The large-scale loss of Arctic sea ice in recent decades is one of the most prominent indicators of the ongoing global climate change. This derives from three main reasons. First, climate change is amplified in the Arctic (“Arctic amplification”, e.g. Pithan et al. (2013)), so consequences of changes in the global-mean climate are more readily observed at high latitudes compared to middle and lower latitudes. Second, while many observables change gradually with global mean climate, Arctic sea ice is among those observables that might eventually cross a binary threshold from “existing” to “non-existing”, which amplifies the perception of the underlying gradual trend. And third, as a consequence, changes in “Arctic sea ice coverage” are easier to grasp and communicate to a general public than changes in more abstract metrics such as “global mean temperature”.
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