Humans are altering the global cycling of carbon (C) on Earth. The addition of billions of tons of greenhouse gases to the atmosphere is changing its heat-trapping capacity, which in turn is changing the Earth's climate. Large amounts of carbon are stored within the soils of terrestrial ecosystems. Recently, attention has been drawn to the thawing of permafrost (permanently frozen ground) as a mechanism that could move significant quantities of stored C from land to atmosphere in response to a changing climate. Because of the size and nature of the permafrost C pool, decomposition of previously frozen, old organic carbon is one of the most likely positive feedbacks from terrestrial ecosystems to climate change in a warmer world.
While ground temperature increases in permafrost regions are well documented with data from permafrost borehole networks, as well as from surface temperature observations, there is a knowledge gap surrounding the response of permafrost carbon to climate change. This Vulnerability of Permafrost Carbon research coordination network (RCN) project will bring together biological and physical carbon cycle researchers. Through a series of meetings, working groups will be established that will address key questions about carbon cycling and vulnerability in permafrost regions and synthesize data and literature. An interactive website will be developed for non-scientists and the media that will synthesize the state of knowledge about permafrost. This RCN will strengthen the interconnection between biological and physical scientists, between early and later career-stage scientists, and will produce new knowledge through synthesis that can be used to quantify the role of permafrost carbon in affecting climate change in the 21st century and beyond.
Normal 0 false false false EN-US JA X-NONE There is a substantial amount of carbon stored in permafrost (nearly twice the amount of carbon in the atmosphere), and that carbon is potentially vulnerable to release to the atmosphere if permafrost thaws. Large releases of carbon from thawing permafrost could enhance global warming and compromise international efforts to control carbon emissions to the atmosphere. Because there are a number of uncertainties about how much and in what form carbon could be released to atmosphere from thawing permafrost, we established the Permafrost Carbon Research Coordination Network, which is now known more generally ass the Permafrost Carbon Network. The objective of the network is to link biological carbon cycle research with well-developed networks in the physical sciences that have traditionally focused on the thermal state of permafrost. Below we describe what we have learned in the project (i.e., the intellectual merit of the project) and the broader impacts of the project on society. The Permafrost Carbon Network has resulted in the development of new databases that better quantify the amount of carbon in soils and permafrost of ecosystems in the northern latitudes. The network has also synthesized information from various studies on the sensitivity of carbon to be released to the atmosphere upon thaw. One synthesis involved releases under well-drained conditions, which can happen if permafrost thaws and causes a drying of the landscape from better drainage. Another synthesis involved releases under poorly drained conditions, which can happen if permafrost thaws and causes a wetting of the landscape by thawing ground ice under conditions where water can’t readily drain. This latter synthesis is relevant to the release of carbon in thawed permafrost as methane, which is produced under poorly drained conditions and is a much more powerful heat trapping gas than carbon dioxide, which is generally produced under well-drained conditions. Because of the importance of the form of release (i.e., methane vs. carbon dioxide), we have also conducted a synthesis study to better understand the conditions under which methane release is most likely. We have also conducted syntheses on what is understood about the historical rates of thaw with respect to how ecosystems may transition to new types. For example, a forest underlain with permafrost can transition to be either a lake or a wetland depending on the amount of ground ice and the drainage conditions after thaw. Finally, we have conducted studies on how models represent carbon in permafrost, and the difference in the responses of models that represent carbon in permafrost in different ways. Our results indicate that models that represent carbon with depth in the permafrost region tend to simulate greater releases of carbon from permafrost soils to the atmosphere. Overall, the studies conducted by the Permafrost Carbon Network indicate that carbon stored in permafrost is quite vulnerable to release upon thaw. Our project has a number of broader impacts relevant to society. First, the conclusion that carbon stored in permafrost is vulnerable to release upon thaw is relevant to international efforts to control the carbon cycle. It suggests that efforts to control the release of greenhouse gases may overshoot their warming targets if they do not take into account the carbon that would be release from permafrost thaw. Our project has also contributed to the training of young scientists through its network structure. The structure of conducting synthesis studies generally pairs a junior scientist with a senior scientist, which offers key training and exposure to young scientists. The accomplishments of the network are available the both the public and the scientific community through a web site that describes current and ongoing activities of the network: www.biology.ufl.edu/permafrostcarbon.
