The potential for snow to supply human water demand in the present and future

Runoff from snowmelt is regarded as a vital water source for people and ecosystems throughout the Northern Hemisphere (NH). Numerous studies point to the threat global warming poses to the timing and magnitude of snow accumulation and melt. But analyses focused on snow supply do not show where changes to snowmelt runoff are likely to present the most pressing adaptation challenges, given sub-annual patterns of human water consumption and water availability from rainfall. We identify the NH basins where present spring and summer snowmelt has the greatest potential to supply the human water demand that would otherwise be unmet by instantaneous rainfall runoff. Using a multi-model ensemble of climate change projections, we find that these basins—which together have a present population of ~2 billion people—are exposed to a 67% risk of decreased snow supply this coming century. Further, in the multi-model mean, 68 basins (with a present population of >300 million people) transition from having sufficient rainfall runoff to meet all present human water demand to having insufficient rainfall runoff. However, internal climate variability creates irreducible uncertainty in the projected future trends in snow resource potential, with about 90% of snow-sensitive basins showing potential for either increases or decreases over the near-term decades. Our results emphasize the importance of snow for fulfilling human water demand in many NH basins, and highlight the need to account for the full range of internal climate variability in developing robust climate risk management decisions.

[1]  Alex Hall,et al.  Assessing Snow Albedo Feedback in Simulated Climate Change , 2022 .

[2]  A. Hall,et al.  On the persistent spread in snow-albedo feedback , 2012, Climate Dynamics.

[3]  C. Field,et al.  Risk Management and Climate Change , 2012 .

[4]  N. Diffenbaugh,et al.  Influence of temperature and precipitation variability on near-term snow trends , 2015, Climate Dynamics.

[5]  Ross Woods,et al.  A precipitation shift from snow towards rain leads to a decrease in streamflow , 2014 .

[6]  S. Tulaczyk,et al.  Trends in spring snowpack over a half-century of climate warming in California, USA , 2005, Annals of Glaciology.

[7]  Michel Meybeck,et al.  Global coastal segmentation and its river catchment contributors: A new look at land‐ocean linkage , 2006 .

[8]  Alex Hall,et al.  Observed Climate–Snowpack Relationships in California and their Implications for the Future , 2008 .

[9]  R. Leconte,et al.  Uncertainty of downscaling method in quantifying the impact of climate change on hydrology , 2011 .

[10]  H. Fowler,et al.  Climate change and mountain water resources: overview and recommendations for research, management and policy , 2011 .

[11]  N. Diffenbaugh,et al.  Future changes in snowmelt‐driven runoff timing over the western US , 2008 .

[12]  T. Barnett,et al.  Potential impacts of a warming climate on water availability in snow-dominated regions , 2005, Nature.

[13]  M. Dettinger,et al.  Changes in Snowmelt Runoff Timing in Western North America under a `Business as Usual' Climate Change Scenario , 2004 .

[14]  C. Tague,et al.  The sensitivity of forest water use to the timing of precipitation and snowmelt recharge in the California Sierra: Implications for a warming climate , 2013 .

[15]  A. Hoekstra,et al.  The water footprint of humanity , 2011, Proceedings of the National Academy of Sciences.

[16]  Michael D. Dettinger,et al.  Trends in Snowfall versus Rainfall in the Western United States , 2006 .

[17]  Veronika Eyring,et al.  Evaluation of Climate Models. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change , 2013 .

[18]  Stewart J. Cohen,et al.  Climate Change 2014: Impacts,Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change , 2014 .

[19]  Martin Scherer,et al.  Response of snow-dependent hydrologic extremes to continued global warming. , 2013, Nature climate change.

[20]  S. Seneviratne,et al.  Investigating soil moisture-climate interactions in a changing climate: A review , 2010 .

[21]  S. Rood,et al.  Declining summer flows of Rocky Mountain rivers: Changing seasonal hydrology and probable impacts on floodplain forests , 2008 .

[22]  R. Stouffer,et al.  Stationarity Is Dead: Whither Water Management? , 2008, Science.

[23]  Philip W. Mote,et al.  Climate-Driven Variability and Trends in Mountain Snowpack in Western North America* , 2006 .

[24]  Karl E. Taylor,et al.  An overview of CMIP5 and the experiment design , 2012 .

[25]  A. Hoekstra,et al.  Global Monthly Water Scarcity: Blue Water Footprints versus Blue Water Availability , 2012, PloS one.

[26]  C. Tebaldi,et al.  Long-term Climate Change: Projections, Commitments and Irreversibility , 2013 .

[27]  S. Schneider,et al.  Emissions pathways, climate change, and impacts on California. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[28]  Corinne Le Quéré,et al.  The challenge to keep global warming below 2 °C , 2013 .

[29]  W. Kurz,et al.  Mountain pine beetle and forest carbon feedback to climate change , 2008, Nature.

[30]  Jennifer C. Adam,et al.  Implications of global climate change for snowmelt hydrology in the twenty‐first century , 2009 .

[31]  Barbara Scherllin-Pirscher,et al.  A new dynamic approach for statistical optimization of GNSS radio occultation bending angles for optimal climate monitoring utility , 2013 .

[32]  Myles T. Collins,et al.  Managing the Risk of Uncertain Threshold Responses: Comparison of Robust, Optimum, and Precautionary Approaches , 2007, Risk analysis : an official publication of the Society for Risk Analysis.

[33]  K.,et al.  The Community Earth System Model (CESM) large ensemble project: a community resource for studying climate change in the presence of internal climate variability , 2015 .

[34]  T. Delworth,et al.  Controls of Global Snow under a Changed Climate , 2013 .

[35]  Michel Lang,et al.  Regional methods for trend detection: Assessing field significance and regional consistency , 2008 .

[36]  N. Diffenbaugh,et al.  Near‐term acceleration of hydroclimatic change in the western U.S. , 2011 .

[37]  P. O’Gorman.  Contrasting responses of mean and extreme snowfall to climate change , 2014, Nature.

[38]  D. Pierson,et al.  Changes in the timing of snowmelt and the seasonality of nutrient loading: can models simulate the impacts on freshwater trophic status? , 2013 .

[39]  T. Pavelsky,et al.  Changes in orographic precipitation patterns caused by a shift from snow to rain , 2012 .

[40]  R. Leconte,et al.  Uncertainty of the impact of climate change on the hydrology of a nordic watershed , 2008 .

[41]  M. Meybeck,et al.  Mountains of the world, water towers for humanity: Typology, mapping, and global significance , 2007 .

[42]  B. Santer,et al.  Human-Induced Changes in the Hydrology of the Western United States , 2008, Science.

[43]  C. Deser,et al.  Uncertainty in climate change projections: the role of internal variability , 2012, Climate Dynamics.

[44]  C. Deser,et al.  Communication of the role of natural variability in future North American climate , 2012 .

[45]  G. McCabe,et al.  Regional patterns and proximal causes of the recent snowpack decline in the Rocky Mountains, U.S. , 2013 .

[46]  Philip W. Mote,et al.  The Response of Northern Hemisphere Snow Cover to a Changing Climate , 2008 .

[47]  Jeffrey P. Walker,et al.  THE GLOBAL LAND DATA ASSIMILATION SYSTEM , 2004 .

[48]  T. Swetnam,et al.  Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity , 2006, Science.

[49]  N. Nakicenovic,et al.  RCP 8.5—A scenario of comparatively high greenhouse gas emissions , 2011 .

[50]  Charles J Vörösmarty,et al.  Geomorphometric attributes of the global system of rivers at 30-minute spatial resolution , 2000 .