Northern hemisphere lake ice cover under contemporary and future climate conditions

湖冰覆盖已被证明是气候变率和变化的一个强有力的指标。最近的研究表明，在过去的50年里，特别是在北方半球（NH）的许多地区，由于冬季和春季气候条件变暖，分裂日期发生得更早。破裂日期，并在较小程度上冻结日期，已被证明是密切相关的变化和趋势，在0 ℃等温线日期以及大规模的大气和海洋环流模式（遥相关），特别是在北美西部。最近记录的过去50年气温和冬季降水趋势以及全球气候模式预测的趋势可能对北方纬度冰盖的时间、持续时间、厚度和组成产生重大影响。反过来，这可能会对NH各地区的能源，水和生物地球化学循环以及水生生态系统产生重要影响。如何湖冰覆盖已经改变了在过去的50年里，什么可能是预计的21世纪世纪气候变暖对冰覆盖的不同深度的湖泊在不同地区的NH的问题，必须进行检查，以获得更深入的了解气候湖泊相互作用在北方纬度。拟议的研究计划将寻求回答这些紧迫的问题。总体目标将是提供一个NH合成的时间和空间变异性和趋势，在湖冰覆盖的遥相关模式在20世纪世纪的下半叶，和合理的情况下，湖冰覆盖的响应，预计未来的气候条件。这项研究的结果将在国际极地年（IPY）期间以及国际气候变化计划（例如气候和冰冻圈（CliC），全球气候观测系统（GCOS），综合全球观测系统（IGOS）-冰冻圈）和国际气候变化专门委员会（IPCC）等评估提供关键数据和信息。

Lake-ice cover has been shown to be a robust indicator of climate variability and change. Recent studies have demonstrated that break-up dates, in particular, have been occurring earlier in many parts of the Northern Hemisphere (NH) over the last 50 years in response to warmer climatic conditions in the winter and spring seasons. Break-up dates, and to a lesser extent freeze-up dates, have been shown to be strongly related to the variability and trends in the 0oC isotherm dates as well as large-scale atmospheric and oceanic circulation patterns (teleconnections), particularly in western North America. The impacts of recently documented trends in air temperature and winter precipitation over the last five decades and those projected by global climate models could be significant on the timing, duration, thickness, and composition of ice cover at northern latitudes. This could, in turn, have an important effect on energy, water and biogeochemical cycling, and aquatic ecosystems in various regions of the NH. How lake-ice cover has changed over the last five decades, and what will likely be the impacts of projected 21st century climate warming on ice cover for lakes of various depths in different regions of the NH are questions that must be examined in order to gain a deeper understanding of climate-lake interactions at northern latitudes. The proposed research program will seek to answer these pressing questions. The overall goal will be to provide a NH synthesis of the temporal and spatial variability and trends in lake ice cover in relation to teleconnection patterns during the second half of the 20th century, and plausible scenarios of the response of lake ice cover to projected future climate conditions. Results from this research will contribute critical data and information during the International Polar Year (IPY) period as well as to international climate change programs (e.g. Climate and Cryosphere (CliC), Global Climate Observing System (GCOS), Integrated Global Observing System (IGOS) - Cryosphere) and assessments such as the International Panel on Climate Change (IPCC).