This op-ed originally appeared in CalMatters under the headline "How California can fight climate change by helping to save tropical forests."

California can expect longer fire seasons, more severe droughts and heatwaves, eroding coastlines, scarcer water, and hotter cities. These are among the grim findings of a new United Nations report on climate change and land.

Rather than merely brace for impact, Californians have the chance to act decisively to prevent the worst by embracing one of the biggest—and most overlooked—solutions: protecting tropical forests.

California already is a leader in the fight against climate change. Last year, our state’s greenhouse gas emissions fell below 1990 levels, even as our population grew by one-third—and our economy more than doubled—since then. Leaders from across the country and around the world visit California to learn about what we’re doing right.

But California on its own is responsible for only 1% of global emissions. Emissions from clearing and burning tropical forests are 12 times greater, according to the report by the Intergovernmental Panel on Climate Change.

If tropical deforestation were its own country, it would be the world’s third-largest carbon emitter, behind China and the United States.

Reducing these emissions from tropical deforestation is not an exotic luxury, nor is it a substitute for more renewable energy and electric vehicles. It’s a necessity—the Intergovernmental Panel on Climate Change report says there’s no way to meet internationally agreed climate goals without curbing deforestation. And while these emissions may seem far away, California has a unique chance to act, by bringing tropical forests into our world-famous cap-and-trade program.

Next month the California Air Resources Board will meet to consider endorsing the California Tropical Forest Standard. California’s climate program has included a tropical forest component from the very beginning. It has undergone extensive expert review and public consultation, attracted support from legislators, and is now ready for implementation.

Endorsing the California Tropical Forest Standard would open the door for tropical states that keep their forests standing to earn income by selling carbon credits.

Right now, forests are being cleared in tropical countries such as Brazil and Indonesia to produce beef, soy, and palm oil. It’s a matter of simple economic arithmetic. Cash crops pay more than trees. The California Tropical Forest Standard would tip the economic scales in favor of keeping more land as forest and growing more crops elsewhere.

Brazil had been one of the world’s biggest climate success stories. It cut the rate of Amazon deforestation by 80% while growing more food on already-cleared land and formally recognizing large areas of land as Indigenous peoples’ territories.

Now deforestation in Brazil is rising again, encouraged by a populist president hostile to indigenous peoples and the environment. The California standard would offer economic support and solidarity to Brazilian states that are a bulwark of resistance.

The California Tropical Forest Standard includes groundbreaking principles of collaboration between state governments and Indigenous peoples, negotiated with and endorsed by 18 Indigenous peoples organizations. It offers a chance to make good on the potential of forest conservation to safeguard the territories of Indigenous peoples and other forest-dependent communities.

Californians stand to benefit immensely. Bringing tropical forests into our climate policy helps us achieve more ambitious climate goals more cheaply. It would safeguard the habitat of two-thirds of plants and animal species and head off thousands of extinctions. There is even evidence that protecting tropical forests supports intercontinental weather patterns that nourish agriculture in California and elsewhere in the United States.

Critics contend that helping protect forests in the tropics diverts from cutting emissions at home. But California’s ambitious target of cutting emissions 80% by 2050 means we can—and must—do both. Furthermore, tropical forest credits are limited to just 2-4% of overall emissions in the cap-and-trade system.

In parallel to the California Tropical Forest Standard, the Legislature is advancing a bill by Assemblyman Ash Kalra, a San Jose Democrat, that would prohibit state contractors from buying agricultural goods grown on recently deforested land.

A deforestation-free procurement act would be a complement, not a substitute, for economically supporting tropical states that protect forests through the California Tropical Forest Standard.

The Intergovernmental Panel on Climate Change has stated that protecting tropical forests is essential to avoiding an unbearably hot future. California must show its leadership once more by acting now.