CLIMATE CHANGE is about to move from the headlines into the personal lives of Californians. While scientists continue to debate the probabilities of various worst-case scenarios — a 31-inch rise in sea level or an 8-degree jump in average temperatures by the year 2100 — few dispute that we face a future of potentially catastrophic environmental conditions if the proliferation of greenhouse gases isn’t checked.

In contrast to the federal government, which only recently recognized the human element in climate change after years of denial, state and local governments, as well as regional agencies, are devising policies that address global warming. Much of this activity is spurred by lawsuits and lobbying by environmental organizations that seek to compel public agencies to consider climate change when making decisions on land use, transportation projects, energy production and other issues.

In California, seven high-profile suits have been filed, mostly by the Center for Biological Diversity, a nonprofit organization based in Arizona. All challenge the legitimacy of environmental impact reports and permit approvals that do not analyze the effects that proposed developments might have on global warming. Most recently, the center, joined by the California attorney general, sued for that reason to block implementation of San Bernardino County’s long-range land-use plan governing development, road construction, utility services and related issues.

Developers, business groups, energy producers, water agencies and local governments are all trying to get out in front of the lawsuits and expected legislation on global warming. They recall the years of struggling to catch up with previous waves of environmental regulation, such as the Endangered Species Act and the Clean Water Act. So far, California has led the way nationally with passage of a law requiring the rate of greenhouse gas emissions in the state to be cut to the 1990 level by 2020, a 25% reduction.

Climate change will create uncertainty and conflict on a variety of fronts in California.

Home construction will become more difficult and costly as its effects on climate change become a factor in the approval process. Already, the Center for Biological Diversity and the Natural Resources Defense Council have challenged three large residential projects in Riverside County and the Sacramento River Delta because the agencies that approved them did not consider their effects on global warming. If such suits prevail, developers will need to learn quickly how to minimize the climate change effects — the “carbon footprint” — of their projects by making them more energy efficient, less traffic generating and less dependent on water, among other things. Otherwise, they may face years of litigation, resulting in higher costs for some projects and abandonment of others.

If sea levels rise 8 to 31 inches over this century, as predicted by the U.N. Intergovernmental Panel on Climate Change, and if severe ocean storms become more common, as groups such as the Global Business Network have warned, development along California’s coast will be further restricted or stopped altogether, in the same way it is occurring in the hurricane-prone Southeastern states.

California’s legendary water wars will intensify as parts of the state compete for reduced supplies caused by global warming. A study published by the National Academy of Sciences predicts higher temperatures and less precipitation inland, resulting in a reduced snowpack in the Sierra and diminished runoff that feeds the state’s rivers, lakes and reservoirs. A study by the National Research Council expresses similar concerns about the Colorado River, a major water source for Southern California. Even though changing weather patterns are expected to increase coastal rainfall, a serious shortage of storage capacity there will allow much of the water to escape into the Pacific.

A federal court in Sacramento has already blocked increased water deliveries from the Sacramento delta to the Central Valley and Southern California, saying the plan failed to address scientific predictions of reduced water supplies because of global warming and how that would affect the habitats of endangered species.

California law requires developers of large housing projects to demonstrate the availability of long-term water supplies for those projects, and state lawmakers are proposing even tougher rules. The state Supreme Court recently halted development of a 6,000-acre community outside Sacramento because its developers could not guarantee water sources. If projections of less water availability because of global warming turn out to be true, this and similar developments may be a thing of the past.

The power shortages that Californians endured in 2001 are likely to become commonplace as rising temperatures produce more frequent heat waves, boosting the demand for air conditioning. Unfortunately, existing electricity plants, especially those burning coal, are among the foremost generators of greenhouse gases. Tougher energy-efficiency standards in construction, better insulation and requirements for fluorescent lighting will help reduce demand for electricity. But until alternative energy sources fill the power gap, climate change will further strain power supplies and sharply raise living costs.

The hotter, drier weather will greatly reduce — or even shut off — access to such popular recreational areas as the San Gabriel and San Bernardino mountains because of the heightened risk of wildfires. Just how dangerous it can be living in urban areas close to parklands was recently demonstrated by the Griffith Park and Catalina Island blazes. Fire officials already are placing stricter controls on development in such fire-prone areas, meaning that communities such as Lake Arrowhead and Idyllwild probably won’t see more housing or tourist facilities.

The Legislature is considering nearly 60 bills on global warming issues. The most prominent ones would require climate change analyses in water supply and transportation planning. The governor’s office is drawing up regulations to implement the law mandating cuts in greenhouse gases. Meantime, the current lawsuits are heading toward decisions, and more suits will surely be filed. However it all plays out, land-use policy and development in California will be forever changed.