An aerial image shows the contrast between forest and agriculture land in Brazil Kate Evans, CIFOR/Flick

World leaders came out of Paris with an international climate agreement seeking to keep global temperature rise below 1.5 degrees Celsius. The following is part of a “What It Takes” series that looks into what we’ll need to do to pull that off.

Bolivia’s Noel Kempff Mercado National Park is one of the largest intact parks in the Amazon basin and a UNESCO World Heritage Site. Back in 1996, the Nature Conservancy partnered with three fossil fuel and energy companies to protect and expand the park in a deal that was supposed to be a model for forest conservation. They got the Bolivian government to ban logging on 1.5 million acres adjacent to the national park, hired park rangers for the new area, and trained locals as eco-tourism guides. It seemed like a win-win: The Nature Conservancy would get a major victory in land conservation. BP, American Electric Power, and Pacificorp would get carbon offsets for their emissions.

The project, however, was controversial and remains so two decades later. While the protected zone’s trees still stand—which, granted, can’t be said about much of the Amazon—critics argue the scheme merely shifted logging to unprotected areas. It’s a phenomenon known as “leakage,” and it plagues all forest conservation initiatives. Leakage is also a climate concern because intact forests store massive amounts of carbon. The designers of the United Nations’ REDD program (Reducing Emissions from Deforestation and Forest Degradation), which was incorporated into the recent Paris climate change agreement, are trying everything in their power to prevent leakage.

Leakage is easy to understand, if hard to stop. Imagine you’re an Amazon logging company. You roll your brush cutters, masticators, and feller-bunchers up to a beautiful stand of trees, ready to harvest some wood, only to discover government rangers have cordoned off your targeted bit of wilderness for conservation. What do you do? Retire from logging and let the forest be? Certainly not. You back your machines up, take a hard left, and cut down the nearest tree stand that doesn’t enjoy official protection.

To prevent this from happening, conservationists must coordinate their efforts at both the national and the international level. So far, however, global attempts to get on the same page have basically failed. According to a 2007 study in the journal Ecological Economics, at least 42 percent of the logging prevented in an average conservation project simply moves elsewhere. In many cases, that figure can be as high as 95 percent—rendering conservation efforts essentially useless from a climate change perspective.

According to a 2010 Greenpeace report, leakage undermined the Nature Conservancy’s initiative in Noel Kempff Mercado. Using updated leakage calculations, estimates of how much carbon the project has offset have fallen from 7.4 million metric tons to slightly more than 1 million. The actual savings, Greenpeace believes, are even less.

Fixing the Leakage (and Fairly)

Breaking a large project into smaller pieces is ordinarily good advice. That’s why a journey of a thousand miles begins with a single step, and why we eat an elephant one bite at a time. But forest conservation may be an exception. It appears that protecting little plots of forest here and there—via the creation of what are called “subnational” projects—may be a waste of time and money.

With REDD’s incorporation into the Paris climate agreement, such patchwork projects will have a difficult time earning sellable offsets. Over the past 10 years, REDD advocates at the United Nations have developed a program in which countries participating in REDD must submit reports showing how their efforts have preserved or expanded forests against a national baseline. Only then can they sell credits to corporations or countries seeking to offset their surplus carbon emissions.

The REDD system, however, still faces two primary challenges. First, even if it minimizes leakage within a country, it’s very difficult to address leakage between countries. Natural and political barriers to such shifts, however, do deter a substantial amount of international leakage.

“Guyana, for example, was concerned that Brazil’s efforts to stop deforestation would send soy farmers over the mountain to their country,” notes Gustavo Silva-Chávez, a climate and forests expert at Forest Trends. “But scientists have told us the soil in Guyana is not suitable for soy production.”

Sometimes, it seems, the earth works to protect itself.

The more significant, and far more talked-about, challenge to REDD is indigenous rights. The forests targeted for conservation are not vast stretches of uninhabited treescape. They provide homes and sustenance to millions of indigenous people, who claim customary ownership of the land. Critics say that by putting national governments in charge of forest conservation and the potential profits from carbon offsets, REDD exacerbates an already extreme imbalance of power between central authorities and local indigenous groups.

Some governments in Africa, for example, claim stewardship over 98 percent of forested land. And Indonesian law permits its government to manage designated forests with little or no input from indigenous groups. Indonesia is moving toward a more accommodative stance, but the situation remains tense, as it does in many other parts of the world. Even dusty academics in developed nations acknowledge that “carbon forestry interventions have tended to reinforce existing power structures and allow elites to capture benefits.”

Ignoring these concerns would be unwise. Indigenous peoples proved their influence at the recent Paris climate meeting, where they played a major role in making plans for climate change mitigation more ambitious. Over the next five years, REDD advocates hope to shift the program from an overwhelmingly government-funded one to one financed by private offsets. If the complaints of indigenous groups resonate, they could scare off crucial corporate dollars.

REDD faces a tricky path forward, but forests are too important to climate change mitigation for us to stop trying to conserve them on a global scale. Cutting down trees undermines the ecosphere’s ability to absorb carbon, and the felled trees themselves eventually decay, sending previously sequestered carbon into the atmosphere. According to the Intergovernmental Panel on Climate Change, deforestation already accounts for 10 percent of global greenhouse gas emissions—approximately the same contribution as every car, plane, boat, bus, and truck in the world combined.

“What we’ve done for the last few decades hasn’t worked,” notes Silva-Chávez. “REDD might not be the ideal solution, but if it does 80 percent of what we want, it’s much better than what we have.”

REDD administrators now must prove that they can scale up and pay for their program while simultaneously addressing fairness concerns, all in the next five to ten years. It is a major challenge. Saving a tree is simple. Noel Kempff and countless other initiatives prove that. Saving forests is complicated.

onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.