Article Sustainable Cities Steve Sanders

Preparing For a Warmer World

Steve Sanders is program director for the California Climate Action Network (CCAN) program of the Institute for Local Government. He can be reached at For more information about CCAN, visit

There is a simple maxim in ecology: “Adapt or perish.” When the environment changes, creatures that can adapt will thrive; those that cannot will struggle to survive and eventually disappear.

California is facing a similar predicament. After decades of scientific research, there is a clear and growing consensus that the environment is changing rapidly – and not for the better. The cause is global warming, and the consequences are monumental.

California is a leader in the growing movement to curb global warming. The state and many local agencies have enacted pioneering policies to reduce the amount of carbon dioxide, methane and other greenhouse gases that enter the atmosphere. These efforts are crucial if we are to avoid the most dismal consequences of climate change. But on their own, they are not sufficient to fully address the challenges posed by climate change.

Adapting to Climate Change

The earth’s climate is a dynamic system that has only recently begun to fully respond to the buildup of heat energy induced by 150 years of industrial activity. Even if California’s ambitious goals to reduce greenhouse gas emissions (to 1990 levels by 2020 and to 80 percent below 1990 levels by 2050) are achieved world wide, global temperatures are expected to continue rising through the mid-21st century and beyond.

Adapting to the changing climate will be essential to secure a livable and sustainable future for California. This poses a leadership challenge for local officials, who are in many ways on the front lines in the struggle to prepare for climate change.

Global warming has the potential to threaten California’s economy, environment, communities and residents in a number of ways, including:

  • Water shortfalls;
  • Distressed landscapes and ecosystems;
  • Increased demand for energy due to higher temperatures and heat waves;
  • Public health threats;
  • Disruption of agricultural productivity; and
  • Rising seas and increased flood risks.

Communities in California and around the world are grappling with the threats from global warming. In some cases, that means intensifying or improving existing ways of managing risks. In other cases, new approaches for dealing with risk are needed for new problems.

Water Supply

California is facing a future of increased water scarcity. The Sierra snowpack acts as a reservoir, gradually releasing melting freshwater to replenish dams and aquifers that store water to be used during the dry spring and summer months. The shrinking snowpack, hotter temperatures and a growing population will place enormous pressure on a declining resource.

While debates are under way at the state level on whether and how to increase water storage, communities have learned that conservation is the first line of defense to deal with shortfalls in water supply. These efforts will be even more critical as the impacts of global warming become more severe.

California cities are pursuing many innovative ways to conserve water. For ex-ample, Santa Rosa’s treated wastewater is recycled to irrigate more than 6,400 acres of farmland, easing pressure on freshwater supplies. Some of the recycled water is even pumped more than 40 miles east and injected into the ground to produce electricity at the Geysers geothermal field, thereby reducing greenhouse gas emissions.

Pasadena is aiming to reduce water use 5 percent citywide by using satellite imagery to determine how much water landscaped areas need throughout the city. According to the Pasadena Water Department, “the new map will provide information that can be used for city planning, stormwater runoff studies and other applications” as well as helping the city to conserve water.

Landscapes and Ecosystems

Few places on Earth are home to as wide a variety of landscapes as California. The state’s unique and varied ecosystems in clude coastal dunes, redwoods, deserts, oak woodlands and alpine mountains. Nearly half of the state is covered by forest, and there are also expansive areas of grasslands and chaparral.

Climate change poses a triple-barreled threat to this natural bounty. First, warming temperatures and changes in precipitation patterns are causing natural habitats to move generally northward and to higher elevations, disrupting natural communities. Some ecosystems may disappear altogether. In addition, as summers become hotter and drier, the risk of catastrophic wildfires is expected to increase. Finally, along with increasing the damage caused by forest fires, higher temperatures also reduce the timber yield of commercial forests.

Scientists and land managers are just beginning to understand the ecological impacts of climate change. As our knowledge grows, local communities will need to adapt their efforts to conserve species and protect endangered habitats. We can no longer assume that ecosystems are stable and that once protected they will remain protected.

Higher Temperatures and Increased Energy Demand

In California, peak electrical demand occurs on hot summer days when the demand for air conditioning rises. The state’s electric power grid is already straining to meet current energy needs. Global warming, combined with the state’s population growth, will place further strain on the system.

According to research compiled by the California Climate Change Center, under the most optimistic scenario, the number of extreme heat days (above 90 degrees) in Los Angeles would increase from less than 20 in 1990 to more than 50 by 2070. If temperatures rise to the medium range, the number of extreme heat days would jump to 80, while at the higher end of the range the number of days would exceed 100. Similar results are projected else where, particularly in the Central Valley and Inland Empire regions where most of the state’s population growth in the coming decades is expected to occur.

Higher temperatures affect energy supply and demand in other ways as well. Fully 20 percent of the state’s electricity is used to pump and move water to serve urban, industrial and agricultural customers. Higher temperatures will increase the need to supply water for irrigation, just when peak demand for air conditioning is at its height. At the same time, the production of electricity from hydropower, which supplies 15 percent of the state’s electricity, could be reduced by as much as 30 percent from diminished summer snow melt flows. The result could over whelm the state’s electrical system.

One important way cities can prepare for the threat of rising temperatures is through a variety of energy efficiency and conservation measures, coupled with programs to generate electricity using low-carbon or no-carbon alternatives. For a wealth of examples, visit the Institute for Local Government’s California Climate Action Network website (

Trees offer another way to combat rising temperatures. Shade trees can significantly reduce the “heat island” effect, where acres of blacktop and dark roofs can raise local temperatures five degrees or more above surrounding areas. Many cities have urban forestry programs designed to lower temperatures, improve air quality and reduce peak energy demand for air conditioning.

For example, the Sacramento Tree Foundation is working with the City of Elk Grove and other communities to double the region’s tree canopy over the next 40 years. The Tree Foundation is also partnering with the Sacramento Municipal Utility District to enlist residents to plant and maintain trees. According to the foundation, nearly 400,000 trees have been planted through the program since 1990.

Public Health

The increased number of severe heat days expected in the future will have serious health consequences. Extreme heat can be a killer, especially for vulnerable populations such as the ill and elderly, children and people without access to air conditioning or medical help.

Extreme heat will also result in higher levels of ozone formation and air pollution, in a state where 90 percent of the population already lives in areas that violate health-based air quality standards. Under the most optimistic projections, the number of days with unhealthy levels of ozone would increase by more than 35 percent in the San Joaquin Valley by 2070. At the medium warming range, the number of unhealthy days would jump by more than 80 percent. Changes in temperature can also make more areas of the state hospitable to infectious disease agents such as mosquitoes and ticks.

The public health community is starting to prepare for the increased threat posed by climate change. Cities with their own public health departments, such as Berke ley , are developing programs to educate residents and policy-makers on the risks and possible preventive measures. However, most cities rely on outside agencies for public health information and services. Cities will need to collaborate with county public health officers, hospitals, clinics and others in the health profession to better understand how to protect the health and well-being of their residents as temperatures rise.


Agriculture is a mainstay of the Califor nia economy. The state produces half the nation’s fruits and vegetables, but the direct and indirect effects of global warming are putting many crops at risk. Higher temperatures can disrupt growing cycles and reduce both the quantity and quality of agricultural products.

For example, most of the state’s dairy farms are located in the Central Valley, where the number of hot days is expected to increase significantly. Higher temperatures could reduce milk production by as much as 20 percent. Similarly, fruit and nut trees require colder nighttime temperatures to bloom properly. Global warming could increase temperatures beyond this critical threshold in many areas where orchards are established. Higher temperatures and changes in precipitation patterns also could expand the range of a number of crop pests and weeds that are difficult and expensive to control.

Local communities can help agriculture respond to the challenge of global warming in a number of ways. Local food-to-market programs can increase the demand for locally grown produce and ensure a more consistent income stream for growers while also reducing the carbon emissions associated with shipping highly processed food over long distances. Implementing water recycling and conservation programs can create a more reliable water supply for local farmers. And farmland protection programs can reduce development pressure on local farms and ranches, encouraging them to stay in business.

Rising Seas, Storms and Flooding

Perhaps the most alarming consequence of global warming is the rise in sea levels that is already occurring, caused by melt ing glacial and sea ice along with thermal expansion, as the temperature of the planet’s oceans continues to increase. As temperatures rise, the frequency and se-verity of storms are also expected to rise, bringing with them the risk of flooding and erosion.

The impact of rising sea levels and more frequent and powerful storms will not be confined to the coast. Already, the average level of the San Francisco Bay has risen 7 inches in the past 150 years, according to the Bay Conservation and Develop ment Commission (BCDC). If sea levels rise another 30 inches, what were once considered 100-year floods caused by storm surges would be expected every 10 years. The BCDC has calculated the impact of a 1-meter rise on Bay Area communities. Among its findings: More than 200 square miles of waterfront land would be submerged, including both the San Francisco and Oakland international airports.

Farther inland, the complex and aging system of levees, weirs and channels that protect the Sacramento and San Joaquin valleys and the San Francisco Bay Delta will become more vulnerable. Higher sea levels, storm surges and torrential rains that melt the Sierra snowpack pose a risk of catastrophic flooding if runoff volumes exceed the system’s design capacity. The risk of a disaster on a par with the Hurricane Katrina flood that inundated New Orleans and coastal Louisiana and Mississippi is a distinct possibility.

Managing the impacts of rising sea levels and the risks of flooding and storm damage will not be easy. Some solutions require state and federal action. Yet local communities can take important steps to address these concerns. For example, placing new development out of harm’s way, investing in flood control and levee maintenance and improvement, reducing the amount of impervious surfaces and creating catchment systems so that stormwater can percolate into the ground are all measures that can help reduce risk.


When it comes to preparing for the consequences of global warming, Yogi Berra was right: “The future ain’t what it used to be.” Many of the plans that local communities have made to address a host of critical issues will need to be rethought to reflect the changing climate. The good news is that we now realize we must think and act differently to create a better future. The challenge is that we have no time to waste.

This article appears in the January 2008 issue of Western City
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