with a biome shift, in which the interior boreal forest is being severely altered and eliminated from many landscape positions, and opportunities for migration upward in mountains or coastward represent the best survival prospect for elements of the boreal forest.
Sharon Stammerjohn, Ocean Sciences Department, University of California, Santa Cruz
Circumpolar averages of sea ice extent show alarming decreases in the Arctic but increases in the Antarctic, presenting a paradoxical picture of polar amplification of climate change. But, changes in circumpolar sea ice extent can be misleading in that they mask much greater regional/seasonal sea ice changes, and thus ocean-atmosphere changes that are critically important for assessing high latitude climate sensitivity (and vulnerability) to global climate change. Regionally Antarctic sea ice has decreased quite dramatically in the high latitude Southeast Pacific Ocean (SPO), while the largest Arctic sea ice decreases have been in the Western Arctic Ocean (WAO). Further, by resolving seasonal sea ice changes during sea ice advance and retreat, we find some extraordinary rates of change: (1) sea ice in the WAO (of ~1 × 106 km2) is advancing 26 days later and retreating 35 days earlier, resulting in a 59-day shorter ice season duration; and (2) sea ice in the high latitude SPO (of ~0.5 × 106 km2) is advancing 48 days later and retreating 35 days earlier, resulting in an 83-day shorter ice season duration. Regionally therefore, sea ice duration is decreasing faster in Antarctica. However, changes are seasonally asymmetric, polar-opposite, but globally similar in timing: fastest during austral autumn sea ice advance and fastest during boreal spring sea ice retreat (both during ~March-June). Given these seasonal asymmetric sea ice changes, we explore how solar ocean warming in spring-summer may be delaying autumn sea ice advance and/or thinning winter sea ice and/or pointing to additional ocean heat sources.
Patricia L. Yager, School of Marine Programs, University of Georgia
High-latitude marine ecosystems are changing rapidly in ways that go far beyond “global warming,” reflecting large deviations from normal for many environmental variables across a wide range of spatial