Synchronous pattern of moisture availability on the southern Tibetan Plateau since 17.5 cal. ka BP – the Tangra Yumco lake sediment record

A possible asynchronicity of the spatial and temporal moisture availability on the Tibetan Plateau has been a controversial subject of discussion in recent years. Here we present the first attempt to systematically investigate possible spatial and temporal variations in moisture availability by examining two lakes, Tangra Yumco and Nam Co, on an east–west transect on the southern Tibetan Plateau using identical proxies for palaeoenvironmental reconstruction. In this study, an independent record from Tangra Yumco was analysed applying a multi‐proxy approach to reconstruct variations in moisture availability since the Lateglacial. Results were subsequently compared with previously published records from Nam Co and additional records from Tso Moriri (northwestern Himalaya) and Naleng Co (southeastern Tibetan Plateau). Our results show that Tangra Yumco was at least partially ice covered prior to 17.1 cal. ka BP. A temperature rise after 17.1 cal. ka BP probably resulted in thawing of the permafrost. At 16.0 cal. ka BP moisture availability increased, representing an initial monsoonal intensification. Warmer conditions between 13.0 and 12.4 cal. ka BP and cooler conditions between 12.4 cal. ka BP and the onset of the Holocene reflect the Bølling‐Allerød and Younger Dryas. At the onset of the Holocene moisture availability rapidly increased, with moisture highest prior to 8.5 cal. ka BP when temperatures were also highest. After 8.5 cal. ka BP the moisture availability gradually decreased and showed only minor amplitude variations. These findings are consistent with the records from large lakes like Nam Co, Tso Moriri, and Naleng Co, revealing a synchronous pattern of moisture availability on the southern Tibetan Plateau.     

Shallow sediment deformation styles in north-western Campeche Knolls,Gulf of Mexico and their controls on the occurrence of hydrocarbon seepage

During German R/V Meteor M67/2 expedition to Campeche Knolls, southern Gulf of Mexico, a set of 2D high resolution seismic data was acquired to study the near-surface sediment structure and its relationship with hydrocarbon seepages in this salt province. The comprehensive survey covered 20 individual bathymetric highs or ridges and identified three principle structural types: Passive Type, Chaopopte Type, and Asymmetric Flap Type. The first type is the result of passive diapirism, whereas the latter two were initialized by a regional compressional event in the Miocene, but are later differently modified by salt tectonism. Chapopote Type structures appear as symmetrical domes, with uplifted coarse-grained Miocene sediments in their cores and rather thin syn-kinematic sediments covering the crests. Asymmetric Flap Type structures are also first folded as domes or ridges, but one flap later subsided together with salt evacuation, resulting in single uplifted monoclines. With the coarse-grained pre-kinematic sediments as reservoir units, both structural types can focus and accumulate hydrocarbons. The geometries of the structures suggest that hydrocarbons are accumulated in the center of the Chapopote Type structures and in the subsided flaps of the Asymmetric Flap Type structures. Hydrocarbon leakage from these thinly sealed reservoirs is regarded as the principle mechanism for the seepage in the study area, and accordingly the most seepage-prone positions are above these reservoirs. The seep locations suggested by analysis of sea-surface oil slick images of SAR satellite data are also examined in this study. These independently derived seep locations confirm the seepage-prone positions to be above the shallow buried reservoirs. This study suggest that the shallow sediment structures control the distribution of the hydrocarbon seeps of the north-western Campeche Knolls, although the hydrocarbons are sourced from the greater depth.     

Impacts and adaptation to climate change in European economies

This paper evaluates the impacts of climate change to European economies under an increase in global mean temperature at +2 °C and +4 °C. It is based on a summary of conclusions from available studies of how climate change may affect various sectors of the economies in different countries. We apply a macroeconomic general equilibrium model, which integrates impacts of climate change on different activities of the economies. Agents adapt by responding to the changes in market conditions following the climatic changes, thus bringing consistency between economic behaviour and adaptation to climate change. Europe is divided into 85 sub-regions in order to capture climate variability and variations in vulnerabilities within countries. We find that the impacts in the +2 °C are moderate throughout Europe, with positive impacts on GDP in some sub-regions and negative impacts down to 0.1 per cent per year in others. At +4 °C, GDP is negatively affected throughout Europe, and most substantially in the southern parts, where it falls by up to 0.7 per cent per year in some sub-regions. We also find that climate change causes differentiations in wages across Europe, which may cause migration from southern parts of Europe to northern parts, especially to the Nordic countries.     

A global assessment of the impact of climate change on water scarcity

This paper presents a global scale assessment of the impact of climate change on water scarcity. Patterns of climate change from 21 Global Climate Models (GCMs) under four SRES scenarios are applied to a global hydrological model to estimate water resources across 1339 watersheds. The Water Crowding Index (WCI) and the Water Stress Index (WSI) are used to calculate exposure to increases and decreases in global water scarcity due to climate change. 1.6 (WCI) and 2.4 (WSI) billion people are estimated to be currently living within watersheds exposed to water scarcity. Using the WCI, by 2050 under the A1B scenario, 0.5 to 3.1 billion people are exposed to an increase in water scarcity due to climate change (range across 21 GCMs). This represents a higher upper-estimate than previous assessments because scenarios are constructed from a wider range of GCMs. A substantial proportion of the uncertainty in the global-scale effect of climate change on water scarcity is due to uncertainty in the estimates for South Asia and East Asia. Sensitivity to the WCI and WSI thresholds that define water scarcity can be comparable to the sensitivity to climate change pattern. More of the world will see an increase in exposure to water scarcity than a decrease due to climate change but this is not consistent across all climate change patterns. Additionally, investigation of the effects of a set of prescribed global mean temperature change scenarios show rapid increases in water scarcity due to climate change across many regions of the globe, up to 2 °C, followed by stabilisation to 4 °C.