The PhD defence and trial lecture will be held in Auditorium 1 in The Geology Building. In some cases, it will be possible to attend the trial lecture and dissertation digitally, in that case a link to Zoom will be posted.
Trial lecture
Tuesday 20 May, 10:15-11:00, Aud 1, The Geology Building:
The physical science of climate intervention: benefits, perils, and pitfalls
Conferral summary (in Norwegian)
Store vulkanutbrudd kan påvirke klimaet ved utslipp av gasser og aerosoler. I sin doktorgradsavhandling har Tómas Zoëga undersøkt klimapåvirkningen av effusive vulkanutbrudd, som er utbrudd uten eksplosiv aktivitet Resultatene fra studien viser at islandske effusive vulkanutbrudd fører til nedkjøling om sommeren, både på høye og midlere breddegrader. Om vinteren fører slike effusive vulkanutbrudd derimot til oppvarming i Arktis.
Main research findings
Popular scientific article about Zoëga`s dissertation:
The climate response to high-latitude effusive volcanic eruptions
Effusive volcanic eruptions are characterised by non-explosive activity. They are relatively gentle compared to their explosive counterparts, often resembling boiling stews rather than fireworks. They can impact climate through their emission of gases into the troposphere and the subsequent formation of aerosols. These aerosols, which are small particles suspended in air, reflect sunlight (shortwave radiation; SW) back to space, leading to cooling of the climate. They also interact with clouds and change their properties. This can lead to clouds reflecting more sunlight, resulting in cooling (the cloud albedo effect), but also increase their ability to trap thermal radiation from the Earth (longwave radiation; LW) close to the ground, resulting in warming (the cloud blanket effect).
In this doctoral thesis, Tómas Zoëga investigates the climate response to high-latitude, long-lasting, effusive volcanic eruptions. This is systematically explored through modelling and observational evidence. The results reveal a highly regional response with a strong seasonal dependency. In agreement with previous studies, these eruptions are found to cause cooling during summer across latitudes. During winter, however, this study finds that effusive volcanic eruptions lead to surface warming in the Arctic through enhanced trapping of terrestrial thermal radiation by thin low-level clouds under limited sunlight. These results highlight processes which play disproportionally large roles in the Arctic, such as the cloud blanket effect mentioned above, and can help us better understand this vulnerable part of the Earth system under the ongoing climate change.
Photo and other information:
Press photo: Tómas Zoëga, portrait; 1500px. Photo: Private
Other photo material: Figure with description and credit as specified in the article above, size 2000px.
