The pledge, which will be officially announced today at COP26 in Glasgow, brings world leaders from 100 nations including Brazil, China, Russia, and Indonesia together to commit to “halt and reverse” deforestation by 2030, and devote a total of $19.2 billion in funding, with $12 billion coming from governments, from 2021 through 2025. The deal was announced late on Monday night by the U.K. government, which is hosting the conference.

The pledge is notable because it brings several prominent forest nations to the table, including Brazil, home to large swaths of the Amazon—one of the world’s greatest carbon sinks—that are imminently under threat from logging and farming. That was made doubly clear earlier this year, when climate scientists reported that the forest was emitting more CO2 than it absorbed, largely owing to fires.

But the deal also draws attention to the failure of previous pledges to end deforestation—the Aichi Declaration in 1993, which set out a target to cut the pace of diversity loss in half by 2020; the 2011 Bonn Challenge to restore 150 million hectares of degraded land by 2020; and, in particular, the New York Declaration on Forests (NYDF), signed in 2014. That deal pledged 200 signatories, including major governments, to reverse deforestation by 2030. In October of this year, signatories said in an update that, while progress is being made in many places, “overall action has fallen short of the speed, scale, and finance required,” in order to meet the goals.

The UN’s Food and Agriculture Organization estimates average annual forest loss since 2010 has reached 10 million hectares a year.

“Political commitment to end deforestation is welcome, but we have been here before and need to learn lessons from past/existing anti-deforestation efforts,” tweeted David Aled Williams, a researcher in resource corruption at the Chr. Michelsen Institute, a development organization, in Norway.

Nonetheless, the COP26 pledge also offers the attention, recommitment and—crucially—funds that the New York Declaration itself pledged. On Tuesday, the NYDF tweeted the announcement, adding: “The first big news of #COP26 is a welcome affirmation of the urgency of halting deforestation by 2030.” And there is hope: The world actually passed “peak deforestation” in the 1980s, according to the Our World In Data project at the University of Oxford, and the amount of land used for agriculture per person has, in fact, sharply dropped.

For the host U.K. government, the announcement—a side deal to the two-week climate negotiations, which began on Sunday—was also a welcome sign of momentum after an unsteady start to the event. The signatories to the pledge also include, crucially, Russia, China and Brazil—whose leaders all declined to attend COP26.

The deforestation pledge isn’t the only major announcement expected on Tuesday. A methane pledge will be announced, with U.S. President Joe Biden due to announce a partnership of 90 countries—including Brazil—to cap the rise in global emissions at 30% by 2030, from a 2020 baseline. Methane stays in the atmosphere for a far shorter period than CO2, but is also far more potent.

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