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Historically, undisturbed forests have played a crucial role in mitigating climate change by absorbing approximately 7.8 billion tonnes of CO2 each year, which amounts to nearly 20% of all human-generated emissions. However, recent findings from the Potsdam Institute for Climate Impact Research (PIK) indicate that this vital carbon storage function is facing increasing hazards due to climate change and human activities such as deforestation. This research raises concerns that neglecting the potential decline in forests’ carbon absorption capacity may severely hinder efforts to meet the targets established by the Paris Agreement, making the objectives not only more challenging but also more costly.
According to Michael Windisch, the principal researcher behind the study published in Nature Communications, “Delaying action leads to disproportionately higher costs.” Windisch elucidates that current climate strategies presume that forests will not only remain undamaged but will also expand. Yet, with the frequency of devastating wildfires, particularly in areas like California, and ongoing deforestation in the Amazon, this assumption becomes increasingly precarious. The study warns that climate change threatens the substantial carbon reservoirs within forests and calls for immediate action to safeguard these resources. Windisch asserts, “If we do not act now to protect the carbon locked in our forests, the financial burden of compensating for potential losses will force us to implement more severe emissions reductions in critical sectors such as energy, industry, and transportation, making those targets increasingly unattainable.”
Understanding the implications of forest carbon loss for climate strategies
The research explores how climate goals can still be met, even with the expectation that forest carbon storage may diminish. The authors employed the REMIND-MAgPIE model, which integrates global land and water use along with energy-economy modeling, in conjunction with the LPJmL global vegetation model to study the implications of natural disturbances and human influence on forests. This rigorous analysis compares proactive policy responses against several scenarios characterized by delayed or shortsighted approaches.
The findings reveal a dramatic escalation in the costs tied to inaction. The authors found that even a mere five-year delay in addressing forest carbon loss could result in a doubling of both the stringency and expense associated with compensatory measures. For example, emissions cuts required in the energy sector would need to be significantly intensified, necessitating an almost two-fold increase in negative emissions capacity, which would in turn require an expansion of land usage. Such additional efforts would inevitably heighten overall costs and could lead to economic setbacks approximately twice as severe as those incurred with prompt action.
Furthermore, the study draws attention to the likelihood that prevailing models may have an overly optimistic outlook on future forest carbon storage, as they tend to overlook disturbances, overestimate CO2 fertilization effects, and underestimate rates of deforestation. To effectively address climate impacts, preserve carbon stocks, and mitigate growing costs, the authors advocate for immediate interventions. Florian Humpenöder, a PIK researcher and co-author of the study, emphasizes the necessity for stringent monitoring of forests to quickly detect declines in carbon sink capacity. He calls for enhanced forest conservation efforts and accelerated decarbonization to ensure realistic projections of forest carbon storage.
“Achieving climate goals while remaining below critical temperature thresholds necessitates more than merely relying on the assumption that forests will stay intact,” concludes Alexander Popp, head of PIK’s Land Use Transition lab and co-author of the study. “In addition to preserving forests, promoting sustainable land use practices is vital—not only for maintaining biodiversity but also to avert severe economic repercussions and secure a stable climate future.”
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