Climate change and crop yields in Zambia: historical effects and future projections

Environment, Development and Sustainability - Rainfed farming systems that are prevalent in sub-Saharan Africa are prone to climate change. Most studies have only estimated the impacts of climate...     

Managing Mediterranean soil resources under global change: expected trends and mitigation strategies

Regional Environmental Change - The soils of the Mediterranean Basin are the products of soil processes that have been governed by a unique convergence of highly differentiated natural and...     

Climate trends and impacts on crop production in the Koshi River basin of Nepal

Understanding crop responses to climate is essential to cope with anticipated changes in temperature and precipitation. We investigated the climate–crop yield relationship and the impact of historical climate on yields of rice, maize and wheat in the Koshi basin of Nepal. The results show significant impact of growing season temperature and precipitation on crop production in the region. Rice, maize and wheat cultivated at altitudes below 1,100, 1,350 and 1,700 m amsl (above mean sea level), respectively, suffer from stress due to higher temperatures particularly during flowering and yield formation stages. Responses of crop yields to a unitary increment in growing season mean temperature vary from ?6 to 16 %, ?4 to 11 % and ?12 to 3 % for rice, maize and wheat, respectively, depending on the location and elevation in the basin. In most parts of the basin, we observe warming trends in growing season mean temperatures of rice, maize and wheat over the last few decades with clear evidence of negative impacts on yields. However, at some high-elevation areas, positive impacts of warming are also observed on rice and maize yields. If the observed trends in temperature continue in future, the impact is likely to be mostly negative on crop production in the basin. However, crop production may gain from the warming at relatively higher altitudes provided other conditions, e.g., water availability, soil fertility, are favorable.     

Mileage-based pricing insurance and its impact on China

Mileage-based pricing insurance,such as PAYD,is known as the"green insurance"because it is low-carbon and environmentally effective,which is the biggest innovation in the global auto insurance industry seen in the past decade.Starting from the perspective of economic externalities,vehicle negative externalities in China are described.In order to introduce mileage-based pricing insurance to the Chinese insurance industry,this paper reviews the current practice of PAYD insurance and its impacts on transport externalities,including air pollution,climate change,energy dependency,congestion,accidents,and others.Finally,enlightenment and policy suggestions are proposed,in the hope of better promoting the low-carbon economy development over the whole of China.     

Variability in crop yields associated with climate anomalies in China over the past three decades

We used simple and explicit methods, as well as improved datasets for climate, crop phenology and yields, to address the association between variability in crop yields and climate anomalies in China from 1980 to 2008. We identified the most favourable and unfavourable climate conditions and the optimum temperatures for crop productivity in different regions of China. We found that the simultaneous occurrence of high temperatures, low precipitation and high solar radiation was unfavourable for wheat, maize and soybean productivity in large portions of northern, northwestern and northeastern China; this was because of droughts induced by warming or an increase in solar radiation. These climate anomalies could cause yield losses of up to 50 % for wheat, maize and soybeans in the arid and semi-arid regions of China. High precipitation and low solar radiation were unfavourable for crop productivity throughout southeastern China and could cause yield losses of approximately 20 % for rice and 50 % for wheat and maize. High temperatures were unfavourable for rice productivity in southwestern China because they induced heat stress, which could cause rice yield losses of approximately 20 %. In contrast, high temperatures and low precipitation were favourable for rice productivity in northeastern and eastern China. We found that the optimum temperatures for high yields were crop specific and had an explicit spatial pattern. These findings improve our understanding of the impacts of extreme climate events on agricultural production in different regions of China.     

Climate change skepticism and index versus standard crop insurance demand in coastal Bangladesh

Regional Environmental Change - This paper investigates if climate change skepticism, farmers’ fatalistic beliefs, and insurance plan design influence interest in crop weather insurance....     

To terrace or not: the short-term impact of bench terraces on soil properties and crop response in the Peruvian Andes

Soil erosion is considered as a serious threat to agricultural development in developing countries. Soil and water conservation measures, such as terraces, are often promoted to combat soil erosion and to increase agricultural production. In this paper, the short-term impact of bench terraces, 2–4 years after their establishment, on soil properties and maize yield in the Peruvian Andes is analysed and discussed. The results show that bench terraces did not result in any short term change in soil properties, such as fertility or infiltration capacity. Nevertheless, the bench terraces resulted in 20% higher yields, due to a higher planting density, compared with adjacent sloping fields. However, this increase in yield was nullified by the loss of area occupied by the bench terraces. Bench terraces should therefore be accompanied with other measures to intensify agriculture, such as irrigation or cash crops, to improve the profitability and uptake of bench terraces in the Andes.     

Exploring the efficiency of bias corrections of regional climate model output for the assessment of future crop yields in Europe

Excessive summer drying and reduced growing season length are expected to reduce European crop yields in future. This may be partly compensated by adapted crop management, increased CO₂ concentration and technological development. For food security, changes in regional to continental crop yield variability may be more important than changes in mean yields. The assessment of changes in regional and larger scale crop variability requires high resolution and spatially consistent future weather, matching a specific climate scenario. Such data could be derived from regional climate models (RCMs), which provide changes in weather patterns. In general, RCM output is heavily biased with respect to observations. Due to the strong nonlinear relation between meteorological input and crop yields, the application of this biased output may result in large biases in the simulated crop yield changes. The use of RCM output only makes sense after sufficient bias correction. This study explores how RCM output can be bias corrected for the assessment of changes in European and subregional scale crop yield variability due to climate change. For this, output of the RCM RACMO of the Royal Netherlands Meteorological Institute was bias corrected and applied within the crop simulation model WOrld FOod STudies to simulate potential and water limited yields of three divergent crops: winter wheat, maize and sugar beets. The bias correction appeared necessary to successfully reproduce the mean yields as simulated with observational data. It also substantially improved the year-to-year variability of seasonal precipitation and radiation within RACMO, but some bias in the interannual variability remained. This is caused by the fact that the applied correction focuses on mean and daily variability. The interannual variability of growing season length, and as a consequence the potential yields too, appeared even deteriorated. Projected decrease in mean crop yields is well in line with earlier studies. No significant change in crop yield variability was found. Yet, only one RCM is analysed in this study, and it is recommended to extend this study with more climate models and a slightly adjusted bias correction taking into account the variability of larger time scales as well.     

Influence of olive mill wastewater in composting and impact of the compost on a Swiss chard crop and soil properties

The suitability of olive mill wastewater (OMW) for composting was studied by the addition of this liquid waste to a mixture of cotton gin waste and sewage sludge, and its composting was compared with that of another pile of similar composition, but without olive mill wastewater. Both piles were composted by the Rutgers static pile system in a pilot plant. To study the effects of both composts on plant yield and soil properties, a plot experiment was carried out with Swiss chard (Beta vulgaris L. var. cicla). Five treatments were applied: mineral fertiliser and two doses (30 and 60 tons ha(-1)) of both composts. The olive mill wastewater addition produced a compost with lower organic matter and nitrate concentrations, higher electrical conductivity, and a stabilised and humified organic matter similar to that of the compost produced without olive mill wastewater. The olive mill wastewater compost application to soil did not injure plants, producing a similar plant yield to both compost without olive mill wastewater and inorganic fertiliser. Also, the accumulation of potentially toxic heavy metals in plants cultivated with organic or mineral fertilisers did not reveal significant differences. The olive mill wastewater compost application to soil also improved the chemical and physicochemical properties of the soil.     

Occurrence of sulfonamide residues along the Ebro River basin: removal in wastewater treatment plants and environmental impact assessment

Sulfonamides (SAs) have become one of the antibiotic families most frequently found in all kind of environmental waters. In the present work, the presence of 16 SAs and one of their acetylated metabolites in different water matrices of the Ebro River basin has been evaluated during two different sampling campaigns carried out in 2007 and 2008. Influent and effluent samples from seven wastewater treatment plants (WWTPs), together with a total of 28 river water samples were analyzed by on-line solid phase extraction-liquid chromathography-tandem mass spectrometry (on-line SPE-LC-MS/MS). Sulfamethoxazole and sulfapyridine were the SAs most frequently detected in WWTPs (96-100%), showing also the highest concentrations, ranging from 27.2 ng L(-1) to 596 ng L(-1) for sulfamethoxazole and from 3.7 ng L(-1) to 227 ng L(-1) for sulfapyridine. Sulfamethoxazole was also the SA most frequently detected in surface waters (85% of the samples) at concentrations between 11 ng L(-1) and 112 ng L(-1). In order to assess the effectiveness of the wastewater treatment in degrading SAs, removal efficiencies in the seven WWTPs were calculated for each individual SA (ranging from 4% to 100%) and correlated to the corresponding hydraulic retention times or residence times of the SAs in the plants. SAs half-lives were also estimated, ranging from to 2.5 hours (sulfadimethoxine) to 128 h (sulfamethazine). The contribution of the WWTPs to the presence of SAs depends on both the load of SAs discharging on the surface water from the WWTP effluent but also on the flow of the receiving waters in the discharge sites and the dilution exerted; WWTP4 exerts the highest pressure on the receiving water course. Finally, the potential environmental risk posed by SAs was evaluated calculating the hazard quotients (HQ) to different non-target organisms in effluent and river water. The degree of susceptibility resulted in algae>daphnia>fish. Sulfamethoxazole was the only SA posing a risk to algae in effluent water, with an HQ>7.     

Peri-urban agro-ecosystems in the Mediterranean: diversity,dynamics, and drivers

Regional Environmental Change - To address sustainability challenges of agro-ecosystems located in Mediterranean urban regions, this paper focuses on the multidisciplinary subject of urban...     

Statistical downscaling for climate change projections in the Mediterranean region: methods and results

Besides dynamical downscaling by regional climate models, statistical downscaling (SD) is a major tool to derive climate change projections on regional or even local scales. For the Mediterranean area, an increasing number of downscaling studies based on different statistical techniques have been published in the last two decades with a broad range of sometimes differing results relating to different variables and regional domains. This paper gives a short review of these Mediterranean downscaling studies mainly considering the following two aspects: (1) what kind of progress has been realized in this field since the early 1990s? The review addresses the inclusion of extremes in downscaling assessments, the development of probabilistic approaches, the extension of predictor sets, the use of ensembles for both dynamical model simulations and statistical model assessments, the consideration of non-stationarities in the predictor–predictand relationships, and some advances related to synoptic downscaling. (2) What are the main regional climate change signals in the Mediterranean area, considering agreed and controversial points also with respect to dynamical models? Best accordance among future projections can be found in seasonal temperatures with lower rates of warming in winter and spring, and, in most cases, higher ones in summer and autumn. Different results are obtained for the intra-annual range of extreme temperatures, but high-temperature conditions are generally expected to increase. Regarding seasonal precipitation, predominant reductions are indicated for spring, summer, and autumn. For winter, however, projections are distinctly different (GCMs: rainfall decrease; RCMs: increase only in the northernmost parts of the Mediterranean region; SD: widespread increases in the northern and western parts in several studies). Different results are obtained for rainfall extremes, but the entire precipitation distribution tends to shift towards higher and lower values. Apart from some sub-regional deviations, there is a predominant increase in future dry period durations. For near-surface winds, only a few studies are available, and they project some decline mainly for the winter season.     

Dissolved radon and gaseous mercury in the Mediterranean seawater

Vertical profiles of radioactive radon gas ((222)Rn) and dissolved gaseous mercury (DGM) in seawater in the Mediterranean Basin have been measured. They were found in the range 1.7-19.3 Bq m(-3) and 22-200 ng m(-3), respectively, at the bottom and 2.0-20.0 Bq m(-3) and 6-80 ng m(-3), respectively, at the surface. Preliminary results indicate a positive correlation between concentrations of both gases at some locations, but not at others. Further analyses will be performed, after (226)Ra contents in sediment and water have been determined, taking into account environmental parameters such as air and water temperatures, barometric pressure and water flow, in order to better interpret these profiles.     

Climate change impact on the PAH photodegradation in soils: Characterization and metabolites identification

Polycyclic aromatic hydrocarbons (PAHs) are airborne pollutants that are deposited on soils. As climate change is already altering temperature and solar radiation, the global warming is suggested to impact the environmental fate of PAHs. This study was aimed at evaluating the effect of climate change on the PAH photodegradation in soils. Samples of Mediterranean soils were subjected to different temperature and light radiation conditions in a climate chamber. Two climate scenarios were considered according to IPCC projections: 1) a base (B) scenario, being temperature and light intensity 20 °C and 9.6 W/m², respectively, and 2) a climate change (CC) scenario, working at 24 °C and 24 W/m², respectively. As expected, low molecular weight PAHs were rapidly volatilized when increasing both temperature and light intensity. In contrast, medium and high molecular weight PAHs presented different photodegradation rates in soils with different texture, which was likely related to the amount of photocatalysts contained in both soils. In turn, the hydrogen isotopic composition of some of the PAHs under study was also investigated to verify any degradation process. Hydrogen isotopes confirmed that benzo(a)pyrene is degraded in both B and CC scenarios, not only under light but also in the darkness, revealing unknown degradation processes occurring when light is lacking. Potential generation pathways of PAH photodegradation by-products were also suggested, being a higher number of metabolites formed in the CC scenario. Consequently, in a more or less near future, although humans might be less exposed to PAHs, they could be exposed to new metabolites of these pollutants, which might be even more toxic.     

Local perspectives on regional challenges: jellyfish proliferation and fish stock management along the Israeli Mediterranean coast

The composition and abundance of marine biota in Israeli marine ecosystems are affected by natural and anthropogenic pressures, including blooms of non-indigenous jellyfish and overfishing. While overfishing is itself a major stressor of fish stocks, it appears that jellyfish may be outcompeting fish for scarce planktonic food resources. Beyond this direct impact on fisheries, jellyfish–ecosystem interactions are also important because of the disturbance they cause to multiple users of marine and coastal resources. This paper documents the concurrent changes in the composition of marine biotic communities, including jellyfish proliferation and dwindling stocks of endemic, commercially valuable fish and the rising rate of bottom trawling in Israeli fisheries. The capacity to deal directly with jellyfish is limited by lack of knowledge about their ecology. Therefore, we suggest that bolstering fish stocks and increasing their competitive advantage in the food web may be instrumental in limiting jellyfish blooms. Coordination of fishing and conservation policies is recommended, as are modifications to marine waste management and deployment of submerged artificial substrates.     

A high-resolution climatological study on the comparison between surface explosive and ordinary cyclones in the Mediterranean

The dynamic and kinematic characteristics of surface explosive cyclones in the Mediterranean are examined and compared to those of ordinary cyclones. The cyclone detection is performed with the tracking algorithm developed in the University of Melbourne, using the 1° × 1° ERA-40 mean sea level pressure dataset for a 40 year period. It is verified that the explosive cyclogenesis in the Mediterranean is mainly a maritime phenomenon, occurring along the northern Mediterranean coast during the cold season. On the contrary, the ordinary cyclogenesis exhibits significant maxima in both continental and maritime environments throughout the year. The explosive cyclones are characterized by longer lifetime and greater propagation speed. They are larger and deeper in the eastern Mediterranean, whereas the ordinary cyclones are deeper in the western and larger in the eastern Mediterranean. The trend analysis revealed that both explosive and ordinary cyclones become less frequent in the Mediterranean basin, while there is a tendency for deeper ordinary cyclones over North Africa and shallower over the Aegean Sea and Cyprus.     

Impacts of climate change on the distribution of species and communities in the Chilean Mediterranean ecosystem

The Mediterranean region of Chile is considered a biodiversity hot spot. An increase in temperature and decrease in precipitation, as projected for the end of this century by global circulation models, would likely change the distribution of the sclerophyllous thorny shrubland and woodland. In order to assess those potential impacts, the MAXENT algorithm was used to project potential changes in the distribution of the Mediterranean ecosystem. Ecological niche models were fitted and used to project the potential distribution of these forest ecosystems by the end of the century. Projections were made using data from the PRECIS model for the A2 and B2 climate change scenarios and two strategies of occupancy: free migration and non-migration. Distribution models of sclerophyllous, woodland and shrubland performed accurately representing current species’ distribution. When we assume non-migration responses under climate change scenarios, results reveal a decrease in the distribution area for all the species. The areas where the highest reduction in a suitable environment was found are located along the coastline, where higher temperature increases have been projected. For native ecosystems from the Andean Range region, such as communities dominated by thorny species, a stable habitat was found, associated with a higher adaptation capability to future climatic projections. Hence, in the future, buffer zones originated by “topo-climatic” conditions might play a key role in protecting Central Chile biodiversity.