Climate Change & Impact on Water Resources in the San Joaquin Valley
Total Page：16
File Type：pdf, Size：1020Kb
Climate Change & Impact on Water Resources in the San Joaquin Valley Roger Bales, UC Merced NASA-MODIS satellite image Since 1895, annual average air temperatures in California have increased by about 1.5oF, with minimum temperatures increasing at a rate almost as that for maximum temperatures (2oF/100 yr & 1oF/100 yr) Intergovernmental Panel on Climate Change st 1 assessment – 1990 – … calculate with confidence that CO2 has been responsible for over half the enhanced greenhouse effect. The unequivocal detection of the enhanced greenhouse effect is not likely for a decade or more. 2nd assessment– 1995 – The balance of evidence suggests a discernible human influence on global climate. 3rd assessment– 2001 – Since the mid-20th century, most of the observed warming is "likely" (greater than 66% probability … ) due to human activities. 4th assessment– 2007 – Warming of the climate system is unequivocal … Most of the global average warming over the past 50 years is "very likely" (greater than 90% probability …) due to human activities. Unmitigated climate change would … exceed the capacity of natural, managed and human systems to adapt. 5th assessment– 2013 – … increases the degree of certainty that human activities are driving the warming the world has experienced, from "very likely" or 90% confidence in 2007, to "extremely likely" or 95% confidence now. Climate warming scenarios for California Increase above 1961-1990 average Source: CA Climate Change Center Climate change & challenges for the Valley − Shift in mountain runoff impacts ag, hydropower − Sea level rise threatens CVP & SWP pumping plants − Rise in energy demand stresses peak production capacity − 2 to 4 times current number of heat-wave days − 50-150% more critically dry years − Warmer nighttime & daytime temperature effects on ag − 25-85% more days conducive to high ozone levels Much of the water supply for the region derives from mountain snowpacks Warming by +4 to +10oF drives significant changes: – rain-vs-snow storms * – snowpack amounts * – snowmelt timing * – flood risk – streamflow timing * – low baseflows – growing seasons * – recharge? – drier soil in summer Precipitation changes? Already observed (*) Spring snowmelt from the Sierra Nevada to the Sacramento River has declined over the past century. Lower water volumes of snowmelt runoff indicate warmer winter temperatures. More precipitation falls as rain instead of snow and directly flows from watersheds before the spring. Reductions in streamflow by the latter half of the century are estimated to lead to more frequent critically dry water years, resulting in less water available to support already threatened ecosystems & species. Annual area burned in California Since 1950, annual acreage burned in wildfires statewide has been increasing. The three largest fire years occurred in the last ten years. A large spike in annual average acreage of conifer & shrubland burned statewide occurred from 2000-2008. In the western United States, large wildfires have become more frequent, increasing in tandem with rising spring & summer temperatures. Sea level along the California coast could be 10-18 inches higher in 2050 than in 2000, & 31-55 inches higher by 2100. Agriculture in California generates more than $30 billion per year, the highest crop value in the nation, provides more than 1 million jobs, & serves as an important source of the nation’s food supply. The sector is already under stress from competing & growing urban & environmental water demands & continuing development on agricultural land The corridor between Merced & Fresno is particularly vulnerable, owing to a combination of climate, crops, land use & socioeconomic factors. Making a water-secure world – the three I’s INFRASTRUCTURE Stronger & more- to store, transport adaptable & treat water INSTITUTIONS HARD SOFT Better & more- accessible INFORMATION Water security: the reliable availability of an acceptable quantity & quality of water for health, livelihoods & production, coupled w/ an acceptable level of water-related risks Water security lies at the heart of climate preparedness Includes both: Madden, The Beast ̶ ‘hard’ options to capture & control water ̶ ‘soft’ tools to manage demand as well as increase supply, e.g. water allocation, conservation, efficiency & land-use planning General feeling in the water community that soft opportunities will be insufficient What California is doing: ̶ Planning for infrastructure ̶ Collaboration & integration in planning, management ̶ More information-intensive decision support Building resiliency in water infrastructure – multi-pronged approach Observations as a foundation for water security J. Parks A new generation of integrated measurements lidar eddy correlation embedded sensor networks isotopes & ions satellite snowcover low-cost sensors sap flow sediment Making a water-secure world – the three I’s INFRASTRUCTURE INSTITUTIONS Managing ecosystem services INFORMATION Managing water is central to climate preparedness; and water management translates into managing ecosystem services. Cities example Roles of mitigation, or greenhouse-gas-emission reduction, vs. adaptation in combating the causes & impacts of climate change. What climate change looks like Sea level rise plus 100- yr flood at SFO NYC transit Queens, NY after Hurricane Sandy Bangladesh after 2011 flood Mass migration during flooding, Pakistan 2010 Illegal immigrants entering Australia, 2010’s Climate-induced migration like Vietnamese boat people, 1970’s? Water & climate warming are factors in violence Recent droughts In 2011 and 2012, drought occurred on almost every continent, partly because of an unusually strong La Niña that caused record rainfall in Australia and led to severe water shortages in Sudan. Hundreds of millions of hectares of crops were destroyed, from wheat in Russia to sugar cane in India. The map (Figure 2) shows how rainfall deviated from the norm in this period and highlights the regions most affected by drought — many of which are major growing regions for the world's top four staple crops. East Africa drought 2011, lack of food aid 2011 E Africa drought. A girl amid the graves of 70 children on the outskirts of Dadaab. Rim Fire, 2013 Shrubs after earlier fire Shasta 1976 http://www.kpbs.org Heat-tolerant workers? Heat-tolerant cattle What does mitigation of climate change look like? Bicycling in Copenhagen Small hydro Renewable energy, de- carbonizing energy Energy production integrated with agriculture Carbon sequestration as part of agriculture .