"The UN is discussing a system of governance of the world’s oceans, amid fears of marine extinction. The greatest threats are warming, oxygen depletion, acidification, and eutrophication. But what does Earth’s past reveal about its future? Parallels can be drawn with the Middle and end-Permian, and Triassic-Jurassic extinctions, in which all aforementioned stresses are implicated. Intense research has revealed much about biotic response to stress but most knowledge derives from the tropics, where the most diverse communities lived. Far less is known about Boreal latitudes. The future of such settings is uncertain, as models struggle to predict what the rate and consequence of change will be near the poles. Are Boreal communities among the most, or least threatened? Earth is usually capable of regulating its climate, but did positive feedback between climate change and biogeochemical cycles reach “tipping points” such that past extinctions were inevitable? Could this happen again? Have Boreal faunas and floras suffered more, or less than tropical counterparts in the past? Are they more, or less at risk now? This project tests the Boreal response to environmental change in three mass extinctions between 260-200 million years ago. Were these communities adapted to stressful conditions and fare better than their tropical counterparts? Or did their niche adaptation leave them susceptible? Extinction patterns and concurrent environmental conditions will be ascertained through fieldwork, fossil and geochemical studies of sections in Spitsbergen. Comparison with tropical communities will reveal similarities and differences in response to change. The necessary long-term study of diverse groups and settings is made possible by extensive low-latitude field collections of the applicant, and comparable data available in the Paleobiology Database. This rigorous test of past environmental stress-extinction links will inform current approaches to the protection of Boreal ecosystems."