Governments globally are committed to increasing forest cover to absorb greenhouse gases, with the UK aiming to plant 30,000 hectares of trees annually until 2050. However, environmental economists warn that transforming farmland into forests carries significant risks, particularly in the context of climate change and economic instability.

Key concerns include the potential displacement of agricultural activities, which could impact food security depending on the location and scale of reforestation efforts.

The study, published in the Proceedings of the National Academy of Sciences (PNAS), examines the UK as a case study, illustrating the complexities introduced by economic and climate uncertainties when balancing carbon removal with agricultural demands.

Lead author Frankie Cho, a PhD graduate from the University of Exeter, explained: "One problem is that, because it is unclear what countries around the world will do to tackle climate change - we don't know how challenging the climate will be in the future. If climate change is extreme, broadleaf trees in southern UK offer the best carbon removal - but that's prime farmland and could be really costly under certain economic futures.

"If climate change is milder, planting conifers on less productive land makes more sense, but those trees will not grow well if conditions are more extreme. The problem is that we don't know what the future holds and can't be certain which type of trees we need to plant and where."

Despite these risks, the research demonstrates that tree planting remains the most cost-effective approach to carbon removal, leveraging recent advancements in decision-making under uncertainty. The study suggests a diversified 'portfolio' approach-planting a mix of tree species across different locations-to mitigate risks and avoid over-reliance on any single planting strategy.

This approach helps minimize potential setbacks from unexpected climate and economic shifts, ensuring that tree-planting efforts remain robust in various future scenarios.

The study further argues that implementing such diversified strategies enhances cost-effectiveness compared to alternative carbon removal methods, such as biomass energy with carbon capture and storage or direct air capture technologies.

Co-author Professor Brett Day from the University of Exeter emphasized: "We don't have any other option that can remove carbon from the atmosphere at the scale and cost that we need to meet our Net Zero targets. While tree-planting carries risks, our study shows that, if done strategically, it remains the best solution we have."

Research Report:Resilient tree-planting strategies for carbon dioxide removal under compounding climate and economic uncertainties

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