Mr Benjamin Redmond Roche

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Arctic sea ice has significantly declined over the past few decades and is predicted to be ice free by the year 2050. Hosting up to 13% of global undiscovered oil reserves and with potential northern shipping routes decreasing transit time by up to 40%, the race to exploit the Arctic is on. The albedo of sea ice is an important component of the Earth’s climate system and plays a key role in global climate change. The albedo of sea ice is also very sensitive to material that act as light absorbing impurities; whilst the effects of black carbon and atmospheric aerosols have previously been described in literature, the effects of oil pollution have not. What is particularly poorly understood is how oil exists at low concentrations over a large spatiotemporal range in cold environments and what their climatic significance may be. Therefore, the primary aim of this thesis is to parameterise the effect of crude oil pollution on sea ice albedo so that an increasingly polluted Arctic can be included in global climate models. 

The thesis is presented as a joint radiative-transfer modelling and experimental study. The radiative-transfer modelling component utilises a coupled atmosphere snow/sea ice model (TUV-snow) that is capable of calculating radiative-transfer parameters from the top of the atmosphere into surface layers of snow and sea ice. Three different types of sea ice (melting, first-year and, multi-year) are assessed for the sensitivity of their albedo to increasing amounts of crude oil. Previously, the model has successfully been applied for both black carbon and atmospheric aerosols and this is the first time that it is used for crude oil. The experimental component utilises the sea ice simulator based at RHUL, allowing for reflectance measurements of artificial sea ice doped with known concentrations of crude oil. These results are then used to validate the accuracy of the TUV-snow model in predicting the light reflectance and extinction coefficient of sea ice as a function of wavelength at different concentrations of crude oil.  

Ultimately, this research provides a quantitative assessment of the climatic effect of crude oil pollution in polar sea ice. I am also interested in the ecology of sea ice ecosystems, particularly how PAR (photosynthetically active radiation) is affected by changes to the ice pack, and continue to collaborate with the ECRU at the University of Helsinki. Additionally, I am learning about the numerous solutions we have to meet the requirements of the energy transition through the training provided by the GeoNetZero CDT.


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