February 13, 2013
Picture a place of rolling agricultural landscapes and expansive megacities, endless deserts and snow capped mountains, California; a land bound together by a struggle for water. Some regions, such as Northern California are blessed with ample water supplies; while California’s largest city in the south, Los Angeles, stretches ever further to meet its growing parchedness.
Now imagine desolation. Arid croplands replace once lush fields, rivers run dry, reservoirs emptied to the last drop, imagine drought. This is the image that is painted regularly across the Californian landscape. We Californians are resilient though, we adapt and ration, as thus we have endured. There is not much to fear as after every drought comes a flourish of rain to revive the sunken land. One must ask then how concerned should Californians be of droughts of the present and future. Droughts of course have different severities and to foresee what the future may hold we must look back at what the past has already told. In concurrence with climate change droughts are expected to increase in persistence and severity in the coming years.
California has just experienced a drought such as the one described in this past year, but on milder terms. The state’s water reservoirs have been gradually filling since the start of the wet season and now most of them are at normal levels according to the California Department of Water Resources. Precipitation levels have also increased to date, about 135% of average rainfall. Presently it seems as if California is in the clear and has no need to worry about a drought.
Historical Drought Patterns
The most recent drought in California occurred from October 2011 to April 2012, but there have been many similar events before. Looking back to when scientists first started keeping rainfall records, we can see that there are numerous years where rainfall did not meet its expected totals. Additionally, we can see that there has been four times where the amount of rainfall failed to meet its average over a ten year span. Episodes like these cause for much alarm because it cripples the local economy, which depends on the growth of agriculture. However, the drought eventually ends as it is succeeded by some years of plentiful precipitation.
Some of this abundant water is stored in groundwater, snowpack, and reservoirs so that it can be used in times of crisis. Starting in the 1950s, California began building infrastructure that would be able to transport large quantities of water from the Sierras, through the Central Valley, and eventually to Southern California. Since then, the California State Water Project has become the world’s largest water and power development system that can provide water to more than 25 million people. From 1987-1991, this system was challenged for the first time when the decline in precipitation led to four out of the five years having less than 50% of normal runoff. Although the system was receiving less water input annually, “it still enabled its agriculture to survive three years of drought with minimal impact” (Zilberman 2011). In the years following, farmers and water districts worked to cut back their use of water and provided people with incentives to conserve it. Thus California has been able to adjust to fairly regular drought patterns and effectively manage water resources in times of drought.
What Future Droughts May Look Like
One of the most pressing concerns for water planners of today is the hydrologic needs of tomorrow. The population of California is expected to grow from 34 million people in 2010 to 51 million in 2050 (California Department of Finance). Population growth brings a concurrent growth of water needs and conflicts among stakeholders. Drought will continue to be a part of the Californian experience in the future and planners must account for this in hydrologic projections. In order to get a more thorough look at what future droughts may encompass we must take a look into the past.
Among the multitude of droughts that have been observed in California one case study is particularly important in the forecast of forthcoming droughts. The Medieval Warm Epoch (900 A.D to 1300 A.D) is characterized by a high frequency of volcanism, increased solar irradiance, and hydrologic anomalies. The hydrologic anomalies mostly encompassed high precipitation rates in some parts of the world and extreme drought conditions in places such as the western United States, particularly California. These anomalies were driven by changing El Nino and La Nina oscillation patterns, which are wet and dry climate patterns respectively. Both of these patterns are driven by temperature, especially warming. This indicates that increased warming in the present day may give birth again to the hydrologic anomalies experienced in the Medieval Warm Epoch; drought conditions similar to those that occurred in the Medieval Warm Epoch would also re-emerge along with the anomalies.
Professor Scott Steine asserts in his publication on persistent droughts that if medieval warming caused persistent droughts in California previously then “future natural or anthropogenically induced warming may cause a recurrence of the extreme drought conditions” (Steine 546). The Intergovernmental Panel on Climate Change also came to the same conclusions on anthropogenically caused warming in its 2007 Climate Change Synthesis Report, to quote “There is also high confidence that many semi-arid areas (e.g. the Mediterranean Basin, western United States, southern Africa and north-eastern Brazil) will suffer a decrease in water resources due to climate change. Drought-affected areas are projected to increase in extent” (IPCC 2007, pg. 49). Based on these reports it is more than likely that droughts will increase in severity if warming continues at the pace it is going. Upon examination of figure 2 one can clearly see that the Western United States projected to be a much drier zone by the end of this century. Future droughts will entail a longer residence time up to several decades and result in greater water shortages, especially in combination with population growth.
California is perfectly capable of handling drought under current climatic conditions using its extensive water management system. In the future climate change will most likely reduce this capability as droughts become more severe and persistent. Couple this with a growing population and we now have a synergistic problem. Californians should prioritize future droughts as one of the biggest challenges to face in the coming years and in turn should address the one of the causes of potentially catastrophic droughts, anthropogenically induced climate change.
This post was authored by Kieran Bartholow, a junior majoring in Environmental Studies, and Minh Ngo, a junior double majoring in Environmental Studies and Earth Science.
Core Writing Team, Pachauri, R.K. and Reisinger, A. (Eds.) “Climate Change 2007 Synthesis Report” IPCC, Geneva, Switzerland. pp 104
“Executive Summary of Hydrologic Conditions in California.” California Department of Water Resources. California Department of Water Resources, 01 Jan. 2013. Web. 01 Feb. 2013.
“Interim Population Projections for California and Its Counties 2010-2050.” California Department of Finance. California Department of Finance, May 2012. Web. 01 Feb. 2013.
Kirk, Tony. “Precipitation And Its Effect On Groundwater Supply In WRD’s Region.” Precipitation And Its Effect On Groundwater Supply In WRD’s Region. Water Replenishment District of Southern California, 2007. Web. 01 Feb. 2013.
Stine, Scott, et al. “Extreme and Persistent Drought in California and Patagonia during Mediaeval Time.” Nature Publishing Group Vol 369 (1994): 546.
Zilberman, David, et al. “Individual and institutional responses to the drought: the case of California agriculture.” Journal of Contemporary Water Research and Education 121.1 (2011): 3.