ALBERT

Description: The genomes of related species contain valuable information on the history of the considered taxa. Great apes in particular exhibit variation of evolutionary patterns along their genomes. However, the great ape data also bring new challenges, such as the presence of incomplete lineage sorting and ancestral shared polymorphisms. Previous methods for genome-scale analysis are restricted to very few individuals or cannot disentangle the contribution of mutation rates and fixation biases. This represents a limitation both for the understanding of these forces as well as for the detection of regions affected by selection. Here, we present a new model designed to estimate mutation rates and fixation biases from genetic variation within and between species. We relax the assumption of instantaneous substitutions, modeling substitutions as mutational events followed by a gradual fixation. Hence, we straightforwardly account for shared ancestral polymorphisms and incomplete lineage sorting. We analyze genome-wide synonymous site alignments of human, chimpanzee, and two orangutan species. From each taxon, we include data from several individuals. We estimate mutation rates and GC-biased gene conversion intensity. We find that both mutation rates and biased gene conversion vary with GC content. We also find lineage-specific differences, with weaker fixation biases in orangutan species, suggesting a reduced historical effective population size. Finally, our results are consistent with directional selection acting on coding sequences in relation to exonic splicing enhancers.

Description: Genetic control of male or female gonad development displays between different groups of organisms a remarkable diversity of "master sex-determining genes" at the top of the genetic hierarchies, whereas downstream components surprisingly appear to be evolutionarily more conserved. Without much further studies, conservation of sequence has been equalized to conservation of function. We have used the medaka fish to investigate the generality of this paradigm. In medaka, the master male sex-determining gene is dmrt1bY , a highly conserved downstream regulator of sex determination in vertebrates. To understand its function in orchestrating the complex gene regulatory network, we have identified targets genes and regulated pathways of Dmrt1bY. Monitoring gene expression and interactions by transgenic fluorescent reporter fish lines, in vivo tissue-chromatin immunoprecipitation and in vitro gene regulation assays revealed concordance but also major discrepancies between mammals and medaka, notably amongst spatial, temporal expression patterns and regulations of the canonical Hedgehog and R-spondin/Wnt/Follistatin signaling pathways. Examination of Foxl2 protein distribution in the medaka ovary defined a new subpopulation of theca cells, where ovarian-type aromatase transcriptional regulation appears to be independent of Foxl2. In summary, these data show that the regulation of the downstream regulatory network of sex determination is less conserved than previously thought.

Description: Climate protection advocacy can learn from the success of the International AIDS Conference in forging a powerful global movement of scientists, non-governmental organizations and civil society. Nature Climate Change 3 850 doi: 10.1038/nclimate1986

Description: Communities of boreal species are spreading northwards as tundra communities recede under climate change in the Arctic. Concurrently, human activities in the Arctic are increasing. This study takes a multidisclinary approach to investigate the potential future distribution of tundra species and to relate the location of refugial areas to disparate land-use practices in northern Alaska. Nature Climate Change 3 931 doi: 10.1038/nclimate1926

Description: Nature Climate Change 3 861 doi: 10.1038/nclimate2017

Description: Nature Climate Change 3 861 doi: 10.1038/nclimate2021

Description: Human lives can be saved when climate disaster prevention is part of international development aid. Nature Climate Change 3 857 doi: 10.1038/nclimate2016

Description: The traditional view of the open ocean is that surface waters should change faster and that the deep waters should be relatively stable. Now research shows that the depths of the Southern Ocean are also rapidly freshening and warming, and that these changes are spreading towards the Equator. Nature Climate Change 3 864 doi: 10.1038/nclimate2014

Description: Ecuador's president has called time on the Yasuní–ITT Initiative. Anna Petherick asks what the world can learn from it. Nature Climate Change 3 859 doi: 10.1038/nclimate2011

Description: Increasing volatility in food markets and the rising incidence of climatic extremes could lead to more frequent spikes in food prices. A global assessment of the reliability of crop simulations in reproducing past failures in major crop types suggests that seasonal forecasts can be useful for monitoring global food production. Nature Climate Change 3 904 doi: 10.1038/nclimate1945

Description: Earth system models (ESMs) generally have crude representations of the responses of soil carbon responses to changing climate. Now an ESM that explicitly represents microbial soil carbon cycling mechanisms is able to simulate carbon pools that closely match observations. Projections from this model produce a much wider range of soil carbon responses to climate change over the twenty-first century than conventional ESMs. Nature Climate Change 3 909 doi: 10.1038/nclimate1951

Description: The long-term loss of carbon from thawing permafrost in Northeast Greenland is quantified for 1996–2008 by repeated sediment sampling and incubation. Although the active layer has increased by 〉1 cm per year, there has not been a detectable decline in carbon stocks. Laboratory studies highlight the potential for fast carbon mobilization under aerobic conditions, but indicate that carbon at near-saturated conditions may remain largely immobilized for decades. Nature Climate Change 3 890 doi: 10.1038/nclimate1955

Description: Synonymous codon usage patterns are shaped by a balance between mutation, drift, and natural selection. To date, detection of translational selection in vertebrates has proven to be a challenging task, obscured by small long-term effective population sizes in larger animals and the existence of isochores in some species. The consensus is that, in such species, natural selection is either completely ineffective at overcoming mutational pressures and genetic drift or perhaps is effective but so weak that it is not detectable. The aim of this research is to understand the interplay between mutation, selection, and genetic drift in vertebrates. We observe that although variation in mutational bias is undoubtedly the dominant force influencing codon usage, translational selection acts as a weak additional factor influencing synonymous codon usage. These observations indicate that translational selection is a widespread phenomenon in vertebrates and is not limited to a few species.

Description: Class IV homeodomain leucine zipper (C4HDZ) genes are plant-specific transcription factors that, based on phenotypes in Arabidopsis thaliana , play an important role in epidermal development. In this study, we sampled all major extant lineages and their closest algal relatives for C4HDZ homologs and phylogenetic analyses result in a gene tree that mirrors land plant evolution with evidence for gene duplications in many lineages, but minimal evidence for gene losses. Our analysis suggests an ancestral C4HDZ gene originated in an algal ancestor of land plants and a single ancestral gene was present in the last common ancestor of land plants. Independent gene duplications are evident within several lineages including mosses, lycophytes, euphyllophytes, seed plants, and, most notably, angiosperms. In recently evolved angiosperm paralogs, we find evidence of pseudogenization via mutations in both coding and regulatory sequences. The increasing complexity of the C4HDZ gene family through the diversification of land plants correlates to increasing complexity in epidermal characters.

Description: Resolving difficult nodes for any part of the vertebrate tree of life often requires analyzing a large number of loci. Developing molecular markers that are workable for the groups of interest is often a bottleneck in phylogenetic research. Here, on the basis of a nested polymerase chain reaction (PCR) strategy, we present a universal toolkit including 102 nuclear protein-coding locus (NPCL) markers for vertebrate phylogenomics. The 102 NPCL markers have a broad range of evolutionary rates, which makes them useful for a wide range of time depths. The new NPCL toolkit has three important advantages compared with all previously developed NPCL sets: 1) the kit is universally applicable across vertebrates, with a PCR success rate of 94.6% in 16 widely divergent tested vertebrate species; 2) more than 90% of PCR reactions produce strong and single bands of the expected sizes that can be directly sequenced; and 3) all cleanup PCR reactions can be sequenced with only two specific universal primers. To test its actual phylogenetic utility, 30 NPCLs from this toolkit were used to address the higher level relationships of living salamanders. Of the 639 target PCR reactions performed on 19 salamanders and several outgroup species, 632 (98.9%) were successful, and 602 (94.1%) were directly sequenced. Concatenation and species-tree analyses on this 30-locus data set produced a fully resolved phylogeny and showed that Cryptobranchoidea (Cryptobranchidae + Hynobiidae) branches first within the salamander tree, followed by Sirenidae. Our experimental tests and our demonstration for a particular case show that our NPCL toolkit is a highly reliable, fast, and cost-effective approach for vertebrate phylogenomic studies and thus has the potential to accelerate the completion of many parts of the vertebrate tree of life.

Description: Genetic incompatibilities are commonly observed between hybridizing species. Although this type of isolating mechanism has received considerable attention, we have few examples describing how genetic incompatibilities evolve. We investigated the evolution of two loci involved in a classic example of a Bateson–Dobzhansky–Muller (BDM) incompatibility in Xiphophorus , a genus of freshwater fishes from northern Central America. Hybrids develop a lethal melanoma due to the interaction of two loci, an oncogene and its repressor. We cloned and sequenced the putative repressor locus in 25 Xiphophorus species and an outgroup species, and determined the status of the oncogene in those species from the literature. Using phylogenetic analyses, we find evidence that a repeat region in the proximal promoter of the repressor is coevolving with the oncogene. The data support a hypothesis that departs from the standard BDM model: it appears the alleles that cause the incompatibilities have coevolved simultaneously within lineages, rather than in allopatric or temporal isolation.

Description: Incompatibility systems in which individuals bearing identical alleles reject each other favor the maintenance of a diversity of alleles. Mushroom mating type loci ( MAT ) encode for dozens or hundreds of incompatibility alleles whose loss from the population is greatly restricted through negative frequency selection, leading to a system of alleles with highly divergent sequences. Here, we use DNA sequences of homeodomain (HD) encoding genes at the MAT locus of five closely related species of the root rot basidiomycete Heterobasidion annosum sensu lato to show that the extended coalescence time of MAT alleles greatly predates speciation in the group, contrasting loci outside of MAT that show allele divergences largely consistent with the species phylogeny with those of MAT , which show rampant trans-species polymorphism. We observe a roughly 6-fold greater genealogical depth and polymorphism of MAT compared with non- MAT that argues for the maintenance of balanced polymorphism for a minimum duration of 24 My based on a molecular-clock calibrated species phylogeny. As with other basidiomycete HD genes, balancing selection appears to be concentrated at the specificity-determining region in the N-terminus of the protein based on identification of codons under selection and the absence of recombination within the region. However, the elevated polymorphism extends into the nonspecificity determining regions as well as a neighboring non- MAT gene, the mitochondrial intermediate peptidase ( MIP ). In doing so, increased divergence should decrease recombination among alleles and as a by-product create incompatibilities in the functional domains not involved in allele recognition but in regulating sexual development.

Description: Here we present computational machinery to efficiently and accurately identify transposable element (TE) insertions in 146 next-generation sequenced inbred strains of Drosophila melanogaster . The panel of lines we use in our study is composed of strains from a pair of genetic mapping resources: the Drosophila Genetic Reference Panel (DGRP) and the Drosophila Synthetic Population Resource (DSPR). We identified 23,087 TE insertions in these lines, of which 83.3% are found in only one line. There are marked differences in the distribution of elements over the genome, with TEs found at higher densities on the X chromosome, and in regions of low recombination. We also identified many more TEs per base pair of intronic sequence and fewer TEs per base pair of exonic sequence than expected if TEs are located at random locations in the euchromatic genome. There was substantial variation in TE load across genes. For example, the paralogs derailed and derailed-2 show a significant difference in the number of TE insertions, potentially reflecting differences in the selection acting on these loci. When considering TE families, we find a very weak effect of gene family size on TE insertions per gene, indicating that as gene family size increases the number of TE insertions in a given gene within that family also increases. TEs are known to be associated with certain phenotypes, and our data will allow investigators using the DGRP and DSPR to assess the functional role of TE insertions in complex trait variation more generally. Notably, because most TEs are very rare and often private to a single line, causative TEs resulting in phenotypic differences among individuals may typically fail to replicate across mapping panels since individual elements are unlikely to segregate in both panels. Our data suggest that "burden tests" that test for the effect of TEs as a class may be more fruitful.

Description: Nature Climate Change 3 861 doi: 10.1038/nclimate2019

Description: The fate of permafrost soil carbon following thaw depends on hydrology. Nature Climate Change 3 865 doi: 10.1038/nclimate2010

Description: Satellite remote sensing has advanced the understanding of the climate system in the short period of observations. This study highlights remote sensing discoveries that were not detected by climate models or conventional observations, and suggests future challenges for the robust determination of climate trends. Nature Climate Change 3 875 doi: 10.1038/nclimate1908

Description: Albedo is a key component in the energy budget of the Arctic region, and a thorough understanding of it is essential for climate modelling. An analysis of the changes in Arctic sea-ice from 1982 to 2009 indicates that late summer sea-ice albedo is becoming dimmer. The rate of albedo decrease is shown to be accelerating over the study period. Nature Climate Change 3 895 doi: 10.1038/nclimate1963

Description: The Iberian lynx has suffered severe population declines in the twentieth century. An ecological modelling study that accounts for the effects of climate change, prey availability and management intervention now shows that lynx are likely to become extinct in the wild in the next 50 years. However, a carefully planned reintroduction program could avert extinction this century. Nature Climate Change 3 899 doi: 10.1038/nclimate1954

Description: A well-organized global grassroots campaign for climate protection could eclipse the IPPC in political influence. Nature Climate Change 3 849 doi: 10.1038/nclimate2023

Description: Nature Climate Change 3 861 doi: 10.1038/nclimate2018

Description: Efforts to tackle climate change have met significant financial and political barriers that have been difficult to overcome. Research now shows that such measures are justified on grounds other than mitigation of climate change. Nature Climate Change 3 863 doi: 10.1038/nclimate2013

Description: Sex determination mechanisms are highly variable across teleost fishes and sexual development is often plastic. Nevertheless, downstream factors establishing the two sexes are presumably conserved. Here, we study sequence evolution and gene expression of core genes of sexual development in a prime model system in evolutionary biology, the East African cichlid fishes. Using the available five cichlid genomes, we test for signs of positive selection in 28 genes including duplicates from the teleost whole-genome duplication, and examine the expression of these candidate genes in three cichlid species. We then focus on a particularly striking case, the A- and B-copies of the aromatase cyp19a1 , and detect different evolutionary trajectories: cyp19a1A evolved under strong positive selection, whereas cyp19a1B remained conserved at the protein level, yet is subject to regulatory changes at its transcription start sites. Importantly, we find shifts in gene expression in both copies. Cyp19a1 is considered the most conserved ovary-factor in vertebrates, and in all teleosts investigated so far, cyp19a1A and cyp19a1B are expressed in ovaries and the brain, respectively. This is not the case in cichlids, where we find new expression patterns in two derived lineages: the A-copy gained a novel testis-function in the Ectodine lineage, whereas the B-copy is overexpressed in the testis of the speciest-richest cichlid group, the Haplochromini. This suggests that even key factors of sexual development, including the sex steroid pathway, are not conserved in fish, supporting the idea that flexibility in sexual determination and differentiation may be a driving force of speciation.

Description: A substantial fraction of the terrestrial carbon sink, past and present, may be incorrectly attributed to environmental change rather than changes in forest management. Nature Climate Change 3 854 doi: 10.1038/nclimate2004

Description: China has recently pushed for investments in large-scale coal-fuelled synthetic natural gas plants. The associated carbon emissions, water needs and wider environmental impacts are, however, mostly neglected and could lock the country into an unsustainable development path. Nature Climate Change 3 852 doi: 10.1038/nclimate1988

Description: Nature Climate Change 3 861 doi: 10.1038/nclimate2020

Description: Trees can provide a multitude of ecosystem services. The current push to plant trees, motivated by the goal of sequestering carbon, raises the question of how tree diversity affects carbon sequestration and other services offered by afforestation/reforestation projects. This Perspective examines the potential benefits of mixed tree planting over a monoculture approach. Nature Climate Change 3 869 doi: 10.1038/nclimate1862

Description: Mitigation of greenhouse gas emissions often reduces co-emitted air pollutants, with advantages for human health. Avoided mortality from air pollution, a co-benefit of CO2 abatement, is estimated under global climate change mitigation scenarios to be in the range of US$50–US$380 per tonne of CO2. This exceeds the projected mitigation costs for 2030 and 2050, and is within the lower range of costs expected in 2100. Nature Climate Change 3 885 doi: 10.1038/nclimate2009

Description: The amount of organic material that microbes assimilate into their biomass is critical in regulating whether soils, the planet's main pool of organic matter, will absorb or emit carbon in a warmer world. Nature Climate Change 3 867 doi: 10.1038/nclimate2015

Description: There is no single correct procedure for the attribution of responsibility for growth in atmospheric CO2 concentrations because results are closely dependant on how carbon sinks are accounted for and linked to emissions. Now research that uses two different approaches—one assuming geographically constrained sinks and the other unconstrained—unambiguously attributes the largest share of the historical increase in CO2 to developed countries. Nature Climate Change 3 926 doi: 10.1038/nclimate1942

Description: Research that combines all available studies of biological responses to regional and global climate change shows that 81–83% of all observations were consistent with the expected impacts of climate change. These findings were replicated across taxa and oceanic basins. Nature Climate Change 3 919 doi: 10.1038/nclimate1958

Description: Extreme weather, rising seas and degraded coastal ecosystems all play a part in escalating the risks that coastal regions are exposed to. Now research into hazards facing the contiguous USA indicates that the likelihood and magnitude of losses can be reduced by intact reefs and coastal vegetation. Nature Climate Change 3 913 doi: 10.1038/nclimate1944

Description: The Great Disruption: How the Climate Crisis will Transform the Global Economy by Paul Gilding

Description: India and China's schemes to reduce greenhouse gases may be delayed and imperfect, but they should be applauded.

Description: The roles that microorganisms play in carbon storage are not fully understood. Now modelling results show that the activity of a single group of soil fungi may significantly enhance ecosystem carbon-storage capacity.

Description: The impacts of climate change on human systems depend not only on the level of emissions but also on how inherently vulnerable these systems are to the changing climate. The large uncertainties over future development and structure of societies and economies mean that the assessment of climate change effects is complex. One way to deal with this complexity is by using scenario analysis that takes account of these socio-economic differences. The challenge is to identify the dimensions along which societies and economies evolve over time in such a way as to cover sufficiently different vulnerability patterns. This conceptual effort is critical for the development of informative scenarios. Here, we identify three dimensions that take into account the most relevant factors that define the vulnerability of human systems to climate change and their ability to adapt to it.

Description: Experiments have shown that ocean acidification due to rising atmospheric carbon dioxide concentrations has deleterious effects on the performance of many marine organisms. However, few empirical or modelling studies have addressed the long-term consequences of ocean acidification for marine ecosystems. Here we show that as pH declines from 8.1 to 7.8 (the change expected if atmospheric carbon dioxide concentrations increase from 390 to 750 ppm, consistent with some scenarios for the end of this century) some organisms benefit, but many more lose out. We investigated coral reefs, seagrasses and sediments that are acclimatized to low pH at three cool and shallow volcanic carbon dioxide seeps in Papua New Guinea. At reduced pH, we observed reductions in coral diversity, recruitment and abundances of structurally complex framework builders, and shifts in competitive interactions between taxa. However, coral cover remained constant between pH 8.1 and ~7.8, because massive Porites corals established dominance over structural corals, despite low rates of calcification. Reef development ceased below pH 7.7. Our empirical data from this unique field setting confirm model predictions that ocean acidification, together with temperature stress, will probably lead to severely reduced diversity, structural complexity and resilience of Indo-Pacific coral reefs within this century.

Description: Living in Denial: Climate Change, Emotions, and Everyday Life by Kari Marie Norgaard

Description: After an earthquake and a huge wave damaged three nuclear reactor cores in Japan, energy and carbon markets around the world were hit with a surge of activity

Description: Having served as President of Ireland and as the United Nations High Commissioner for Human Rights, Mary Robinson has now returned home with a new mission — to bring a human face to climate change.

Description: Geographer Robert McDonald gathered a team of hydrologists, freshwater ecologists, urban planners and demographers to estimate the impacts of urban growth and climate change on future water availability for major cities in the developing world.

Description: The biological world is responding rapidly to a changing climate, but attempts to attribute individual impacts to rising greenhouse gases are ill-advised.

Description: A global private carbon-labelling scheme for consumer products could fill the climate-policy gap by influencing the behaviour of consumers and corporate supply chains.

Description: Mounting evidence that climate change will impact food security demonstrates the need to adapt food systems to future conditions. New work sheds light on the measures that will be needed to do so, and what the gains of implementing them might be.

Description: Hot: Living Through the Next Fifty Years on Earth by Mark Hertsgaard

Description: With a burgeoning population and a warming climate. How the world might quell food-price volatility in the long-term.

Description: The El Niño/Southern Oscillation (ENSO) is the dominant mode of interannual climate variability on Earth, alternating between anomalously warm (El Niño) and cold (La Niña) conditions in the tropical Pacific at intervals of 2–8 years. The amplitude of ENSO variability affects the occurrence and predictability of climate extremes around the world, but our ability to detect and predict changes in ENSO amplitude is limited by the fact that the instrumental record is too short to characterize its natural variability. Here we use the North American Drought Atlas—a database of drought reconstructions based on tree-ring records—to produce a continuous, annually resolved record of ENSO variability over the past 1,100 years. Our record is in broad agreement with independent, ENSO-sensitive proxy records in the Pacific and surrounding regions. Together, these records indicate that ENSO amplitude exhibits a quasi-regular cycle of 50–90 years that is closely coupled to the tropical Pacific mean state. Anomalously warm conditions in the eastern Pacific are associated with enhanced ENSO variability, consistent with model simulations. The quasi-periodic ENSO amplitude modulation reported here offers a key observational constraint for improving models and their prediction of ENSO behaviour linked to global warming.

Description: Recovery of the ozone hole and increasing greenhouse-gas concentrations have opposite effects on the jet stream. New model experiments indicate that they will cancel each other out over coming decades, leaving storm tracks at a stand still.

Description: The Clean Development Mechanism was designed to allow emissions reductions and sustainable development to proceed hand-in-hand. Analysis now addresses the question of whether — 14 years after its creation — it can be reformed sufficiently to serve current needs.

Description: One of the reasons that people may not take action to mitigate climate change is that they lack first-hand experience of its potential consequences. From this perspective, individuals who have direct experience of phenomena that may be linked to climate change would be more likely to be concerned by the issue and thus more inclined to undertake sustainable behaviours. So far, the evidence available to test this hypothesis is limited, and in part contradictory. Here we use national survey data collected from 1,822 individuals across the UK in 2010, to examine the links between direct flooding experience, perceptions of climate change and preparedness to reduce energy use. We show that those who report experience of flooding express more concern over climate change, see it as less uncertain and feel more confident that their actions will have an effect on climate change. Importantly, these perceptual differences also translate into a greater willingness to save energy to mitigate climate change. Highlighting links between local weather events and climate change is therefore likely to be a useful strategy for increasing concern and action.

Description: New approaches are needed to accelerate understanding of climate impacts on crop yields, particularly in tropical regions. Past studies have relied mainly on crop-simulation models or statistical analyses based on reported harvest data, each with considerable uncertainties and limited applicability to tropical systems. However, a wealth of historical crop-trial data exists in the tropics that has been previously untapped for climate research. Using a data set of more than 20,000 historical maize trials in Africa, combined with daily weather data, we show a nonlinear relationship between warming and yields. Each degree day spent above 30 °C reduced the final yield by 1% under optimal rain-fed conditions, and by 1.7% under drought conditions. These results are consistent with studies of temperate maize germplasm in other regions, and indicate the key role of moisture in maize’s ability to cope with heat. Roughly 65% of present maize-growing areas in Africa would experience yield losses for 1 °C of warming under optimal rain-fed management, with 100% of areas harmed by warming under drought conditions. The results indicate that data generated by international networks of crop experimenters represent a potential boon to research aimed at quantifying climate impacts and prioritizing adaptation responses, especially in regions such as Africa that are typically thought to be data-poor.

Description: NASA scientist Drew Shindell teamed up with experts in health, agriculture and economics to investigate the potential impacts of imposing tight vehicle-emission standards in developing countries.

Description: A major challenge facing climate scientists is explaining to non-specialists the risks and uncertainties surrounding potential changes over the coming years, decades and centuries. Although there are many guidelines for climate communication, there is little empirical evidence of their efficacy, whether for dispassionately explaining the science or for persuading people to act in more sustainable ways. Moreover, climate communication faces new challenges as assessments of climate-related changes confront uncertainty more explicitly and adopt risk-based approaches to evaluating impacts. Given its critical importance, public understanding of climate science deserves the strongest possible communications science to convey the practical implications of large, complex, uncertain physical, biological and social processes. Here, we identify the communications science that is needed to meet this challenge and the ambitious, interdisciplinary initiative that its effective application to climate science requires.

Description: An assessment of future ecosystem services and human well-being in the Great Barrier Reef region, led by social-ecological system scientist Erin Bohensky, draws on expertise in ecology, economics, sociology, geography, hydrology and oceanography.

Description: Adaptation is still mitigation's poor cousin, in political and economic terms. However, efforts to better define adaptation — and the areas that would benefit most from climate aid — may help in achieving parity.

Description: Words of caution on communication.

Description: Climate change presents a tremendous opportunity for discovery that will move us towards a better understanding of the physical workings of our planet and of our role as its exploiters and guardians.

Description: Climate scientists are under pressure to make their data — and their methods — more openly available, both to fellow scientists and the public. Now, open-access climate science is becoming easier than ever.

Description: How much of an influence are our peers when it comes to being green?

Description: Non-CO2 air pollutants from motor vehicles have traditionally been controlled to protect air quality and health, but also affect climate. We use global composition–climate modelling to examine the integrated impacts of adopting stringent European on-road vehicle-emission standards for these pollutants in 2015 in many developing countries. Relative to no extra controls, the tight standards lead to annual benefits in 2030 and beyond of 120,000–280,000 avoided premature air pollution-related deaths, 6.1–19.7 million metric tons of avoided ozone-related yield losses of major food crops, $US0.6–2.4 trillion avoided health damage and $US1.1–4.3 billion avoided agricultural damage, and mitigation of 0.20 (+0.14/−0.17)  °C of Northern Hemisphere extratropical warming during 2040–2070. Tighter vehicle-emission standards are thus extremely likely to mitigate short-term climate change in most cases, in addition to providing large improvements in human health and food security. These standards will not reduce CO2 emissions, however, which is required to mitigate long-term climate change.

Description: Those frustrated with political inertia on climate change are increasingly seeking an alternative route through the courts, but here too they are likely to see slow progress.

Description: On 9 May this year, the Intergovernmental Panel on Climate Change released a special report on the role of renewable energy in mitigating climate change. Georgie Weedon speaks to Ottmar Edenhofer, co-chair of the working group behind the report, about its key findings and implications.

Description: Current policies to reduce emissions from forest loss could mean that rising demand for food is not met. A new approach to forest conservation that reduces emissions while meeting demand for agricultural products may be feasible, but more expensive.

Description: Over half of all anthropogenic carbon dioxide emissions into the atmosphere are removed naturally by land and ocean carbon sinks. New analysis indicates that the land sink is increasing in some surprising places.

Description: The Cancún Agreements provide strong backing for a REDD+ (Reducing Emissions from Deforestation and Forest Degradation) mechanism whereby developed countries pay developing ones for forest conservation. REDD+ has potential to simultaneously deliver cost-effective climate change mitigation and human development. However, most REDD+ analysis has used coarse-scale data, overlooked important opportunity costs to tropical forest users and failed to consider how to best invest funds to limit leakage, that is, merely displacing deforestation. Here we examine these issues for Tanzania, a REDD+ country, by comparing district-scale carbon losses from deforestation with the opportunity costs of carbon conservation. Opportunity costs are estimated as rents from both agriculture and charcoal production (the most important proximate causes of regional forest conversion). As an alternative we also calculate the implementation costs of alleviating the demand for forest conversion—thereby addressing the problem of leakage—by raising agricultural yields on existing cropland and increasing charcoal fuel-use efficiency. The implementation costs exceed the opportunity costs of carbon conservation (medians of US$6.50 versus US$3.90 per Mg CO2), so effective REDD+ policies may cost more than simpler estimates suggest. However, even if agricultural yields are doubled, implementation is possible at the competitive price of ~US$12 per Mg CO2.

Description: Laboratory studies indicate that warming can eventually push cold-blooded organisms past their physiological limits, with detrimental effects on growth. Now evidence from the field indicates that this phenomenon is occurring in the Tasman Sea.

Description: The timing of seasonal events such as flowering and migration is changing as the climate warms, reshuffling the order in which such events take place each year. Now research sheds light on the causes of changes in the timing of butterfly emergence.

Description: The production of traded goods accounts for a significant proportion of global greenhouse-gas emissions. Now analysis reveals that emissions embodied in imports from developing countries have out-stripped emission reductions made by developed countries at home over the past 20 years.

Description: Understanding climate change impacts on transportation systemsis particularly critical in northern latitudes, where subzero temperatures restrict shipping, but enable passage of ground vehicles over frozen soil and water surfaces. Although the major transport challenges related to climate warming are understood, so far there have been no quantitative projections of Arctic transport system change. Here we present a new modelling framework to quantify changing access to oceans and landscapes northward of 40° N by mid-century. The analysis integrates climate and sea-ice model scenarios1, 2 with topography, hydrography, land cover, transportation infrastructure and human settlements. Declining sea-ice concentration and thickness suggest faster travel and improved access to existing (+5 to +28%) and theoretical (+11 to +37%) offshore exclusive economic zones of Canada, Greenland, Russia and the US. The Northern Sea Route, Arctic Bridge and North Pole routes are projected to become fully accessible from July–September, averaging ~11, 15 and 16 days to traverse, respectively, whereas the Northwest Passage will not. All eight Arctic states are projected to suffer steep declines (−11 to −82%) in accessibility inland, driven by lost potential for winter road construction caused by milder winters and deeper snow accumulation.

Description: Sectors such as steel manufacturing are looking to make the same products using less raw material. Adopted more widely, this approach could go a long way to cutting emissions.

Description: The European Union faces the challenge of integrating new measures to achieve energy efficiency with existing climate policies.

Description: Climate change can affect organisms both directly, by affecting their physiology, growth, and behaviour, and indirectly, for example through effects on ecosystem structure and function. For ectotherms, or ‘cold-blooded’ animals, warming will directly affect their metabolism, with growth rates in temperate species predicted to increase initially as temperatures rise, but then decline as individuals struggle to maintain cardiac function and respiration in the face of increased metabolic demands. We provide evidence consistent with this prediction for a marine fish (Cheilodactylus spectabilis) in the Tasman Sea; one of the most rapidly warming regions of the Southern Hemisphere ocean. We estimated changes in the species’ growth rate over a 90-year period using otoliths—bony structures that fish use for orientation and detection of movement—and compared these changes to temperature trends across the species’ distribution. Increasing temperatures coincide with increased growth for populations in the middle of the species range, but with reduced growth for those at the warm northern edge of the species’ distribution, indicating that temperatures may have already reached levels associated with increased metabolic costs. If warming continues, the direct metabolic effects of increasing temperatures on this species may lead to declining productivity and range contraction.

Description: How will our choices shape the future? That's a question researchers are keen to answer, and with a new approach to how the climate community develops scenarios, they are coming that bit closer to answering it.

Description: Estimates of how much food we can grow in a warmer world are out of date. Researchers need to switch to more rigorous multi-model ensembles.

Description: Climate change is known to affect the carbon balance of Arctic tundra ecosystems by influencing plant growth and decomposition. Less predictable climate-driven biotic events, such as disease outbreaks, are now shown to potentially shift these ecosystems from net carbon sinks to sources.

Description: Climate change has reached the level of a 'scientific consensus', but is not yet a 'social consensus'. New analysis highlights that a growing divide between liberals and conservatives in the American public is a major obstacle to achieving this end.

Description: The causes of the severe drought in the Sahel in the 1970s and 1980s are uncertain. Now a study provides the firmest evidence so far that emissions of aerosols from industrialized countries played a significant role, but other forcings cannot be ruled out yet.

Description: With its short-term focus, the financial sector is largely turning its back on the climate challenge, shows a new study.