Controls of Global Snow under a Changed Climate

• Published in: Journal of climate Vol. 26; no. 15; pp. 5537 - 5562
• Main Authors: Kapnick, Sarah B., Delworth, Thomas L.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.08.2013
• Subjects: Altitude; Atmospheric chemistry; Atmospheric composition; Atmospheric models; Boundary conditions; Carbon dioxide; Climate change; Climate models; Climatic zones; Climatology; Climatology. Bioclimatology. Climate change; Cold; Control simulation; Earth, ocean, space; Exact sciences and technology; External geophysics; Fluid dynamics; Geographical distribution; Geophysical fluids; Global climate models; Global warming; High altitude; High resolution; High-altitude environments; Hydroclimate; Hydrodynamics; Latitude; Mean temperatures; Meteorology; Modeling; Modelling; Mountain regions; Northern hemisphere; Precipitation; Radiative forcing; Resolution; Runoff; Simulation; Simulations; Snow; Snowfall; Statistical methods; Temperature; Trends; Variables; Water in the atmosphere (humidity, clouds, evaporation, precipitation); Coupled model; Southern Hemisphere; atmospheric precipitation; radiative transfer; climate warming; Climate models; digital simulation; Climate prediction; greenhouse gas; Northern Hemisphere; global change; snow; Forcing; climate change; high resolution
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/jcli-d-12-00528.1

This study assesses the ability of a newly developed high-resolution coupled model from the Geophysical Fluid Dynamics Laboratory to simulate the cold-season hydroclimate in the present climate and examines its response to climate change forcing. Output is assessed from a 280-yr control simulation that is based on 1990 atmospheric composition and an idealized 140-yr future simulation in which atmospheric carbon dioxide increases at 1% yr−1until doubling in year 70 and then remains constant. When compared with a low-resolution model, the high-resolution model is found to better represent the geographic distribution of snow variables in the present climate. In response to idealized radiative forcing changes, both models produce similar global-scale responses in which global-mean temperature and total precipitation increase while snowfall decreases. Zonally, snowfall tends to decrease in the low to midlatitudes and increase in the mid- to high latitudes. At the regional scale, the high- and low-resolution models sometimes diverge in the sign of projected snowfall changes; the high-resolution model exhibits future increases in a few select high-altitude regions, notably the northwestern Himalaya region and small regions in the Andes and southwestern Yukon, Canada. Despite such local signals, there is an almost universal reduction in snowfall as a percent of total precipitation in both models. By using a simple multivariate model, temperature is shown to drive these trends by decreasing snowfall almost everywhere while precipitation increases snowfall in the high altitudes and mid- to high latitudes. Mountainous regions of snowfall increases in the high-resolution model exhibit a unique dominance of the positive contribution from precipitation over temperature.