Mineral magnetic and geochemical records of late Glacial climatic change from two northwest European carbonate lakes

We present the results of mineral magnetic measurements and geochemical analyses of late Glacial sediments from two marl-precipitating lakes in the Northwest of England. Mineral magnetic assemblages dominated by detrital and/or authigenic ferrimagnetic minerals, and enhanced delivery of metal elements, characterise a lower (Oldest Dryas) and an upper (Younger Dryas) phase of catchment instability, with detrital clay and silt sedimentation. Magnetic mineral assemblages with lower concentrations of finer ferrimagnetic grains characterise the authigenic carbonate sediments (marls). The marls indicate both enhanced lake productivity and catchment stability in response to prevailing warm conditions during the Bølling - Allerød Interstadial. The Bølling - Allerød marl phase contains two short-term, low amplitude shifts characterised by changes in the concentration and the size of ferrimagnetic grains. These shifts may represent the Older Dryas and the Amphi-Atlantic Oscillation, short-lived Northern hemisphere climatic deteriorations. Overall, the results suggest that marl lakes are sensitive indicators of Lateglacial climatic change, and that these changes are readily identifiable through the use of mineral magnetic measurements.     

Ocean urea fertilization for carbon credits poses high ecological risks

The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.     

Directions in VLBI technology

Magnetic tape recording, disc recording, and global electronic networks are advancing rapidly, promising both evolutionary and revolutionary impacts on the way VLBI is conducted. In this paper, we will examine the state-of-the-art technologies that may have application to VLBI and consider the current and projected costs in each of these areas.     

Climate change, ambient ozone, and health in 50 US cities

We investigated how climate change could affect ambient ozone concentrations and the subsequent human health impacts. Hourly concentrations were estimated for 50 eastern US cities for five representative summers each in the 1990s and 2050s, reflecting current and projected future climates, respectively. Estimates of future concentrations were based on the IPCC A2 scenario using global climate, regional climate, and regional air quality models. This work does not explore the effects of future changes in anthropogenic emissions, but isolates the impact of altered climate on ozone and health. The cities’ ozone levels are estimated to increase under predicted future climatic conditions, with the largest increases in cities with present-day high pollution. On average across the 50 cities, the summertime daily 1-h maximum increased 4.8 ppb, with the largest increase at 9.6 ppb. The average number of days/summer exceeding the 8-h regulatory standard increased 68%. Elevated ozone levels correspond to approximately a 0.11% to 0.27% increase in daily total mortality. While actual future ozone concentrations depend on climate and other influences such as changes in emissions of anthropogenic precursors, the results presented here indicate that with other factors constant, climate change could detrimentally affect air quality and thereby harm human health.     

Sensitivity of Offshore Surface Fluxes and Sea Breezes to the Spatial Distribution of Sea-Surface Temperature

A series of numerical sensitivity experiments is performed to quantify the impact of sea-surface temperature (SST) distribution on offshore surface fluxes and simulated sea-breeze dynamics. The SST simulations of two mid-latitude sea-breeze events over coastal New England are performed using a spatially-uniform SST, as well as spatially-varying SST datasets of 32- and 1-km horizontal resolutions. Offshore surface heat and buoyancy fluxes vary in response to the SST distribution. Local sea-breeze circulations are relatively insensitive, with minimal differences in vertical structure and propagation speed among the experiments. The largest thermal perturbations are confined to the lowest 10% of the sea-breeze column due to the relatively high stability of the mid-Atlantic marine atmospheric boundary layer (ABL) suppressing vertical mixing, resulting in the depth of the marine layer remaining unchanged. Minimal impacts on the column-averaged virtual potential temperature and sea-breeze depth translates to small changes in sea-breeze propagation speed. This indicates that the use of datasets with a fine-scale SST may not produce more accurate sea-breeze simulations in highly stable marine ABL regimes, though may prove more beneficial in less stable sub-tropical environments.     

CLIMATE CHANGE, AGRICULTURE AND WETLANDS IN EASTERN EUROPE: VULNERABILITY, ADAPTATION AND POLICY

Naturally-occurring wetlands perform such functions as flood control, pollution filtration, nutrient recycling, sediment accretion, groundwater recharge and water supply, erosion control, and plant and wildlife preservation. A large concentration of wetlands is located in Eastern Europe. A significant amount of Eastern European wetlands has been converted to agricultural use in the past, and remaining wetlands are subject to agricultural drainage. Drained wetlands are used as prime agriculture lands for a variety of food crops. Other agricultural uses of wetlands range from growing Phragmites australis (common reed) for thatch and livestock feed, to collecting peat for heating and cooking fuel. Altered hydrologic regimes due to global climate change could further exacerbate encroachment of agricultural land use into wetlands. The vulnerability and adaptation studies of the U.S. Country Studies Program are used to analyze where climate change impacts to agriculture may likewise impact wetland areas. Scenarios indicate higher temperatures and greater evapotranspiration altering the hydrologic regime such that freshwater wetlands are potentially vulnerable in Bulgaria, Czech Republic, and Russia, and that coastal wetlands are at risk in Estonia. Runoff is identified as a key hydrological parameter affecting wetland function. Since wetland losses may increase as a result of climate-change-induced impacts to agriculture, precautionary management options are reviewed, such as establishing buffer areas, promoting sustainable uses of wetlands, and restoration of farmed or mined wetland areas. These options may reduce the extent of negative agricultural impacts on wetlands due to global climate change.     

Petrogenesis and structural petrology of high-pressure metabasalt pods,Sivrihisar, Turkey

Lawsonite eclogite pods ranging in size from 3 cm to 6 m occur in lawsonite blueschist and eclogite facies metasedimentary and metabasaltic rocks in the Sivrihisar Massif, Turkey. Some pods have a core of lawsonite eclogite surrounded by alternating, centimeter-scale layers of lawsonite blueschist, eclogite, and transitional eclogite–blueschist, all with similar basaltic bulk composition. These pods also contain texturally late lawsonite-rich veins and layers. Most eclogites and blueschists within the pods lack reaction textures, but some blueschists near pod margins contain texturally complex garnet as well as glaucophane rims on omphacite, suggesting retrogression of eclogite to blueschist. Phase diagrams (pseudosections) calculated for the lawsonite eclogite core of a meter-scale pod indicate that the eclogite equilibrated at ∼22–24 kbar, ∼520°C. Lawsonite eclogite and blueschist at the tectonized margin of the same pod equilibrated at similar temperatures and slightly lower pressures. The composite eclogite–blueschist pod is foliated, lineated, and folded. An earlier generation of lineated omphacite in the pod core has a different spatial orientation than the lineation at the pod margin, although electron backscattered diffraction data show that core and rim omphacite have similar lattice preferred orientation patterns. Petrologic and structural data are consistent with mechanical formation of pods by folding and dissection of eclogite layers at high-P, and localized retrogression at pod margins during initial stages of exhumation at P–T conditions >425°C, 16 kbar.