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31.
Julian Ramirez-Villegas Mike Salazar Andy Jarvis Carlos E. Navarro-Racines 《Climatic change》2012,115(3-4):611-628
Policy measures regarding adaptation to climate change include efforts to adjust socio-economic and ecologic systems. Colombia has undertaken various measures in terms of climate change mitigation and adaptation since becoming a party of the Kyoto protocol in 2001 and a party of the United Nations Framework Convention on Climate Change (UNFCCC) in 1995. The first national communication to the UNFCCC stated how Colombian agriculture will be severely impacted under different emission scenarios and time frames. The analyses in this document further support that climate change will severely threaten the socioeconomics of Colombian agriculture. We first query national data sources to characterize the agricultural sector. We then use 17 Global Circulation Model (GCM) outputs to quantify how Colombian agricultural production may be affected by climate change, and show the expected changes to years 2040–2069 (“2050”) under the A2 scenario of the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (SRES-A2) and the overall trends in both precipitation and temperature to 2100. We then evaluate expected changes within different regions and measure the proportion of area affected within each crop’s distributional range. By 2050, climatic change in Colombia will likely impact 3.5 million people, 14?% of national GDP corresponding to agriculture, employment of 21?% of the population, agro-industries, supply chains, and food and nutritional security. If no adaptation measures are taken, 80?% of crops would be impacted in more than 60?% of their current areas of cultivation, with particularly severe impacts in high value perennial and exportable crops. Impacts also include soil degradation and organic matter losses in the Andes hillsides; likely flooding in the Caribbean and Pacific coasts; niche losses for coffee, fruit, cocoa, and bananas; changes in prevalence of pests and diseases; and increases in the vulnerabilities of non-technically developed smallholders. There is, however, still time to change the current levels of vulnerability if a multidisciplinary focus (i.e., agronomic, economic, and social) in vulnerable sectors is undertaken. Each sub-sector and the Government need to invest in: (1) data collection, (2) detailed, regionally-based impact assessments, (3) research and development, and (4) extension and technology transfer. Support to vulnerable smallholders should be given by the state in the form of agricultural insurance systems contextualized under the phenomenon of climate change. A national coordination scheme led by (but not restricted to) the Ministry of Agriculture and Rural Development (MADR) with the contributions of national and international institutions is needed to address agricultural adaptation. 相似文献
32.
Salazar S 《Marine pollution bulletin》2003,47(7-8):313-318
Following the Jessica oil spill, a total of 79 oiled Galápagos sea lions (Zalophus wollebaeki) were recorded around the islands of San Cristóbal, Santa Fé, Isabela and Floreana. Almost half of these animals required washing and other treatment. One sea lion death and a high incidence of conjunctivitis and burns were detected during the period of the oil spill. Sea lion populations exhibited a tendency for decline in the first months following the spill at all three colonies monitored close to the grounding site on San Cristóbal. By comparison, declines of similar magnitude occurred at only one of six sea lion colonies monitored on islands more distant from the spill. However, no significant decreases in population numbers were detected for any colony in the year following the spill. Galápagos sea lion populations were partially recovering from the much more catastrophic impact of the 1997/98 El Ni?o. 相似文献
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34.
C. Brunini F. Azpilicueta M. Gende E. Camilion A. Aragón Ángel M. Hernandez-Pajares M. Juan J. Sanz Dagoberto Salazar 《Journal of Geodesy》2011,85(12):931-939
This paper presents a technique for ingesting ground- and space-based dual-frequency GPS observations into a semi-empirical
global electron density model. The NeQuick-2 model is used as the basis for describing the global electron density distribution.
This model is mainly driven by the F2 ionosphere layer parameters (i.e. the electron density, N
m
F2, and the height, h
m
F2 of the F2 peak), which, in the absence of directly measured values, are computed from the ITU-R database (ITU-R 1997). This database was established using observations collected from 1954 to 1958 by a network of around 150 ionospheric sounders
with uneven global coverage. It allows computing monthly median values of N
m
F2 and h
m
F2 (intra-month variations are averaged), for low and high solar activity. For intermediate solar activity a linear interpolation
must be performed. Ground-based GNSS observations from a global network of ~350 receivers are pre-processed in order to retrieve
slant total electron content (sTEC) information, and space-based GPS observations (radio occultation data from the FORMOSAT-3/COSMIC
constellation) are pre-processed to retrieve electron density (ED) information. Both, sTEC and ED are ingested into the NeQuick-2
model in order to adapt N
m
F2 and h
m
F2, and reduce simultaneously both, the observed minus computed sTEC and ED differences. The first experimental results presented
in this paper suggest that the data ingestion technique is self consistent and able to reduce the observed minus computed
sTEC and ED differences to ~25–30% of the values computed from the ITU-R database. Although sTEC and ED are both derived from
GPS observations, independent algorithm and models are used to compute their values from ground-based GPS observations and
space-based FORMOSAT-3/COSMIC radio occultations. This fact encourages us to pursue this research with the aim to improve
the results presented here and assess their accuracy in a reliable way. 相似文献
35.
Betina J. Lomovasky Fausto N. Firstater Alex Gamarra Salazar Jaime Mendo Oscar O. Iribarne 《Journal of Sea Research》2011,65(2):205-212
Macrobenthic soft bottom community assemblages were studied from December 2006 to December 2007 at Paracas Bay (Atenas Beach, 13°45' S, 76°17' W, Peru), including the period of the tsunami of 15 August 2007, providing a unique opportunity to assess the effects of this type of natural disturbance in soft bottom marine ecosystems. The results show that the tsunami affected the soft bottom community assemblage by changing the sediment granulometry, the biomass and abundance of epifaunal species, and by increasing the silt proportion. The event affected all functional groups, resulting in an increased numbers and biomass of filter feeder and grazers that were followed soon after by predators during the post-tsunami period. A similar pattern was observed for biomass and the abundance of infaunal species without changing the functional groups. The slow recovery observed after four months was likely related to the loss of sediment stability. In summary, there were differences in the structure and composition of soft bottom macrofaunal assemblages before and after the earthquake and posterior tsunami disturbance, forcing benthic communities to initiate re-colonisation processes. 相似文献
36.
Climatic variability arising from the coupling between ocean temperature and sea-ice extent is studied in a spatially distributed system. A spatial degree of freedom is crudely introduced by the coupling, through energy transfer, of two box models each of which describes a different space region. The evolution equations are cast into a normal form and some qualitative features of this general class of models are predicted. It is shown, both analytically and numerically, that internally generated complexity in the form of aperiodic behaviour can be a natural consequence of spatially distributed systems. 相似文献
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38.
Volcán Fuego erupted ash and ash flows during September 1971 and February–March 1973. The ash flows were restricted to existing drainage channels. Most damage was due to subsequent mud flows and floods. A catastrophe can be expected if the ash flows or mud flows increase in volume and overflow their channels in future eruptions. The only practical remedial measure is temporary evacuation, a formidable social and economic undertaking for an underdeveloped nation. Conscious of this, the geologist at the scene is unsure at what point to recommend evacuation. Probably the volcanologist can make his most useful direct contribution to society by cooperating in studies on the effect of volcanism on agriculture. The lives and wealth saved by even a slight increase in agricultural productivity would vastly outweigh losses due to volcanic disasters. 相似文献
39.
Rurik Romero Fernando Barra Mathieu Leisen Eduardo Salazar José María González-Jiménez Martin Reich 《International Geology Review》2020,62(5):598-613
ABSTRACTU-Pb detrital zircon age patterns are presented for nine samples of metapelites from the metamorphic basement of south-central Chile between 37° and 40°S, along with detrital zircon ages for a sample from the Piedra Santa metamorphic complex and a crystallization age of the Chachil plutonic complex, farther east in Argentina. Two distinct zircon age patterns are identified. One is a pattern with a dominant population of zircons at ca. 470 Ma (Ordovician), a widespread presence of Mesoproterozoic ages (1200 ? 1000 Ma), and a Carboniferous maximum deposition age indicated by the youngest zircon population. The second pattern is drastically different, with a main population of Permian zircons, a 290–250 Ma maximum deposition age, and a minor contribution of Pennsylvanian age zircons. Our results, coupled with previously reported metamorphic ages, show that the patterns reflect the presence of different tectonic blocks separated by the Mocha-Villarrica Fault Zone at 39°S. Metapelites north of this structure have the Ordovician-dominated pattern characteristic of the Western Series of the Paleozoic basement, and those south of the fault show the Permian-dominated pattern observed in the younger high-pressure metapelites from the Bahía Mansa metamorphic complex. The Piedra Santa metamorphic complex also shows the Ordovician-dominated pattern and was intruded by the Chachil plutonic complex dated here at ca. 303 Ma. Therefore, the Piedra Santa complex is interpreted as coeval with the Chilean metamorphic basement. The present dislocation of blocks with different ages is attributed to continental-scale dextral strike-slip tectonics along the Huincul Fault Zone, Argentina, which extends to the west as the Mocha-Villarrica Fault Zone in Chile. 相似文献
40.
During nine field transplant tests in San Diego Bay (1987–1990), juvenile mussels were exposed to mean concentrations of tributyltin (TBT) in ambient seawater ranging from 2 to 530 ng liter−1 for 12 weeks under natural conditions. A total of 79 cages with 18 mussels each were monitored at 18 different sites. Growth and seawater TBT concentrations were measured weekly or on alternate weeks (biweekly). Mean growth rates ranged from 17 to 505 mg week−1 (0·2 to 2·5 mm week−1). Accumulation of TBT in mussel tissues was measured at the end of each 12-week test exposure and ranged from 0·1 to 3·2 μg g−1 TBT wet weight. The frequency of the measurements and the integration of chemical and biological measurements improved the accuracy of the assessment over more traditional approaches. Growth was significantly related to seawater and tissue TBT. The statistical relationships with growth effects were used to estimate chemical effect zones for TBT in San Diego Bay. Site-specific differences were distinguished by additional statistical analyses and consideration of environmental significance. 相似文献