How has soil quality changed in California over the past 60 years? Using the known locations of archived samples collected by the soil survey staff in the 1940s and 1950s, we resampled 125 locations in California from the Imperial Valley in the south to Tehama county in the north and analyzed samples for properties important to plant production. We collected three samples from the 0- to 25-cm depth at each location and air-dried them for analysis. For each 1945 and 2001 sample pH, electrical conductivity, total nitrogen, total carbon, plant available phosphorus, texture and color was measured. We compared the data across the entire state as well as by current land-use, and geographic region. Across the state, plant-available phosphorus, total carbon, pH, and percent clay increased significantly (95% confidence level) as did percent silt and total nitrogen (90% confidence). In contrast, electrical conductivity, and percent sand decreased significantly (95% confidence). Chroma also decreased significantly statewide (90% confidence level). The degree of change varied according to land-use and geographic region. Based on this sample, California's soil quality has not significantly decreased over the past 60 years. These results also suggest that defining and evaluating soil quality is difficult due to conflicting trends and interpretations of soil quality indices.
This project is the most detailed study ever undertaken on the potential effect of climate change on California. This work examines a broad array of potentially affected sectors as well as the interactions between climate change and increased population, economic growth, and technological change. It considers a wide range of climate change scenarios, ranging from warmer and much wetter to warmer and much drier. Most climate models estimate that precipitation will increase. Climate change is likely to have substantial impacts on California. The location of natural vegetation will change dramatically. Productivity could increase under wetter conditions and biodiversity could be reduced under drier conditions. The combined effects of climate change and urbanization on vegetation could adversely affect some critical systems. Timber production may initially increase and then decrease, but producers and consumers may be more affected by changes in global timber prices. Higher temperatures will cause the snowpack to melt earlier in the year, increasing flood risks. Changes in the water supply are very sensitive to changes in precipitation. Agriculture will most likely demand more water, although population and economic growth will decrease the sector's allocation of water. Climate change could affect agriculture more favorably in northern California than in the south, but changes in technology may have a far greater impact statewide. Energy expenditures are projected to rise significantly. The costs involved in protecting coastal resources may rise as well, but by much smaller amounts. Finally, impacts on human health will be very sensitive to changes in climate variability.
Acclimation capacity underlies susceptibility to climate change. Stillman, Jonathan H.
Recent reports have presented meta-analyses of global biological impacts of climate change. However, there is debate as to the level of confidence ascribed to the certainty that global climate change has caused the observed biological changes. Two important considerations in the assessment of how climate change will impact organisms are how close organisms are to their thermal limits in nature and an understanding of how organisms respond to increasing habitat temperatures, especially the degree to which organisms are able to adjust, or acclimatize, their thermal sensitivity. The effects of thermal acclimation on thermal limits of cardiac function in four congeneric species of marine invertebrates from different thermal habitats are described. Thus, by understanding the biological bases that underlie the responses of organisms to increasing habitat temperature, we can increase our certainty of the direct impacts that climate change has on life in nature.
Additive effects of simulated climate changes, elevated CO2, and nitrogen deposition on grassland diversity.. Zavaleta, Erika S.; Shaw, M. Rebecca; Chiariello, Nona R.; Mooney, Harold A. & Field, Christopher B..
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC164642/ DOI: 10.1073/pnas.0932734100
Biodiversity responses to ongoing climate and atmospheric changes will affect both ecosystem processes and the delivery of ecosystem goods and services. Combined effects of co-occurring global changes on diversity, however, are poorly understood. We examined plant diversity responses in a California annual grassland to manipulations of four global environmental changes, singly and in combination: elevated CO2, warming, precipitation, and nitrogen deposition. After 3 years, elevated CO2 and nitrogen deposition each reduced plant diversity, whereas elevated precipitation increased it and warming had no significant effect. Diversity responses to both single and combined global change treatments were driven overwhelmingly by gains and losses of forb species, which make up most of the native plant diversity in California grasslands. Diversity responses across treatments also showed no consistent relationship to net primary production responses, illustrating that the diversity effects of these environmental changes could not be explained simply by changes in productivity. In two- to four-way combinations, simulated global changes did not interact in any of their effects on diversity. Our results show that climate and atmospheric changes can rapidly alter biological diversity, with combined effects that, at least in some settings, are simple, additive combinations of single-factor effects.
Ambient single particle analysis in Riverside, California by aerosol time-of-flight mass spectrometry during the SCOS97-NARSTO. Pastor, S. H.; Allen, J. O.; Hughes, L. S.; Bhave, P.; Cass, G. R. & Prather, K. A..
Single-particle measurements were made using aerosol time-of-flight mass spectrometry (ATOFMS) instruments in conjunction with the 1997 Southern California Ozone Study-North American Research Strategy for Tropospheric Ozone (SCOS97-NARSTO). The size and chemical composition of individual ambient particles in Riverside, CA during the summer of 1997 are described. Data collected using co-located micro-orifice uniform deposit impactors (MOUDI) impactors are used to scale the ATOFMS number counts, providing a unique picture of the particle population which complements information obtained using traditional sizing and composition analysis techniques in this and previous studies. Changes in single particle composition are observed over time, and compared and contrasted with observed changes in visibility, ozone, and PM10 concentrations. Details are provided on changes in the particle size and composition observed during three morning periods with low ozone and elevated PM10 !
A Micrometerological investigation of a restored California Wetland Ecosystem. Anderson, Frank E; Snyder, Richard L; Miller, Robin L & Drexler, Judith.
American Meteorological Society:
http://dx.doi.org/10.1175/BAMS-84-9-1170 DOI: 10.1175/BAMS-84-9-1170
Water flowing through the delta prevents saltwater intrusion into freshwater ecosystems. Continued subsidence, however, seriously threatens the levee system in the delta and levee breaks could result in saltwater intrusion and contamination of the freshwater supply used by 22 million southern Californians.
A Micrometerological investigation of a restored California Wetland Ecosystem. Frank E. Anderson, Richard L. Snyder, Robin L. Miller & Judith Drexler.
American Meteorological Society:
Water flowing through the delta prevents saltwater intrusion into freshwater ecosystems. Continued subsidence however seriously threatens the levee system in the delta and levee breaks could result in saltwater intrusion and contamination of the freshwater supply used by 22 million southern Californians.
A multiyear regional climate hindcast for the western United States using the mesoscale atmospheric simulation model. Kim, Jinwon & Lee, Jung-Eun.
Journal of Hydrometeorology:
In preparation for studying the effects of increased CO2 on the hydrologic cycle in the western United States, an 8-yr hindcast was performed using a regional climate model (RCM) driven by the large-scale forcing from the NCEP-NCAR reanalysis. The simulated precipitation characteristics agree well with observations, especially in the winter. The simulated precipitation compares with rain gauge data at similar accuracy as the NCEP reanalysis, but the RCM-generated precipitation is more accurate than the reanalysis data at the scales of individual basins. Important characteristics of the hydrologic cycle of the region, such as seasonal snowfall, frequency of heavy and extreme daily precipitation events, and interannual variations of precipitation associated with the North American monsoon are also well represented in the hindcast. Compared to the Climate Research Unit, University of East Anglia (CRU), analysis, the simulated low-level air temperatures show cold biases except in summer. The temperature biases are difficult to quantify, however, due to suspected warm biases in the CRU data. The RCM overestimates surface insolation and outgoing longwave radiation at the top of the atmosphere (OLR-TOA). The errors in the simulated radiation are smaller over the land than the ocean. Both simulated and observed OLR-TOA suggest strong influence of low-level temperatures on the seasonal variations of OLR-TOA in the region. The results suggest that the RCM employed in this study possesses reasonable skill for studying regional climate change signals in the western United States.
Appendix B: Base Case Forecast of California Transportation Energy Demand (Task 2). Kavalec, Chris; Stamets, Leigh; Perez, Pat; Matthews, Scott W & Therkelsen, Robert L.
California Energy Commission and California Air Resources Board :
This staff report was prepared as part of the AB 2076 (Chapter 936, Statutes of 2000) analysis. Assembly Bill 2076 (Chapter 936, Statutes of 2000) requires the California Energy Commission and the California Air Resources Board to develop and submit a strategy to the Legislature to reduce petroleum dependence in California. The statute requires the strategy to include goals for reducing the rate of growth in the demand for petroleum fuels. Options to be considered include increasing transportation energy efficiency and using non-petroleum fuels and advanced transportation technologies including alternative fueled vehicles and hybrid vehicles. The Energy Commission and the Air Resources Board have developed a program and methodologies to evaluate and analyze these possible options. The goal of this effort is to provide policy makers with a robust analysis of the possible measures that could be implemented to meet the fuel demands of consumers and industry. This analysis needs to account for the cost of these measures as well as the benefits. The overall effort is guided by consultant services provided by Acurex Environmental, an Arthur D. Little Company.
Climate change has the potential to affect many aspects of California'the survival of its unique ecosystems, its ability to produce electricity, the natural resources that support its economy, its supply of water and agricultural products, and the health of its citizens. This effort evaluated the PIER-funded studies that examined the potential impacts from climate change on these sectors, to create a knowledge base for research on climate change impacts in California and to identify paths and priorities for future research. The researchers found that those studies provided an invaluable benchmark for future research on regional climate change impacts, both in California and elsewhere. Simultaneously, they emphasize that the studies' findings be viewed not as specific predictions of future climate and impacts, but as a sensitivity analysis that considers a range of potential outcomes. The reviewers provide a series of recommendations for future studies on climate change impacts in California, involving extensions and improvements in data, methods, and modeling techniques.