Adaptation to climate change in Africa: Challenges and opportunities identified from Ethiopia   总被引：6，自引：0，他引：6  

Declan Conway  E. Lisa F. Schipper 《Global Environmental Change》2011,21(1):227-237

Africa is widely held to be highly vulnerable to future climate change and Ethiopia is often cited as one of the most extreme examples. With this in mind we seek to identify entry points to integrate short- to medium-term climate risk reduction within development activities in Africa, drawing from experiences in Ethiopia. To achieve this we employ a range of data and methods. We examine the changing nature of climate risks using analysis of recent climate variability, future climate scenarios and their secondary impacts. We assess the effects of climate variability on agricultural production and national GDP. Entry points and knowledge gaps in relation to mainstreaming climate risks in Ethiopia are identified using the Government's plan for poverty reduction. We end with a case study incorporating climate risks through drought insurance within the current social protection programme in Ethiopia, which provides support to 8.3 million people.Rainfall behaviour in Ethiopia shows no marked emergent changes and future climate projections show continued warming but very mixed patterns of rainfall change. Economic analysis highlights sensitivities within the economy to large-scale drought, however, while the effects are clear in major drought years in other years the relationship is weak. For social protection fairly small positive and negative effects on the number of recipients and frequency of cash payments during drought occur under the extreme range of climate model rainfall projections (2020s).Our analysis highlights several important challenges and opportunities for addressing climate risks. Challenges primarily relate to the large uncertainties in climate projections for parts of Africa, a weak evidence base of complex, often non-deterministic, climate-society interactions and institutional issues. Opportunities relate to the potential for low-regrets measures to reduce vulnerability to current climate variability which can be integrated with relatively modest effort within a shift in Africa from a disaster-focused view of climate to a long-term perspective that emphasises livelihood security and vulnerability reduction.  相似文献   

Distribution, magnitude and characterization of the toxicity of Ukrainian estuarine sediments     

Burgess RM  Konovets IM  Kipnis LS  Lyashenko AV  Grintsov VA  Petrov AN  Terletskaya AV  Milyukin MV  Povolotskii MI  Demchenko VY  Bogoslovskaya TA  Topkin YV  Vorobyova TV  Portis LM  Ho KT 《Marine pollution bulletin》2011,62(11):2442-2462

During the Soviet era, Ukraine was an important industrial and agricultural region of the Soviet Union. This industrial and agricultural activity resulted in contamination of Ukraine’s estuaries with legacy anthropogenic pollutants. Investigations on the toxicological effects of this estuarine contamination have been limited. For this research, we measured the toxicity of contaminated sediments from four Ukrainian estuaries to several aquatic organisms over 3 years. Sediment chemical analyses and whole sediment toxicity identification evaluations (TIEs) were also performed to determine the classes of contaminants contributing to toxicity. Toxic sediments were observed in several of the Ukrainian estuaries and chemical analyses of the sediments demonstrated anthropogenic contaminants were widely distributed. Contaminants were also detected in macrobenthic organisms collected from the sediments. Several lines of evidence, including TIEs, indicated hydrophobic organic chemicals (HOCs) were contributing substantially to observed toxicity. This information can guide environmental managers to prioritize portions of the estuaries requiring remediation.  相似文献   

Biogeochemical factors affecting the presence of Po in groundwater     

Ralph L. Seiler  Lisa L. StillingsNichole Cutler  Laina SalonenIisa Outola 《Applied Geochemistry》2011,26(4):526-539

The discovery of natural ²¹⁰Po enrichment at levels exceeding 500 mBq/L in numerous domestic wells in northern Nevada, USA, led to a geochemical investigation of the processes responsible for its mobilization. ²¹⁰Po activities in 63 domestic and public-supply wells ranged from below 1 mBq/L to 6590 ± 590 mBq/L, among the highest reported levels in the USA. There is little spatial or depth variability in ²¹⁰Pb activity in study-area sediments and mobilization of a few percent of the ²¹⁰Po in the sediments would account for all of the ²¹⁰Po in water. Stable-isotope measurements indicate SO₄ reduction has occurred in all ²¹⁰Po contaminated wells. Sulfide species are not accumulating in the groundwater in much of Lahontan Valley, probably because of S cycling involving microbial SO₄ reduction, abiotic oxidation of H₂S to S⁰ by Mn(IV), followed by microbial disproportionation of S⁰ to H₂S and SO₄. The high pH, Ca depletion, MnCO₃ saturation, and presence of S⁰ in Lahontan Valley groundwater may be consequences of the anaerobic S cycling. Consistent with data from naturally-enriched wells in Florida, ²¹⁰Po activities begin to decrease when aqueous sulfide species begin to accumulate. This may be due to formation and precipitation of PoS, however, Eh-pH diagrams suggest PoS would not be stable in study-area groundwater. An alternative explanation for the study area is that H₂S accumulation begins when anaerobic S cycling stops because Mn oxides are depleted and their reduction is no longer releasing ²¹⁰Po. Common features of ²¹⁰Po-enriched groundwater were identified by comparing the radiological and geochemical data from Nevada with data from naturally-enriched wells in Finland, and Florida and Maryland in the USA. Values of pH ranged from <5 in Florida wells to >9 in Nevada wells, indicating that pH is not critical in determining whether ²¹⁰Po is present. Where U is present in the sediments, the data suggest ²¹⁰Po levels may be elevated in aquifers with (1) SO₄-reducing waters with low H₂S concentrations, or (2) anoxic or oxic waters with extremely high Rn activities, particularly if the water is turbid.  相似文献   

Micronekton abundance and biomass in Hawaiian waters as influenced by seamounts, eddies, and the moon   总被引：1，自引：0，他引：1  

Jeffrey C. Drazen  Lisa G. De Forest  Reka Domokos 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(5):557-566

Micronekton abundance, biomass, and community composition was determined from 58 Cobb trawl samples taken from 2005 to 2008 at several locations in the lee of the Hawaiian Islands. The results indicated a strong influence of the lunar illumination on micronekton abundance and biomass. This effect was evident in shallow night tows and probably was the result of lunar light affecting the nighttime depths of migrating species. The abundance and biomass of micronekton is remarkably consistent between years and areas in Hawaiian waters after the affects of moon phase are accounted for. Micronekton, principally migratory myctophids, were reduced over the summit of Cross Seamount but not Finch Seamount that has a summit below the daytime depth of most migrators. However, during a new moon, micronekton abundance over Cross seamount was similar to surrounding areas either because of altered migration patterns or because predators such as tunas cannot forage as effectively at night without lunar illumination. Species belonging to the Hawaiian mesopelagic boundary layer community were found to vary in presence and abundance between years at Cross Seamount suggesting that a consistent seamount associated fauna does not exist. Sparse sampling of a cyclonic mid-ocean eddy suggested very high micronekton abundance and biomass both in shallow waters at night but also at depth during the day. Although preliminary, these results suggest that eddies may aggregate the micronekton which probably feed on the enhanced secondary productivity.  相似文献   

Modelling Boundary-Layer Clouds With a Statistical Cloud Scheme and a Second-Order Turbulence Closure     

K. Abdella  N. McFarlane 《Boundary-Layer Meteorology》2001,98(3):387-410

We present a second-order turbulence model for the cloudy planetary boundary layer (PBL), which includes a statistical scheme of the sub-grid scale condensation. The model contains prognostic equations for the turbulent kinetic energy, total water, and liquid water temperature, the latter two being assumed to be conservative variables. Using these conservative thermodynamic variables the condensation process is formulated as a function of the departure of the total water from saturation and its variance. The computation of the variance requires second moment correlations which are modelled through the parameterization of the third-order moments using a convective mass-flux formulation. The inclusion of these third moments and new assumptions on heat flux transport lead to a nonlocal turbulence scheme with counter-gradient effects. The final form for the heat flux turns out to be a linearized version of a previously established result. For the statistical cloud formulation, a linear combination of a Gaussian and a positively skewed distribution function is used with a modified liquid water flux expression to account fornon-Gaussian behaviour.The effect of the turbulence scheme on the boundary-layer cloud structure is discussed and the performance of the model is tested by comparing it against the large eddy simulation (LES) of the undisturbed period of the Atlantic Stratocumulus Transition Experiment (ASTEX). The model is able to produce both mean and turbulent quantities that are in reasonable agreement with the LES output of ASTEX.  相似文献   

Analysis of Ground-Water Flow and Injection Fluid Transport in the Floridan Aquifer Near Pensacola, Florida   总被引：1，自引：0，他引：1  

David S. Ward  James W. Mercer  Lisa L. August 《Ground water》1992,30(3):403-414

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‘This was different’: transferring climate mitigation knowledge practices south to south with the MAPS programme     

Lisa Kane  Michael Boulle 《Climate Policy》2018,18(9):1177-1188

This article is a case study of the Mitigation Action Plans and Scenarios programme (MAPS) which worked in climate change mitigation and development policy-making spaces in Brazil, Chile, Colombia, Peru and South Africa from 2010–2015. The MAPS programme was focused on achieving change in the commitment of southern decision makers to mitigate against climate change through government-mandated, stakeholder processes which generated evidence making a case for a low carbon transition. The article draws on reflective materials generated in the last year of the project. The value of MAPS was found in the well-tested data and evidence-driven scenario building; locally specific and country-driven processes; a culture of knowledge sharing through facilitated communities of practice; the role of professional facilitation in process design and in conducting stakeholder processes; shared experiences of working in the south, and particularly with cultural differences and conflict; and new ways of working south–south with each other, and with donors. These MAPS programme experiences stood in contrast to previous north–south knowledge sharing involvements. Theoretically, the article asks whether MAPS represents southern theory-making (after Connell, 2007). It concludes that through the action-oriented, facilitated co-production way of working on climate change in the south, MAPS represents an understanding of southern theory that challenges the orthodoxy of global knowledge production. MAPS emphasizes the need for theorizing in, and of, the south, and connecting policy and practices.

Key policy insights

• Climate change mitigation work in the south faces poorly resourced, fragmented, under-capacitated governance structures, often in conflicted settings.

• Given conflicted settings, skilled facilitation is an integral part of knowledge-making processes.

• Strong local communities of practice, who undertake learning-by-doing and are connected to ‘stubborn’ development realities, are also key to knowledge-making.

• Intentional co-production of data and evidence enable peer-to-peer learning and the trust-building which is vital to strong communities of practice.

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Characterizing the Relative Importance Assigned to Physical Variables by Climate Scientists when Assessing Atmospheric Climate Model Fidelity     

Susannah M.BURROWS  Aritra DASGUPTA  Sarah REEHL  Lisa BRAMER  Po-Lun MA  Philip J.RASCH  Yun QIAN 《大气科学进展》2018,35(9):1101-1113

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Linking hurricane landfalls,precipitation variability,fires, and vegetation response over the past millennium from analysis of coastal lagoon sediments,southwestern Dominican Republic     

Allison R. LeBlanc  Lisa M. Kennedy  Kam-biu Liu  Chad S. Lane 《Journal of Paleolimnology》2017,58(2):135-150

We reconstructed the late-Holocene environmental history of a coastal lagoon in semi-arid southwestern Hispaniola through multiproxy analysis of a sediment core, including pollen, macroscopic and microscopic charcoal, loss-on-ignition analysis (LOI), stable isotope analysis, bulk density, and magnetic susceptibility. Four chronological accelerator mass spectrometry radiocarbon dates indicated that our core represents the past ~1000 years. We interpreted ten hurricanes events over the past millennium from high-resolution geological proxies, LOI data, and ostracod valve stable oxygen isotope data, thus producing the first long record of hurricanes from the Dominican Republic. Geological proxies indicated a high-energy event abruptly changed the ecosystem state of our core site from a shallow mangrove wetland to a lacustrine environment ~330 cal yr BP. We interpret the driver of that event to be the landfall of a strong hurricane that initiated lowland flooding, mangrove mortality, and subsequent peat collapse at the core site. Pollen data indicated that during the relatively moist Medieval Warm Period (MWP), hurricanes led to temporary declines in tropical dry forest taxa that recovered within several decades following disturbance. By comparison, during the relatively arid Little Ice Age (LIA), when precipitation was highly variable in the circum-Caribbean, closely spaced hurricanes seemed to delay forest recovery. Sedimentary charcoal concentrations revealed increased fire activity after inferred hurricane landfalls in the MWP, providing evidence of a link between enhanced biomass and fuel availability during moister periods and burning in recently disturbed dry forests and scrub of our semi-arid study region. Our interpretations of increased aridity and precipitation variability, indicated by alternating thin layers of microbial mats with evaporite layers, along with more frequent hurricanes from ~330 cal yr BP to present, generally agree with other sedimentary records from the circum-Caribbean, and may be linked to a more southerly position of the Intertropical Convergence Zone during the LIA.  相似文献   

Late syn‐rift evolution of the Vingleia Fault Complex,Halten Terrace,offshore Mid‐Norway; a test of rift basin tectono‐stratigraphic models          下载免费PDF全文

Gavin M. Elliott  Christopher A.‐L. Jackson  Robert L. Gawthorpe  Paul Wilson  Ian R. Sharp  Lisa Michelsen 《Basin Research》2017,29(Z1):465-487

Rift basin tectono‐stratigraphic models indicate that normal fault growth controls the sedimentology and stratigraphic architecture of syn‐rift deposits. However, such models have rarely been tested by observations from natural examples and thus remain largely conceptual. In this study we integrate 3D seismic reflection, and biostratigraphically constrained core and wireline log data from the Vingleia Fault Complex, Halten Terrace, offshore Mid‐Norway to test rift basin tectono‐stratigraphic models. The geometry of the basin‐bounding fault and its hangingwall, and the syn‐rift stratal architecture, vary along strike. The fault is planar along a much of its length, bounding a half‐graben containing a faultward‐thickening syn‐rift wedge. Locally, however, the fault has a ramp‐flat‐ramp geometry, with the hangingwall defined by a fault‐parallel anticline‐syncline pair. Here, an unusual bipartite syn‐rift architecture is observed, comprising a lower faultward‐expanding and an upper faultward‐thinning wedge. Fine‐grained basinfloor deposits dominate the syn‐rift succession, although isolated coarse clastics occur. The spatial and temporal distribution of these coarse clastics is complex due to syn‐depositional movement on the Vingleia Fault Complex. High rates of accommodation generation in the fault hangingwall led to aggradational stacking of fan deltas that rapidly (<5 km) pinch out basinward into offshore mudstone. In the south of the basin, rapid strain localization meant that relay ramps were short‐lived and did not represent major, long‐lived sediment entry points. In contrast, in the north, strain localization occurred later in the rift event, thus progradational shorefaces developed and persisted for a relatively long time in relay ramps developed between unlinked fault segments. The footwall of the Vingleia Fault Complex was characterized by relatively low rates of accommodation generation, with relatively thin, progradational hangingwall shorelines developed downdip of the fault block apex, sometime after the onset of sediment supply to the hangingwall. We show that rift basin tectono‐stratigraphic models need modifying to take into account along‐strike variability in fault structure and basin physiography, and the timing and style of syn‐rift sediment dispersal and facies, in both hangingwall and footwall locations.  相似文献