Climate Change for the Mountain Accord

If you love the central Wasatch Mountains, you might want to start following or get involved with the Mountain Accord, an initiative that is currently underway to develop a vision for an area spanning from the Wasatch Front to the Wasatch Back.  For more details see mountainaccord.com or their Get Involved page.

Knowledge of current climate and projections for the future are an important part of the Mountain Accord process. Court Strong (University of Utah), Tim Bardsley (Western Water Assessment), and I have been providing guidance and analyses to the Mountain Accord team to assist them in this effort, and I thought I would share some of the key graphs and figures below, as I thought they would be of interest to many readers.  

One key point with regards to climate model projections for the Central Wasatch Range.  It's difficult to imagine a situation in which our climate does not warm, barring some dramatic change in volcanic activity, decrease in the output of the sun, or calamity to civilization.  Indeed, the models consistently project a warmer future, with the rate of warming varying depending on future greenhouse gas emissions and the model.  Precipitation (liquid precipitation equivalent), however, is more uncertain and the models produce a wide range of future outcomes, some drier, some wetter, and some near current averages.

Snowfall Sensitivity

Percentage of precipitation (liquid equivalent) that currently falls as snow that would instead fall as rain per ºC of warming.  Based on Jones (2010).  Source: Steenburgh, J., 2014: Secrets of the Greatest Snow on Earth. Utah State University Press, in press.

Monthly Runoff Sensitivity

Average monthly flow sensitivities as percentage decrease in flow per 1°F for City Creek, Parleys Creek, Big Cottonwood Creek, Little Cottonwood Creek, and the Four Creeks combined.  Source: Bardsley, T., A. Wood, M. Hobbins, T. Kirkham, L. Briefer, J. Niermeyer, and S. Burian, 2013: Planning for an uncertain future: Climate change sensitivity assessment toward adaptation planning for public water supply. Earth Interactions, 17, 1-26.

Annual Runoff Sensitivity

 Average annual volume decrease under various projected temperature changes for City Creek (CK), Parleys Creek (PC), Big Cottonwood Creek (BCW), Little Cottonwood Creek (LCW), Provo River (Provo), Weber River (Weber) and Duchesne River (Duches).  Source: Bardsley, T., A. Wood, M. Hobbins, T. Kirkham, L. Briefer, J. Niermeyer, and S. Burian, 2013: Planning for an uncertain future: Climate change sensitivity assessment toward adaptation planning for public water supply. Earth Interactions, 17, 1-26.

Greenhouse Gas Scenarios for the Future

Greenhouse gas concentration trajectories (CO2) equivalent adopted by the IPCC for its fifth assessment report, 2013 (AR5).  Source: RCP Database version 2.0.5, http://tntcat.iiasa.ac.at:8787/RcpDb/dsd?Action=htmlpage&page=compare.

Projected Seasonal and Annual Temperature Change for the Central Wasatch Region

Projected seasonal and annual near-surface air temperature change over the central Wasatch and surrounding region for the 30-year periods centered on 2040 (2026–2055), 2060 (2046–2075), and 2085 (2070–2099) relative to 1976-2005.  See Fig. 6 for emissions scenarios.  Winter is December through February,  Spring is March through May, Summer is June through August, and Fall is September through October.  Bars show the average change across the model runs, whiskers the range between the 25th and 75th percentile of the model runs, and dots the range between the 10th and 90th percentile of the model runs.  Source: http://gdo-dcp.ucllnl.org/downscaled_cmip_projections/dcpInterface.html

Projected Precipitation Trends

Projected seasonal and annual precipitation change over the central Wasatch and surrounding region for the 30-year periods centered on 2040 (2026–2055), 2060 (2046–2075), and 2085 (2070–2099) relative to 1976-2005.  See Fig. 6 for emissions scenarios.  Winter is December through February, Spring is March through May, Summer is June through August, and Fall is September through October.  Bars show the average change across the model runs, whiskers the range between the 25th and 75th percentile of the model runs, and dots the range between the 10th and 90th percentile of the model runs. Source: http://gdo-dcp.ucllnl.org/downscaled_cmip_projections/dcpInterface.html

Mean Trends in Snow Related Variables

Mean trends (%/year) in snow-related variables in the “Wasatch Mountain Region” (orange in left figure) derived using downscaled climate models for the RCP4.5 (center) and the RCP8.5 (right) climate scenarios.  SWE/P = Fraction of precipitation from 1 Oct – 31 Mar that remains in the snowpack on 1 April.  SWE = Amount of water contained in the snowpack on 1 Apr.  SFE/P = Fraction of total water in the precipitation from 1 Oct – 31 Mar that has fallen as snow. 95% confidence interval indicated by pink shading, green stippling, and vertical bars, respectively.  Source: Pierce, D. W., and D. R. Cayan, 2013: The uneven response of different snow measures to human-induced climate warming.  J. Climate, 26, 4148–4167.