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and/or exposure of buried infrastructure.60 Furthermore, increased storm intensity and frequency could affect the ability of flood-control facilities, including levees,to handle storm events. Air Quality Scientists project that the annual average maximum daily temperatures in California could rise by 2.4 to 3.2°C in the next 50 years and by 3.1 to 4.9°C in the next century.61 Higher temperatures are conducive to air pollution formation,and rising temperatures could therefore result in worsened air quality in California.As a result, climate change may increase the concentration of ground-level ozone, but the magnitude of the effect, and therefore its indirect effects,are uncertain. In addition, as temperatures have increased in recent years,the area burned by wildfires throughout the State has increased, and wildfires have occurred at higher elevations in the Sierra Nevada Mountains.62 If higher temperatures continue to be accompanied by an increase in the incidence and extent of large wildfires, air quality could worsen. Severe heat accompanied by drier conditions and poor air quality could increase the number of heat-related deaths, illnesses, and asthma attacks throughout the State. However, if higher temperatures are accompanied by wetter, rather than drier conditions, the rains could tend to temporarily clear the air of particulate pollution,which would effectively reduce the number of large wildfires and thereby ameliorate the pollution associated with them.63 Water Supply Analysis of paleoclimatic data (such as tree-ring reconstructions of stream flow and precipitation) indicates a history of naturally and widely varying hydrologic conditions in California and the west, including a pattern of recurring and extended droughts. Uncertainty remains with respect to the overall impact of climate change on future precipitation trends and water supplies in California. Year-to-year variability in Statewide precipitation levels has increased since 1980, meaning that wet and dry precipitation extremes have become more common.64 This uncertainty regarding future precipitation trends complicates the analysis of future water demand, especially where the relationship between climate change and its potential effect on water demand is not well understood.The average early spring snowpack in the western U.S., including the Sierra Nevada Mountains,decreased by about 10 percent during the last century. During the same period,sea level rose over 0.15 meter along the central and southern California coasts.65 The Sierra snowpack provides the majority of California's water supply as snow that accumulates during wet winters is released slowly during the dry months of spring and summer.A warmer climate is predicted to reduce the fraction of precipitation that falls as snow and the amount of snowfall at lower elevations,thereby reducing the total snowpack.66 Projections indicate that average spring 60 California,State of.2018.California's Fourth Climate Change Assessment Statewide Summary Report.August 27,2018. https://www.e n ergy.ca.gov/sites/defa u It/fi I es/2019-11/Statewi de_Reports-SUM-CCCA4-2018-013_Statewid e_Su m m a ry_Report_ADA.pdf 61 Ibid. 62 Ibid. 63 California Natural Resources Agency.2009.2009 California Climate Adaptation Strategy.March 2009. http://resources.ca.gov/docs/climate/Statewide—Ada ptation_Strategy.pdf 64 California Department of Water Resources.2018.Indicators of Climate Change in California.May 2018. https://oeh ha.ca.gov/media/downloads/climate-change/report/2018caindicatorsreportmay2018.pdf 65 California,State of.2018.California's Fourth Climate Change Assessment Statewide Summary Report.August 27,2018. htt ps://www.en a rgy.ca.gov/sites/defa u It/fi les/2019-11/Statewide_Re ports-SUM-CCCA4-2018-013_Statewid e_Su m ma ry_Repo rt_A DA.pdf 66 Ibid.