Project

Discipline

Stratospheric aerosol; Ozone layer evolution; Numerical Modeling; Volcanos; Stratospheric dynamics; Future Climate

Lead
Die Ozonschicht schützt Lebewesen vor der Ultraviolettstrahlung der Sonne und hat zudem einen Einfluss auf atmosphärische Winde und das Oberflächenklima. In der zweiten Hälfte des 20. Jahrhunderts wurde die Ozonschicht durch von der Industrie produzierte Chlor enthaltende ozonabbauende Substanzen beschädigt. Das Montreal-Protokoll, welches als Ziel das Einstellen dieser gefährlichen Substanzen und den Schutz der Ozonschicht verfolgte, wurde 1987 unterzeichnet. Die meisten globalen numerischen Modelle sagen eine Erholung der Ozonschicht im 21. Jahrhundert voraus, die Anzeichen der Regeneration sind jedoch nicht streng über Beobachtungsdaten ermittelt worden. Des Weiteren existieren noch immer verschiedene Bedrohungen für die Ozonschicht, deren Auswirkungen auf die Ozonschicht Regeneration untersucht werden sollten.
Lay summary
Inhalt und Ziel des Forschungsprojekts Unsere übergeordneten Ziele sind das Verhalten der Ozonschicht in der Vergangenheit zu verstehen, ihre zukünftige Entwicklung vorhersagen zu können und zusätzliche Massnahmen vorzuschlagen, welche die Regeneration der Ozonschicht sicherstellen sollen. Im Einzelnen werden wir (i) die vergangenen Trends der Ozonschicht in der unteren Stratosphäre erklären, (ii) die Rolle des Montreal-Protokolls im Unterstützen der Ozonschicht-Regeneration und im Schützen des Klimas neu aufarbeiten und (iii) das zukünftige Verhalten der Ozonschicht voraussagen unter Berücksichtigung sehr kurzlebiger Spezies, neu entdeckter ozonabbauenden Substanzen, der Sonnen- und Vulkanaktivität, so wie möglicher Klimainterventionen. Wir möchten zusätzlich (iv) die Unsicherheiten in der Aerosolbelastung bestimmen, indem wir an internationalen Projekten teilnehmen und (v) unser Aerosol-Mikrophysikmodell auf das Erforschen von möglichen explosionsartigen Vulkanausbrüchen in der Zukunft vorbereiten. Wissenschaftlicher und sozialer Kontext des Forschungsprojekts Unsere Arbeit wird neue und wichtige Informationen über den Zustand der Ozonschicht und ihrer Regeneration liefern, sowie über zukünftige Klimaveränderungen. Unsere Resultate werden einen Weg aufzeigen können, wie die Regeneration der Ozonschicht erreicht werden kann, selbst wenn extrem unvorteilhafte zukünftige Szenarien eintreffen sollten, und werden es den politischen Entscheidungsträgern erlauben, eine geeignete Strategie zum Umgehen von Umweltrisiken zu wählen. Das Projekt wird zusätzlich die Teilnahme der Schweiz an internationalen Ozon-Gutachten ausbauen und den Standpunkt der Schweiz in Bezug auf nachhaltige Entwicklung untermauern.

Direct link to Lay Summary

Last update: 19.10.2018

Lead
The ozone layer protects living organisms from the solar ultraviolet radiation and impacts also the atmospheric winds and surface climate. In the second half of 20th century the ozone layer was harmed by chlorine containing ozone destroying substances produced by industries. The Montreal Protocol aimed at phasing out these dangerous species and saving ozone layer was approved in 1987. Most of the global numerical models project the ozone layer recovery in the 21st century, however the recovery signs of it have not been robustly established from observational data. Moreover, there are still a number of different threats for the ozone layer and their implication for the ozone layer recovery should be studied.
Lay summary
Content and goal of the research project Our overarching goal is to understand the past behavior, predict future evolution of the ozone layer and recommend additional measures to guarantee the ozone recovery. In detail, we will (i) explain past ozone layer trends in the lower stratosphere, (ii) revisit the role of the Montreal Protocol in sustaining recovery of the ozone layer and protecting climate and (iii) project future behavior of the ozone layer considering very-short lived species, newly discovered ozone depleting substances, solar and volcanic activity, as well as possible climate intervention. We also aim to evaluate (iv) uncertainties in the stratospheric aerosol loading, by participating in international projects and (v) prepare our aerosol microphysics model for the study of possible future explosive volcanic eruptions. Scientific and social context of the research project Our work will provide new and important information about the ozone layer state and recovery as well as about future climate changes. Our results will advise a way to achieve ozone recovery even if extremely unfavorable future scenarios play out and allow policy makers to choose proper strategy to avoid environmental risks. The project will also allow to expand Switzerland participation in international ozone assessments as well as to underpin Switzerland policy positions on sustainable development.

Direct link to Lay Summary

Last update: 19.10.2018

Number	Title	Start	Funding scheme

Background: The ozone layer plays an important role in shielding the biosphere from dangerous solar ultraviolet radiation, shapes the temperature structure of the stratosphere, and consequently has a direct impact on the general circulation and surface climate. The discovery of the ozone hole led to a strong limitation of the production of halogen containing ozone destroying substances (hODS) in 1987 through the Montreal Protocol and its Amendments (MPA). This measure aimed to be a protective hand over the ozone layer. While global models project an intact future for the ozone layer in the 21st century, its recovery has not been robustly established from observational data. Rationale: The widely expected future ozone recovery and the efficiency of the MPA is now being questioned due to disagreement between models and observations. As such, this now inspires a search for missing processes or unaccounted driving factors in models. Recent publications suggested several candidates: (i) changes in the meridional circulation in a warming climate; (ii) a decline of the solar activity; (iii) the influence of halogen containing very-short lived species; (iv) emissions of halogen containing gases unaccounted for by the MPA; (v) uncertainties in the stratospheric aerosol loading; (vi) the treatment of the diffusion in the global models. All these issues will be carefully investigated in the proposed project. Overall objective: Understand the past behavior, and future prediction of ozone layer evolution. Specific aims: (i) Explain past ozone layer trends in the lower stratosphere. (ii) Revisit the role of the Montreal Protocol in sustaining recovery of the ozone layer and protecting climate. (iii) Project future behavior of the ozone layer considering very-short lived species, newly discovered hODS, solar and volcanic activity, as well as possible climate intervention. (iv) Investigate and suggest additional measures to guarantee ozone layer recovery. (v) Evaluate uncertainties in the stratospheric aerosol loading, by participating in international ISA-MIP project, and estimate its potential impact on the ozone in the lower stratosphere. (vi) Validate the aerosol microphysics module and prepare for future explosive volcanic eruptions participating in international VolRES project.Methods: We intend to use our new atmosphere-ocean-aerosol-chemistry-climate model (AOACCM) SOCOLv4 which consists of MPI-MET Earth System model (ESM) coupled to chemical and sulfate aerosol modules. The model output will be compared to observations and other models using comprehensive statistical tools. Expected results: (i) Establish the processes responsible for the persistent ozone depletion in the lower stratosphere. (ii) Newly assessing and judging the benefits of the MPA, which is an issue of utmost importance for sustainable development of the environment. (iii) Assess the potential danger for the ozone layer recovery from very-short lived substances, newly discovered hODS, solar and volcanic activity, as well as possible climate intervention. (iv) Suggest possible additional measures to guarantee ozone layer recovery. (v) Characterize the uncertainties in stratospheric aerosol loading. Impact: The project will provide understanding and direction how to protect the ozone layer and to make more accurate climate predictions. An impact on society and policy makers is foreseen, because we will suggest a way to guarantee ozone recovery even if extremely unfavorable future scenarios play out. The project will allow to continue Switzerland participation in international assessments and activities aimed at the ozone layer conservation as well as to underpin Switzerland policy positions on sustainable development.