Published online by Cambridge University Press: 10 January 2011
Introduction
It is likely that global climate will change substantially in coming decades (IPCC, 2007) and will have a series of impacts on the operation of geomorphological hazards as a result of changes in temperatures, precipitation amounts and intensities, and soil moisture conditions. Some environments will change more than others – ‘geomorphological hotspots’ (Goudie, 1996, 2006a), especially when crucial thresholds are crossed. Ice caps and glaciers will melt, permafrost will thin and retreat, shorelines will be subject to inundation by rising sea-levels, extreme hydrological events (both floods and droughts) may become more frequent, and dune and dust activity may change.
There are four types of reasons why some geomorphological processes, hazards and landform assemblages will show substantial modification as climate changes.
Threshold reliance
Some landforms and landforming processes are prone to change across crucial thresholds of temperature and precipitation. For example, the melting of components of the cryosphere is strongly temperature dependent and permafrost can only exist where mean annual temperatures are negative. Thus, as temperatures rise, permafrost will move polewards and/or upwards in altitude and the depth of summer thaw will change (Couture and Pollard, 2007). The mass balance of glaciers is largely controlled by the relative significance of ablation and snow nourishment and these in turn depend on temperatures and precipitation amounts. Likewise, stream flow, especially in dry regions, can vary greatly with modest changes in moisture caused by changes in evapotranspiration.
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