California could face a public health crisis from global warming, experts warned at a July 30 symposium in Sacramento on the health impacts of climate change. They pointed to global warming induced weather extremes like last summer\u2019s record wave, which caused heat-related deaths and illness. \u201cLast summer\u2019s heat wave is not an isolated event folks. There\u2019s more of this to come,\u201d warned Mark Horton, director of the California Department of Public Health. Global warming will likely exacerbate air pollution and increase respiratory illnesses and deaths, particularly among children and the elderly, said former Assemblymember Fran Pavley, co-author of the Global Warming Solutions Act of 2006. Climate change also indirectly will cause infectious diseases, floods, and wildfires, health officials warned. \u201cIf tomorrow we could accomplish what we set out to do in 2005 things will continue to get worse before they will get better even under the best of circumstances,\u201d Horton said. The symposium assessed last July\u2019s record heat wave in California as a consequence of climate change. It was co-sponsored by the Health Department, the California Air Resources Board, and the Office of Environmental Health Hazard Assessment. The agencies plan to develop a coordinated statewide strategy, infrastructure, emergency response, and precautions to prepare for future heat waves, which are expected to become commonplace in a warmer world. With temperatures in California projected to rise between 2 to 9 degrees Fahrenheit during this century heat-related deaths could increase two- to eight-fold without adequate emissions controls, said Deborah Drechsler, Air Board air pollution specialist. Background levels of particulate matter and ozone will increase without strong emission controls, creating adverse health impacts. Public health officials believe that many more people succumbed from last July\u2019s heat wave than the 140 heat-related deaths recorded by the state\u2019s 58 county coroners who didn\u2019t account for patients under medical care and other unsuspicious deaths. Most of the deaths occurred in desert and valley inland counties where temperatures soared well above 105 degrees Fahrenheit for two consecutive weeks. Most deaths from last summer\u2019s heat wave were among the elderly, chronically ill, low-income, infants, and Hispanic farm workers exposed to the heat. Heat waves in California have increased since the 1970s in magnitude, extent, and intensity, said Alexander Gershunov, a climate scientist with the Scripps Institute of Oceanography and the University of California at San Diego. Last July\u2019s heat wave was unprecedented in duration and recorded the highest night-time temperatures throughout the state, said Gershunov, who studied weather records for California since 1948. Night-time temperatures have been increasing more than daytime temperatures by several degrees Fahrenheit all over California. Weather records show a clear warming trend in California, Gershunov said. Each successive decade has experienced greater heat wave activity than the previous decade at a rapidly accelerating pace. California heat waves are caused by upper atmospheric conditions of high pressure over the Great Basin and low pressure off the coast. Beginning July 14, 2006, a huge mass of moist tropical air dragged moisture from the south over the state and kept pumping it. On July 23, the peak day, a huge pressure gradient spread all the way from the Great Plains to the California coast. The water vapor content in the atmosphere has been twice as wet as normal at night over California and Nevada while remaining at normal levels during the daytime. This is a classic description of the greenhouse effect. Moisture or water vapor is the most prevalent greenhouse gas in the Earth\u2019s atmosphere, accounting for over 80 percent compared to CO2 which contributes only 12 percent. Background ozone is increasing in California, which already has many days of unacceptable levels of ozone and particulate matter, said Nehzat Motellebi of the Air Resources Board. Higher temperatures will strengthen low level conditions increasing ozone formation.