Old Forests Store More Carbon than Young Ones—and That Matters for US Climate Goals

A new paper shows that because mature forests store substantially more carbon than young forests, avoiding losses of existing forests provides more carbon storage benefits than adding new forests.


Oct. 19, 2023

News Type

Press Release

💡 What’s the story?

Forests, which remove carbon dioxide from the atmosphere, are key players in the United States’ quest to meet its climate goals. But a new paper published by researchers from Resources for the Future (RFF) shows that not all forests are the same. The team shows that because mature forests store substantially more carbon than young forests, avoiding losses of existing forests provides more carbon storage benefits than adding new forests.

The findings are relevant to both policy and academic circles. Some major models and policy decisions keep tabs primarily on the net loss or growth of US forests, assuming that deforestation can be offset by afforestation in a one-to-one ratio.

However, the new RFF modeling shows that this is not the case: avoided deforestation has twice the carbon benefits as afforestation. The results show that interactions between forest conditions and land use are more complicated than common “net-change” models may suggest. Failing to consider these complexities, the researchers point out, can lead experts and policymakers to overestimate the value of afforestation as part of US climate strategy.

“We know that forests are effective carbon sinks, but they are complicated systems that are challenging to model. Our results show that there are significant interactions between land-use changes and forest conditions that make some forests better at carbon storage than others.”

—David Wear, Nonresident Senior Fellow

📈 How do we know? 

A new RFF model, the Carbon and Land Use Model (CALM), considers forest conditions such as age and management strategies, as well as land-use information to pinpoint forests’ carbon dioxide removal capabilities.

The researchers compared their detailed modeling results to results from a net-change model to see how the estimates differed over a 45-year period. They found that the net-change model underestimated carbon dioxide removal loss due to forest land-use change by 54–59 percent.

While the disparity was stronger in some regions than in others, the net-change model underestimated carbon dioxide removal capabilities in all ecological provinces across the United States.

🌲 What does this mean for climate policies?

The research suggests that policies hinging on the mantra of “no net forest loss” are less helpful for meeting US climate goals than policies that prevent deforestation specifically. While the carbon removal benefits of afforestation do eventually even out with the benefits of prevented deforestation, the scales don’t balance until years after US climate goals need to be met. Afforestation programs coupled with avoided deforestation provides the policy pathway with the greatest potential to expand forest climate benefits.

At the core of the new research is the idea that accurate modeling informs good policy. With accurate data and modeling that does not assume that the costs of deforestation and benefits of afforestation cancel each other out, decisionmakers can design strategies that maximize carbon dioxide removal and protect valuable carbon sinks.

“We found that it is incredibly beneficial to keep mature forests around. Planting trees to make up for deforestation isn’t an ideal solution. It’s important that policymakers and researchers consider this: We don’t want to be left scratching our heads in a warmer world and wondering where our math went wrong.”

—Matthew Wibbenmeyer, Fellow

📚 Where can I learn more?

To learn more, read the working paper, “Land-Use Change, No-Net-Loss Policies, and Effects on Carbon Dioxide Removals,” by RFF Nonresident Senior Fellow David N. Wear and Fellow Matthew Wibbenmeyer.

Resources for the Future (RFF) is an independent, nonprofit research institution in Washington, DC. Its mission is to improve environmental, energy, and natural resource decisions through impartial economic research and policy engagement. RFF is committed to being the most widely trusted source of research insights and policy solutions leading to a healthy environment and a thriving economy.

Unless otherwise stated, the views expressed here are those of the individual authors and may differ from those of other RFF experts, its officers, or its directors. RFF does not take positions on specific legislative proposals.

For more information, please see our media resources page or contact Media Relations and Communications Specialist Annie McDarris.

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