Abstract
Abstract. Changes in snow water equivalent (SWE) over Northern Hemisphere (NH) landmasses are investigated for the early (2016–2035), middle (2046–2065) and late (2080–2099) 21st century using a multi-model ensemble from 20 global climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5). The multi-model ensemble was found to provide a realistic estimate of observed NH mean winter SWE compared to the GlobSnow product. The multi-model ensemble projects significant decreases in SWE over the 21st century for most regions of the NH for representative concentration pathways (RCPs) 2.6, 4.5 and 8.5. This decrease is particularly evident over the Tibetan Plateau and North America. The only region with projected increases is eastern Siberia. Projected reductions in mean annual SWE exhibit a latitudinal gradient with the largest relative changes over lower latitudes. SWE is projected to undergo the largest decreases in the spring period where it is most strongly negatively correlated with air temperature. The reduction in snowfall amount from warming is shown to be the main contributor to projected changes in SWE during September to May over the NH.
Highlights
Snow is a key component of the cryosphere and plays a fundamental role in global climate due to its high albedo and cooling effect (Vavrus, 2007)
Satellite data show that Northern Hemisphere (NH) terrestrial snow cover extent has experienced significant decreases from earlier melt over the period from ∼ 1970 (Vaughan et al, 2013), and this trend is projected to continue in the future with an estimated projected decrease in NH spring snow cover of 25 % by the end of the 21st century for representative concentration pathway (RCP) RCP8.5 (Collins et al, 2013)
Snow water equivalent (SWE) responds to both precipitation and air temperature which are both projected to increase in the 21st century (Collins et al, 2013) and the magnitude and seasonal character of the change represents a complex interplay between a shortened snow accumulation period, the fraction of precipitation that falls as snow and the frequency and intensity of winter thaw events (Räisänen, 2008; Brown and Mote, 2009)
Summary
Snow is a key component of the cryosphere and plays a fundamental role in global climate due to its high albedo and cooling effect (Vavrus, 2007). Snow cover represents a spatially and temporally integrated response to snowfall events (Brown and Mote, 2009), and is closely related to air temperature at the hemispheric scale (Brutel-Vuilmet et al, 2013). Räisänen (2008) showed that projected winter SWE change over the NH could be approximately divided into increasing and decreasing zones based on the −20 ◦C isotherm for November–March air temperature, with increasing SWE only observed over very cold regions. We focus primarily on temporal and spatial changes in SWE and on variations in the relationship between SWE and climate for each RCP during different periods of the 21st century.
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