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Ricciardi Rasmussen 1999.pdf
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TRB Library
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PEK-RIC
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Richard Silverman 1989.pdf
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TRB Library
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PEK-RIC
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Richardson 1993.pdf
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PEK-RIC
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Richardson Yokley 1996.pdf
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PEK-RIC
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Richardson, BJ
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Expertise Search
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Riggs Webb Lake Texoma.pdf
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TRB Library
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RID-SCH
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Rising air and stream-water temperatures in Chesapeake Bay region, USA
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Monthly mean air temperature (AT) at 85 sites and instantaneous stream-water temperature (WT) at 129 sites for 1960–2010 are examined for the mid-Atlantic region, USA. Temperature anomalies for two periods, 1961–1985 and 1985–2010, relative to the climate normal period of 1971–2000, indicate that the latter period was statistically signifi- cantly warmer than the former for both mean AT and WT. Statistically significant temporal trends across the region of 0.023 °C per year for AT and 0.028 °C per year for WT are detected using simple linear regression. Sensitivity analyses show that the irregularly sampled WT data are appropriate for trend analyses, resulting in conservative estimates of trend magnitude. Relations between 190 landscape factors and significant trends in AT-WT relations are examined using principal components analysis. Measures of major dams and deciduous forest are correlated with WT increasing slower than AT, whereas agriculture in the absence of major dams is correlated with WT increasing faster than AT. Increasing WT trends are detected despite increasing trends in streamflow in the northern part of the study area. Continued warming of contributing streams to Chesapeake Bay likely will result in shifts in distributions of aquatic biota and contribute to worsened eutrophic conditions in the bay and its estuaries.
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Climate Science Documents
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Rising atmospheric carbon dioxide concentration and the future of C 4 crops for food and fuel
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Crops with the C4 photosynthetic pathway are vital to global food supply, particularly in the tropical regions where human well-being and agricultural productivity are most closely linked. While rising atmospheric [CO2 ] is the driving force behind the greater temperatures and water stress, which threaten to reduce future crop yields, it also has the potential to directly benefit crop physiology. The nature of C4 plant responses to elevated [CO2 ] has been controversial. Recent evidence from free-air CO2 enrichment (FACE) experiments suggests that elevated [CO2] does not directly stimulate C4 photosynthesis. Nonetheless, drought stress can be ameliorated at elevated [CO2] as a result of lower stomatal conductance and greater intercellular [CO2]. Therefore, unlike C3 crops for which there is a direct enhancement of photosynthesis by elevated [CO2 ], C4 crops will only benefit from elevated [CO2 ] in times and places of drought stress. Current projections of future crop yields have assumed that rising [CO2] will directly enhance photosynthesis in all situations and, therefore, are likely to be overly optimistic. Additional experiments are needed to evaluate the extent to which amelioration of drought stress by elevated [CO2 ] will improve C4 crop yields for food and fuel over the range of C4 crop growing conditions and genotypes.
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Climate Science Documents
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Rising temperature depletes soil moisture and exacerbates severe drought conditions across southeast Australia
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Over the past decade the southern catchments of the Murray Darling Basin (MDB), responsible for much of Australia’s agricultural output, have experienced a severe drought (termed the ‘‘Big Dry’’) with record high temperatures and record low inflow. We find that during the Big Dry the sensitivity of soil moisture to rainfall decline is over 80% higher than during the World War II drought from 1937 – 1945. A relationship exists between soil moisture and temperature independent of rainfall, particularly in austral spring and summer. Annually, a rise of 1°C leads to a 9% reduction in soil moisture over the southern MDB, contributing to the recent high sensitivity. Since 1950, the impact from rising temperature contributes to 45% of the total soil moisture reduction. In a warming climate, as the same process also leads to an inflow reduction, the reduced water availability can only be mitigated by increased rainfall. Other implications for future climate change are discussed.
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Climate Science Documents
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Risk Assessment
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Assessing wildfire risk is important for natural resource managers, communities, and others with an interest in mitigating that risk. Wildfire risk assessment allows stakeholders to coordinate risk reduction projects, including prescribed fire, and to work with each other to better prepare for wildfires.
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Wildfire
