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601.
The impact of future climate change on West African crop yields: What does the recent literature say? 总被引:2,自引:0,他引:2
Philippe Roudier Benjamin SultanPhilippe Quirion Alexis Berg 《Global Environmental Change》2011,21(3):1073-1083
In West Africa, agriculture, mainly rainfed, is a major economic sector and the one most vulnerable to climate change. A meta-database of future crop yields, built up from 16 recent studies, is used to provide an overall assessment of the potential impact of climate change on yields, and to analyze sources of uncertainty.Despite a large dispersion of yield changes ranging from −50% to +90%, the median is a yield loss near −11%. This negative impact is assessed by both empirical and process-based crop models whereas the Ricardian approach gives very contrasted results, even within a single study. The predicted impact is larger in northern West Africa (Sudano-Sahelian countries, −18% median response) than in southern West Africa (Guinean countries, −13%) which is likely due to drier and warmer projections in the northern part of West Africa. Moreover, negative impacts on crop productivity increase in severity as warming intensifies, with a median yield loss near −15% with most intense warming, highlighting the importance of global warming mitigation.The consistently negative impact of climate change results mainly from the temperature whose increase projected by climate models is much larger relative to precipitation change. However, rainfall changes, still uncertain in climate projections, have the potential to exacerbate or mitigate this impact depending on whether rainfall decreases or increases. Finally, results highlight the pivotal role that the carbon fertilization effect may have on the sign and amplitude of change in crop yields. This effect is particularly strong for a high carbon dioxide concentration scenario and for C3 crops (e.g. soybean, cassava). As staple crops are mainly C4 (e.g. maize, millet, sorghum) in WA, this positive effect is less significant for the region. 相似文献
602.
This study analyzed the foraging behavior of the gastropod Nassarius pullus on garbage-impacted sandy shores of Talim Bay, Batangas, Philippines. The effect of different levels of plastic garbage cover on foraging efficiency was investigated. Controlled in situ baiting experiments were conducted to quantify aspects of foraging behavior as affected by the levels of plastic litter cover in the foraging area. The results of the study indicated that the gastropod’s efficiency in locating and in moving towards a food item generally decreased as the level of plastic cover increased. Prolonged food searching time and increased self-burial in sand were highly correlated with increased plastic cover. The accuracy of orientation towards the actual position of the bait decreased significantly when the amount of plastic cover increased to 50%. These results are consistent with the significant decreases in the abundance of the gastropod observed during periods of deposition of large amounts of plastic and other debris on the shore. 相似文献
603.
Over the last century, geomorphic processes along the Middle Rio Grande have been altered by flood control and bank stabilization projects, intensified land and water use, and climate change. In response to potential risks to infrastructure and ecological integrity, recent (1985–2008) adjustment was investigated and historic (1918–1985) changes in Rio Grande channel planform through the Albuquerque, New Mexico, area were reviewed, especially in relation to changes in annual peak discharge and river engineering measures. Using a GIS, channel characteristics were digitized from georeferenced photographs and analyzed with particular attention to quantifying potential measurement error and its propagation. Error associated with average channel widths and channel area ranged between 4 and 13%. For smaller polygons, e.g. islands, error was higher (11 to 40% for width and >200% for area) because width error is large relative to polygon width. Between 1918 and 1963, average channel widths decreased 8 m/yr, from 516 ± 67 m to 176 ± 7 m, mostly due to decreasing peak flows and the implementation of flood control and other engineering measures. From 1985 to 2008, widths decreased 0·7 m/yr, from 176 ± 23 m to 146 ± 5 m, accompanied by an increase in vegetated island area which largely coincided with low flow periods. Narrowing was concentrated at tributary inputs and in the upstream part of the reach, where bedload trapping by Cochiti Dam has caused degradation. Bank protection structures and dense vegetation limit bank erosion in the reach, but erosion is significant where expanding islands, incision, and increased meandering force water against banks. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
604.
Candace Grand Pre Stephen J. Culver David J. Mallinson Kathleen M. Farrell D. Reide Corbett Benjamin P. Horton Caroline Hillier Stanley R. Riggs Scott W. Snyder Martin A. Buzas 《Quaternary Research》2011,76(3):319-334
Foraminiferal analyses of 404 contiguous samples, supported by diatom, lithologic, geochronologic and seismic data, reveal both rapid and gradual Holocene paleoenvironmental changes in an 8.21-m vibracore taken from southern Pamlico Sound, North Carolina. Data record initial flooding of a latest Pleistocene river drainage and the formation of an estuary 9000 yr ago. Estuarine conditions were punctuated by two intervals of marine influence from approximately 4100 to 3700 and 1150 to 500 cal yr BP. Foraminiferal assemblages in the muddy sand facies that accumulated during these intervals contain many well-preserved benthic foraminiferal species, which occur today in open marine settings as deep as the mid shelf, and significant numbers of well-preserved planktonic foraminifera, some typical of Gulf Stream waters. We postulate that these marine-influenced units resulted from temporary destruction of the southern Outer Banks barrier islands by hurricanes. The second increase in marine influence is coeval with increased rate of sea-level rise and a peak in Atlantic tropical cyclone activity during the Medieval Climate Anomaly. This high-resolution analysis demonstrates the range of environmental variability and the rapidity of coastal change that can result from the interplay of changing climate, sea level and geomorphology in an estuarine setting. 相似文献
605.
Nicholas Deichmann John Clinton Stephan Husen Benjamin Edwards Florian Haslinger Donat Fäh Domenico Giardini Philipp Kästli Urs Kradolfer Stefan Wiemer 《Swiss Journal of Geoscience》2011,104(3):537-547
This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during
2010. During this period, 407 earthquakes and 85 quarry blasts were detected and located in the region under consideration.
With a total of only 19 events with ML ≥ 2.5, the seismic activity in the year 2010 was below the average over the previous 35 years. The two most noteworthy earthquakes
were the ML 3.4 Barrhorn event near Sankt Niklaus (VS) and the ML 3.0 event of Feldkirch, both of which produced shaking of intensity IV. 相似文献
606.
The Role of Ground-Based GPS Meteorological Observations in Numerical Weather Prediction 总被引:3,自引:0,他引:3
For lack of sufficient observations, the definition of atmospheric moisture fields (including water vapor and clouds) remains
a difficult problem whose solution is essential for improved weather forecasts. Moisture fields are under-observed in time
and space, primarily because the distribution of water in the atmosphere is highly variable. Because water is important in
weather and climate processes, a significant effort has been expended to develop new or improved remote sensing systems to
mitigate this problem. One such system uses ground-based Global Positoning System (GPS) receivers to make accurate all-weather
estimates of atmospheric refractivity at very low cost. This largely unanticipated application of GPS had led to a new and
potentially significant upper-air observing system for meteorological agencies and researchers around the world (Wolfe & Gutman,
2000). The first and most mature use of GPS for this purpose is in the estimation of integrated (total column) precipitable
water vapor above a fixed site (Duan et al., 1996, with improvements by Niell, 1996, and Fang et al., 1998). The techniques
currently used by the National Oceanic and Atmospheric Administration's Forecast Systems Laboratory (NOAA/FSL) to collect,
process, and distribute GPS water vapor observations are mature and almost ready for transition to operational use. NOAA/FSL
has shown that GPS integrated water vapor data can be used effectively in objective (i. e., numerical weather prediction)
and subjective weather forecasting. To understand the strengths and limitations of GPS for weather forecasting, it is essential
to understant what types of information are currently available to forecasters and modelers, and how models use the data to
describe the current and probable future state of the atmosphere. It is also important to understand the current trends in
modern weather prediction to ensure that GPS observing system play a significant role in the future. ? 2001 John Wiley & Sons,
Inc. 相似文献
607.
608.
There is increasing concern that avoiding climate change impacts will require proactive adaptation, particularly for infrastructure systems with long lifespans. However, one challenge in adaptation is the uncertainty surrounding climate change projections generated by general circulation models (GCMs). This uncertainty has been addressed in different ways. For example, some researchers use ensembles of GCMs to generate probabilistic climate change projections, but these projections can be highly sensitive to assumptions about model independence and weighting schemes. Because of these issues, others argue that robustness-based approaches to climate adaptation are more appropriate, since they do not rely on a precise probabilistic representation of uncertainty. In this research, we present a new approach for characterizing climate change risks that leverages robust decision frameworks and probabilistic GCM ensembles. The scenario discovery process is used to search across a multi-dimensional space and identify climate scenarios most associated with system failure, and a Bayesian statistical model informed by GCM projections is then developed to estimate the probability of those scenarios. This provides an important advancement in that it can incorporate decision-relevant climate variables beyond mean temperature and precipitation and account for uncertainty in probabilistic estimates in a straightforward way. We also suggest several advancements building on prior approaches to Bayesian modeling of climate change projections to make them more broadly applicable. We demonstrate the methodology using proposed water resources infrastructure in Lake Tana, Ethiopia, where GCM disagreement on changes in future rainfall presents a major challenge for infrastructure planning. 相似文献
609.
Although carbonate-associated sulfate (CAS) is used widely as a proxy for the sulfur isotope composition of ancient seawater, little is known about the effects of diagenesis on retention of primary δ34S signals. Our case study of the Key Largo Limestone, Pleistocene, Florida, is the first systematic assessment of the impact of meteoric diagenesis on CAS properties. Geochemical and petrographic data show that meteoric diagenesis has affected the exposed coralline facies to varying degrees, yielding differences now expressed as sharp reaction fronts between primary and secondary carbonate minerals within individual coral heads. Specifically, analyses across high-resolution transects in the Key Largo Limestone show that concentrations of strontium and sodium decrease across the recrystallization front from original aragonite to meteoric low-magnesium calcite by factors of roughly 5 and 10, respectively. Predictably, δ18O values decrease across these same fronts. The δ13C relationships are more complex, with the most depleted values observed in the latest-formed calcite. Such trends likely reflect carbon isotope buffering capacity that decreased as reaction progressed, as well as protracted development of soil profiles and the associated terrestrial biomass and thus depleted δ13C during sea-level lowstand. Conversely, δ34S values of CAS vary within a narrow ‘buffered’ range from 20.6 to 22.6‰ (compared to 20.8-22.0‰ of coeval Pleistocene seawater) across the same mineralogical transition, despite sulfate concentrations that drop in the diagenetic calcite by an average factor of 12. Collectively, these data point to robust preservation of primary δ34S for carbonates that have experienced intense meteoric diagenesis, which is encouraging news for those using the isotopic composition of CAS as a paleoceanographic proxy. At the same time, the vulnerability of CAS concentrations to diagenetic resetting is clear. 相似文献
610.
Rachel Sleeter Benjamin M. Sleeter Brianna Williams Dianna Hogan Todd Hawbaker Zhiliang Zhu 《Carbon balance and management》2017,12(1):2