Droughts, Climate Change, and the Energy System Guido Franco Team Lead for Climate Change and Environmental Research Sonya Ziaja Research Lead for Energy Water Climate Nexus Joint Agency Workshop on California’s Drought Responses Sacramento, California August 28, 2015

Regional Climate Variability: California Climate variability in California is relatively large. 2014 was the warmest year in the historical record. The historical record of more than 100 years is relatively short to fully characterize natural climate variability. Data Sources: California Climate Tracker and NASA

Average 4-year Winter Temperature and Precipitation: Sierra Nevada Region Average precipitation in the 2012 to 2015 period was not unusual in the historical record. Average temperature was exceptionally high. Data Source: California Climate Tracker

Risk of Prolonged Droughts: Southwest Global climate models seem to underestimate the risk of droughts. A study* using paleorecord and historical data to better characterize natural variability suggests that: The risk of a 10 year drought in this century is about 80%. The likelihood of longer lived drought events (>35 years) is between 20% and 50%. * Ault, T., J. Cole, J. Overpeck, G. Pederson, and D. Meko, 2014: Assessing the risk of persistent drought using climate model simulations and paleoclimate data. J. Climate. doi:10.1175/JCLI-D-12-00282.1

Current Practice for Water Reservoir Management Water managers use simple rule curves to operate large water reservoirs. Typically no precipitation forecasts are used for management, only observed precipitation. Oroville Rule Curve Willis, A.D., J. R. Lund, et al., 2011. Climate Change and Flood Operations in the Sacramento Basin, California. San Francisco Estuary & Watershed Science.

Using Modern Management Tools Probabilistic hydrologic forecasts and a modern decision support tool (INFORM) In simulations, INFORM outperforms current management practices in climate scenarios with very dry years.

Adaptation Option to Dry Forms of Climate Change Several studies suggest that storing water in aquifers is an attractive option. Groundwater recharge in wet years and withdrawal in dry years. UC Davis conducted a preliminary study identifying recharge areas in current agricultural areas. O’Geen, A.T., et al., 2015. Soil suitability index identifies potential areas for groundwater banking on agricultural lands. California Agriculture.

Electricity Consumption for Water Pumping Electricity consumption for groundwater pumping is significant. The drought increases the total amount of water pumped and the depth from which the water is withdrawn increasing total electricity demand. Navigant/GEI Study 1 for CPUC, 2010

Natural Gas System and Subsidence The figure shows subsiding areas and the location of natural gas pipelines. A recent study from NASA/JPL reports substantial acceleration of subsidence during the on-going drought. Subsidence MAY compromise the integrity of natural gas pipelines. Created by Sonya Ziaja and Jordan Scavo 2014

Subsidence and Abandoned/Plugged Wells There are about 100,000 abandoned/plugged wells as reported in a database maintained by DOGGR. Studies suggests that subsidence may compromise the integrity of the well casing and create pathways for the migration of methane to the atmosphere. Preliminary measurements at abandoned/plugged wells in California suggests that some wells are leaking methane. Gas well protruding 46 cm (1.5 feet), 2 years after it was painted. Source: Borchers and Carpenter 2014 Created by Stoms, Ziaja, Hou, and Franco

Subsidence is Variable Source: Farr et al. JPL 2015. Subsidence in the San Joaquin Valley, Jul.2007-Dec. 2010.

Source: Farr et al. JPL 2015. Subsidence around Sacramento, May-Nov Source: Farr et al. JPL 2015. Subsidence around Sacramento, May-Nov. 2014. 5 inches in six months, with no prior subsidence at Arbuckle.

Conclusions Higher temperatures has made this drought significantly worse. If we consider paleorecord data, analyses suggest greatly increased chances of mega droughts. Options for altered management of surface and underground reservoirs should be explored further. Potential for climate feedbacks depending on joint management of groundwater water and energy resources.

Thank you! Disclaimer: The views and opinions in this presentation do not necessarily represent the views and opinions of the Energy Commission or the State of California.