No going back - Limited reversibility of regional climate changes under overshoot

Pfleiderer, Peter; Schleußner, Carl-Friedrich; Sillmann, Jana

doi:10.22541/au.168245326.65777676/v1

Cited by 2 publications

(1 citation statement)

References 30 publications

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“…There is considerable uncertainty in the response of the climate system to the decline of emissions, and it is not clear how reversible GMT is after emissions cease [35][36][37][38] . Regional climate responses show high variability indicating that regional climatic changes might only be partially reversible 39,40 . Further, we cannot exclude that reinforcing feedbacks, which will ultimately lead to tipping, have already been triggered in the slow-onset cryospheric tipping elements 10,17 .…”

Section: Discussionmentioning

confidence: 99%

Achieving net zero greenhouse gas emissions critical to limit climate tipping risks

Möller,

Högner,

Schleussner

et al. 2023

Preprint

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Under current emission trajectories, at least temporarily overshooting the Paris global warming limit of 1.5 °C above pre-industrial levels is a distinct possibility. Permanently exceeding this limit would substantially increase the risks of triggering several climate tipping elements with associated high-end impacts on human societies and the Earth system. It is essential to assess this risk under emission pathways that temporarily overshoot 1.5 °C. Here, we investigate the tipping risks associated with a number of policy-relevant future emission scenarios, using a stylised Earth system model that comprises four interconnected core tipping elements. We find that tipping risks until 2300 increase by 5 % for every tenth of a degree above 1.5 °C if global warming levels do not return to 1.5 °C or lower by the end of this century. If overshoots above 1.5 °C are limited in both peak temperature and duration (return below 1.5 °C in 2100), tipping risks until 2300 can be kept below 3 %. We show that achieving and maintaining at least net-zero greenhouse gas emissions is paramount to minimise tipping risks on multi-century timescales. Our results underscore that stringent emission reductions in the current decade in line with the Paris Agreement 1.5 °C limit are critical for planetary stability.

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Section: Discussionmentioning

confidence: 99%

Achieving net zero greenhouse gas emissions critical to limit climate tipping risks

Möller,

Högner,

Schleussner

et al. 2023

Preprint

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A perspective on the next generation of Earth system model scenarios: towards representative emission pathways (REPs)

Meinshausen,

Schleussner,

Beyer

et al. 2024

Geosci. Model Dev.

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Abstract. In every Intergovernmental Panel on Climate Change (IPCC) Assessment cycle, a multitude of scenarios are assessed, with different scope and emphasis throughout the various Working Group reports and special reports, as well as their respective chapters. Within the reports, the ambition is to integrate knowledge on possible climate futures across the Working Groups and scientific research domains based on a small set of “framing pathways” such as the so-called representative concentration pathways (RCPs) in the Fifth IPCC Assessment Report (AR5) and the shared socioeconomic pathway (SSP) scenarios in the Sixth Assessment Report (AR6). This perspective, initiated by discussions at the IPCC Bangkok workshop in April 2023 on the “Use of Scenarios in AR6 and Subsequent Assessments”, is intended to serve as one of the community contributions to highlight the needs for the next generation of framing pathways that is being advanced under the Coupled Model Intercomparison Project (CMIP) umbrella, which will influence or even predicate the IPCC AR7 consideration of framing pathways. Here we suggest several policy research objectives that such a set of framing pathways should ideally fulfil, including mitigation needs for meeting the Paris Agreement objectives, the risks associated with carbon removal strategies, the consequences of delay in enacting that mitigation, guidance for adaptation needs, loss and damage, and for achieving mitigation in the wider context of societal development goals. Based on this context, we suggest that the next generation of climate scenarios for Earth system models should evolve towards representative emission pathways (REPs) and suggest key categories for such pathways. These framing pathways should address the most critical mitigation policy and adaptation plans that need to be implemented over the next 10 years. In our view, the most important categories are those relevant in the context of the Paris Agreement long-term goal, specifically an immediate action (low overshoot) 1.5 °C pathway and a delayed action (high overshoot) 1.5 °C pathway. Two other key categories are a pathway category approximately in line with current (as expressed by 2023) near- and long-term policy objectives, as well as a higher-emission category that is approximately in line with “current policies” (as expressed by 2023). We also argue for the scientific and policy relevance in exploring two “worlds that could have been”. One of these categories has high-emission trajectories well above what is implied by current policies and the other has very-low-emission trajectories which assume that global mitigation action in line with limiting warming to 1.5 °C without overshoot had begun in 2015. Finally, we note that the timely provision of new scientific information on pathways is critical to inform the development and implementation of climate policy. Under the Paris Agreement, for the second global stocktake, which will occur in 2028, and to inform subsequent development of nationally determined contributions (NDCs) up to 2040, scientific inputs are required by 2027. These needs should be carefully considered in the development timeline of community modelling activities, including those under CMIP7.

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No going back - Limited reversibility of regional climate changes under overshoot

Cited by 2 publications

References 30 publications

Achieving net zero greenhouse gas emissions critical to limit climate tipping risks

Achieving net zero greenhouse gas emissions critical to limit climate tipping risks

A perspective on the next generation of Earth system model scenarios: towards representative emission pathways (REPs)

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