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Bemisia tabaci (the tobacco whitefly) is an important agricultural pest of global significance primarily because of its ability to transmit multiple damaging plant viruses. To date, UK outbreaks of the whitefly have been restricted to glasshouses and there are no records of the whitefly establishing outdoors during the summer. This is despite the fact that annual degree-day models (that estimate accumulated warmth over the year above the development threshold), indicate that B. tabaci has the thermal potential for multiple summer generations in the UK. A set of 49 climate indices calculated using the present day climate (1986–2015) were therefore compared between the UK and the south of France, where B. tabaci is able to establish outdoors, to identify the factors limiting its establishment. The number of cold days and nights in summer, as well as the time spent within the whitefly’s optimum temperature range, were most significantly different between the two areas. These indices may impact the development of B. tabaci and offer an explanation for the absence of the whitefly outdoors in the UK during the summer. Further analyses undertaken with climate projections suggest that in a 2–4°C warmer world this pest could pose a risk to outdoor UK crops in July and August. A clear south-north gradient can be demonstrated for these indices. Linking any possible northwards spread of B. tabaci populations outdoors in France with changes in these indices could therefore provide an important indicator of any change in the risks of outdoor populations of this species developing in the UK. The effectiveness of climate indices in pest risk analysis is compellingly demonstrated, and it is recommended that in-depth comparisons of climatic indices between areas of pest presence and absence are conducted in other situations where forecasting the risks of pest establishment are complex and challenging. [ABSTRACT FROM AUTHOR]

The impact of rising CO 2 on future climate remains uncertain but the evidence for high CO 2 in the palaeorecord suggests that past climates could provide a potentially quantifiable indication of climate in a high-CO 2 world. One such past time period is the late Miocene (11.6–5.3 Ma), for which CO 2 reconstructions indicate higher levels than those of preindustrial, and similar to the present atmospheric level (~ 400 ppm). The late Miocene palaeorecord suggests a much warmer and wetter Northern Hemisphere than preindustrial. However, vegetation feedbacks are an important component of the climate system and vegetation distribution reconstructions from the palaeorecord have been shown to be very different to the present vegetation distribution. We examine the roles that different vegetation and palaeogeography play in climate sensitivity for the late Miocene and consider the implications for potential future climate change. To do this we use coupled atmosphere-ocean-vegetation simulations of late Miocene and potential modern climates forced by three different CO 2 concentrations with vegetation perturbation experiments and make quantitative comparisons to the palaeorecord. Optimal regions to target late Miocene palaeodata acquisition for the purposes of informing about future climate include North America, northern Africa, Australia, Paraguay and southern Brazil, and northeastern Asia. These regions are those which the model results predict to be most sensitive to CO 2 forcing, but where the local temperature response to CO 2 forcing is similar between the simulated potential modern and late Miocene climates. The model results suggest that climate sensitivity to CO 2 forcing is directly affected by the palaeogeographic configuration and that the inferred climate sensitivity for doubled CO 2 is 0.5–0.8 °C higher for the late Miocene than we might expect for future climate because of differences in synergy. The greater land mass at high northern latitudes during the late Miocene and the differences in vegetation distribution predictions that result, combined with differences in ocean circulation and the effect of sea ice, make the late Miocene boundary conditions more sensitive to CO 2 forcing than the modern boundary conditions. [ABSTRACT FROM AUTHOR]

This document provides a summary of a hackathon event organized by the Ministry of Justice (MoJ) and Aon, a reinsurance company, to explore the social impacts of climate change. The hackathon focused on developing consistent scenarios for future climate risk, understanding uncertainties in European windstorm modeling, and providing real-time context for extreme weather events. The teams developed tools and methodologies to assess the severity and potential impact of extreme events on insured losses. The collaboration between the MoJ, Aon, and participants from various institutions aims to further research and develop papers and grant proposals in these areas. [Extracted from the article]

Summary 1. The relative constancy of the lower limit on Earth's atmospheric CO2 concentration ([CO2]a) during major tectonic episodes over the final 24 million years (Ma) of the Cenozoic is surprising because they are expected to draw-down [CO2]a by enhancing chemical weathering and carbonate deposition on the seafloor. That [CO2]a did not drop to extremely low values suggests the existence of feedback mechanisms that slow silicate weathering as [CO2]a declines. One proposed mechanism is a negative feedback mediated through CO2 starvation of land plants in active orogenic regions compromising the efficiency of the primary carboxylating enzyme in C3 plants (Rubisco) and diminishing productivity and terrestrial weathering. 2. The CO2 starvation hypothesis is developed further by identifying four key related mechanisms: decreasing net primary production leading to (i) decreasing below-ground C allocation, reducing the surface area of contact between minerals and roots and mycorrhizal fungi and (ii) reduced demand for soil nutrients decreasing the active exudation of protons and organic acids by fine roots and mycorrhizas; (iii) lower carbon cost-for-nutrient benefits of arbuscular mycorrhizas (AM) favouring AM over ectomycorrhizal root-fungal symbioses, which are less effective at mineral weathering, and (iv) conversion of forest to C3 and C4 grassland arresting Ca leaching from soils. 3. We evaluated the global importance of mechanisms 1 and 2 in silicate weathering under a changing late Miocene [CO2]a and climate using a process-based model describing the effects of plants and mycorrhizal fungi on the biological proton cycle and soil chemistry. The model captures what we believe are the key processes controlling the pH of the mycorrhizosphere and includes numerical routines for calculating weathering rates on basalt and granite using simple yet rigorous equilibrium chemistry and rate laws. 4. Our simulations indicate a reduction in the capacity of the terrestrial biosphere to weather continental silicate rocks by a factor of four in response to successively decreasing [CO2]a values (400, 280, 180 and 100 p.p.m.) and associated late Miocene (11.6-5.3 Ma) cooling. Marked reductions in terrestrial weathering could effectively limit biologically mediated long-term carbon sequestration in marine sediments. 5. These results support the idea of terrestrial vegetation acting as a negative feedback mechanism that counteracts substantial declines in [CO2]a linked to increased production of fresh weatherable minerals in warm, low-latitude, active orogenic regions. [ABSTRACT FROM AUTHOR]

Cetaceans use sound for communication, navigation and finding prey. Most extant odontocetes produce broadband (BB) biosonar clicks covering frequency ranges from tens of kilohertz to 150–170 kHz. In contrast, the biosonar clicks of some odontocetes are unique, being narrow in bandwidth with high centroid frequency (NBHF), peak frequencies being at 125–140 kHz and bandwidths of 11–20 kHz. Thirteen species within four families (Phocoenidae, Pontoporiidae, Kogiidae, Delphinidae) are known to produce these signals, implying convergent evolution under strong selective drivers. Several hypotheses have been proposed, including acoustic crypsis to escape predation by killer whales, but none has provided comprehensive explanation of the timing of NBHF evolution and the pressures driving sound production to such extremes. Using molecular phylogenetics and the cochlea anatomy of extinct and extant taxa, we demonstrate that early NBHF adaptations occurred at least 10 Mya, and possibly up to 18 Mya, indicating that killer whales cannot have been the sole driving force of NBHF signals, but that now extinct odontocetes may have provided similar pressures. Using palaeoclimate modelling, we further demonstrate that the upper advantageous spectral window for NBHF signals at around 130 kHz has persisted throughout most of the global sea area since the mid-Miocene, covering all known instances of NBHF evolution. [ABSTRACT FROM AUTHOR]