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| Effects of Warming the Deep Soil and Permafrost on Ecosystem Carbon Balance in Alaskan Tundra: A Coupled Measurement and Modeling Approach | |
| 项目编号 | DE-SC0014062 |
| Schuur, Edward | |
| 项目主持机构 | Northern Arizona University |
| 开始日期 | 2015-08-01 |
| 结束日期 | 2016-07-31 |
| 英文摘要 | Sustained and substantial carbon (C) release from the Arctic is a wildcard with the potential to alter the future trajectory of climate change. While modern climate change is largely due to human activities, the future path also depends on the responses of terrestrial and ocean systems. A key societal question is whether there are tipping points, global C cycle surprises that will make climate change effects such as sea-level rise, extreme weather, droughts, and impacts on agriculture occur faster than currently projected by models. Recently, attention has been drawn to permafrost (perennially frozen ground) thaw as a mechanism that could move significant quantities of Arctic C into the atmosphere in response to a changing climate. This so-called vulnerable C pool has been identified to be susceptible to both the direct and indirect effects of climate change, but the level of risk and timescale of change is currently highly uncertain. The goal of this proposal is to address the following overarching question: How will regional variation in the response of permafrost ecosystem C balance to warming and thaw affect atmospheric carbon dioxide and methane concentrations and future climate? We hypothesize that the transfer of old soil C to the atmosphere will occur as a result of permafrost thaw and the microbial decomposition of soil organic matter. Because permafrost C has accumulated over thousands of years, radiocarbon dating of respired C provides a unique and sensitive fingerprint for tracking changes in the permafrost C pool that affect climate. This is likely to be the only technology that can detect the release of permafrost C directly. The critical question centers on how fast this process will occur. Abrupt releases of greenhouse gas forecast to cause trillions of dollars of economic damage to global society contrast with predictions of slower, sustained C gas release that would give society more time to adapt. Recent advances in the measurement and application of radiocarbon technology to the global C cycle and climate change are uniquely poised to address this question. Deployment of radiocarbon technologies enables us to observe and detect changes in the permafrost C pool, and predict the magnitude, timing, and form of C release to the atmosphere. We are testing the overarching question using a combination of field and laboratory experiments to measure isotope ratios and C fluxes in a tundra ecosystem exposed to experimental warming and drying. Field measurements center on the establishment of a two-factor experimental warming using a snow fence and open top chambers to increase winter and summer temperatures alone, and in combination, at a tundra field site at the Eight Mile Lake watershed near Healy, (interior) Alaska. The objective of this experimental warming is to significantly raise air and deep soil temperatures and increase the depth of thaw. We expect the effect of warming to be influenced by landscape drainage. The drying manipulation lowers the water table under warming and control simulating’s conditions that are expected to characterize some of moisture conditions across the Arctic landscape in a warmer climate.Field and lab measurements are combined with modeling using data assimilation techniques that utilize measurement streams from the multifactor experiment to derive parameter values for large-scale models. In particular, this modeling work focuses on the utility of radiocarbon measurements for constraining slow C pools, and the effect of ecosystem acclimation on C balance projections. The proposed long-term multifactor experiment provides an important experimental framework to address the permafrost C feedback, and provides unique insight alongside existing and planned Arctic networks that are based primarily on observation alone. In summary, high latitude soils may act as a significant positive feedback to climate change if the old C that forms the bulk of the soil pool is respired to the atmosphere following permafrost thaw. This old C, if lost to the atmosphere, should be detectable in the radiocarbon respired from the ecosystem. The combination of high precision isotopic techniques, an ecosystem-scale field manipulation, and improvements to ecosystem models will help further develop an approach that could be useful for widespread monitoring of the response of high latitude ecosystems to global environmental change. The data sets and modeling simulations generated by this project will interface with ongoing synthesis that is underway through the Permafrost Carbon Network as a foundation for increasing, distilling, and communicating our understanding of change in this remote region with its important consequences for global climate and society. |
| 学科分类 | 09 - 环境科学;06 - 生物科学 |
| 资助机构 | US-DOE |
| 项目经费 | 28847.59 |
| 项目类型 | Grant |
| 国家 | US |
| 语种 | 英语 |
| 文献类型 | 项目 |
| 条目标识符 | http://gcip.llas.ac.cn/handle/2XKMVOVA/74118 |
| 推荐引用方式 GB/T 7714 | Schuur, Edward.Effects of Warming the Deep Soil and Permafrost on Ecosystem Carbon Balance in Alaskan Tundra: A Coupled Measurement and Modeling Approach.2015. |
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