Collaborative Research: Holocene Drought Cycles and Impacts on the Northern Great Plains

本研究将利用对北部大平原封闭盆地湖泊岩心的高分辨率分析来确定全新世干旱的频率、强度、持续时间、周期性和同步性，并研究植被和火灾如何对干旱做出反应。由于北部大平原的植被和湖泊对干旱高度敏感，该地区为记录美国大陆中部十年至世纪尺度的气候周期提供了绝佳的机会。可行的假设是，来自单一地点的干旱信号是区域性的，干旱在整个地区是同步的。为了验证这一假设，该研究将利用湖泊沉积物矿物学、化石花粉、木炭的碳同位素和木炭丰度，在年代际尺度上详细重建北部大平原的干旱周期。这将有助于评估中大陆气候与北大西洋地区之间的遥相关关系，北大西洋地区最近的调查已将世纪至千年尺度的气候振荡与太阳辐照度的变化联系起来。该研究在自然科学和社会科学领域具有广泛影响的潜力。利用大气模式对北部大平原地区的干旱影响进行预测，需要了解自然干旱变率。来自古科学的证据表明，20世纪的干旱（例如，沙尘暴）甚至不能为最近发生的严重干旱的范围提供视角。历史证据不完整，古科学数据尚未在适当的时间和空间尺度上收集，以评估过去干旱的强度、周期性和影响。

This study will utilize high-resolution analysis of cores from closed-basin lakes in the northern Great Plains to determine the frequency, intensity, duration, periodicity, and synchrony of droughts during the Holocene and to examine how vegetation and fire responded to drought. Since vegetation and lakes in the Northern Great Plains are highly sensitive to drought, this region offers an extraordinary opportunity to document decadal- to-century scale climate cycles in the mid-continental United States. The working hypothesis is that the signal of drought from a single site is regional and that droughts were synchronous across the region. To test this hypothesis, the study will utilize lake-sediment mineralogy, fossil pollen, carbon isotopes of charcoal, and charcoal abundance to develop detailed reconstruction of drought cycles from the Northern Great Plains at a decadal scale. This will facilitate evaluation of the teleconnections between mid-continental climate and the North Atlantic region, where recent investigations have linked century to millennial scale climate oscillations to variations in solar irradiance. This research has the potential for broad impact in range of physical and social sciences. Assessment of drought impacts forecast by atmospheric models for the Northern Great Plains requires understanding of natural drought variability. Evidence from paleoscience suggests that 20th century droughts (e.g., the Dust Bowl) do not provide perspective on the range of severe droughts that have occurred in even the recent past. Historical evidence is incomplete and paleoscience data have not yet been assembled at appropriate temporal and spatial scales to assess the intensity, periodicity, and impacts of past droughts.