De-convolving the effects of rising atmospheric CO2, solar dimming, and afforestation on usable water and carbon sequestration potential in the Southeastern U.S.

消除大气中二氧化碳含量上升、太阳变暗和植树造林对美国东南部可用水和碳封存潜力的影响

• 批准号: 0628432
• 负责人: Gabriel Katul
• 金额: $ 44.55万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-15 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0628432&HistoricalAwards=false
• 关键词: De; convolving; effects; rising; atmospheric

Katul0628432De-convolving the effects of rising atmospheric CO2, solar dimming, and afforestation on usable water and carbon sequestration potential in the Southeastern U.S.Much attention is directed to assessing how anthropogenic CO2 emissions and climate change impact soil water losses and continental runoff, as reflected in both the Water and Carbon Cycles Science Plans proposed by United States Global Change Research Program (USGCRP) and the 2001 Intergovernmental Panel on Climate Change (IPCC) report. A number of recent studies suggest that continental runoff increased throughout the 20th century despite a rapid increase in water consumption by humans and their activities. The reason for the increase in runoff remains a subject of debate, though it is commonly attributed to either an increase in precipitation (P) or a decrease in evapotranspiration (ET) over the 20th century. While the increase in P can be explained by warming trends, the reduction in ET, especially at sub-continental scales, is more complex. The three plausible explanations for reductions in ET are: (1) Less energy and light input due to solar dimming with lower light levels reducing mean stomatal conductance to water vapor (gc), (2) lower gc due to elevated atmospheric CO2, and (3) land-use change to vegetation that consumes less water. The interplay between these three mechanisms can be explored on a number of scales ranging from the ecosystem level to watershed to sub-continental region. Using a combination of ecosystem models and detailed field experiments, we will investigate how solar dimming, increases in atmospheric CO2, and increases in forested area alter water availability and gross ecosystem CO2 exchange in the Southeastern (SE) U.S., a region that is considered among the most productive in the U.S. in terms of carbon sequestration. The SE provides an ideal case study due to rapid afforestation (and reforestation) over the past 100 years and the minor change in precipitation over the past 50 years. The project's intellectual merit is to elucidate the mechanisms leading to global runoff increases over the past 50 years, and to assess whether runoff time series contain a discernable signal of climate change. Recognizing that carbon sequestration will play an increasing role in regional and national policy in the future, and that water resources currently play a major role, the broader impact of this project is to contribute the scientific foundation, data, and models that can guide ecosystem valuation for C-H2O tradeoffs upon conversion among land cover types. The educational benefit of the project is to support two graduate students, providing them with a unique experience in the state of the art techniques in measurement and modeling of biosphere-atmosphere exchange rates while interacting with a broad interdisciplinary team of physical and biological scientists working on water and carbon cycling at Duke University.

Katul0628432解卷积大气中二氧化碳含量上升、太阳变暗和植树造林对美国东南部可用水和碳封存潜力的影响。很多注意力集中在评估人为二氧化碳排放和气候变化如何影响土壤水流失和大陆径流，如美国全球变化研究计划 (USGCRP) 和 2001 年政府间气候变化专门委员会提出的水和碳循环科学计划（政府间气候变化专门委员会）报告。 最近的一些研究表明，尽管人类及其活动的耗水量迅速增加，但整个 20 世纪大陆径流仍在增加。径流增加的原因仍然是一个争论的话题，尽管它通常归因于 20 世纪降水量 (P) 的增加或蒸散量 (ET) 的减少。 虽然磷的增加可以用变暖趋势来解释，但蒸散的减少，特别是在次大陆尺度上，则更为复杂。 ET 减少的三种可能的解释是：（1）由于太阳变暗而导致能量和光输入减少，较低的光照水平降低了水蒸气的平均气孔导度（gc），（2）由于大气中二氧化碳含量升高而导致 gc 降低，以及（ 3）土地利用转变为消耗更少水的植被。这三种机制之间的相互作用可以在从生态系统层面到流域再到次大陆区域的多个尺度上进行探索。结合生态系统模型和详细的实地实验，我们将研究太阳变暗、大气二氧化碳增加和森林面积增加如何改变美国东南部 (SE) 的可用水量和生态系统总二氧化碳交换，该地区被认为是就碳封存而言，它是美国最具生产力的。由于过去 100 年来的快速造林（和重新造林）以及过去 50 年来降水量的微小变化，SE 提供了一个理想的案例研究。 该项目的智力价值在于阐明导致过去 50 年全球径流增加的机制，并评估径流时间序列是否包含可辨别的气候变化信号。 认识到碳封存将在未来的区域和国家政策中发挥越来越重要的作用，并且水资源目前发挥着重要作用，该项目更广泛的影响是提供可指导生态系统评估的科学基础、数据和模型土地覆盖类型之间转换时的 C-H2O 权衡。 该项目的教育效益是支持两名研究生，为他们提供生物圈-大气汇率测量和建模的最先进技术的独特经验，同时与致力于研究的物理和生物科学家组成的广泛跨学科团队互动。杜克大学的水和碳循环。