Assessing the Future of The Arctic Sea Ice Cover: Processes, Variability and Implications

Graduate Thesis Or Dissertation

Citations

Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/b5644s77x

Abstract

Uncertainty in climate predictions arises from three distinct sources: the internal variability of the climate system, which refers to natural fluctuations in climate that occur even in the absence of external forcing, model or structural uncertainty, as different models make different assumptions and hence simulate somewhat different changes in climate in response to the same forcing, and scenario uncertainty, which represents humankind’s free will concerning future climate change. In this thesis, we evaluate projections of Arctic sea ice in the context of these different sources of uncertainty. In particular, we show that internal variability, not scenario uncertainty, will ultimately determine the year of first summer ice-free conditions in the Arctic, in addition to the contribution from model uncertainty. Moreover, the increased inter-annual variability in late historical biomass burning forcing is found to cause a strong acceleration in sea ice decline in the early 21^st century in several CMIP6 models, with model uncertainty affecting how different CMIP6 models respond to this forcing. Finally, we focus on the implications of scenario uncertainty on the changing sea ice cover through the lens of trans-border exchange of sea ice between the exclusive economic zones of the Arctic states. These different perspectives on climate model uncertainty allow for an improved understanding of the processes, variability and implications of a diminishing Arctic sea ice cover.

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