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  • How to spend a dwindling greenhouse gas budget

    Deforestation_Pixabay_Jan2018
    The Paris Agreement is based on emission scenarios that move from a sluggish phase-out of fossil fuels to largescale late-century negative emissions. In a new study in the journal Nature Climate Change authors argue that a new set of scenarios needs to be generated and analysed to inform the policy process on robust timing of climate mitigation, with the aim of avoiding negative side effects. Image by: Pixabay.

     

    The 2015 climate summit in Paris galvanized global commitments to an ambitious yet vaguely defined goal of climate stabilization. The Paris Agreement is based on emission scenarios that move from a sluggish phase-out of fossil fuels to largescale late-century negative emissions. At the same time, some scientists argue that the model based scenarios with 1.5 °C and even 2 °C temperature change targets seem unattainable and detached from current political realities. Alternative pathways of early deployment of negative emission technologies need to be considered to ensure that climate targets are reached safely and sustainably

    In a new study in the journal Nature Climate Change, authors scrutinize the dominant climate mitigation scenario archetype that projects low global decarbonization rates in the first half of this century followed by large negative emissions in the second half, thanks to carbon dioxide removal (CDR) technologies. Authors call this approach to mitigation the ‘Late- Century CDR’ scenario archetype.

    This archetype is consistent with nearly all of 2 °C scenarios covered by the IPCC’s Fifth Assessment Report (AR5), 87% of which deploy CDR technologies in the second half of the century. The authors consider that, following this predominant archetype might not only turn out to be a risky strategy, but may lead to significant environmental damages and may also be economically inefficient. In Late-Century CDR scenarios, CDR mostly in the form of bioenergy with carbon capture and storage (BECCS) typically removes the equivalent of 20 years of current GHG emissions to reverse the temporary GHG budget overshoot that is tolerated earlier on. The authors point out that the challenges and uncertainties associated with CDR are well described in the scientific literature, yet the scientific and political debate addressing the consequences of large-scale and late deployment of CDR as a backstop strategy is only at an early stage.

    Authors argue that a new set of scenarios needs to be generated and analysed to inform the policy process on robust timing of climate mitigation, with the aim of avoiding negative side effects. “Essentially, three attributes characterize such budget-constrained scenarios: the timing and magnitude of global peak net emissions and the speed of decline thereafter; the maximum amount of allowable deployment of biomass-based CDRs; and an admissible risk threshold associated with a temperature overshoot”, noted Prof. Obersteiner from the Ecosystems Services and Management Program, International Institute for Applied Systems Analysis (IIASA) Laxenburg, Austria.

    The study concludes that the timing of mitigation actions, in particular of negative emission technologies, needs to be urgently revisited in the analyses of ambitious climate targets. They argue that considerations of both intergenerational equity and climate/environment safety motivate early and moderate — rather than extreme — deployment of negative emission technologies as well as a timely peak in net carbon emissions as early as 2020. As a consequence all of the near-term and mid-century net emission reduction, targets should be, according to the authors, reformulated to include targets of early action on CDR technology portfolios.

    “Transforming the 570 million farms to be climate smart and incentivizing 1.6 billion people who economically depend on forests to become early movers in No Overshoot and Minimize CDR scenarios is a formidable global policy challenge. We call for a discourse on effective strategies, starting with more detailed global gap assessments of the archetypes, and then mainstreaming the gained insights into Nationally Determined Contributions and implementation plans”, said Prof. Josep Peñuelas from CREAF-CSIC Barcelona.

    Journal Reference: Obersteiner, M., Bednar, J., Wagner, F., Gasser, T., Ciais, P., Forsell, N., Frank, S., Havlik, P., Valin, H., Janssens, I.A., Peñuelas, J., Schmidt-Traub, G. 2018. How to spend a dwindling greenhouse gas budget. Nature Climate Change 8, 7-10. doi: 10.1038/s41558-017-0045-1

    Mapping local and global variability in plant trait distributions

    Butler_et al_PNAS_2017.tif
    Specific leaf area (SLA), and dry mass-based concentrations of leaf nitrogen (Nm) and phosphorus (Pm) are used in this study to better capture the response of the land surface component of the Earth System to environmental change. Image: Butler, E.E., et al. 2017. Proceedings of the National Academy of Sciences

     

    Our ability to understand and predict the response of ecosystems to a changing environment depends on quantifying vegetation functional diversity. However, representing this diversity at the global scale is challenging. Typically, in Earth Systems Models, characterization of plant diversity has been limited to grouping related species into Plant Functional Types (PFTs), with all trait variation in a PFT collapsed into a single mean value that is applied globally.

    In a new study in the journal Proceedings of the National Academy of Sciences authors created fine-grained global maps of plant trait distributions that can be applied to Earth System Models by using the largest global plant trait database and state of the art Bayesian modeling. “Here, we use an updated version of the largest global database of plant traits coupled with modern Bayesian spatial statistical modeling techniques to capture local and global variability in plant traits. This combination allows the representation of trait variation both within pixels on a gridded land surface as well as across global environmental gradients”, said Dr. Butler from Department of Forest Resources, University of Minnesota.

    Focusing on a set of plant traits closely coupled to photosynthesis and foliar respiration – specific leaf area (SLA), and dry mass-based concentrations of leaf nitrogen (Nm) and phosphorus (Pm), authors characterize how traits vary within and among over 50,000 ~ 50 × 50 km cells across the entire vegetated land surface. “The importance of these traits (SLA, Nm, Pm) and the more advanced representation of functional diversity developed here may be used to better capture the response of the land surface component of the Earth System to environmental change”, said Prof. Josep Peñuelas from CREAF-CSIC Barcelona.

    This endeavor advances prior trait mapping by generating global maps that preserve variability across scales by using modern Bayesian spatial statistical modeling in combination with a database over three times larger than previous analyses. “Our maps reveal that the most diverse grid cells possess trait variability close to the range of global PFT means”, said Dr. Butler from Department of Forest Resources, University of Minnesota.

     

    Journal Reference: Butler, E.E., Datta, A., Flores-Moreno, H., Chen, M., Wythers, K.R., Fazayeli, F., Banerjee, A., Atkin, O.K., Kattge, J., Amiaud, B., Blonder, B., Boenisch, G., Bond-Lamberty, B., Brown, K.A., Byun, C., Campetella, G., Cerabolini, B.E.L., Cornelissen, J.H.C., Craine, J.M., Craven, D., de Vries, F.T., Díaz, S., Domingues, T., Forey, E., Gonzalez, A., Gross, N., Han, W., Hattingh, W.N.,  Hickler, T., Jansen, S., Kramer, K., Kraft, N.J.B., Kurokawa, H., Laughlin, D.C., Meir, P., Minden, V.,  Niinemets, Ü., Onoda, Y., Peñuelas, J., Read, Q., Valladares Ros, F., Sack, L., Schamp, B.,  Soudzilovskaia, N.A., Spasojevic, M.J., Sosinski, E., Thornton, P., van Bodegom, P.M.,  Williams, M., Wirth, C., Reich, P.B.. 2017. Mapping local and global variability in plant trait distributions. Proceedings of the National Academy of Sciences.

    Microbial mass movements

    Flying aircrafts_ESA_Sept2017
    Global transport, tourism, waste disposal have changed biogeographic patterns for microorganisms. In this study authors point to the importance of the dispersal of cells and genes by human activities. The picture presents a flight map showing 15,000 simultaneously flying aircrafts based on 25 million positions (European Space Agency (ESA)).

     

    For several billion years, microorganisms and the genes they carry have mainly been moved by physical forces such as air and water currents. These forces generated biogeographic patterns for microorganisms that are similar to those of animals and plants.

    In a new study in the journal Science authors note that humans and animals now move on an unprecedented scale, and this movement actively transports and enriches a specific subset of microorganisms.

    “Humans in the past 100 years have changed these natural dynamics by transporting large numbers of cells to new locations through waste disposal, tourism, and global transport and by modifying selection pressures at those locations. As a consequence, we are substantially altering microbial biogeography”, said Prof. Josep Peñuelas from CREAF-CSIC Barcelona.

    Dissemination through wastewater

    Wastewater carries high densities of microorganisms and their cargo genes. It should be noted that, globally, some 359,000 km2 of croplands depend on irrigation with urban wastewater, 80% of which undergoes little or no treatment. Therefore, the use of wastewater or manure in agriculture contaminates fruits, vegetables, and farm animals which in turn are distributed globally. Wastewater also contains pollutants with biological effects (as metals, antibiotics or disinfectants). These compounds stimulate bacterial stress response systems that increase mutation rates which, in turn, confer adaptive advantages on at least a subset of cells arriving at a new location.

    For a sense of the importance of this adaptive advantage, authors consider the clinical class 1 integron. This DNA element acquires foreign genes from the environment and has played a central role in spreading antibiotic resistance among bacterial pathogens. DNA sequencing data show that it had the origin in a single cell, in the early 20th century. Millions to billions of copies of this element now exists in every gram of feces from human and domestic animals. This remarkable increase in its abundance and distribution has been driven by antibiotic selection, increases in human population, and dissemination via global transport.

    The role of human and material movement

    This study points out that humans and agricultural animals now comprise 35 times as much biomass as wild terrestrial mammals. The bacteria shed in feces, therefore, mainly represent the gut microbiota of humans and agricultural animals (cattle, sheep, goats, pigs, and chickens) and they have vastly increased in both abundance and distribution, particularly in the last century. “Efficiency of dispersal is enhanced by the 1.2 billion international tourist movements per year, as evidenced by the rapid spread of bacterial clones and antibiotic resistance genes between continents”, emphasizes Prof. Micahel Gillings from Macquarie University, Sydney .

    The study also points out that humans additionally promote dispersal of microbial cells via mass movement of materials. In this regard it should be noted that human activities now move more soil, sand, and rock than all natural processes combined. As an example, natural fluvial erosion is 21 gigatons (Gt) per year, much lower than the75 Gt per year eroded by agriculture. “This erosion transports very large numbers of bacteria, given that soil can contain more than a billion microbial cells per gram. Movements on this scale have consequences for human health, agriculture, and ecosystem functions, such as increasing the spread of human pathogens and threatening sustainable food productivity”, said Prof. Yong-Guan Zhu from Chinese Academy of Science.

    Changes to biogeochemical cycles

    According to this study, changes in the distribution and abundance of microorganisms, and the resultant changes in microbial ecosystems will affect biogeochemical cycles driven by microbial activity. “Knowledge of the connections between microbial biodiversity and landscape-scale biogeochemical processes, as well as below-ground ecosystems, will be essential to predict the magnitude and direction of these changes”, said Prof. Josep Peñuelas from CREAF-CSIC Barcelona.

    Linking the rapidly expanding databases generated by environmental genomics with biogeochemical models could reveal changes in nutrient cycles. “This fusion of genomics and Earth system science is a first step to understanding how the biochemical functions of microorganisms could be altered, temporally and spatially, by global change”, said Prof. Yong-Guan Zhu from Chinese Academy of Science.

    Unlocking the complexity

    There is a recent growing trend for monitoring the environmental dissemination of genes, particularly those that confer phenotypes of direct relevance to human and animal health. In this sense, Prof. Josep Peñuelas points to the high importance of understanding how human activities cause systematic changes in ecosystems and highlight the priority of investigating microbial invasions, microbial extinctions, and perturbations to microbial ecosystems.

     

    Journal Reference: Zhu, Y.G., Gillings, M., Simonet, P., Stekel, D., Banwart, S., Penuelas, J. 2017. Microbial mass movements. Science 357 (6356), 1099-1100.

    Shifting from a fertilization-dominated to a warming-dominated period

    Penuelas_Nature_Shifting_Sept2017
    In a new study in the journal Nature Ecology and Evolution researchers argue that a slowdown of the CO2 and N fertilization effects on ecosystem carbon sequestration and the rapid emergence of negative ecosystem impacts from global climate change might drive a change from a fertilization-dominated to a warming-dominated period. Photos by Pixabay

     

    Natural ecosystems currently remove on average each year an amount of carbon dioxide equivalent to about one third of human-caused carbon dioxide (CO2) emissions from fossil fuel burning and cement production. There are numerous evidences which show that the efficiency of natural land ecosystems to absorb the increasing fossil fuel and cement emissions does not keep their path.

    In a new study in the journal Nature Ecology and Evolution authors hypothesize that the progressive long term weakening of the natural land sink relative to fossil fuel CO2 emissions marks the beginning of a transition from a vegetation fertilization-dominated period to a period dominated by nutrient and climate constraints on plant growth, and larger climate change impacts (e.g., heatwaves).

    There are many unknowns in the timing of this transition, so in light of the recent Paris COP21 agreement, a better understanding of climate change impacts on carbon stocks remains paramount to understand the level of climate mitigation required to achieve agreed temperature goals, indicates Prof Josep Peñuelas from CREAF-CSIC Barcelona.

    Human fertilization changes productivity and carbon residence in ecosystems

    Human activities result in increasing atmospheric concentrations of CO2, N inputs to ecosystems and temperature. This leads to enhanced metabolism of organism and lengthening the growing seasons. Plants can consequently grow more. The magnitude of carbon sinks and their duration depend both on the rate of increase of carbon inputs and on the residence time of the carbon being taken up by ecosystems explain Drs Shilong Piao from Academy of Sciences in Pekin and Jordi Sardans from CREAF in Barcelona.

    Authors point out that several studies realized at global scale, in all biomes, suggest that trends of increasing sinks may be slowing down. A remaining question is whether in regions where carbon sinks may be slowing down, this is due to stalling productivity or to reducing residence times.

    Likely limitations for enhancement of carbon sinks

    The anthropogenic increases in CO2 and atmospheric nitrogen deposition are not matched by a similar increase in the inputs of other key nutrients such as phosphorus (P) and/or potassium (K). Current evidence suggests an overall shortage of P which will act as a limiting factor to meet the increasing demand for plant growth. “A better understanding of the factors that regulate exchanges between pools of “available” and “unavailable” soil P is critically needed”, said Prof. Ivan Janssens from University of Antwerp.

    The higher nocturnal temperatures enhance night respiration, Prof. Josep Canadell pointed out. Moreover, severe regional heatwaves are also likely to become more frequent in a changing climate, and their negative impact on terrestrial carbon sequestration may thus also become important. “For example, the 2003 heatwave decreased European gross primary productivity by 30%, which resulted in a strong anomalous net source of carbon dioxide to the atmosphere; this effect is the equivalent of reversing four years of net ecosystem carbon sequestration in the European continent”, said Prof. Philippe Ciais from LSCE Paris.

    In recent decades large-scale droughts have reduced seasonal NPP in the Southern and Northern hemispheres and weakened the terrestrial carbon sink. However, as Drs Marcos Fernandez-Martinez and Jofre Carnicer from CREAF-CSIC Barcelona point out, there is an inherent difficulty in quantifying the response of NPP to drought because it depends on the timing of drought during the growing season, and on ecosystem properties of resistance to drought.

    Furthermore, it should be taken into account that most land use changes, fires, and harvests, which are expected to increase in the future reduce residence times, thereby reducing the sink capacity of the land biosphere as noticed by Prof Michael Obersteiner from IIASA Vienna.

    Due to the above, the potential saturation or slower increase of the sink capacity of terrestrial ecosystems, or even its transition into a source of CO2, could be expected. Moreover, for Prof. Josep Peñuelas from CREAF-CSIC Barcelona, current climate models do not necessarily well represent extreme events due to coarse resolution (eg. extreme precipitation, wind storms and tropical cyclones) or to insufficiently constrained soil-atmosphere interactions. At this point, authors point out that these models could improve its prediction capacity through the addition of factors outlined above. “Such improved models could then help understanding the responses to different levels of global warming (especially in the range 1.5-3°C according to the Paris agreement and current intended policies)”, said Prof. Josep Peñuelas from CREAF-CSIC Barcelona.

    Shift from a fertilization to a warming period

    This study presents multiple evidences suggesting limits to the buffering capacity of the biosphere. Thus, Prof. Josep Peñuelas indicates that a slowdown of the CO2 and N fertilization effects on ecosystem carbon sequestration and the rapid emergence of negative ecosystem impacts from global climate change might drive a shift from an Anthropocene period dominated by fertilization to another period characterized by saturated fertilization and strong climate change.

    For Prof. Peñuelas, although the climate has not yet changed dramatically in the Anthropocene, the coming decades will undoubtedly be different. Prof. Vautard from LSCE Paris explains that “A warming of 2 °C would slightly increase the frequency of 2003-like heatwaves in Northern France, but a warming of 3 °C would instead produce very different conditions, with one summer like that of 2003 occurring every three or four years, which would therefore affect the forests carbon sink in Europe much more than in the past”.

    There is also the possibility of low probability but high impact phenomena which would lead to rapid positive feedbacks to the climate system (e.g. massive dieback of Amazon rainforest because of reduced rainfall or a dramatic temperature drop in the North Atlantic because of the collapse of the ocean current). “The occurrence of this phenomena is highly uncertain, particularly for low temperature scenarios. However, it is much more certain that we are currently entering a new warming period where ecosystems are put under increasing stresses”, said Prof. Josep Peñuelas from CREAF-CSIC Barcelona.

    This study was funded by the European Research Council Synergy grant ERC-2013-SyG-610028

    Journal Reference: Peñuelas, P., Ciais, P., Canadell, J., Janssens, I., Fernandez-Martinez, M., Carnicer, J., Obersteiner, M., Piao, S., Vautard, R., Sardans, J. 2017. Shifting from a fertilization-dominated to a warming-dominated period. Nature Ecology and Evolution.

    Atmospheric deposition, CO2, and change in the land carbon sink

    Fum_bosc_Marcos_Agost2017
    The reduction in acidic deposition of nitrogen and Sulphur should lead to a slow recovery of forests to a pre-acid deposition state. Photo by Pixabay

     

    Human activities result in increasing atmospheric concentrations of CO2 that affects the terrestrial biosphere in multiple ways: warming the climate, increasing photosynthesis (CO2 fertilization), decreasing transpiration by stimulating stomatal closure and changing the stoichiometry of carbon, nitrogen and phosphorus (C:N:P) in ecosystem carbon pools. Concentrations of atmospheric carbon dioxide (CO2) have continued to increase whereas, due to air-quality policies, atmospheric deposition of sulphur and nitrogen has declined in Europe and the USA during recent decades.

    Terrestrial ecosystems are key components of the global carbon cycle, as indicated by the fact that, since the 1960s, they have been sequestering an average of about 30% of the annual anthropogenic CO2 emitted into the atmosphere.

    In a new study in the journal Scientific Reports authors used time series of flux observations from 23 forests distributed throughout Europe and the USA, and generalised mixed models to end up finding  that forest-level net ecosystem production and gross primary production have increased by 1% annually from 1995 to 2011.

    In this study, authors test the hypothesis that gross primary production, ecosystem respiration and the net C-sink strength (net land-atmosphere CO2 flux) or net ecosystem production (NEP), have accelerated during the last two decades because of the increased atmospheric CO2 concentrations and temperature, and because of the recovery from high loads of S deposition in Europe and North America. “We expected these deposition reductions to have modulated the biogeochemical effects of rising CO2” added Dr. Marcos Fernández-Martínez from CREAF-CSIC Barcelona

    Statistical models indicated that increasing atmospheric CO2 was the most important factor driving the increasing strength of carbon sinks in these forests. Authors also found that the reduction of sulphur deposition in Europe and the USA led to higher recovery in ecosystem respiration than in gross primary production, thus limiting the increase of carbon sequestration. By contrast, the study shows that trends in climate and nitrogen deposition did not significantly contribute to changing carbon fluxes during the studied period. “Our findings support the hypothesis of a general CO2-fertilization effect on vegetation growth and suggest that, so far unknown, sulphur deposition plays a significant role in the carbon balance of forests in industrialized regions”, said Prof. Josep Peñuelas from CREAF-CSIC Barcelona

    “Our results show the need to include the effects of changing atmospheric composition, beyond CO2, to assess future dynamics of carbon-climate feedbacks not currently considered in earth system/climate modelling”, said Dr. Fernández-Martínez from CREAF-CSIC Barcelona

    This study was funded by the European Research Council Synergy grant ERC-2013-SyG-610028, the Spanish Government project CGL2016-79835-P and the Catalan Government grant FI-2013

    Journal Reference: Fernández-Martínez, M., Vicca, S., Janssens, I.A., Ciais, P., Obersteiner, M., Bartrons, M., Sardans, J., Verger, A., Canadell, J.G., Chevallier, F., Wang, X., Bernhofer, C., Curtis, P.S., Gianelle, D., Grünwald, T., Heinesch, B., Ibrom, A., Knohl, A., Laurila, T., Law, B.E., Limousin, J.M., Longdoz, B., Loustau, D., Mammarella, I., Matteucci, G., Monson, R.K., Montagnani, L., Moors, E.J., Munger, J.W., Papale, D., Piao, S.L., Peñuelas, J. 2017. Atmospheric deposition, CO2, and change in the land carbon sink. Scientific Reports.

    Relative contribution of groundwater to plant transpiration estimated with stable isotopes

    Pi_arrels_Barbeta_Agost2017
    Water is generally taken up by roots (with important exceptions), so root structure and function should play a central role in research of plant-water relations. Photo by Pixabay

     

    Water stored underground in the saturated and subsurface zones below the soil are important sources of water for plants in water-limited ecosystems. Arid and seasonally dry ecosystems contain the deepest root systems, and some species grow roots to depths of more than 4 m, even in temperate and tropical ecosystems. The presence of deep-rooted plants worldwide, however, suggests that the use of groundwater is not restricted to arid and seasonally dry ecosystems.

    In a new study in the journal Scientific Reports authors compiled the available data (71 species) on the relative contribution of groundwater to plant water estimated using stable isotopes and mixing models, which provided information about relative groundwater use, and analysed their variation across different climates, seasons, plant types, edaphic conditions, and landscape positions.

    Plant use of groundwater was more likely at sites with a pronounced dry season, and represented on average 49 per cent of transpired water in dry seasons and 28 per cent in wet seasons. The relative contribution of groundwater to plant-water uptake was higher on rocky substrates (saprolite, fractured bedrock), which had reduced groundwater uptake when this source was deep belowground.

    Notably, authors found that the connectivity between groundwater pools and plant water is quantitatively larger and more widespread than reported by recent global estimations based on isotopic averaged values. Thus, “in order to improve the representation of groundwater-surface interactions in models, a quantification of the relative contribution of groundwater to transpiration and its variability across environmental gradients was required”, said Dr. Adrià Barbeta from CREAF-CSIC Barcelona, now in INRA Bourdeaux

    Prof. Josep Peñuelas from CREAF-CSIC Barcelona claims also that “further research on plant-water sources in boreal, polar regions and tropical rainforests would help our understanding of the global patterns of groundwater uptake and may substantially improve the biosphere-atmosphere models by a realistic representation of this important component of the water cycle”.

    This study was funded by the European Research Council Synergy grant ERC-2013-SyG-610028, the Spanish Government project CGL2016-79835-P and the Catalan Government grant FI-2013

    Journal Reference: Barbeta, A., Peñuelas, J. 2017. Relative contribution of groundwater to plant transpiration estimated with stable isotopes. Scientific Reports

    β-Ocimene, a Key Floral and Foliar Volatile Involved in Multiple Interactions between Plants and Other Organisms

    Farre_Armengol_PR_agost2017
    Plants generally synthesize and emit species-specific floral volatile organic compounds (VOCs) mixtures to attract pollinators by mixing several of these common VOCs. Photo by Pexels

     

    More than 1700 volatile organic compounds (VOCs) have been identified in the floral scents of flowering plants. These VOCs are not equally distributed across the phylogeny of flowering plants, so that the commonness and predominance of these compounds in floral scents varies widely among species. Common floral VOCs have a widespread phylogenetic distribution, which means that they are present in the floral scents of many species from different plant families. Instead, less common floral VOCs are only present in plants that are pollinated by specific pollinator groups with specific innate preferences for those VOCs.

    β-Ocimene is a very common plant volatile released in important amounts from the leaves and flowers of many plant species. This acyclic monoterpene can play several biological functions in plants, by potentially affecting floral visitors and also by mediating defensive responses to herbivory.

    In a new study in the journal Molecules authors indicated that the ubiquity and high relative abundance of β-ocimene in the floral scents of species from most plant families and from different pollination syndromes (ranging from generalism to specialism) strongly suggest that this terpenoid may play an important role in the attraction of pollinators to flowers.

    In this study authors compiled abundant evidence from published studies that supports β-ocimene as a generalist attractant of a wide spectrum of pollinators. They found no studies testing behavioural responses of pollinators to β-ocimene, that could directly demonstrate or deny the function of β-ocimene in pollinator attraction; but “several case studies support that the emissions of β-ocimene in flowers of different species follow marked temporal and spatial patterns of emission, which are typical from floral volatile organic compound (VOC) emissions that are involved in pollinator attraction”, said Dr. Gerard Farré-Armengol from CREAF-CSIC Barcelona, now in the University of Salzburg.

    Furthermore, important β-ocimene emissions are induced from vegetative plant tissues after herbivory in many species, which have relevant functions in the establishment of tritrophic interactions. Authors thus conclude that β-ocimene is a key plant volatile with multiple relevant functions in plants, depending on the organ and the time of emission.

    Experimental behavioural studies on pure β-ocimene conducted with pollinating insects will be necessary to prove the assumptions made here. “In view of the presented indirect evidences, we strongly encourage the inclusion of β-ocimene alone or in combination with other floral volatiles in coupled gas chromatography electroantennographic detection (GC-EAD) analyses and behavioural tests when conducting future studies in order to provide a solid experimental proof for the assumptions made in the study”, said Prof. Josep Peñuelas from CREAF-CSIC Barcelona.

    This study was funded by the European Research Council Synergy grant ERC-2013-SyG-610028, the Spanish Government project CGL2016-79835-P and the Catalan Government grant FI-2013

    Journal Reference: Farré-Armengol, G., Filella, I., Llusià, J., Peñuelas, J. 2017. β-Ocimene, a Key Floral and Foliar Volatile Involved in Multiple Interactions between Plants and Other Organisms. Molecules 2017, 22, 1148; doi: 10.3390/molecules22071148.

    Temperature increase reduces global yields of major crops in four independent estimates

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    Understanding climate change is critical to ensure global food security. In this study authors combine four analytical methods to assess the impact of increasing temperatures on yields of wheat, rice, maize and soybean. Photo by Pexels

     

    All agricultural production is vulnerable to climate change including wheat, rice, maize and soybean that provide two-thirds of human caloric intake. Assessing the impact of global temperature increase on production of these major crops is therefore critical to maintain global food supply.

    In a new study in the journal Proceedings of the National Academy of Sciences authors investigated the impacts of temperature on yields of the four crops by compiling extensive published results from four analytical methods: global grid-based and local point-based models, statistical regressions and field-warming experiments.

    “By combining four different methods, our comprehensive assessment of the impacts of increasing temperatures on major global crops shows substantial risks for agricultural production, already stagnating in some parts of the world”, said Prof. Josep Peñuelas from CREAF-CSIC Barcelona.

    The study shows that results from the different methods consistently indicate negative temperature impacts on crop yield at the global scale, generally underpinned by similar impacts at country and site scales. Without CO2 fertilization, effective adaptation and genetic improvement, each degree Celsius increase in global mean temperature would on average reduce global yields of wheat by 6.0%, rice by 3.2%, maize by 7.4% and soybean by 3.1%. In any case, researchers point out that results are highly heterogeneous across crops and geographical areas with some positive impact estimates.

    Multi-method analyses improved the confidence in assessments of future climate impacts on global major crops, and suggest crop- and region-specific adaptation strategies to ensure food security for an increasing world population.

    Journal Reference: Zhao, C., Liu, B., Piao, S., Wang, X., Lobell, D., Huang, Y., Huang, M., Yao, Y., Bassu, S., Ciais, P., Durand, J-L., Elliott, L., Ewert, F., Janssens, I., Li, T., Lin, E., Liu, Q., Martre, P., Müller, C., Peng, S., Peñuelas, J., Ruane, A., Wallach, D., Wang, T., Wu, D., Liu, Z., Zhu, Y., Zhu, Z., Asseng, S. 2017. Temperature increase reduces global yields of major crops in four independent estimates. Proceedings of the National Academy of Sciences.

    The secret plant communication – Las comunicaciones secretas de las plantas

    The websites of disseminating scientific knowledge SINC (La Ciencia es Notica) and NCYT (Notícias de la Ciencia y la Tecnología) have published an article on The secret plant communication, that includes declarations of Prof Josep Penuelas about Volatile organic compounds and plants communication.

    SINC read the full text in Spanish

    NCYT read the full text Spanish

     

    Weakening temperature control on the interannual variations of spring carbon uptake across northern lands

    Piao_et al_Nat Clim Change_2017
    For the past decade, boreal forests have been a net carbon sink; but a new study in the journal Nature Climate Change show that the relationship between spring temperature and carbon uptake has recently shifted. Photo by Pexels

     

    Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems; but the sink-or-source status of arctic tundra cannot be deduced from current observations.

    In a new study in the journal Nature Climate Change researchers use 34 years of atmospheric CO2 concentration measurements at Barrow, Alaska (BRW, 71 N) to show that the interannual relationship between spring temperature and carbon uptake has recently shifted. They use two indicators: the spring zero-crossing date of atmospheric CO2 (SZC) and the magnitude ofCO2 drawdown between May and June (SCC).

    The previously reported strong correlation between SZC, SCC and spring land temperature (ST) was found in the first 17 years of measurements, but disappeared in the last 17 years. As a result, the sensitivity of both SZC and SCC to warming decreased. Simulations done in the study with an atmospheric transport model coupled to a terrestrial ecosystem model suggest that the weakened interannual correlation of SZC and SCC with ST in the last 17 years is attributable to the declining temperature response of spring net primary productivity (NPP) rather than to changes in heterotrophic respiration or in atmospheric transport patterns.

    “Several mechanisms could explain the apparent weakening response of NPP in spring to interannual temperature variations.  A first possible mechanism is that winter warming comes with a loss of chilling, other possible mechanisms are the possible limitations of shorter day lengths when the growing season progressively advances earlier into the spring, and increasing occurrence of extreme events. Further studies are needed to verify these potential mechanisms”, said Prof. Josep Penuelas from CREAF-CSIC Barcelona.

    Prof Penuelas notes that their results show that the linkage between spring carbon uptake and temperature is not a stable property of northern ecosystems. However, because of the relatively short run of CO2 observations, it remains uncertain whether the observed decrease in interannual correlation of spring carbon uptake with temperature reflects decadal variability, or a long-term shift in the ecological response of boreal and arctic regions to warming.

    This study received support from the European Research Council Synergy grant ERC-2013-SyG-610028.

    Journal Reference: Piao, S., Liu, Z., Wang, T.,Peng, S., Ciais, P., Huang, M., Ahlstrom, A., Burkhart, J., Chevallier, F., Janssens, I., Jeong, S., Lin, X., Mao, J., Miller, J., Mohammat, A., Myneni, R., Penuelas, J., Shi, X., Stohl, A., Yao, Y., Zhu, Z., Tans, P. 2017. Weakening temperature control on the inter-annual variations of spring carbon uptake across northern lands. Nature Climate Change, doi: 10.1038/nclimate3277.

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    • For the time being, forests are helping to slow CO2 accumulation and climate change
      true
      A study led by CREAF shows that decreases in pollutant deposition and the increase in atmospheric CO2 have stimulated photosynthesis and carbon sequestration in forests. Therefore, it is crucial to understand how carbon circulates in the atmosphere, in living organisms, oceans, and soils in order to anticipate the effects of climate... Read more »
    • Rising temperatures threaten global agricultural production
      true
      The production of essential crops such as wheat, maize, rice, and soybean will be substantially reduced. Effective measures for climate change adaptation will be necessary, as well as  improvements in crop genetics in order to reduce the impacts of climate change.  Wheat crop. Source: Pixabay (CC0) Global temperature increase will cause production... Read more »
    • The greening of the earth is reaching its limit
      true
      A new study led by Josep Peñuelas and published in Nature Ecology and Evolution reveals that CO2 abundance in the atmosphere no longer has a powerful fertilizing effect on vegetation. The greening that has been observed in recent years is slowing and this will cause CO2 levels in the atmosphere... Read more »
    • Humans are causing mass movements of bacteria around the world
      true
      In an article in the journal Science, Josep Peñuelas warns that we must immediately begin studying the changes we are causing in the microbial world, improve water treatment systems, and change crop fertilization practices.  Pepole. Credit: Mike PD (CC-BY) Similar to rats, foxes, tigers and pandas, some microbes are gaining ground and... Read more »
    • Climate change is already threatening the Mediterranean ecosystems of Catalonia
      true
      An extensive review of studies and databases reveals that drought and an increase in temperature are already causing species substitutions, greater aridity, higher forest fire risk, lower soil fertility, and lower water availability, among other negative impacts. Scrublands of the Garraf Natural Park. Credit: Jorge Franganillo (CC BY 3.0) A large research... Read more »
    • Achieving the COP21 agreements is currently far-fetched
      true
      The COP21 set the maximum temperature increase for 2100 at 1.5° C. The only scenario which would allow achievement of this goal would require vastly reducing human CO2 emissions, significantly increasing the prominence of renewable energies, and the use of some type of artificial carbon sequestration technology. Carbon emissions from an... Read more »
    • Plants absorb pharmaceuticals and personal-care products carried by irrigation water
      true
      Pharmaceutical and personal-care products for human and animal use are increasingly released into the environment.  Water used in crop irrigation can carry chemicals that plants absorb. Source: Pixabay Plants act as excellent tracers of global pollution because they are present in almost all areas of the planet and accumulate chemical compounds present... Read more »
    • Plausible rice yield losses under future climate warming
      true
      Josep Peñuelas leads a study which suggests that rice yield will be more senstive to climate warming. Adaptatation polices to climate change are urgently needed to reduce its effect on rice yield. Rice field. Source: Pixabay Rice is the staple food for more than 50% of the world’s population. Reliable prediction of... Read more »
    • Phosphorus, once only a nutrient, has become a contaminant on a global scale
      true
      Freshwater ecosystems near densely populated areas have levels of phosphorus which are very high and out of balance with nitrogen levels. This has resulted in altered ecosystem functioning, lower water quality, and has made water conservation more difficult. The eutrophic lake Dianchi in China. The condition of the lake’s water makes... Read more »
    • Remote sensing of leaf pigments will improve climate change models
      true
      An international team of researchers co-led by Josep Peñuelas (CSIC and CREAF) has developed a new method for monitoring changes in the photosynthetic activity of perennial conifers throughout the year. This new technique, based on the analysis of remote sensing images captured by satellites, will improve global models of atmospheric... Read more »
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    • Los hombres de países ricos son cada vez más altos porque tienen una dieta más rica en nitrógeno y fosforo
      true
      Hay una diferencia de altura de 23 cm entre los países con un PIB más alto y los que lo tienen más bajo. Esta diferencia ha crecido 1,5 cm los últimos 30 años. La dieta rica en productos de origen animal y más variada asegura que los países ricos reciban... Read more »
    • Los bosques frenan, de momento, el aumento de CO2 y el cambio climático
      true
      Un estudio liderado por el CREAF constata que la disminución de las deposiciones de contaminantes, y sobre todo el incremento de CO2 atmosférico, han estimulado la fotosíntesis y el secuestro de carbono por parte de los bosques. Es clave entender cómo circula el carbono entre la atmósfera, los seres vivos,... Read more »
    • Josep Peñuelas aparece en la lista de científicos más influyentes del mundo
      true
      La lista 2017 Highly Cited Researchers recoge el 1% de científicos y científicas más citados en 21 campos de investigación. Es la tercera vez que Peñuelas recibe el reconocimiento. Josep Peñuelas El investigador del CSIC en el CREAF Josep Peñuelas es uno de los científicos más influyentes en el campo del Medio Ambiente y... Read more »
    • Josep Peñuelas explica el movimento en masa de las bacterias, en ‘La Contra’
      true
      El investigador del CSIC en el CREAF habla, en la página posterior de La Vanguardia, sobre el papel de los humanos en el movimiento y cambio en masa de las comunidades de bacterias en el mundo. La periodista Ima Sanchís entrevistaba ayer 30 de octubre al investigador del CSIC en el... Read more »
    • El aumento de temperatura amenaza la producción agrícola mundial
      true
      El trigo, el maíz, el arroz y la soja, cuatro cultivos esenciales para los humanos, verán reducida sustancialmente su producción. Serán necesarias medidas efectivas de adaptación al cambio climático y mejoras genéticas para reducir el impacto del cambio climático sobre los cultivos.  Camp de trigo. Funte: Pixabay (CC0) El aumento de temperatura... Read more »
    • El reverdecimiento de la tierra está llegando a su límite
      true
      Un nuevo estudio liderado por Josep Peñuelas y publicado en Nature Ecology and Evolution revela que la abundancia de CO2 en la atmósfera ya no tiene el potente efecto fertilizante que tenía hasta ahora sobre la vegetación. El reverdecimiento que se había observado en los últimos años se está frenando... Read more »
    • El cambio climático ya amenaza los ecosistemas mediterráneos de Cataluña
      true
      Una extensa revisión de estudios y registros de datos indica que la sequía y el aumento de temperatura ya provocan sustituciones de especies, mayor aridez y riesgo de incendio, y menor fertilidad del suelo y disponibilidad de agua, entre otros efectos negativos. Matorral del Parque Natural del Garraf. Autor: Jorge Franganillo... Read more »
    • La revista Nature busca los mejores mentores científicos de España
      true
      Un mentor tutela la trayectoria de diferentes investigadores y les sirve de guía en su carrera científica. Ahora, un jurado convocado por Nature, que preside este año Josep Peñuelas, quiere premiar a los y las mejores de España. La convocatoria para presentarse está abierta.  Un premio de 10.000 euros es lo que... Read more »
    • Llegar a los acuerdos de la COP21 es hoy por hoy una utopía
      true
      La COP21 fijaba un aumento máximo de la temperatura en 2100 de 1,5 ºC respecto la de los niveles preindustriales. Sólo un escenario donde se reduzcan mucho las emisiones humanas de CO2, haya un crecimiento importante de las renovables, y quizás con la aplicación de tecnología de secuestro artificial de... Read more »
    • Los cultivos absorben los productos farmacéuticos y cosméticos presentes en el agua de riego
      true
      Los productos farmacéuticos y de cuidado personal para uso humano y animal están incrementando su presencia en el medio ambiente. Hay que tener en cuenta además que su eliminación en las plantas de tratamiento para aguas residuales es incompleta. El agua que se emplea en el riego de cultivos puede llevar... Read more »
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    • Els homes de països rics són cada cop més alts perquè tenen una dieta més rica en nitrogen i fòsfor
      true
      Hi ha una diferència d’alçada de 23 cm de mitjana entre els països amb un PIB més alt i els que el tenen més baix. Aquesta diferència ha crescut 1,5 cm els darrers 30 anys. La dieta rica en productes d’origen animal i més variada assegura que els països rics... Read more »
    • Els boscos frenen, de moment, l’augment de CO2 i el canvi climàtic
      true
      Un estudi liderat pel CREAF constata que la disminució de les deposicions de contaminants, i sobretot l’increment de CO2 atmosfèric, han estimulat la fotosíntesi i el segrest de carboni per part dels boscos. És clau, doncs, entendre com circula el carboni entre l’atmosfera, els éssers vius, els oceans i els... Read more »
    • Josep Peñuelas apareix a la llista de científics més influents del món
      true
      La llista 2017 Highly Cited Researchers recull l’1% d’investigadors i investigadores més citats en 21 camps de recerca. És la tercera vegada que Peñuelas rep la distinció. Josep Peñuelas L’investigador del CSIC al CREAF Josep Peñuelas és un dels científics més influents en el camp del Medi Ambient i Ecologia, segons la llista 2017... Read more »
    • En Josep Peñuelas explica el moviment en massa dels bacteris, a ‘La Contra’
      true
      L’investigador del CSIC al CREAF parla, a la darrera pàgina de La Vanguardia, sobre el paper dels humans en el moviment i canvi en massa de les comunitats de bacteris al món. La periodista Ima Sanchís entrevistaba ahir 30 d’octubre l’investigador del CSIC al CREAF Josep Peñuelas. Arrel d’un article publicat recentment... Read more »
    • L’augment de temperatura amenaça la producció agrícola mundial
      true
      El blat, el blat de moro, l’arròs i la soja, quatre conreus essencials per als humans, veuran reduïda substancialment la seva producció. Seran necessàries mesures efectives d’adaptació al canvi climàtic i millores genètiques per reduir l’impacte del canvi climàtic sobre els cultius.  Camp de blat. Font: Pixabay (CC0) L’augment de temperatura global... Read more »
    • El reverdiment de la terra està arribant al seu límit
      true
      Un nou estudi publicat a Nature Ecology and Evolution revela que l’abundància de CO2 a l’atmosfera ja no té el potent efecte fertilitzant que tenia fins ara sobre la vegetació. El reverdiment que s’havia observat els darrers anys s’està frenant i això farà que els nivells de CO2 a l’atmosfera... Read more »
    • Els humans estem movent en massa els bacteris de tot el món
      true
      Josep Peñuelas alerta a Science que cal estudiar immediatament els canvis que estem provocant al món microbià, millorar els sistemes de tractament de les aigües i canviar les formes d’adobar els cultius.  Persones Autor: Mike PD (CC-BY) Igual que les rates, les guineus, els tigres i els pandes, alguns microbis estan guanyant... Read more »
    • El canvi climàtic ja amenaça els ecosistemes mediterranis de Catalunya
      true
      Una extensa revisió d’estudis i registres de dades indica que la sequera i l’augment de temperatura ja provoquen substitucions d’espècies, major aridesa i risc d’incendi, i menor fertilitat del sòl i disponibilitat d’aigua, entre d’altres efectes negatius. Matollar del Parc Natural del Garraf. Autor: Jorge Franganillo (CC BY 3.0) Un extens equip... Read more »
    • La revista Nature busca els millors mentors científics d’Espanya
      true
      Un mentor tutela la trajectòria de diferents investigadors i els serveix de guia en la seva carrera científica. Ara, un jurat convocat per Nature, que presideix enguany en Josep Peñuelas, vol premiar els i les millors d’Espanya. La convocatòria per presentar-s’hi està oberta. Un premi de 10.000 euros és el que... Read more »
    • Arribar als acords de la COP21 és ara per ara una utopia
      true
      La COP21 fixava un augment màxim de la temperatura el 2100 en 1,5 ºC respecte la dels nivells preindustrials. Només un escenari on es redueixin molt les emissions humanes de CO2, hi hagi un creixement important de les renovables, i potser amb una aplicació de tecnologies de segrest artificial de... Read more »