Department of Physical Geography and Quaternary Geology, Stockholm University, Sweden.
Ambio. 2011 Jun;40(4):361-9. doi: 10.1007/s13280-010-0109-1.
Rapid changes to the Arctic hydrological cycle challenge both our process understanding and our ability to find appropriate adaptation strategies. We have investigated the relevance and accuracy development of climate change projections for assessment of water cycle changes in major Arctic drainage basins. Results show relatively good agreement of climate model projections with observed temperature changes, but high model inaccuracy relative to available observation data for precipitation changes. Direct observations further show systematically larger (smaller) runoff than precipitation increases (decreases). This result is partly attributable to uncertainties and systematic bias in precipitation observations, but still indicates that some of the observed increase in Arctic river runoff is due to water storage changes, for example melting permafrost and/or groundwater storage changes, within the drainage basins. Such causes of runoff change affect sea level, in addition to ocean salinity, and inland water resources, ecosystems, and infrastructure. Process-based hydrological modeling and observations, which can resolve changes in evapotranspiration, and groundwater and permafrost storage at and below river basin scales, are needed in order to accurately interpret and translate climate-driven precipitation changes to changes in freshwater cycling and runoff. In contrast to this need, our results show that the density of Arctic runoff monitoring has become increasingly biased and less relevant by decreasing most and being lowest in river basins with the largest expected climatic changes.
北极水文循环的快速变化既挑战了我们对这一过程的理解，也挑战了我们寻找适当适应策略的能力。我们研究了气候变化预测对主要北极流域水循环变化评估的相关性和准确性发展。结果表明，气候模式预测与观测到的温度变化相对吻合，但与可获得的降水变化观测数据相比，模式预测的准确性较高。直接观测进一步表明，径流量的增加（减少）明显大于降水的增加（减少）。这一结果部分归因于降水观测中的不确定性和系统偏差，但仍表明观测到的北极河流径流量增加部分是由于流域内的储水变化，例如永冻土融化和/或地下水储存变化。这些径流量变化的原因除了影响海洋盐度外，还会影响海平面、内陆水资源、生态系统和基础设施。为了准确解释和转化气候驱动的降水变化对淡水循环和径流量的影响，需要基于过程的水文模型和观测，这些模型和观测可以分辨流域尺度及以下的蒸散、地下水和永冻土储存的变化。与这一需求形成对比的是，我们的研究结果表明，北极径流监测的密度变得越来越有偏差，而且越来越不相关，在预计气候变化最大的流域中，监测的密度最低。
