Evaluating temporal trade-offs in climate effects from carbon dioxide removal strategies across different metrics

Strategies to remove carbon dioxide from the atmosphere, known as carbon dioxide removal (CDR), are being pursued given the urgency of climate change. However, CDR measures may unintentionally increase emissions of other climate forcers. If emissions of potent short-lived climate forcers (like methane) are increased, the CDR mechanism could potentially worsen climate change in the near-term despite benefiting the climate in the long-term. This temporal trade-off can be easily overlooked when employing the standard climate metric used for assessments— carbon dioxide equivalent (CO 2 e) using a 100 year global warming potential (GWP)—because it solely conveys the long-term warming impacts of a pulse of emissions. A more sophisticated assessment method is needed to reveal potential temporal trade-offs in climate benefits—important information for effective decision making. In this study, we compare three climate impact assessment approaches of increasing complexity to evaluate temporal trade-offs in climate benefits from CDR strategies: (1) the standard CO 2 e using GWP approach with both 20 and 100 year time horizons (GWP20 and GWP100, respectively, or dual-valued CO 2 e); (2) a variation of GWP that considers the climate impact of continuous emissions over time (known as technology warming potential (TWP); and (3) reduced complexity climate models. We use wetland restoration as a case study because studies have shown that it may remove carbon dioxide from the atmosphere, while also increasing methane emissions. Analyzing eleven rewetting scenarios, we find that all approaches identify temporal tradeoffs. The TWP and reduced complexity climate model results are largely consistent and reveal drawbacks of the dual-valued CO 2 e that considers pulse rather than continuous emissions. Given the accessibility of the TWP approach relative to reduced complexity climate models, we recommend its use for most stakeholders. Overall, our findings emphasize the need to thoroughly assess potential climate trade-offs of CDR measures across all timescales

Atmospheric sciences · Biology · Carbon dioxide · Carbon dioxide in Earth's atmosphere · Carbon sequestration · Climate change · Climatology · Wetland · Climate Change Policy and Economics · demographic modeling and climate adaptation · Environmental Science · Peatlands and Wetlands Ecology · Ecology · Geology

• Greenhouse-gas emission targets for limiting global warming to 2 °C

  Open Access•Malte Meinshausen, Nicolai Meinshausen et al.•Nature•2009

  Add to list

• The Empirics of Wetland Valuation

  Open Access•Luke M Brander, Raymond J G M Florax et al.•Environmental and Resource…•2006

  Add to list

• Emulating coupled atmosphere-ocean and carbon cycle models with a simpler model, Magicc6 – Part 1

  Open Access•Malte Meinshausen, S C B Raper et al.•Atmospheric Chemistry and Physics•2011

  Add to list

• The shared socio-economic pathway (SSP) greenhouse gas concentrations and their extensions to 2500

  Open Access•Malte Meinshausen, Zebedee Nicholls et al.•Geoscientific Model Development•2020

  Add to list

• Acting rapidly to deploy readily available methane mitigation measures by sector can immediately slow global warming

  Open Access•Ilissa Ocko, Tianyi Sun et al.•Environmental Research Letters•2021

  Add to list

• Significant feedbacks of wetland methane release on climate change and the causes of their uncertainty

  Open Access•Nicola Gedney, Chris Huntingford et al.•Environmental Research Letters•2019

  Add to list