Managing the Risk of Temperature Overshoot

Recent UN analysis suggests that it’s now increasingly likely we will overshoot global warming of 1.5°C. Such overshoot – even if temporary – poses increasingly severe risks to natural and human systems across the planet. Despite accelerated efforts to reduce greenhouse gas emissions, develop carbon removal options and invest in adaptation, the risks of overshoot are becoming increasingly salient. Solar radiation modification is being explored as a potential supplementary option to existing efforts, to help temporarily alleviate some of these risks. But even if effective, solar radiation modification may introduce new risks of its own, and its feasibility and impacts remain poorly understood. Of course, new risks arise from many responses to climate change, including maladaptation, or the adverse side effects of some emissions reduction or removal options.

Given the growing likelihood of temperature overshoot, a precautionary approach to managing the current and future risks it poses, will require a better understanding of the relative risks faced with or without different response options. Improving our ability to answer questions such as “would overall risks to human and natural systems increase with or without solar radiation modification?” will become increasingly important for policymakers thinking about how to reduce exposure to overshoot risks or climate tipping points. Such understanding will also be crucial for strengthening governance of response options that aim to reduce risk, which may or may not include solar radiation modification (for which international governance is currently largely weak or missing).

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