Engaging in Climate Change: Arctic Cloud-Sea Ice Feedbacks in Observations, Climate Models, and the Classroom

Morrison, Ariel Lena

Graduate Thesis Or Dissertation

Engaging in Climate Change: Arctic Cloud-Sea Ice Feedbacks in Observations, Climate Models, and the Classroom Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/mw22v5474

Abstract

The Arctic is the fastest changing region in the world in response to increased greenhouse gas emissions and is projected to become seasonally sea ice-free over the next century. Arctic cloud-sea ice feedbacks are a source of uncertainty for predicting rates of future sea ice loss. Beyond scientific research, effectively communicating new climate change findings is complex because climate incorporates many science disciplines and can be polarizing. Here I use satellite observations, global climate model output, and a controlled education laboratory experiment to advance Arctic climate science and communication. In Part One, I isolate the influence of sea ice cover on Arctic Ocean clouds by using a novel surface mask to restrict the analysis to where sea ice concentration varies. Spaceborne lidar observations show no difference in summer cloud fraction or opacity profiles over sea ice and over open water, indicating no summer cloud response to sea ice variability. During the fall, however, total and opaque cloud fraction are larger over open water than over sea ice. Observed fall sea ice loss cannot be explained by natural variability alone, so these observed increases in fall cloud cover over open water can be linked to human activities. In Part Two, I use a climate model that reproduces observed cloud-sea ice relationships to assess future cloud-sea ice feedbacks. No future summer cloud-sea ice feedback emerges, suggesting that shortwave summer cloud feedbacks will not slow long-term summer sea ice loss. In contrast, a positive non-summer cloud-sea ice feedback strengthens as the Arctic warms. Most broadly, Parts One and Two show evidence for a strong positive cloud-sea ice feedback driven mainly by the cloud response to sea ice loss in non-summer months. Part Three is education research. I analyze the impact of several active learning strategies on student engagement in climate change in a controlled setting. Speaking in small groups or in front of their peers is most engaging for all students. Important for climate change education and communication, speaking increases engagement in climate science for all learners, especially for non-experts. This dissertation shows the value of bridging the gap between researchers and learners.

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