Seminar 12 in the Series: From Science to Solutions: The State of the Carbon Cycle, the 2nd State of the Carbon Cycle Report (SOCCR2). We plan to host this series series on Tuesdays, 2/26-5/28.
Factors that control terrestrial carbon storage in unmanaged arctic and boreal ecosystems are changing. Surface air temperature change is amplified in high-latitude regions, as seen in the Arctic where temperature rise is about 2.5 times faster than that for the whole Earth. Permafrost temperatures have been increasing over the last 40 years. Disturbance by fire (particularly fire frequency and extreme fire years) is higher now than in the middle of the last century. Soils in the northern circumpolar permafrost zone store 1,460 to 1,600 petagrams of organic carbon (Pg C), almost twice the amount contained in the atmosphere and about an order of magnitude more carbon than contained in plant biomass (55 Pg C), woody debris (16 Pg C), and litter (29 Pg C) in the boreal forest and tundra biome combined. This large permafrost zone soil carbon pool has accumulated over hundreds to thousands of years, and there are additional reservoirs in subsea permafrost and regions of deep sediments that are not added to this estimate because of data scarcity. Following the current trajectory of global and Arctic warming, 5% to 15% of the organic soil carbon stored in the northern circumpolar permafrost zone (mean 10% value equal to 146 to 160 Pg C) is considered vulnerable to release to the atmosphere by the year 2100. However, a recent model intercomparison project suggested that additional plant carbon uptake, growth, and deposition of new carbon into soil would together completely offset any soil carbon loss this century, and that it would take several centuries before cumulative losses from soils would overwhelm new carbon uptake. However, model projections do not always match current empirical measurements or other assessments, suggesting that structural features of many models are still limited in representing Arctic and boreal zone processes. At the same time, the intercomparison indicated that future scenarios with limited human greenhouse gas emissions would reduce changes to high latitude ecosystems. Together, the loss of carbon from thawing permafrost soils and disturbance by fire in combination with offsetting plant uptake response determines the net effect of high latitudes on the carbon cycle of both North America and the globe.
About the Speaker:
Dr. Ted Schuur is a Professor in the Center for Ecosystem Science and Society at Northern Arizona University. He is an ecologist who has studied links between ecosystems and climate in locations across Alaska and the Arctic. His work on this topic has included more than two decades of field research and, in this time, has resulted in more than 150 peer-reviewed publications in high-impact journals. He is the also the lead investigator for the Permafrost Carbon Network, an international consortium of researchers aimed at synthesizing new knowledge on permafrost carbon and climate. He graduated Magna Cum Laude with a BS from the University of Michigan and he received a PhD from the University of California-Berkeley.
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