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Disputas: Zachary Scott McGraw

Ph.d.-kandidat Zachary Scott McGraw ved Institutt for geofag, Det matematisk-naturvitenskapelige fakultet, vil forsvare avhandlingen Global radiative impacts of aerosol variations through mixed-phase and cirrus clouds for graden Philosophiae Doctor.

Zachary Scott McGraw. Foto: Privat

Zachary Scott McGraw. Foto: Privat

Disputas og prøveforelesning avholdes digitalt ved bruk av Zoom. Verten av Zoom-møtet vil moderere det tekniske mens disputasleder moderer disputasen. 

Prøveforelesning

30.11.2020, 14:00, Zoom (videolink)

The Role of Clouds in Polar Amplification

Kreeringssammendrag

Aerosoler er samlinger med små luftbårne partikler av for eksempel sot og ørkenstøv. Aerosoler i atmosfæren kan endre jordens klima i en grad som er ukjent, og de gir store usikkerheter ved klimafremskrivninger. Blant annet kan de endre skyenes evner til å reflektere og absorbere stråling. I dette doktorgradsarbeidet er det utført simuleringer av aerosolers klimapåvirkning ved skyer som inneholder is. Studien viser at aerosoler har potensiale for å gi betydelig påvirkning, med naturlige grenser for størrelsen.

Hovedfunn

Populærvitenskapelig artikkel om McGraws avhandling:

Global radiative impacts of aerosol variations through mixed-phase and cirrus clouds

Aerosols can warm or cool the Earth by affecting clouds’ abilities to reflect and absorb radiation. This influence is one of the greatest uncertainties in projections of future climate and limits the ability for the scientific community to bound greenhouse gas impacts.

This dissertation focuses on the potential for aerosol changes to alter Earth’s global climate, particularly by influencing the abilities of ice-containing clouds to form and interact with radiation. Associated impacts are evaluated for the presence of man-made soot aerosol, changes in naturally emitted dust from deserts, and a combination of aerosol changes since the pre-industrial era. Here, global-scale aerosol impacts are quantified and constrained using computer simulations of Earth’s climate system. Findings suggest that man-made soot aerosol may cool the Earth through its influence on ice clouds, while substantial changes to desert dust in clouds may have limited global impacts due to opposing influences on different regions and types of radiation.

As greenhouse emissions continue to pose a global threat, creative ways to offset the resulting warming – known as geoengineering strategies – have been sought. One proposal has been to harness the ability for aerosols to influence ice clouds’ abilities to interact with radiation. An additional component of the dissertation supports the potential for deliberate aerosol injections in ice clouds to counteract the damage from climate change.

Foto og annen informasjon:

Pressefoto: Zachary Scott McGraw, portrett; 280px. Foto: Privat

Publisert 18. nov. 2020 11:41 - Sist endret 27. sep. 2023 13:53