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An observational constraint on the uncertainty in stratospheric water vapour projections

Nowack, Peer ORCID iD icon 1; Ceppi, Paulo; Davis, Sean; Chiodo, Gabriel; Ball, Will; Diallo, Mohamadou A.; Hassler, Birgit; Jia, Yue; Keeble, James; Joshi, Manoj
1 Institut für Theoretische Informatik (ITI), Karlsruher Institut für Technologie (KIT)

Abstract:

Future increases in stratospheric water vapour (SWV) risk amplifying climate change and slowing down the recovery of the ozone layer. However, state-of-the-art climate models strongly disagree on the magnitude of these increases under global warming1,2. Uncertainty primarily arises from the challenges inherent in modelling the many complex processes leading to dehydration of air during its tropical ascent into the stratosphere3. Here we derive an observational constraint on this longstanding uncertainty factor in Earth's climate change response. Following a statistical learning approach4,5, we infer historical co-variations between the UTLS temperature structure and tropical lower SWV concentrations. For climate models, we demonstrate that these historically constrained relationships are also highly predictive of the SWV response under strong 4xCO1,2 forcing. By extension, we obtain an observationally constrained range for concentration changes per degree of global warming of 0.31±0.39 ppmv K-1 (90% confidence interval). Our constraint represents a 50% decrease in the 95th percentile of the climate model uncertainty distribution, which has major implications for surface warming, ozone recovery, and the tropospheric circulation response under climate change.
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Zugehörige Institution(en) am KIT Institut für Theoretische Informatik (ITI)
Publikationstyp Proceedingsbeitrag
Publikationsjahr 2024
Sprache Englisch
Identifikator KITopen-ID: 1000171457
Erschienen in EGU General Assembly 2023, Wien, 24th –28th Apr 2023 (EGU23)
Veranstaltung European Geosciences Union General Assembly (EGU 2023), Wien, Österreich, 23.04.2023 – 28.04.2023
Verlag Copernicus
Serie EGU23 ; 2943
Vorab online veröffentlicht am 15.05.2023
Nachgewiesen in OpenAlex
Dimensions
Globale Ziele für nachhaltige Entwicklung Ziel 13 – Maßnahmen zum Klimaschutz

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Originalveröffentlichung
DOI: 10.5194/egusphere-egu23-2943
Seitenaufrufe: 21
seit 10.06.2024
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