Abstract
Adapting to increasing climate risks while deploying renewables to stabilize the climate will require large amounts of energy and materials, which will initially cause emissions. We provide an estimate of the CO
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emissions embedded in this broader climate transition, which were previously poorly quantified. Fossil fuel energy use to deploy renewables contributes the vast majority of embedded emissions, with a much smaller contribution from adaptation. As a result, embedded emissions increase substantially for slower decarbonization pathways. However, when renewables are rapidly deployed, the ongoing transition can be powered by cleaner energy, minimizing embedded emissions. Our results demonstrate an underappreciated benefit of enhanced climate ambition and the importance of accounting for embedded transition emissions to achieve climate objectives.
Climate change necessitates a global effort to reduce greenhouse gas emissions while adapting to increased climate risks. This broader climate transition will involve large-scale global interventions including renewable energy deployment, coastal protection and retreat, and enhanced space cooling, all of which will result in CO
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emissions from energy and materials use. Yet, the magnitude of the emissions embedded in these interventions remains unconstrained, opening the potential for underaccounting of emissions and conflicts or synergies between mitigation and adaptation goals. Here, we use a suite of models to estimate the CO
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emissions embedded in the broader climate transition. For a gradual decarbonization pathway limiting warming to 2 °C, selected adaptation-related interventions will emit ∼1.3 GtCO
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through 2100, while emissions from energy used to deploy renewable capacity are much larger at ∼95 GtCO
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. Together, these emissions are equivalent to over 2 y of current global emissions and 8.3% of the remaining carbon budget for 2 °C. Total embedded transition emissions are reduced by ∼80% to 21.2 GtCO
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under a rapid pathway limiting warming to 1.5 °C. However, they roughly double to 185 GtCO
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under a delayed pathway consistent with current policies (2.7 °C warming by 2100), mainly because a slower transition relies more on fossil fuel energy. Our results provide a holistic assessment of carbon emissions from the transition itself and suggest that these emissions can be minimized through more ambitious energy decarbonization. We argue that the emissions from mitigation, but likely much less so from adaptation, are of sufficient magnitude to merit greater consideration in climate science and policy.
