UN Warns Tree Planting May Backfire As Climate Fix, Says Wildfire Risks Could Make It Worse

Tree planting has long been promoted as a powerful tool to fight climate change. Trees absorb carbon dioxide from the air, store it, and help cool the planet. But a new United Nations-affiliated report warns that in some regions, planting more trees could actually worsen global warming.

The report was released by the United Nations University Institute for Water, Environment and Health (UNU-INWEH), and it says that wildfires are now turning forests, once considered climate heroes, into massive sources of carbon emissions.

How trees can become carbon emitters

In recent years, wildfires have become more frequent and intense in places like Canada, Australia, the Amazon, and Siberia. In 2023, Canadian forest fires alone released more greenhouse gases than any country in the world except China and India.

The report says that climate policies, including those involving carbon offsets and reforestation, often fail to consider the emissions caused by such fires. This is especially true in systems like the voluntary carbon market, where companies pay to protect or plant forests to "offset" their own pollution.

But if these forests burn, all the carbon stored in the trees is released, sometimes in much larger amounts than expected, adding to climate change instead of reducing it.

Why carbon offset systems may be flawed

The voluntary carbon market is largely unregulated and depends on assumptions that forests will remain intact for decades. However, the report says that these assumptions are often based on outdated science and historical fire data that no longer reflect today's reality.

“Forests are changing,” said lead author Ju Hyoung Lee.“We can't treat them like they were 20 years ago.”

Certification agencies like Verra, which approve forest projects for carbon offsets, often underestimate fire risks because they don't fully include recent wildfire data. These agencies may overlook how fast-growing trees in hotter, drier climates are more likely to catch fire and burn quickly.

More trees, more fire risk?

While planting trees might seem like an obvious climate solution, the report warns that it can backfire in regions prone to heatwaves and drought. Fast-growing forests can actually dry out the soil and create more fuel for future fires.

This creates a dangerous cycle: climate change causes more heat and drought, which makes forests more flammable. Then, when wildfires erupt, they release even more carbon into the atmosphere, making climate change worse.

"Planting more and more trees in such an environment will likely increase carbon emissions due to future fires," the report states.

What can be done?

The report calls for major changes in how forest-based climate programs are designed and approved. It recommends:

• Monitoring forest conditions more carefully.
• Using satellite data to spot areas at high wildfire risk.
• Updating certification standards to include recent fire trends.
• Considering rainfall patterns, soil health, and future climate risks before planting trees.

Kaveh Madani, director of UNU-INWEH, said:“Not all forest programs are bad, but if we keep using outdated science and ignore growing wildfire threats, we risk making the climate crisis even worse.”

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