The year-long unprecedented European heat and drought of 1540 – a worst case

The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in the global warming-influenced future. However, a recent reconstruction of spring–summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km², we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models.     

Spectral observations for near-Earth objects including potential target 4660 Nereus : Results from Meudon remote observations at the NASA Infrared Telescope Facility (IRTF)

We present visible and near-infrared spectral measurements for the highly accessible spacecraft target 4660 Nereus and three additional near-Earth objects displaying diverse color characteristics. All near-infrared measurements were carried out during the first remote observing operations between the Observatoire de Paris at Meudon and Mauna Kea, Hawaii. From Meudon, we had fine pointing and guiding control of the NASA Infrared Telescope Facility 3.0-m telescope and the near-infrared spectrograph “SpeX” to measure asteroid spectra in the range 0.8-. The efficiency of the observation was virtually the same as if the observers had been on location. We combine our near-infrared results with complementary 0.4- spectral measurements. Nereus is found to be a rare Xe-type asteroid with a composition that may be analogous to very high albedo enstatite achondrite (aubrite) meteorites, leading to a diameter estimate of less than . 1685 Toro displays a classic S-type spectrum while a steeper visible wavelength slope and a less pronounced absorption feature for 1943 Anteros places it in the L-class. Also unusual is the apparent olivine-rich spectrum for 4142 Dersu-Uzala, which is classified as an A-type.     

Size, density and composition of cell-mineral aggregates formed during anoxygenic phototrophic Fe(II) oxidation: Impact on modern and ancient environments

Cell-Fe(III) mineral aggregates produced by anoxygenic Fe(II)-oxidizing photoautotrophic microorganisms (photoferrotrophs) may be influential in the modern Fe cycle and were likely an integral part of ancient biogeochemical cycles on early Earth. While studies have focused on the environmental conditions under which modern photoferrotrophs grow and the kinetics, physiology and mechanism of Fe(II) oxidation, no systematic analyses of the physico-chemical characteristics of those aggregates, such as shape, size, density and chemical composition, have as yet been conducted. Herein, experimental results show most aggregates are bulbous or ragged in shape, with an average particle size of 10-40 μm, and densities that typically range between 2.0 and 2.4 g/cm³; the cell fraction of the aggregates increased and their density decreased with initial Fe(II) concentration. The mineralogy of the ferric iron phase depended on the composition of the medium: goethite formed in cultures grown by oxidation of dissolved Fe(II) medium in the presence of low phosphate concentrations, while poorly ordered ferrihydrite (or Fe(III) phosphates) formed when amorphous Fe(II) minerals (Fe(II)-phosphates) and high concentrations of phosphate were initially present. Importantly, in all experiments, a fraction of the photoautotrophic cells remained planktonic, demonstrating a constant stoichiometric excess of Fe(III) compared to the autotrophically fixed carbon in the biogenic precipitate. These results not only have an important bearing on nutrient and trace element cycling in the modern water column, but the size, shape and composition of the aggregates can be used to estimate aggregate reactivity during sediment diagenesis over short and geologic time scales.     

A regional comparison of the effects of climate change on agricultural crops in Europe

The effects of climate change will be felt by most farmers in Europe over the next decades. This study provides consistent results of the impact of climate change on arable agriculture in Europe by using high resolution climate data, socio-economic data, and impact assessment models, including farmer adaptation. All scenarios are consistent with the spatial distribution of effects, exacerbating regional disparities and current vulnerability to climate. Since the results assume no restrictions on the use of water for irrigation or on the application of agrochemicals, they may be considered optimistic from the production point of view and somewhat pessimistic from the environmental point of view. The results provide an estimate of the regional economic impact of climate change, as well as insights into the importance of mitigation and adaptation policies.