1,800 Years of abrupt climate change, severe fire, and accelerated erosion, Sierra Nevada, California, USA. Wathen, Stephen F.
http://dx.doi.org/10.1007/s10584-011-0046-4 DOI: 10.1007/s10584-011-0046-4
This paper provides both a detailed history of environmental change in the Sierra Nevada over the past 1,800 years and evidence for climate teleconnections between the Sierra Nevada and Greenland during the late Holocene. A review of Greenland ice core data suggests that the magnitudes of abrupt changes in temperature and precipitation increased beginning c. 3,700 and 3,000 years ago, respectively. Precipitation increased abruptly 1,300 years ago. Comparing paleotemperature data from Cirque Peak, CAwith paleoprecipitation data from Pyramid Lake, NV suggests that hot temperatures occurred at the beginnings of most severe droughts in the Sierra Nevada over the past 1,800 years. Severe fires and erosion also occurred at Coburn Lake, CA at the beginning of all severe droughts in the Sierra Nevada over the past 1,800 years. This suggests that abrupt climate change during the late Holocene caused vegetation and mountain slopes in some areas to be out of equilibrium with abruptly changed climates. Finally, the ending of drought conditions in Greenland coincided with the beginning of drought conditions in the Sierra Nevada over the past 1,800 years, perhaps as a result of the rapidly changed locations of the Earth's major precipitation belts during abrupt climate change events.
21st 1 Century Precipitation Changes over the Los Angeles Region . Berg, N., A. Hall, F. Sun, S. Capps, D. Walton, B. Langenbrunner, and J. Neelin.
Journal of Climate:
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.
A Bird in Our Hand: Weighing Uncertainty about the Past against Uncertainty about the Future in Channel Islands National Park. Scott A. Morrison.
The George Wright Forum:
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.
Accumulated winter chill is decreasing in the fruit growing regions of California. Baldocchi, Dennis & Wong, Simon.
http://dx.doi.org/10.1007/s10584-007-9367-8 DOI: 10.1007/s10584-007-9367-8
We examined trends in accumulated winter chill across the fruit growing region of central California and its internal coastal valleys. We tested the hypothesis that global warming is in motion in California and is causing accumulated winter chill to decrease across the fruit and nut growing regions of California. The detection of potential trends in accumulated winter chill (between 0 and 7.2°C) was determined using two complementary climate datasets. The California Irrigation Management Information System (CIMIS) contains hourly climate data and is suitable for computing accumulated chill hours and chill degree-hours. But, its longest data records extend back only to the 1980s. The National Weather Service Coop climate record is longer, extending beyond the 1950s at many sites. But its datasets only contain information on daily maximum and minimum temperatures. To assess long term trends in winter chill accumulation, we developed an algorithm that converted information from daily maximum and minimum temperature into accumulated hours of winter chill and summations of chill-degree hours. These inferred calculations of chill hour accumulation were tested with and validated by direct measurements from hourly-based data from the CIMIS network. With the combined climate datasets, we found that the annual accumulation of winter chill hours and chill degree hours is diminishing across the fruit and nut growing regions of California. Observed trends in winter chill range between -50 and -260 chill hours per decade. We also applied our analytical algorithm to project changes in winter chill using regional climate projections of temperature for three regions in the Central Valley. Predicted rates of reduced winter chill, for the period between 1950 and 2100, are on the order of -40 per decade. By the end of the 21st century, orchards in California are expected to experience less than 500 chill hours per winter. This chronic and steady reduction in winter chill is expected to have deleterious economic and culinary impact on fruit and nut production in California by the end of the 21st Century.
A cellphone based system for large-scale monitoring of black carbon. N. Ramanathan, M. Lukac, T. Ahmed A. Kar P.S. Praveen T. Honles I. Leong I.H. Rehman J.J. Schauer V. Ramanathan.
Black carbon aerosols are a major component of soot and are also a major contributor to global and regional climate change. Reliable and cost-effective systems to measure near-surface black carbon (BC) mass concentrations (hereafter denoted as [BC]) globally are necessary to validate air pollution and climate models and to evaluate the effectiveness of BC mitigation actions. Toward this goal we describe a new wireless, low-cost, ultra low-power, BC cellphone based monitoring system (BC_CBM). BC_CBMintegrates a Miniaturized Aerosol filter Sampler (MAS) with a cellphone for filter image collection, transmission and image analysis for determining [BC] in real time. The BC aerosols in the air accumulate on the MAS quartz filter, resulting in a coloration of the filter. A photograph of the filter is captured by the cellphone camera and transmitted by the cellphone to the analytics component of BC_CBM. The analytics component compares the image with a calibrated reference scale (also included in the photograph) to estimate [BC]. We demonstrate with field data collected from vastly differing environments, ranging from southern California to rural regions in the Indo-Gangetic plains of Northern India, that the total BC deposited on the filter is directly and uniquely related to the reflectance of the filter in the redwavelength, irrespective of its source or how the particles were deposited. [BC] varied from 0.1 to 1 mgm-3 in Southern California and from 10 to 200 mgm-3 in rural India in our field studies. In spite of the 3 orders of magnitude variation in [BC], the BC_CBM system was able to determine the [BC] well within the experimental error of two independent reference instruments for both indoor air and outdoor ambient air. Accurate, global-scale measurements of [BC] in urban and remote rural locations, enabled by the wireless, low-cost, ultra low-power operation of BC_CBM, will make it possible to better capture the large spatial and temporal variations in [BC], informing climate science, health, and policy.
A Changing Framework for Urban Water Systems. Hering, Janet G.; Waite, T. David; Luthy, Richard G.; Drewes, Jorg E. & Sedlak, David L..
Environmental Science & Technology:
http://dx.doi.org/10.1021/es4007096 DOI: 10.1021/es4007096
Urban water infrastructure and the institutions responsible for its management have gradually evolved over the past two centuries. Today, they are under increasing stress as water scarcity and a growing recognition of the importance of factors other than the cost of service provision are forcing a reexamination of long-held ideas. Research and development that supports new technological approaches and more effective management strategies are needed to ensure that the emerging framework for urban water systems will meet future societal needs.
A Climate Change Vulnerability Assessment of California's At-Risk Birds. Gardali, Thomas; Seavy, Nathaniel E.; DiGaudio, Ryan T. & Comrack, Lyann A..
http://dx.doi.org/10.1371%2Fjournal.pone.0029507 DOI: 10.1371%2Fjournal.pone.0029507
Conservationists must develop new strategies and adapt existing tools to address the consequences of anthropogenic climate change. To support statewide climate change adaptation, we developed a framework for assessing climate change vulnerability of California's at-risk birds and integrating it into the existing California Bird Species of Special Concern list. We defined climate vulnerability as the amount of evidence that climate change will negatively impact a population. We quantified climate vulnerability by scoring sensitivity (intrinsic characteristics of an organism that make it vulnerable) and exposure (the magnitude of climate change expected) for each taxon. Using the combined sensitivity and exposure scores as an index, we ranked 358 avian taxa, and classified 128 as vulnerable to climate change. Birds associated with wetlands had the largest representation on the list relative to other habitat groups. Of the 29 state or federally listed taxa, 21 were also classified as climate vulnerable, further raising their conservation concern. Integrating climate vulnerability and California's Bird Species of Special Concern list resulted in the addition of five taxa and an increase in priority rank for ten. Our process illustrates a simple, immediate action that can be taken to inform climate change adaptation strategies for wildlife.
A cold phase of the East Pacific triggers new phytoplankton blooms in San Francisco Bay. Cloern, James E.; Jassby, Alan D.; Thompson, Janet K. & Hieb, Kathryn A..
http://dx.doi.org/10.1073/pnas.0706151104 DOI: 10.1073/pnas.0706151104
Ecological observations sustained over decades often reveal abrupt changes in biological communities that signal altered ecosystem states. We report a large shift in the biological communities of San Francisco Bay, first detected as increasing phytoplankton biomass and occurrences of new seasonal blooms that began in 1999. This phytoplankton increase is paradoxical because it occurred in an era of decreasing wastewater nutrient inputs and reduced nitrogen and phosphorus concentrations, contrary to the guiding paradigm that algal biomass in estuaries increases in proportion to nutrient inputs from their watersheds. Coincidental changes included sharp declines in the abundance of bivalve mollusks, the key phytoplankton consumers in this estuary, and record high abundances of several bivalve predators: Bay shrimp, English sole, and Dungeness crab. The phytoplankton increase is consistent with a trophic cascade resulting from heightened predation on bivalves and suppression of their filtration control on phytoplankton growth. These community changes in San Francisco Bay across three trophic levels followed a state change in the California Current System characterized by increased upwelling intensity, amplified primary production, and strengthened southerly flows. These diagnostic features of the East Pacific "cold phase" lead to strong recruitment and immigration of juvenile flatfish and crustaceans into estuaries where they feed and develop. This study, built from three decades of observation, reveals a previously unrecognized mechanism of ocean-estuary connectivity. Interdecadal oceanic regime changes can propagate into estuaries, altering their community structure and efficiency of transforming land-derived nutrients into algal biomass.