Our reaction to catastrophes, no matter how imminent, is too often denial and disbelief. We hear that great chunks of Antarctica and Greenland will melt, wind and tidal patterns will shift, severe weather will occur with increasing frequency, and species will die out as habitats disappear. Greenlanders and penguins need to make lots of adjustments, but how will we, here in California, adapt to a hotter, stormier, and perhaps wetter world?
In 2004, California’s Public Energy Commission linked with institutions such as Scripps, UC Berkeley, UC Davis, and Lawrence Berkeley Laboratory, to form the state Climate Change Center, charged with investigating what will happen as the temperature rises over the next century. In a new report, “Our Changing Climate: Assessing the Risks to California,” scientists speculate on the impacts of three different emissions scenarios. In a best-case low emissions scenario, we would shift immediately to more efficient technologies to lower our use of fossil fuels. But even in this version, atmospheric concentration of carbon dioxide doubles by 2100. Climate models predict a 3-5.5¡F temperature increase as a result. In the medium emissions scenario, emissions grow over the next century but as other energies come online, the rate slows. In this version, atmospheric carbon dioxide triples by 2100, with a predicted 5.5 to 8¡F increase in temperature. If we persist in denial and continue with “business as usual,” carbon dioxide in the atmosphere more than triples, resulting in temperatures 8-10¡F higher.
The results were less conclusive about rainfall, but the models suggest that while the amount might remain the same, the location and form of precipitation could change. Sea level will rise due to melting ice and thermal expansion of water. Between 1900 and 2003, sea level at the Golden Gate Bridge rose 8.15 inches, and that level is predicted to increase 22 to 35 more inches over the next hundred years. And yes, expect more severe weather, including droughts, heat waves, and massive storms. Big surprise—the forecasted rise in state population from 37 million to 55 million won’t help our plight.
Dr. Michael Hanemann, head of the California Climate Change Center at UC Berkeley, says that in terms of the state’s water resources, “the crucial thing is timing and location.” Hanemann explains that 80 percent of precipitation falls between October and March, but 75 percent of that is used between April and September, primarily for agricultural irrigation. The state’s snow pack helps cope with the timing difference by acting as a natural reservoir.
The current system relies heavily on the Sierra Nevada snow pack to supply water during spring and summer months. Significant snow packs also form in the Cascades north of the Central Valley. Snow packs form a third of California’s water storage, and melt accounts for more than a third of the state’s usable surface water supply. But the snow pack could diminish by as much as 70 to 90 percent by the end of the century due to changes in precipitation and temperature. Precipitation will fall as rain rather than snow when temperatures increase, and what snow there is could melt earlier. Unless another form of storage is developed, less water will be available during the summer.
More water can be stored in existing reservoirs, but current policy is to leave reservoirs partially empty to provide space for snow melt and protect against winter and spring flooding. More reservoirs could be built but at prohibitively high economic and environmental costs.
Meanwhile, rising sea levels threaten California’s drinking water quality. Higher sea levels increase the chances of sea water intrusion into coastal groundwater basins. In an average year, 30 percent of urban and agricultural water needs are met with groundwater. In drought years, this figure increases to 40 percent. And as more people move to the state, the demands on groundwater will grow.
Freshwater injections into coastal aquifers to prevent ocean water moving farther inland can act as hydraulic barriers, and California Department of Water Resources officials can develop policies that restrict well construction and other activities that use groundwater. Seawalls could protect the coast from rising sea levels. These measures also come at a cost and are often unpopular, so they’re less likely to be championed by politicians and policymakers.
Another threat to California’s water is the likelihood of flooding in the Sacramento-San Joaquin Valley. The State Water Project relies heavily on water from the Delta to supply two-thirds of California’s population and 600,000 acres of farmland. Most of the Delta is at or below sea level, and the bottoms of all Delta waterways are below sea level. The Delta is protected from breaching by 1,100 miles of levees, some already on the verge of collapse. As the sea level rises, levees are likely to fail. Many Californians get their drinking water from the Delta, which will also be subject to seawater intrusion if levees fail. Salinity could increase to unacceptable levels, taking weeks or even months to return to normal.
Not only does sea level rise threaten water quality, all coastal areas will face higher risks of flooding. Rising sea levels puts more pressure on levees and seawalls while more severe storms will damage them further. Areas most at risk include Santa Cruz and the Delta. The Climate Change Center predicts that billions of dollars will be spent for flood control and to repair damage.
Along with rising seas and changing rainfall patterns, our state is likely to get hotter. Assuming that all else remains constant, the temperature increase of 5.5 to 8¡F predicted by the medium emissions scenario will lead to a 3-6 percent increase in energy consumption: hot people turn on air conditioners. California spent about $26 billion on electricity in 2003. If the cost remains constant, expenditures on electricity could increase by $780 million to $1.56 billion. However, because 15 percent of state-generated electricity comes from hydropower generated from the snowmelt, electricity will probably become more expensive. Increased development in California’s interior will also increase energy use, so these estimates are extremely conservative.
A hotter climate will also affect the state’s agricultural bonanza. California produces over half the fruits, nuts, and vegetables in the nation. As of this June, 374,600 people were employed as farm workers. When you count people processing and selling food, the number of Californians employed in agriculture is considerably higher. In 2003, the value of the crops produced totaled almost $30 billion. Most of this production occurs in the Central Valley, where hotter weather will make already bad working conditions less tolerable.
Warming increases the length of the growing season. A longer growing season can increase the quantity of some produce, such as wine grapes. But warmer temperatures will decrease quality. For example, if temperatures rise by 6¡F, grapes will have higher sugar content and less acidity, making them unsuitable for winemaking. Warmer temperatures during the growing season will also increase fruit development rates. Fruit will ripen at a smaller size.
And change in timing of the growing season affects plant pollination. An early spring could throw off the timing between plants flowering and the emergence of their pollinators, decreasing the chances that flowers will become fruit. Pollen itself is extremely sensitive to warm temperatures, so earlier, warmer springs will result in lower pollen viability. As if all this isn’t enough, consider pests. Higher temperatures and growth seasons mean that pests and weeds multiply faster—and they can expand their range. For example, pink bollworms are a problem for cotton farmers in the south, but winter frosts in the north kill them off. An increase of 3 to 4.5¡F in winter temperatures would allow the pink bollworm’s range to expand northward.
Warmer temperatures during the winter will also affect fruit yield. Fruit trees need from 200 to 1,200 hours of winter chill during which temperatures are below 45¡F in order to flower, but climate models predict that there will not be sufficient winter chill by 2100 for many fruits.
Finally, warmer temperatures promote the release of volatile hydrocarbons from plants. These compounds react with nitrous oxides in the atmosphere to produce ozone that is toxic to plants.
Agriculture will also make increasing demands of California’s water resources. Higher temperatures mean that plants need more water to sustain themselves, but farmers have less storage than urban users so agriculture will be more heavily affected by shortages. The predicted increase in intensity and frequency of severe weather events adds even more complexity to the situation. In an average year, agriculture will be able to cope with global warming, but Hanemann says that in the worst cases, which could be a third of the time, there may not be enough water to go around. The number of dry years is expected to double.
Models predict not only an increase in average temperature, but an increased duration and frequency of heat waves, which will in turn increase air pollution. California already has the poorest air quality in the nation—and it will probably worsen because high temperatures promote the formation of air pollutants. If temperatures rise from 5.5 to 80 F, the number of days with weather conducive to ozone formation in the San Joaquin Valley will increase by 75 percent. Also, scientists predict that large wildfires, which release fine particulates and increase air pollution, could be up to 55 percent more frequent due to increased temperature. Air pollution exacerbates a wide variety of health problems, including asthma and other acute respiratory and cardiovascular diseases.
In addition to worsening preexisting health conditions, high temperatures increase the risk of death from dehydration, heat stroke, heart attack, stroke, and respiratory distress. By 2050, heat-related mortality in urban centers, such as Sacramento, could double or triple. Most affected will be the elderly, young, ill, and poor.
With these scary scenarios lurking just around the corner, the next few years will make a critical difference in just how dire things will be. Hanemann says California has the resources to cope with global warming, but we need to act now. We need to start preparing because some consequences are now inevitable. “There will be effects early in the century that require action now,” Hanemann says. “We need to start actively planning for adaptation to water supply problems and increased heat waves. We need to plan because we’ll experience these things in the next decade or so.”
Hanemann believes the state needs to participate in the international efforts to reduce heat-trapping emissions. The point of the impact studies performed by the California Climate Change Center is to illustrate that reducing emissions is both significant and doable. “Comparing impacts associated with business-as-usual and preventing a more than doubling of carbon dioxide in the atmosphere sheds light on why it’s important to moderate growth and emissions,” he says.
Consider that California is the fourth largest economy in the world and the twelfth highest emitter of greenhouse gases. We have the power to change global emissions standards and affect not only our own future but also that of those Greenlanders and penguins—in fact, the future of the earth.
Read it and weep at http://www.climatechange.ca.gov/documents/index.html
