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Browse publications gathered by the California Energy Commission that focus on climate change issues relevant to the State of California. Find both PIER research papers as well as relevant articles published in peer reviewed journals.

Publications Published in 2012


  1. Multi-model projections of twenty-first century North Pacific winter wave climate under the IPCC A2 scenario. Nicholas E. Graham, Daniel R. Cayan, Peter D. Bromirski Reinhard E. Flick.
    Climate Dynamics: 2012
    http://dx.doi.org/10.1007/s00382-012-1435-8
    DOI: 10.1007/s00382-012-1435-8
    Notes
    A dynamical wave model implemented over the North Pacific Ocean was forced with winds from three coupled global climate models (CGCMs) run under a medium-to-high scenario for greenhouse gas emissions through the twenty-first century. The results are analyzed with respect to changes in upper quantiles of significant wave height (90th and 99th percentile HS) during boreal winter. The three CGCMs produce surprisingly similar patterns of change in winter wave climate during the century, with waves becoming 10-15 % smaller over the lower mid-latitudes of the North Pacific, particularly in the central and western ocean. These decreases are closely associated with decreasing windspeeds along the southern flank of the main core of the westerlies. At higher latitudes, 99th percentile wave heights generally increase, though the patterns of change are less uniform than at lower latitudes. The increased wave heights at high latitudes appear to be due a variety of wind-related factors including both increased windspeeds and changes in the structure of the wind field, these varying from model to model. For one of the CGCMs, a commonly used statistical approach for estimating seasonal quantiles of HS on the basis of seasonal mean sea level pressure (SLP) is used to develop a regression model from 60 years of twentieth century data as a training set, and then applied using twenty-first century SLP data. The statistical model reproduces the general pattern of decreasing twenty-first century wave heights south of *40 N, but underestimates the magnitude of the changes by *50-70 %, reflecting relatively weak coupling between sea level pressure and wave heights in the CGCM data and loss of variability in the statistically projected wave heights.


  2. On the Sources of Methane to the Los Angeles Atmosphere. Wennberg, Paul O.; Mui, Wilton; Wunch, Debra; Kort, Eric A.; Blake, Donald R.; Atlas, Elliot L.; Santoni, Gregory W.; Wofsy, Steven C.; Diskin, Glenn S.; Jeong, Seongeun & Fischer, Marc L..
    Environmental Science & Technology: 2012
    http://dx.doi.org/10.1021/es301138y
    DOI: 10.1021/es301138y
    Notes
    We use historical and new atmospheric trace gas observations to refine the estimated source of methane (CH(4)) emitted into California's South Coast Air Basin (the larger Los Angeles metropolitan region). Referenced to the California Air Resources Board (CARB) CO emissions inventory, total CH(4) emissions are 0.44 ± 0.15 Tg each year. To investigate the possible contribution of fossil fuel emissions, we use ambient air observations of methane (CH(4)), ethane (C(2)H(6)), and carbon monoxide (CO), together with measured C(2)H(6) to CH(4) enhancement ratios in the Los Angeles natural gas supply. The observed atmospheric C(2)H(6) to CH(4) ratio during the ARCTAS (2008) and CalNex (2010) aircraft campaigns is similar to the ratio of these gases in the natural gas supplied to the basin during both these campaigns. Thus, at the upper limit (assuming that the only major source of atmospheric C(2)H(6) is fugitive emissions from the natural gas infrastructure) these data are consistent with the attribution of most (0.39 ± 0.15 Tg yr(-1)) of the excess CH(4) in the basin to uncombusted losses from the natural gas system (approximately 2.5-6% of natural gas delivered to basin customers). However, there are other sources of C(2)H(6) in the region. In particular, emissions of C(2)H(6) (and CH(4)) from natural gas seeps as well as those associated with petroleum production, both of which are poorly known, will reduce the inferred contribution of the natural gas infrastructure to the total CH(4) emissions, potentially significantly. This study highlights both the value and challenges associated with the use of ethane as a tracer for fugitive emissions from the natural gas production and distribution system.


  3. Projections of declining surface-water availability for the southwestern United States. Richard Seager, Mingfang Ting, Cuihua Li, Naomi Naik, Ben Cook, Jennifer Nakamura & Haibo Liu.
    Nature Climate Change: 2012
    Notes
    Global warming driven by rising greenhouse-gas concentrations is expected to cause wet regions of the tropics and mid to high latitudes to get wetter and subtropical dry regions to get drier and expand polewards. Over southwest North America, models project a steady drop in precipitation minus evapotranspiration, P, E, the net flux of water at the land surface leading to, for example, a decline in Colorado River flow. This would cause widespread and important social and ecological consequences. Here, using new simulations from the Coupled Model Intercomparison Project Five, to be assessed in Intergovernmental Panel on Climate Change Assessment Report Five, we extend previous work by examining changes in P, E, runoff and soil moisture by season and for three different water resource regions. Focusing on the near future, 2021-2040, the new simulations project declines in surface-water availability across the southwest that translate into reduced soil moisture and runoff in California and Nevada, the Colorado River headwaters and Texas.


  4. Rapid Progression of Ocean Acidification in the California Current System. Nicolas Gruber, Claudine Hauri, Zouhair Lachkar Damian Loher Thomas L. Frolicher Gian-Kasper Plattner.
    Science: 2012
    Notes
    Nearshore waters of the California Current System (California CS) already have a low carbonate saturation state, making them particularly susceptible to ocean acidification. We used eddy-resolving model simulations to study the potential development of ocean acidification in this system up to the year 2050 under the Special Report on Emissions Scenarios A2 and B1 scenarios. In both scenarios, the saturation state of aragonite Ω(arag) is projected to drop rapidly, with much of the nearshore region developing summer-long undersaturation in the top 60 meters within the next 30 years. By 2050, waters with Ω(arag) above 1.5 will have largely disappeared, and more than half of the waters will be undersaturated year-round. Habitats along the sea floor will become exposed to year-round undersaturation within the next 20 to 30 years. These projected events have potentially major implications for the rich and diverse ecosystem that characterizes the California CS.


  5. Remote Sensing of the Terrestrial Water Cycle. .
    : 2012

  6. Representing Energy Price Variability in Long- and Medium-Term Hydropower Optimization. Olivares, M. & Lund, J..
    Journal of Water Resources Planning and Management: 2012
    http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29WR.1943-5452.0000214
    Notes
    Representing peak and off-peak energy prices is often difficult in hydropower modeling because the time scale of price variability (hours or less) is much shorter than that needed for many operations planning models (days to months). This work extends and examines the reliability of an existing approximate method to incorporate hourly energy price information into revenue functions used in hydropower reservoir optimization models with larger time steps (weekly, monthly, etc). The method assumes constant head, an exogenously known frequency distribution for hourly prices during each modeled time period (day, week, month) and a revenue-maximizing operational strategy that allocates hydropower releases in order of decreasing hourly price. The method is extended to the case with minimum instream flows requirements. The reliability of the method was tested for the cases with and without minimum instream flow requirements. Revenue estimates for a hypothetical hydropower site were compared with the exact optimal revenue from solving the hourly optimization problem within one week, showing less than 1% error using a finely discretized price frequency curve.


  7. Seasonal variation of CH4 emissions from central California. Seongeun Jeong, Chuanfeng Zhao, Arlyn E. Andrews, Laura Bianco, James M. Wilczak, Marc L. Fischer.
    Geophysical Research Letters: 2012
    Notes
    We estimate seasonal variations in methane (CH4) emissions from central California from December 2007 through November 2008 by comparing CH4 mixing ratios measured at a tall tower with transport model predictions based on a global 1 a priori CH4 emissions map (EDGAR32) and a 10 km seasonally varying California-specific map, calibrated to statewide by CH4 emission totals. Atmospheric particle trajectories and surface footprints are computed using the Weather Research and Forecasting and Stochastic Time-Inverted Lagrangian Transport models. Uncertainties due to wind velocity and boundary layer mixing depth are evaluated using measurements from radar wind profilers. CH4 signals calculated using the EDGAR32 emission model are larger than those based on the California-specific model and in better agreement with measurements. However, Bayesian inverse analyses using the California-specific and EDGAR32 maps yield comparable annually averaged posterior CH4 emissions totaling 1.55  0.24 times and 1.84  0.27 times larger than the California-specific prior emissions, respectively, for a region of central California within approximately 150 km of the tower. If these results are applicable across California, state total CH4 emissions would account for approximately 9% of state total greenhouse gas emissions. Spatial resolution of emissions within the region near the tower reveal seasonality expected from several biogenic sources, but correlations in the posterior errors on emissions from both prior models indicate that the tower footprints do not resolve spatial structure of emissions. This suggests that including additional towers in a measurement network will improve the regional specificity of the posterior estimates.


  8. Severe and sustained drought in southern California and the West: Present conditions and insights from the past on causes and impacts Present conditions and insights from the past on causes and impacts. Glen M. MacDonald.
    Department of Geography, UCLA Quaternary International: 2012
    DOI: 10.1016/j.quaint.2007.03.012
    Notes
    <p><span style="font-family: AdvTimes; font-size: xx-small;"><span style="font-family: AdvTimes; font-size: xx-small;"> <p>Southern California and much of the western United States face a chronic challenge of limited water supply due to high potential</p> <p>evaporation and low precipitation coupled with frequent droughts. Mitigation approaches include the use of ground water, reliance on</p> <p>water from river systems fed by mountainous regions that have relatively high precipitation, and the construction of extensive aqueduct</p> <p>and water storage systems. In southern California the present infrastructure is capable of insulating large water districts against the</p> <p>typical annual and multi-annual droughts experienced over the past 100 years. However, paleoclimatic records indicate that the region is</p> <p>also prone to much longer droughts, including a prolonged episode of generally arid conditions and severe droughts extending from the</p> <p>9th through 14th centuries. This period is sometimes referred to as the medieval climate anomaly. Archaeological evidence suggests that</p> <p>prehistoric populations such as the Anasazi in the Southwest and the Chumash in southern California were impacted by mega-drought</p> <p>conditions during the medieval climate anomaly. These groups appear to have displayed a variety of responses&mdash;ranging from increased</p> <p>violence and the abandonment of some regions, to the development of greater cultural complexity and material infrastructure.</p> <p>Paleoclimatological and paleooceanographic data indicate that the arid conditions in western North America during the medieval</p> <p>climate anomaly were produced by the prolonged occurrence of cool surface waters in the eastern Pacific. Recent climate model</p> <p>experiments suggest relatively small increases in insolation and decreases in atmospheric volcanic emission concentrations can trigger</p> <p>such depressions of eastern Pacific temperatures. It is thus possible that a similar event could occur in the future due to natural or</p> <p>anthropogenic causes.</p> </span></span></p>


  9. Switch: a planning tool for power systems with large shares of intermittent renewable energy. Fripp, M..
    Environmental Science & Technology: 2012
    http://dx.doi.org/10.1021/es204645c
    DOI: 10.1021/es204645c
    Notes
    Wind and solar power are highly variable, so it is it unclear how large a role they can play in future power systems. This work introduces a new open-source electricity planning model--Switch--that identifies the least-cost strategy for using renewable and conventional generators and transmission in a large power system over a multidecade period. Switch includes an unprecedented amount of spatial and temporal detail, making it possible to address a new type of question about the optimal design and operation of power systems with large amounts of renewable power. A case study of California for 2012-2027 finds that there is no maximum possible penetration of wind and solar power--these resources could potentially be used to reduce emissions 90% or more below 1990 levels without reducing reliability or severely raising the cost of electricity. This work also finds that policies that encourage customers to shift electricity demand to times when renewable power is most abundant (e.g., well-timed charging of electric vehicles) could make it possible to achieve radical emission reductions at moderate costs.


  10. Technical Report B – Water Supply Assessment. .
    U.S. Department of the Interior Bureau of Reclamation February 2012 : 2012

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