation by 80 percent by 2020 in return for guaranteed performance-based finance. Indeed, the prospect of being able to sell forest-carbon credits into California’s compliance market was a key initial stimulus to subnational leadership on the climate agenda in forest-rich developing countries.

Shortly after the US election, this video of Governor Schwarzenegger started turning up in peoples’ Facebook newsfeeds (27 million views so far), explaining that California managed both a large reduction in emissions and an equally sizable increase in its economy. In characteristically direct fashion, the governor reminded viewers of the simple fact that action to reduce climate emissions does not mean economic meltdown. Our book analyses the case of Brazil, which managed to reduce deforestation in the Amazon region by 80 percent in a decade, while at the same time increasing agricultural production.

But the governors’ efforts are unlikely to succeed without private sector action as well. As described in our book, conversion of forests to commercial-scale production of globally traded commodities such as beef, soy, palm oil, and timber has emerged as the leading cause of tropical deforestation, and vested interests in business-as-usual forest clearing are strong. But thanks to hard-edged civil society advocacy, an increasing number of companies—ranging from producers to traders to manufacturers and retailers—have pledged to achieve “zero deforestation” in their supply chains.

Marrakech saw the launch of several new internet platforms that utilize satellite imagery and trade data to allow the public to track the progress of both jurisdictions and companies in reducing deforestation. Such increased transparency is sure to provide incentives to implement both government and private commitments.

While the withdrawal of federal leadership on climate change would be contrary to US interests at home and abroad, action by many other players—subnational jurisdictions and the private sector particularly—may provide us with a ray of hope.