Net zero-emission pathways reduce the physical and economic risks of climate change

Drouet, Laurent; Bosetti, Valentina; Padoan, Simone A.; Reis, Lara Aleluia; Bertram, Christoph; Longa, F. Dalla; Després, Jacques; Emmerling, Johannes; Fosse, Florian; Fragkiadakis, Kostas; Frank, Stefan; Fricko, Oliver; Fujimori, Shinichiro; Harmsen, Mathijs; Krey, Volker; Oshiro, Ken; Nogueira, Larissa P.; Paroussos, Leonidas; Piontek, Franziska; Riahi, Keywan; Rochedo, Pedro; Schaeffer, Roberto; Takakura, Jun’ya; Wijst, Kaj-Ivar van der; Zwaan, Bob van der; Vuuren, Detlef van; Vrontisi, Zoi; Weitzel, Matthias; Zakeri, Behnam; Tavoni, Massimo

doi:10.1038/s41558-021-01218-z

Cited by 52 publications

(39 citation statements)

References 39 publications

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“…To further analyse the characteristics of scenario categories beyond the analysis in AR6 we use the concept of overshoot degree years (ODY), which is similar to what was shown as "overshoot severity" in Table 2.SM.12 in SR1.5 (Forster et al, 2018), and was included in the metadata of the SR1.5 scenario database (Rogelj et al, 2018;Huppmann et al, 2018b) as "exceedance severity". Inspired by Geden and Löschel, (2017) and recent scenario studies investigating temperature overshoot (Drouet et al, 2021;Riahi et al, 2021;Johansson, 2021;Tachiiri et al, 2019).…”

Section: Overshoot Degree Yearsmentioning

confidence: 99%

The IPCC Sixth Assessment Report WGIII climate assessment of mitigation pathways: from emissions to global temperatures

Kikstra

Nicholls

Smith

et al. 2022

Preprint

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Abstract. While the IPCC’s physical science report usually assesses a handful of future scenarios, the IPCC Sixth Assessment Working Group III report (AR6 WGIII) on climate mitigation assesses hundreds to thousands of future emissions scenarios. A key task is to assess the global-mean temperature outcomes of these scenarios in a consistent manner, given the challenge that the emission scenarios from different integrated assessment models come with different sectoral and gas-to-gas coverage and cannot all be assessed consistently by complex Earth System Models. In this work, we describe the “climate assessment” workflow and its methods, including infilling of missing emissions and emissions harmonisation as applied to 1,202 mitigation scenarios in AR6 WGIII. We evaluate the global-mean temperature projections and effective radiative forcing characteristics (ERF) of climate emulators FaIRv1.6.2, MAGICCv7.5.3, and CICERO-SCM, discuss overshoot severity of the mitigation pathways using overshoot degree years, and look at an interpretation of compatibility with the Paris Agreement. We find that the lowest class of emission scenarios that limit global warming to “1.5 °C (with a probability of greater than 50 %) with no or limited overshoot” includes 90 scenarios for MAGICCv7.5.3, and 196 for FaIRv1.6.2. For the MAGICCv7.5.3 results, “limited overshoot” typically implies exceedance of median temperature projections of up to about 0.1 °C for up to a few decades, before returning to below 1.5 °C by or before the year 2100. For more than half of the scenarios of this category that comply with three criteria for being “Paris-compatible”, including net-zero or net-negative greenhouse gas (GHG) emissions, are projected to see median temperatures decline by about 0.3–0.4 °C after peaking at 1.5–1.6 °C in 2035–2055. We compare the methods applied in AR6 with the methods used for SR1.5 and discuss the implications. This article also introduces a ‘climate-assessment’ Python package which allows for fully reproducing the IPCC AR6 WGIII temperature assessment. This work can be the start of a community tool for assessing the temperature outcomes related to emissions pathways, and potential further work extending the workflow from emissions to global climate by downscaling climate characteristics to a regional level and calculating impacts.

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Section: Overshoot Degree Yearsmentioning

confidence: 99%

The IPCC Sixth Assessment Report WGIII climate assessment of mitigation pathways: from emissions to global temperatures

Kikstra

Nicholls

Smith

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Under overshoot pathways, important differences between regions are expected in the magnitude, duration, and spatial patterning of extreme events. For example, Brazil and western and southern Africa are projected to be particularly at risk of heatwaves under a 1.5°C overshoot scenario [ 16 ]. In general, climate-related extreme events are projected to be unevenly distributed across the world under global warming, with tropical and subtropical regions experiencing larger increases in exposure to extreme events compared to higher latitudes [ 28 ].…”

Section: The Press and Pulse Of Temperature Overshootmentioning

confidence: 99%

“…Overshoot scenarios are also expected to have larger negative impacts relating to crop growth duration, drought and impacts from climate extremes than scenarios with no overshoot [ 16 ]. Reduced agricultural productivity under overshoot could further transform natural tracts of land for agriculture.…”

Section: Risks From Land-use Change For Temperature Overshootmentioning

confidence: 99%

“…A temperature overshoot is defined as the temporary exceedance of a specified global warming level followed by a decline to or below that level during a specified time period [ 14 ]. Indeed, the IPCC Special Report on global warming of 1.5°C indicates that the majority of emissions scenarios (90%) limiting warming to 1.5°C by 2100 include a temperature overshoot period [ 15 ], although more recent scenario approaches produce a wider set of no or very limited overshoot pathways [ 16 ]. The magnitude of the overshoot can vary widely, and in most scenarios the duration of the overshoot is at least a decade and typically multiple decades.…”

Section: Introductionmentioning

confidence: 99%

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Risks to biodiversity from temperature overshoot pathways

Meyer

Bentley

Odoulami

et al. 2022

Phil. Trans. R. Soc. B

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Temperature overshoot pathways entail exceeding a specified global warming level (e.g. 1.5°C or 2°C) followed by a decline in warming, achieved through anthropogenically enhanced CO 2 removal from the atmosphere. However, risks to biodiversity from temperature overshoot pathways are poorly described. Here, we explore biodiversity risks from overshoot by synthesizing existing knowledge and quantifying the dynamics of exposure and de-exposure to potentially dangerous temperatures for more than 30 000 species for a 2°C overshoot scenario. Our results suggest that climate risk to biodiversity from temperature overshoot pathways will arrive suddenly, but decrease only gradually. Peak exposure for biodiversity occurs around the same time as peak global warming, but the rate of de-exposure lags behind the temperature decline. While the global overshoot period lasts around 60 years, the duration of elevated exposure of marine and terrestrial biodiversity is substantially longer (around 100 and 130 years, respectively), with some ecological communities never returning to pre-overshoot exposure levels. Key biodiversity impacts may be irreversible and reliance on widespread CO 2 removal to reduce warming poses additional risks to biodiversity through altered land use. Avoiding any temperature overshoot must be a priority for reducing biodiversity risks from climate change, followed by limiting the magnitude and duration of any overshoot. More integrated models that include direct and indirect impacts from overshoot are needed to inform policy. This article is part of the theme issue ‘Ecological complexity and the biosphere: the next 30 years’.

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“…The combination of carbon pricing and extraction bans anticipates decarbonization because the production constraint created by the extraction ban in the supply regions is more binding than the implicit constraint produced by carbon pricing. Thus, integrating fossil-extraction bans with global carbon pricing increases the mitigation effort early on and reduces the reliance on NETs (Figure 2 (b)), a desirable feature both because these technologies are currently expensive and unavailable at scale and because lower budget overshoot reduces climate risk 20 . This is especially visible for the WITCH model (11% reduction of carbon sequestered by Biomass with Carbon Capture and Storage, 36% reduction of carbon avoided by fossil CCS, 96% reduction of carbon sequestered by Direct Air Capture, cumulative values to 2100) which relies more in negative emissions, but holds true also for TIAM-UCL (3% reduction in carbon sequestered by BECCS and 6% reduction of carbon avoided by fossil CCS), REMIND (35% reduction of carbon sequestered by DAC, 35% reduction of carbon avoided by fossil CCS and 2.5% reduction of carbon sequestered by BECCS), and PROMETHEUS (9% reduction of Fossil CCS and 18% reduction of BECCS in 2050).…”

Section: Emission Pathways and Carbon Budgetsmentioning

confidence: 99%

Fossil-extraction bans are not enough to achieve the Paris agreement but can facilitate it

Andreoni

Reis

Drouet

et al. 2021

Preprint

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Given concerns about the ambition and effectiveness of current climate pledges, a case has been made for the integration of demand-side policies such as carbon pricing with supply-side bans on fossil fuel extraction. However, little is known about their interplay in the context of climate stabilization. Here, we present the first multi-model assessment quantifying the effectiveness of supply-side policies and their interactions with demand-side ones. We design narratives of fossil fuel bans and explore a variety of scenarios with four process-based integrated assessment models. We find that supply side treaties reduce emissions but not enough to stabilize temperature increase to well below 2°C. When combined with demand-side policies, supply side policies reduce the required carbon price to meet the Paris goals, dampen reliance on CO2 removal and increase investment in renewable energy while increasing fossil producer revenues. The results indicate the opportunity to integrate price-based policies with fossil bans when exploring climate neutrality pathways.

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Net zero-emission pathways reduce the physical and economic risks of climate change

Cited by 52 publications

References 39 publications

The IPCC Sixth Assessment Report WGIII climate assessment of mitigation pathways: from emissions to global temperatures

The IPCC Sixth Assessment Report WGIII climate assessment of mitigation pathways: from emissions to global temperatures

Risks to biodiversity from temperature overshoot pathways

Fossil-extraction bans are not enough to achieve the Paris agreement but can facilitate it

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