On the right side, Padang Sugihan Wildlife Reserve in Sumatra, Indonesia, is nearly devoid of trees due to years of illegal logging and wildfires. On the left, communities have replanted lands with oil palm. Faizal Abdul Aziz, CIFOR

Landscape restoration: Is it working?

Scientists challenge the Bonn Challenge; its creator responds

A recent study by scientists at University College London (UCL) and the University of Edinburgh has raised concerns about the Bonn Challenge, questioning the impact the implementation of its goals are likely to have on climate change.

Their paper was recently published in Nature, and suggests that current plans by countries pledging areas for planting trees as part of the Challenge might not meet the goal of the Intergovernmental Panel on Climate Change  (IPCC) to limit global warming to 1.5 degrees Celsius.. 

The researchers wanted to “look at the big picture,” says Simon Lewis, lead author of the paper and professor of global-change science at UCL. “It makes sense on a local level to have the land required to produce all sorts of social, economic and environmental benefits,” he says. “But when you zoom out and look at the aggregate effect of all those decisions, then we don’t get to the place where we want to get to.”

Their argument that restoration efforts aren’t ultimately diminishing carbon emissions to the point we need made headlines when the paper was released. Yet from the perspective of the architects of the Bonn Challenge, the spirit in which restoration is carried out raises an important question: Is it solely to offset carbon dioxide, or is it to help people, in whatever form that comes?

Here, we hear from the authors of the paper as well as Horst Freiberg, hailed as the creator of the Challenge, on both sides of the restorative story.

Walking through Indonesian rubber gardens. Rifky, CIFOR


Lewis and his colleagues consulted restoration plans from 24 of the 43 countries that have promised to contribute to the Bonn Challenge’s goal of restoring 150 million hectares by 2020 and 350 million hectares by 2030. So far, the land pledged for restoration under both the Challenge and as part of the Paris Agreement on Climate Change adds up to 292 million hectares, with countries taking three approaches: allowing degraded land to return to natural forest, converting barren land to commercial tree plantations, and promoting agroforestry by combining crops, such as coffee or maize, with tree cover.

“However,” the paper notes, “plantations are the most popular restoration plan: 45 percent of all commitments involve planting vast monocultures of trees as profitable enterprises.” Another 21 percent is slated for agroforestry. According to the study, in that scenario, 16 pentagrams – or 16 billion tons – of carbon will be sequestered by 2100 if naturally regenerated forests are protected. The IPCC has suggested that 199 petagrams of carbon must be removed from the atmosphere via new storage in ecosystems by the end of the century to cap global warming at 1.5 degrees.

Lewis points out that the findings are based on estimates, as many countries have yet to provide details of what types of restoration they will carry out, or what species they will plant in their production forests.

“Because we don’t know what species are going to be planted,” he says, “our first assessment is that countries with restoration efforts that said they’re going to do plantations, are, we assume, going to plant the thing that’s commonest to the same environment in the same country, because the market is there, the knowhow is there. It’s [already] being done. If we apply that criteria, then almost all of these plantations go toward the pulp and paper industry.”

Fast-growing trees do sequester carbon, but they will soon be cut down, leaving waste products to decompose and put emissions back into the atmosphere. Since only a small fraction of paper products is recycled, says Lewis, “most of it is simply going to decompose after some short amount of time and end up back in the atmosphere as carbon dioxide. So it’s not being locked out of the atmosphere and onto the land surface, or into long-term wood products.”

It is possible, he adds, that the monoculture plantations might produce timber for the construction industry, for example, which would sequester carbon for long periods of time. “But these short-rotation plantations, which are the vast majority in the tropics, are not storing much carbon in the land or in the products themselves.”

Another problem identified by the scientists is market saturation. “The enormous expansion of plantations in the tropics and subtropics, and what that means for the prices of those commodities,” is also of concern, says Lewis.

Horst Freiberg takes part in restoration efforts during a Bonn Challenge summit in Brazil, 2018. Raquel Maia Arvelos, CIFOR


According to Freiberg, a former division head in Germany’s environment ministry, it is essential to consider the context in which the Challenge was born.

Based on the Aichi targets of 2010 and the Cancun Conference of Parties resolutions that same year, the Challenge presented “a window of opportunity,” Freiberg says. “We took that opportunity and raised the profile of restoration to the highest political level. It was taken up by many other governments and international processes and organizations.

“The Bonn Challenge prepared an acceptable initiative for many countries, which gave them a broader goal where they could say, ‘restoration is an issue for us and we contribute to this goal.’

“We did not identify any target or criteria to become part of that initiative,” he adds. “We only said, ‘look, it’s an international goal that everybody can use to organize, on a national level, their own initiatives, strategies, or concepts in order to get restoration started.’ ”

Freiberg remains convinced that if restoration criteria had been imposed on participating governments, the whole enterprise “would not have taken off.”

In that sense, he agrees that the Bonn Challenge is less about carbon maximization and far more about improving livelihoods and getting countries to improve their behavior in managing ecosystems and conserve their natural resources. “This was the driving idea,” he says. “We also want to get deforestation down to zero by 2030.”

Lewis and his co-authors, meanwhile, are calling for countries to increase the proportion of land to be generated into natural forest, especially in the humid tropics, focusing on degraded forests and partly wooded areas. “Each additional 8.6 million hectares sequesters another (petagram) by 2100,” their paper states.

For Freiberg, planting fast-growing trees for commercial purposes on otherwise barren land is a start, and part of an ongoing process. “If there is no other solution then fast-growing trees can be a solution, and are a solution,” he says.

“We do hope that over time, when the first revenues come back, that something changes in the composition, taking up native trees that can be combined and give you over the years a much higher perspective of improving your income.

“But it takes time,” he emphasizes. “It is a process, which is not done in two or three years, but over 30, 40, or 50 years. It’s about changing minds. And this is actually happening on the ground.”

Indeed, as countries’ domestic agroforestry revenues improve, he adds, scientists and NGOs should come together and look for ways to support governments to take the next step and restore ecosystems. “This is the expectation I would have,” he says.

Lewis agrees that industrialized countries “need to pay people in the tropics for that massive uptake in carbon, for essentially bailing the world out for the previous inaction of people in the global north. It’s essential in terms of stabilizing climate that that happens.”

Different countries have to play their differentiated roles,” he says, “and one of those that can be played is in restoring forests where they grow fast and there’s lots of biodiversity. But people from outside need to apply as much assistance, both financial and technical, as possible to help that happen.”

Article tags

Bonn challengecarboncarbon emissionscarbon sequestrationcommoditiesforest landscape restorationlandscape restorationplantationsrestorationsustainable landscapestrees



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