High resolution paleoclimate records and scenarios of climate change and variability

拟议研究的目的是扩大西部内陆地区对湿度敏感的树木年轮年表网络，并将这些高分辨率古气候数据用于a)创建年度和季节性降水及径流的长时间(300-800年)替代记录，b)确定低于特定阈值的水文气候条件(干旱、低流量)的长期可能性，c)确定水文气候循环的长度、频率和强迫作用，d)测试和验证全球气候模型对降水和干旱的模拟，e)确定生态系统对气候多变性的反应，以及f)制定未来气候变化及其影响的设想。对目标c)至f)的研究将涉及与地球、大气、生物和社会科学的同事合作。科学方法将包括对干旱地区的树木年轮进行战略性采样，以增加我们重建干旱和溪流的长度和密度。研究的目标将是那些从湖泊沉积物中获得古生态记录的地点，以及气候影响情景预测流量减少的流域。我们将把我们的草原干旱年轮记录与晚全新世干旱变化的仪器记录和替代记录、海洋表面温度异常以及最近干旱的气候学联系起来。我们将在我们的树轮记录和GCM控制运行以及未来气候的温室强迫模拟之间比较特定规模的水文气候事件的频率分布。拟议研究的意义在于，利用高分辨率的古气候(树木年轮)数据，比仪器记录所提供的关于河流流量和干旱的视角更长，并将古气候数据应用于生成未来气候情景的过程。新的方面包括将GCM模拟的气候变异性与年轮捕获的气候信号联系起来，将高分辨率的古气候和古生态记录结合起来，以调查生态系统对气候变异性的反应，以及向负责规划适应气候变异性和变化的决策者提供古气候数据。

The objective of the proposed research is to expand a network of moisture-sensitive tree-ring chronologies in the western interior and apply these high-resolution paleoclimatic data to a) creating long (300-800 years) proxy records of annual and seasonal precipitation and streamflow, b) determining the long-term probability of hydroclimatic conditions (drought, low flows) below specific thresholds, c) identifying the length, frequency and forcing of hydroclimatic cycles, d) testing and verifying global climate model (GCM) simulations of precipitation and drought, e) determining the response of ecosystems to climatic variability, and f) developing scenarios of future climate change and its impacts. Research on objectives c) to f) will involve collaboration with colleagues in the earth, atmospheric, biological and social sciences. The scientific approach will include the strategic sampling of tree rings at dry sites to increase the length and density of our reconstructions of drought and streamflow. Research will be targeted at sites where paleoecological records have been derived from lake sediments, and in watersheds where climate impact scenarios forecast decreasing flow. We will correlate our tree-ring records of prairie drought with instrumental and proxy records of late-Holocene shifts in aridity, sea surface temperatures anomalies, and the climatology of recent droughts. The frequency distributions of hydroclimatic events of specific magnitudes will be compared between our tree-ring records and GCM control runs and greenhouse-forced simulations of future climate. The significance of the proposed research is the use of high-resolution paleoclimatic (tree-ring) data to gain a longer perspective on stream flow and drought than provided by instrumental records, and the application of paleoclimatic data to the process of generating scenarios of future climate. Novel aspects include relating the climate variability simulated by GCMs to the climate signals captured by tree rings, coupling high-resolution paleoclimatic and paleoecological records to investigate the response of ecosystems to climatic variability, and delivering paleoclimatic data to decision makers responsible for the planning of adaptation to climate variability and change.