Snow and albedo climate change impacts across the United States Northern Great Plains

S R Fassnacht,N B H Venable,F Saavedra,M L Cherry

doi:10.5194/tc-10-329-2016

Abstract

Abstract. In areas with a seasonal snowpack, a warmer climate could cause less snowfall, a shallower snowpack, and a change in the timing of snowmelt, all which could reduce the winter albedo and yield an increase in net short-wave radiation. Trends in temperature, precipitation (total and as snow), days with precipitation and snow, and winter albedo were investigated over the 60-year period from 1951 to 2010 for 20 meteorological stations across the Northern Great Plains. This is an area where snow accumulation is shallow but persistent for most of the winter (November to March). The most consistent trends were minimum temperature and days with precipitation, both of which increased at a majority of the stations. Among the stations included, a decrease in the modelled winter albedo was more prevalent than an increase. There was substantial spatial variability in the climate trends. For most variables, the period of record used influenced the magnitude and sign of the significant trends.

Highlights

While global annual temperatures have increased by 0.74 ◦C in the past century and 1.3 ◦C in the past 50 years, these temperature increases are not consistent across the globe (IPCC, 2007)
The annual average maximum and minimum temperature were calculated for each year in degrees Celsius
Minimum temperatures increased at nine stations averaging 2.74 ◦C per century, with significant Tmin cooling only at Kimball

Summary

Introduction

While global annual temperatures have increased by 0.74 ◦C in the past century and 1.3 ◦C in the past 50 years, these temperature increases are not consistent across the globe (IPCC, 2007). Temperatures are increasing much more rapidly than the global average rate, and increases are not uniform for annual maximum and minimum temperatures. Trends in annual minimum temperatures are important for snowpack properties. Snowfall and snowpack trends are an important issue in semi-arid to arid climates where water demand already surpasses supply (Stewart, 2009). The western United States has already seen earlier snowmelt and peak discharge in snow-dominated river systems of up to 20 days earlier (Stewart, 2009). The western United States has seen widespread declines in springtime snow water equivalent (SWE) from 1925 to 2000 (Mote et al, 2005)

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