The impacts of climate change on the winter hardiness zones of woody plants in Europe

The potential impacts of climate change on potatoes cropping in the Peruvian highlands (Altiplano) is assessed using climate projections for 2071–2100, obtained from the HadRM3P regional atmospheric model of the Hadley Centre. The atmospheric model is run under two different special report on emission scenarios: high CO₂ concentration (A2) and moderate CO₂ concentration (B2) for four locations situated in the surroundings of Lake Titicaca. The two main varieties of potato cultivated in the area are studied: the Andean potato (Solanum tuberosum) and the bitter potato (Solanum juzepczukii). A simple process-oriented model is used to quantify the climatic impacts on crops cycles and yields by combining the effects of temperature on phenology, of radiation and CO₂ on maximum yield and of water balance on yield deficit. In future climates, air temperature systematically increases, precipitation tends to increase at the beginning of the rainy season and slightly decreases during the rest of the season. The direct effects of these climatic changes are earlier planting dates, less planting failures and shorter crop cycles in all the four locations and for both scenarios. Consequently, the harvesting dates occur systematically earlier: roughly in January for the Andean potato instead of March in the current situation and in February for the bitter potato instead of April. Overall, yield deficits will be higher under climate change than in the current climate. There will be a strong negative impact on yields for S. tuberosum (stronger under A2 scenario than under B2); the impact on S. juzepczukii yields, however, appears to be relatively mixed and not so negative.     

Sharp images of young stellar objects

We present high resolution infrared images of the pre-main sequence star V536 Aql and polarization maps of the reflection nebula IRN Cha observed with the SHARP camera on the ESO NTT. Extended structures are observed near V536 Aql. The polarization pattern of IRN Cha is typical of a centrally illuminated source but with a central band of anomalously oriented polarization believed to occur in an optically thick disk.     

Uranium accumulation during weathering of Cañon Diablo meteoritic iron

Abstract— Cañon Diablo meteoritic iron oxide consists mainly of goethite and maghemite and contains 209 to 630 ppb uranium compared to <0.02 ppb in the unweathered octahedrite. Significant radioactive disequilibria between ²³⁸U, ²³⁴U and ²³⁰Th indicate that uranium was sorbed from soil porewater during terrestrial weathering after meteorite impact 50 ka ago. Depending on the model assumed for U uptake, corrected ²³⁰Th-²³⁴U ages of 24 to 48 ka were obtained. While the data presented may not allow an unambiguous interpretation, the potential of this approach in obtaining minimum terrestrial ages for weathered meteorites is demonstrated.     

Oxidation of Sb(III) to Sb(V) by O2 and H2O2 in aqueous solutions

The rates of Sb(III) oxidation by O₂ and H₂O₂ were determined in homogeneous aqueous solutions. Above pH 10, the oxidation reaction of Sb(III) with O₂ was first order with respect to the Sb(III) concentration and inversely proportional to the H⁺ concentrations at a constant O₂ content of 0.22 × 10⁻³ M. Pseudo-first-order rate coefficients, k_obs, ranged from 3.5 × 10⁻⁸ s⁻¹ to 2.5 × 10⁻⁶ s⁻¹ at pH values between 10.9 and 12.9. The relationship between k_obs and pH was:

     

Impact of prescribed Arctic sea ice thickness in simulations of the present and future climate

This paper describes atmospheric general circulation model climate change experiments in which the Arctic sea-ice thickness is either fixed to 3 m or somewhat more realistically parameterized in order to take into account essentially the spatial variability of Arctic sea-ice thickness, which is, to a first approximation, a function of ice type (perennial or seasonal). It is shown that, both at present and at the end of the twenty-first century (under the SRES-A1B greenhouse gas scenario), the impact of a variable sea-ice thickness compared to a uniform value is essentially limited to the cold seasons and the lower troposphere. However, because first-year ice is scarce in the Central Arctic today, but not under SRES-A1B conditions at the end of the twenty-first century, and because the impact of a sea-ice thickness reduction can be masked by changes of the open water fraction, the spatial and temporal patterns of the effect of sea-ice thinning on the atmosphere differ between the two periods considered. As a consequence, not only the climate simulated at a given period, but also the simulated Arctic climate change over the twenty-first century is affected by the way sea-ice thickness is prescribed.     

An Integrated Assessment of changes in the thermohaline circulation

This paper discusses the risks of a shutdown of the thermohaline circulation (THC) for the climate system, for ecosystems in and around the North Atlantic as well as for fisheries and agriculture by way of an Integrated Assessment. The climate model simulations are based on greenhouse gas scenarios for the 21st century and beyond. A shutdown of the THC, complete by 2150, is triggered if increased freshwater input from inland ice melt or enhanced runoff is assumed. The shutdown retards the greenhouse gas-induced atmospheric warming trend in the Northern Hemisphere, but does not lead to a persistent net cooling. Due to the simulated THC shutdown the sea level at the North Atlantic shores rises by up to 80 cm by 2150, in addition to the global sea level rise. This could potentially be a serious impact that requires expensive coastal protection measures. A reduction of marine net primary productivity is associated with the impacts of warming rather than a THC shutdown. Regional shifts in the currents in the Nordic Seas could strongly deteriorate survival chances for cod larvae and juveniles. This could lead to cod fisheries becoming unprofitable by the end of the 21st century. While regional socioeconomic impacts might be large, damages would be probably small in relation to the respective gross national products. Terrestrial ecosystem productivity is affected much more by the fertilization from the increasing CO₂ concentration than by a THC shutdown. In addition, the level of warming in the 22nd to 24th century favours crop production in northern Europe a lot, no matter whether the THC shuts down or not. CO₂ emissions corridors aimed at limiting the risk of a THC breakdown to 10% or less are narrow, requiring departure from business-as-usual in the next few decades. The uncertainty about THC risks is still high. This is seen in model analyses as well as in the experts’ views that were elicited. The overview of results presented here is the outcome of the Integrated Assessment project INTEGRATION.