Dynamics of permafrost submitted to a warning climate

永久冻土覆盖了加拿大约45%的地区，因此北方地貌的演变高度依赖于永久冻土随时间的沉积和退化的动态。气候变化在多年冻土的动态中起着关键作用。不断变化的温度、降水和沉积体制影响着多年冻土的热状态和力学性质。从长期来看，加拿大北部预测的气候变暖情景表明，永久冻土将受到显著影响。这些变化将通过自然环境和水文循环的变化对北方生态系统产生深远影响。在地面多冰的地方，永久冻土对气候条件的调整将引发与侵蚀、地面冰融化、融化-沉降和地表质量运动有关的热岩溶和热侵蚀过程。人类活动将进一步加剧这些自然过程。近几十年来，加拿大北部多年冻土区经历了持续的增长，并有望在不久的将来经历巨大的发展。人口增长以及石油、天然气和采矿勘探需要修建更多的公路、铁路、简易机场和管道，这对环境造成了沉重的压力。基础设施的建设不可避免地通过对地表的扰动来影响下伏永久冻土的热状况。受损基础设施的经常性维护、修复、重建和重新安置的费用将变得非常昂贵。这项研究计划的总体目标是回答自然环境中永久冻土退化的紧迫问题，并将其应用于交通基础设施。这项研究计划建议采用实地地貌学方法来研究不同时间尺度(一年到几十年)的多年冻土退化过程的基本原理，并开发工程技术来防止永久冻土退化和恢复(重新冻结)融化的永久冻土。这项研究计划将帮助加拿大社区、政府和行业制定以科学为基础的适应战略，以应对变暖和不断变化的永久冻土环境。

Permafrost covers about 45% of Canada and therefore Northern landscape evolution is highly dependent on the dynamics of permafrost aggradation and degradation through time. Climatic changes play a key role in the dynamics of permafrost. Changing temperature, precipitation and sedimentary regimes affect the thermal state and the mechanics of permafrost. On the long term, the projected climate warming scenarios for Northern Canada suggest that the permafrost will be markedly affected. These changes will have a profound impact on northern ecosystems via changes in the physical environment and the hydrological cycle. Where the ground is ice-rich the adjustment of the permafrost to climatic conditions will induce thermokarst and thermo-erosion processes related to erosion, ground ice melting, thaw-settlement and mass movement of the surface. These natural processes will be further exacerbated by human activities. In the recent decades, Northern permafrost regions of Canada have experienced a sustained growth and are expected to undergo a tremendous development in the near future. Population growth, as well as oil, gas and mining exploration require the construction of additional roads, railways, airstrips and pipelines which create heavy pressures on the environment. The construction of infrastructures inevitably affects the thermal regime of the underlying permafrost through disturbance of the surface. Recurrent maintenance operations, rehabilitation, reconstruction and relocalization of damaged infrastructures will become very costly. This general objective of this research program is to answer pressing questions of permafrost degradation in natural settings and applied to transport infratsructures. This research program proposes to adopt a field-based geomorphological approach to study the fundamentals of permafrost degradation processes on various time scales (year to decades) and to develop engineering techniques to prevent permafrost degradation and to rehabilitate (re-freeze) thawed permafrost. This research program will help Canadian communities, governments and the industry to develop science-based adaptation strategies to cope with warming and changing permafrost environments.