[MCN] Snow: What's it good for? What are the 6 major global trends?
lance at wildrockies.org
Sun Apr 22 15:06:36 EDT 2018
Water Resources Research - Published online 2 MAY 2017
Above link gets you access to the free pdf.
Or, because I already grabbed it, you can get it from me. Feel free to ask.
Water and life from snow: A trillion dollar science question
Matthew Sturm1 , Michael A. Goldstein2 , and Charles Parr1
1Geophysical Institute, University of Alaska-Fairbanks, Fairbanks, Alaska, USA,
2Finance Division, Babson College, Wellesley, Massachusetts, USA
Excerpts [ bold added ]
The Importance of Snow
About one sixth of the world’s population (1.2 billion people) relies on snowmelt water for agriculture and human consumption [Barnett et al., 2005], while virtually all of the world’s population benefits from the climate services provided by snow.
Vast areas of the world receive the bulk of their annual precipitation in the form of snow (Figure 1), and even in California, where most of the population lives in a largely snow-free zone near the coast, the water people drink and their electrical power is largely derived from mountain snowmelt [cf. Sibley, 1977; Kahrl, 1979]. The same Sierra snowpack sustains a $47 billion per year California agribusiness [CDFA, 2017].
The climate benefits of snow, while harder to quantify or monetize, may actually be worth more. These arise mostly from the superlative reflectance of solar energy by snow [Warren, 1982] and the vast area of the Earth that is snow covered each year (Figure 1). The combination produces an enhanced cooling critical to the Earth’s heat budget [Groisman et al., 1994]. For example, late-lying spring snow in northern Canada, Alaska, and Siberia (an area of 19 3 106 km2) sheds about 2 3 1012 GJ of energy per year back to space, an amount that otherwise might have heated our planet (data from Flanner et al. ). This cooling benefit doubles when we add in the effect of snow-covered Arctic sea ice [Curry et al., 1995]. Economic losses from reductions in snow-covered area [Mudryk et al., 2017], and the associated losses of Earth cooling, have been valued at $575 billion [Euskirchen et al., 2013; see also Lutz and Howarth, 2015]. Beyond these essential life services, snow also provides a platform for the multibillion dollar outdoor recreation industry [Burakowski and Magnusson, 2012].
Despite difficulties, there are clear, and generally negative, trends in snow resources: [ bold added ]
1. The global extent of snow-covered area on land has been declining over the past 30 years [Brown, 2000;Derksen and Brown2012;Kunkel et al., 2016;Mudryk et al., 2017].
2. The mass of this snow (it’s SWE) is also declining [Brown, 2000;
Mote, 2006;Clow, 2010;Hamlet et al.,2005;Kunkel et al., 2016], a trend also observed on Arctic sea ice [Webster et al., 2014]. This trend appears to be a direct consequence of warming global temperatures [Mote et al., 2005].
3. The snow that does fall is melting sooner, producing earlier stream runoff and decreasing the period during which snow covers the ground [Brown, 2000;Laternser and Schneebeli, 2003;Stewart et al., 2005;
Clow, 2010;Liston and Hiemstra, 2011;Kunkel et al., 2016].
4. In many places, particularly those with a more maritime climate, winter precipitation is arriving increasingly as rain [McCabe et al
., 2007;Ye et al., 2008;Cohen et al., 2015], a trend associated with increasing flood risk in snow-covered mountain areas [Allamano et al
., 2009]. This trend also appears to be having an adverse impact on wildlife and transportation.
5. The number and intensity of winter snowfall events appears to be declining [Lute and Abatzoglou, 2014;Lute et al, 2015]; since these often account for the majority of the winter snow deposited in some locations, the trend is consistent with (2).
6. The worldwide reduction in glacier mass balance [Gardner et al
., 2013] also implies a loss of snow on glaciers and ice sheets, again a partial confirmation of (2). All of these trends are consistent with (and feedback to) a warming climate. Currently predicted by climate
models [Raisanen, 2008;Dominguez et al., 2012], but yet to be observed, is an increase in winter precipitation due to a warmer atmosphere.
” … housing growth poses the main threat to protected areas in the United States
whereas deforestation is the main threat in developing countries."
Volker C. Radeloff, Susan I. Stewart et al. Housing growth in and near United States
protected areas limits their conservation value. PNAS. January 12, 2010.
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