Publications Published in 2003

1. A 60-year history of California soil quality using paired samples. De Clerck, F.; Singer, M. J.; Lindert, P..
   Geoderma: 2003
   Notes
   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.
   
   
   
2. Abrupt climate change. Alley, R. B.; Marotzke, J.; Nordhaus, W. D.; Overpeck, J. T.; Peteet, D. M.; Pielke, R. A.; Pierrehumbert, R. T.; Rhines, P. B.; Stocker, T. F.; Talley, L. D.; Wallace, J. M..
   Science: 2003
   Notes
   Large, abrupt, and widespread climate changes with major impacts have occurred repeatedly in the past, when the Earth system was forced across thresholds. Although abrupt climate changes can occur for many reasons, it is conceivable that human forcing of climate change is increasing the probability of large, abrupt events. Were such an event to recur, the economic and ecological impacts could be large and potentially serious. Unpredictability exhibited near climate thresholds in simple models shows that some uncertainty will always be associated with projections. In light of these uncertainties, policy-makers should consider expanding research into abrupt climate change, improving monitoring systems, and taking actions designed to enhance the adaptability and resilience of ecosystems and economies.
   
   
   
3. A California Model of Climate Change Impacts on Timber Markets, Appendix XII in Wilson, T., L. Williams, J. Smith, and R Mendelsohn, Global Climate Change and California: Potential Implications for Ecosystems, Health, and the Economy (2003). Robert Mendelsohn.
   California Energy Commission: 2003
   Notes
   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.
   
   
   
4. Acclimation capacity underlies susceptibility to climate change. Stillman, Jonathan H.
   Science: 2003
   Notes
   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.
   
   
   
5. Accurate Estimation of Forest Carbon Stocks by 3-D Remote Sensing of Individual Trees. Omasa, Kenji; Qui, Guo Yu; Watanuki, Kenichi; Yoshimi, Kenji; Akiyama, Yukihide.
   Environmental Science & Technology: 2003
   Notes
   Forests are one of the most important carbon sinks on Earth. However, owing to the complex structure, variable geography, and large area of forests, accurate estimation of forest carbon stocks is still a challenge for both site surveying and remote sensing. For these reasons, the Kyoto Protocol requires the establishment of methodologies for estimating the carbon stocks of forests (Kyoto Protocol, Article 5). A possible solution to this challenge is to remotely measure the carbon stocks of every tree in an entire forest. Here, we present a methodology for estimating carbon stocks of a Japanese cedar forest by using a high-resolution, helicopter-borne 3-dimensional (3-D) scanning lidar system that measures the 3-D canopy structure of every tree in a forest. Results show that a digital image (10-cm mesh) of woody canopy can be acquired. The treetop can be detected automatically with a reasonable accuracy. The absolute error ranges for tree height measurements are within 42 cm. Allometric relationships of height to carbon stocks then permit estimation of total carbon storage by measurement of carbon stocks of every tree. Thus, we suggest that our methodology can be used to accurately estimate the carbon stocks of Japanese cedar forests at a stand scale. Periodic measurements will reveal changes in forest carbon stocks.
   
   
   
6. Additive effects of simulated climate changes, elevated CO. Zavaleta, Erika S.; Shaw, M. Rebecca; Chiariello, Nona R.; Mooney, Harold A.; Field, Christopher B..
   Proceedings of the National Academy of Sciences of the United States of America: 2003
   Notes
   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 CO
   
   
   
7. A globally coherent fingerprint of climate change impacts across natural systems. Parmesan, Camille; Yohe, Gary.
   Nature: 2003
   Notes
   Causal attribution of recent biological trends to climate change is complicated because non-climatic influences dominate local, short-term biological changes. Any underlying signal from climate change is likely to be revealed by analyses that seek systematic trends across diverse species and geographic regions; however, debates within the Intergovernmental Panel on Climate Change (IPCC) reveal several definitions of a 'systematic trend'. Here, we explore these differences, apply diverse analyses to more than 1,700 species, and show that recent biological trends match climate change predictions. Global meta-analyses documented significant range shifts averaging 6.1 km per decade towards the poles (or metres per decade upward), and significant mean advancement of spring events by 2.3 days per decade. We define a diagnostic fingerprint of temporal and spatial 'sign-switching' responses uniquely predicted by twentieth century climate trends. Among appropriate long-term/large-scale/multi-species data sets, this diagnostic fingerprint was found for 279 species. This suite of analyses generates 'very high confidence' (as laid down by the IPCC) that climate change is already affecting living systems.
   
   
   
8. A guide to CO2 sequestration. Lackner, K. S..
   Science: 2003
   Notes
   Climate change concerns may soon force drastic reductions in CO
   
   
   
9. Air conditioning market saturation and long-term response of residential cooling energy demand to climate change. Sailor, D J; Pavlova, A A.
   Energy: 2003
   Notes
   Existing state-level models relating climate parameters to residential electricity consumption indicate a nominal sensitivity of 2–4% for each degree Celsius increase in ambient temperatures. Long-term climate change will also impact electricity consumption through corresponding increases in the market saturation of air conditioning. In this paper we use air conditioning market saturation data for 39 US cities to develop a generalized functional relationship between market saturation and cooling degree days. The slope of this saturation curve is particularly high for cities that currently have low to moderate saturation. As a result, the total response of per capita electricity consumption to long-term warming may be much higher than previously thought. A detailed analysis of 12 cities in four states shows that for some cities changes in market saturation may be two to three times more important than the role of weather sensitivity of current loads. While actual behavioral response to climate change will be more complicated than that captured in our model of market saturation, this approach provides a new perspective on the sensitivity of space conditioning electricity consumption in the US to climate change.
   
   
   
10. Air pollution and climate-forcing impacts of a global hydrogen economy. Schultz, M. G.; Diehl, T.; Brasseur, G. P.; Zittel, W..
    Science: 2003
    Notes
    If today's surface traffic fleet were powered entirely by hydrogen fuel cell technology, anthropogenic emissions of the ozone precursors nitrogen oxide (NOx) and carbon monoxide could be reduced by up to 50%, leading to significant improvements in air quality throughout the Northern Hemisphere. Model simulations of such a scenario predict a decrease in global OH and an increased lifetime of methane, caused primarily by the reduction of the NOx emissions. The sign of the change in climate forcing caused by carbon dioxide and methane depends on the technology used to generate the molecular hydrogen. A possible rise in atmospheric hydrogen concentrations is unlikely to cause significant perturbations of the climate system.