Planting trees remains one of the most effective ways to remove carbon dioxide (CO₂) from the atmosphere, although it is associated with climate and economic uncertainties, experts say in a new study. focused on the United Kingdom. This analysis evaluates various tree planting strategies and provides recommendations for policymakers on how to minimize risks and maximize the effectiveness of this ecological measure.

Key findings of the study

The study shows that large-scale tree planting is key to the decarbonisation plans of many countries, including the UK. However, decisions about the number of trees to plant, their species and where to plant them are subject to considerable uncertainty. For example, species that are suitable today may not thrive in future climate conditions that are constantly changing.

Uncertainty and risks

The researchers emphasize that without a proper strategy, tree planting can pose significant financial risks. Ignoring climatic and economic uncertainties can lead to inefficient investments. To mitigate these risks, they recommend planting diversification and a portfolio approach that allows for risk distribution across different tree species and locations.

Portfolio approach and diversification

Portfolio analysis, unlike traditional scenarios, examines the full range of possible future conditions and allows for the selection of an investment portfolio that achieves a balance between risk and reward. Diversification of species and locations ensures that if one tree species in one area does not perform as expected, other species and locations can compensate for these deficiencies, minimizing overall risk.

Cost-effectiveness of tree planting

Despite the ongoing risks, tree planting is considered a highly cost-effective method of removing CO₂ compared to alternative carbon capture technologies. The study used a spatially explicit integrated environmental-economic model of the UK and analysed different tree planting strategies under 4,000 realistic scenarios of future climate and economic variables.

Integration with other CDR technologies

In addition to tree planting alone, experts recommend incorporating other CO₂ removal technologies into the portfolio of measures. Combining different methods can reduce overall risks and ensure a more stable and effective transition to climate neutrality.

Forest ecosystem services

Planting trees not only provides CO₂ removal, but also a wide range of ecosystem services, such as flood mitigation, improved water quality, biodiversity support, and noise and air pollution reduction. This comprehensive approach increases the overall value of forests and strengthens their role in combating climate change.

Opportunities for developing countries

Developing countries can harness the potential of renewable energy and tree planting to address energy access challenges while contributing to global efforts to reduce emissions. Integrating climate information into planning enables the efficient use of renewable resources and strengthens the energy security of these countries.

The study demonstrates that tree planting, when properly managed and diversified, is a cost-effective and low-risk method of removing CO₂. Combining environmental-economic modelling with modern risk-aversion optimisation methods, it provides policymakers with valuable guidance for complex environmental decisions influenced by climate and economic uncertainties. The paper thus offers important insights for all those involved in shaping sustainable development and climate change strategies, and underlines the importance of integrating different approaches and technologies to achieve global climate goals. Spring

Glossary of terms

• CDR (Carbon Dioxide Removal): Processes that remove carbon dioxide directly from the atmosphere and store it for a long time.
• CER (Climate-Economy Realization): One of 4,000 time-consistent trajectories that describe future climate and economic variables.
• NPV (Net Present Value): The difference between the present value of cash inflows and the present value of cash outflows over a period of time. NPV is used in capital budgeting and investment planning to analyze the profitability of a proposed investment or project.
• SCC (Social Cost of Carbon): An estimate of the monetary value of the damage caused by the emission of one ton of carbon dioxide into the atmosphere in a given year.
• Portfolio Optimization: A mathematical process used to select the best possible portfolio (asset allocation) from a set of portfolios according to a specific objective.
• Risk Aversion: Characteristics of an investor who prefers lower returns with certain risk to higher returns with uncertain risk.
• Downside Risk: The potential for an investment to lose value.
• CVaR (Conditional Value-at-Risk): A risk measure that quantifies the expected loss during an adverse period.
• BECCS (Bioenergy with Carbon Capture and Storage): A process that involves growing biomass, using it to produce energy, and capturing and storing the CO2 that is released during the process.
• DACCS (Direct Air Carbon Capture and Storage): A technology that directly removes CO2 from the air and stores it permanently.
• Hedging: An investment position that is intended to minimize the risk of loss from another investment.