Collaborative Research: Climate controls on carbon accumulation in upland permafrost at millennial scales

Organic-rich surficial materials of the Arctic are a storehouse of frozen carbon (C) of global consequence. Climate ultimately controls the exchange of carbon between this reservoir and the atmosphere, but the long-term relation between climate and permafrost carbon is highly uncertain. This study draws from climate changes that occurred during the recent geologic past (late glacial and Holocene), which serve as natural experiments, to quantify the long-term (millennial-scale) relation between climate and the mass of carbon that accumulated under distinctly different climate states. Whereas previous studies of the effects of climate changes on permafrost carbon have generally focused on lakes and peatlands of low-lying terrain, this study provides complementary information from upland deposits that mantle hilly terrain, possibly the least-well known component of the arctic frozen organic carbon inventory. The project applies and develops new approaches to investigating the relation between climate and carbon sequestration in an understudied setting and at long time scales by bringing together expertise in Arctic paleoecology, paleoclimatology, surficial geology, geochronology and quantitative geomorphology. This paleo perspective provides a unique approach to help infer how permafrost and its C reservoir may react in the future.

北极富含有机质的表层物质是具有全球意义的冻结碳（C）储存库。气候最终控制着该储库与大气之间的碳交换，但气候与多年冻土（permafrost）碳之间的长期关系仍高度不确定。本研究利用近期地质历史时期发生的气候变化（晚冰期（late glacial）和全新世（Holocene））作为自然实验，量化了气候与在截然不同气候状态下积累的碳质量之间的长期（千年尺度（millennial-scale））关系。此前关于气候变化对多年冻土碳影响的研究通常聚焦于低洼地带的湖泊和泥炭地（peatlands），而本研究则从覆盖丘陵地带的高地沉积物中提供了补充信息——这些沉积物可能是北极冻结有机碳库中了解最少的组成部分。该项目通过整合北极古生态学（paleoecology）、古气候学（paleoclimatology）、表层地质学（surficial geology）、地质年代学（geochronology）和定量地貌学（quantitative geomorphology）领域的专业知识，在研究不足的环境和长时间尺度下，应用并开发了探究气候与碳封存（carbon sequestration）之间关系的新方法。这种古视角提供了一种独特方法，有助于推断多年冻土及其碳储库未来可能的反应。