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The joint WWRP–WCRP Subseasonal to Seasonal Prediction Project (e.g., Robertson et al. 2014) created a global repository of experimental or operational near-real-time S2S forecasts and reforecasts (hindcasts) from 11 international meteorological institutions, cohosted by ECMWF and CMA (Vitart et al. 2017). These data are publicly accessible by researchers and users (https://apps.ecmwf.int/datasets/data/s2s and http://s2s.cma.cn/index). With the exception of the fourth case study, which uses GloSea5 forecasts (MacLachlan et al. 2015), all case studies use selected S2S forecasts and reforecasts that are available from this repository, providing a consistent basis for S2S forecast skill assessment and evaluation of their utility. The subseasonal-to-seasonal (S2S) predictive time scale, encompassing lead times ranging from 2 weeks to a season, is at the frontier of forecasting science. Forecasts on this time scale provide opportunities for enhanced application-focused capabilities to complement existing weather and climate services and products. There is, however, a “knowledge–value” gap, where a lack of evidence and awareness of the potential socioeconomic benefits of S2S forecasts limits their wider uptake. To address this gap, here we present the first global community effort at summarizing relevant applications of S2S forecasts to guide further decision-making and support the continued development of S2S forecasts and related services. Focusing on 12 sectoral case studies spanning public health, agriculture, water resource management, renewable energy and utilities, and emergency management and response, we draw on recent advancements to explore their application and utility. These case studies mark a significant step forward in moving from potential to actual S2S forecasting applications. We show that by placing user needs at the forefront of S2S forecast development—demonstrating both skill and utility across sectors—this dialogue can be used to help promote and accelerate the awareness, value, and cogeneration of S2S forecasts. We also highlight that while S2S forecasts are increasingly gaining interest among users, incorporating probabilistic S2S forecasts into existing decision-making operations is not trivial. Nevertheless, S2S forecasting represents a significant opportunity to generate useful, usable, and actionable forecast applications for and with users that will increasingly unlock the potential of this forecasting time scale. DD gratefully acknowledges support from the Swiss National Science Foundation through project PP00P2_170523. For case study 1, ACP and WTKH were funded by the U.K. Climate Resilience Programme, supported by the UKRI Strategic Priorities Fund. RWL was funded by NERC Grant NE/P00678/1 and by the BER DOE Office of Science Federal Award DE-SC0020324. TS was funded by NERC Independent Research Fellowship (NE/P018637/1). CMG and DB were funded by the Helmholtz Young Investigator Group “SPREADOUT” Grant VH-NG-1243. Case study 2 was supported by the U.K. Global Challenges Research Fund NE/P021077/1 (GCRF African SWIFT) and the Tertiary Education Trust Fund (TETFUND) of Nigeria TETFund/DR&D/CE/NRF/STI/73/VOL.1. EO thanks Adrian Tomkins of ICTP, Italy, for his contribution. Case study 3 was undertaken as part of the Columbia World Project, ACToday, Columbia University (https://iri.columbia.edu/actoday/). Case study 4 was supported by the ForPAc (Towards Forecast-based Preparedness Action) project within the NERC/FCDO SHEAR Programme NE/P000428/1, NE/P000673/1, and NE/P000568/1. Case study 5 was undertaken as part of the International Research Applications Project, funded by the U.S. National Oceanic and Atmospheric Administration. EO thanks IRAP project colleagues at The University of Arizona, Indian Meteorological Department, Regional Integrated Multi-Hazard Early Warning System for Africa and Asia, and two of Bihar’s State Agricultural Universities for their contributions. For case study 6, CASC thanks Conselho Nacional de Desenvolvimento Científico e Tecnológico Process 305206/2019-2 and Fundação de Amparo à Pesquisa do Estado de São Paulo Process 2015/50687-8 (CLIMAX Project) for their support. For case study 7, DW’s contributions were carried out under contract with the National Aeronautics and Space Administration. Case study 8 was funded by the EU Horizon 2020 Research and Innovation Programme Grant 7767874 (S2S4E). We also acknowledge the Subseasonal-to-Seasonal Project’s Real-Time Pilot Initiative for providing access to real-time forecasts. For case study 9, TIC-LCPE Hydro-04 was funded by the University of Strathclyde’s Low Carbon Power and Energy program. JB was supported by EPSRC Innovation Fellowship EP/R023484/1. We thank Andrew Low and Richard Hearnden from SSE Renewables for their input. Case study 10 was supported by the Earth Systems and Climate Change Hub under the Australian Government’s National Environmental Science Program, and the Decadal Climate Forecasting Project (CSIRO). Case study 11 was funded by the Technologies for Sustainable Built Environments Centre, Reading University, in conjunction with the EPSRC Grant EP/G037787/1 and BT PLC. Case study 12 was funded through the framework service contract for operating the EFAS Computational Center Contract 198702 and the Copernicus Fire Danger Computations Contract 389730 295 in support of the Copernicus Emergency Management Service and Early Warning Systems between the Joint Research Centre and ECMWF. Peer Reviewed "Article signat per 60 autors/es: Christopher J. White, Daniela I. V. Domeisen, Nachiketa Acharya, Elijah A. Adefisan, Michael L. Anderson, Stella Aura, Ahmed A. Balogun, Douglas Bertram, Sonia Bluhm, David J. Brayshaw, Jethro Browell, Dominik Büeler, Andrew Charlton-Perez, Xandre Chourio, Isadora Christel, Caio A. S. Coelho, Michael J. DeFlorio, Luca Delle Monache, Francesca Di Giuseppe, Ana María García-Solórzano, Peter B. Gibson, Lisa Goddard, Carmen González Romero, Richard J. Graham, Robert M. Graham, Christian M. Grams, Alan Halford, W. T. Katty Huang, Kjeld Jensen, Mary Kilavi, Kamoru A. Lawal, Robert W. Lee, David MacLeod, Andrea Manrique-Suñén, Eduardo S. P. R. Martins, Carolyn J. Maxwell, William J. Merryfield, Ángel G. Muñoz, Eniola Olaniyan, George Otieno, John A. Oyedepo, Lluís Palma, Ilias G. Pechlivanidis, Diego Pons, F. Martin Ralph, Dirceu S. Reis Jr., Tomas A. Remenyi, James S. Risbey, Donald J. C. Robertson, Andrew W. Robertson, Stefan Smith, Albert Soret, Ting Sun, Martin C. Todd, Carly R. Tozer, Francisco C. Vasconcelos Jr., Ilaria Vigo, Duane E. Waliser, Fredrik Wetterhall, and Robert G. Wilson"

The provision of climate services has the potential to generate adaptive capacity and help coffee farmers become or remain profitable by integrating climate information in a risk-management framework. Yet, in order to achieve this goal, it is necessary to identify the local demand for climate information, the relationships between coffee yield and climate variables, farmers’ perceptions, and to examine the potential actions that can be realistically put in place by farmers at the local level. In this study, we assessed the climate information demands from coffee farmers and their perception on the climate impacts to coffee yield in the Samalá watershed in Guatemala. After co-identifying the related candidate climate predictors, we propose an objective, flexible forecast system for coffee yield based on precipitation. The system, known as NextGen, analyzes multiple historical climate drivers to identify candidate predictors, and provides both deterministic and probabilistic forecasts for the target season. To illustrate the approach, a NextGen implementation is conducted in the Samalá watershed in southwestern Guatemala. The results suggest that accumulated June-July-August precipitation provides the highest predictive skill associated with coffee yield for this region. In addition to a formal cross-validated skill assessment, retrospective forecasts for the period 1989-2009 were compared to agriculturalists’ perception on the climate impacts to coffee yield at the farm level. We conclude with examples of how demand-based climate service provision in this location can inform adaptation strategies like optimum shade, pest control, and fertilization schemes months in advance. These potential adaptation strategies were validated by local agricultural technicians at the study site.

The aim of this work is to assess the horizontal distribution of aerosols during winter and spring 2017, in San Juan city, Argentina, and its relationship with the land use. The concentration of PM2.5 at ground level in 54 points of the city and the aerosol optical deep were measured. A supervised classification to obtain a land use map was performed. Statistical analysis was carried out considering 5 variables values in the 54 points, related to the particulate material (PM) emission: AOD, LST, NDVI, NDWI from satellite products and PM2.5 from field measurements. The data were analyzed considering the spatial, seasonal and meteorological variation, and the land use classes.The results indicate that 3 concentric rings can be considered in the studied area and 4 zones are distinguished: urban, peri-urban, periphery and industrial. The average PM2.5 concentrations was 18.7 μg/m3, and the season of maximum concentration was in winter. For AOD the average was 0.83, and the maximum registered during spring. PM2.5 concentrations presented a Pearson’s correlation coefficient with AOD higher than 0.65 in areas classified as peri-urban and industrial periphery. Regarding the meteorological variables, LST and wind showed the highest correlation with AOD and PM2.5. NDVI and NDWI present negative correlation with aerosol concentrations, so in areas with more vegetation and higher soil moisture which indicates that aeolian soil erosion is an important PM emission.

Despite continued forest loss and extensive demand for wood products throughout Guatemala, the locally managed and protected forests of Totonicapan remain some of the most intact within the country. Here, we study the growth rings of Guatemalan fir (Pinaceae, Abies guatemalensis Rehder, pinabete) at Totonicapan to assess environmental influences on tree growth and the potential vulnerability of these forests to climate change in the western highlands. We find that late summer and dry season precipitation are critical drivers in annual ring-width variability and that tree growth responds negatively to warm sea surface temperature anomalies in the eastern tropical Pacific. Considering our results in light of future climate model projections for Central America, we suggest that these forests will become increasingly susceptible to widespread drying and higher temperatures. Such shifts could fundamentally jeopardize an endemic and endangered tree species that has traditionally been preserved by K’iche’ communal governance and that is highly regarded for its ecosystem services and role in the Guatemalan economy. resumen: A pesar de la perdida continua de bosques y la amplia demanda de productos maderables en toda Guatemala, los bosques protegidos y manejados por las comunidades locales de Totonicapan forman parte de algunos de los mas intactos del pais. En este estudio analizamos los anillos del tronco arboreo de pinabete (Pinaceae, Abies guatemalensis Rehder) de Totonicapan para evaluar las influencias ambientales sobre el crecimiento arboreo y la vulnerabilidad de los bosques ante potenciales cambios en el ambiente en el altiplano del pais. Encontramos que la precipitacion al final del verano y la de la estacion seca son claves para la variabilidad anual del crecimiento arboreo y que los arboles responden negativamente a las anomalias calidas de las temperaturas de la superficie del mar en el Pacifico tropical oriental. Considerando nuestros resultados ante las proyecciones de modelos climaticos para Centroamerica, sugerimos que estos bosques van a ser cada vez mas susceptibles a sequias generalizadas y aumentos en la temperatura. Estos cambios pueden poner en peligro una especie ende-mica y amenazada que tradicionalmente ha sido conservada por la gobernanza comunal de los K’iche’ y que es altamente valorada por sus servicios ecosistemicos y su rol en la economia guatemalteca.

Guatemala's population is dependent on cash crops and subsistence agriculture, the yield of which depends on both the timing and quantity of rainfall. Detailed knowledge about Guatemala's past, cur...

This paper scrutinizes the assertion that knowledge gaps concerning health risks from climate change are unjust, and must be addressed, because they hinder evidence-led interventions to protect vulnerable populations. First, we construct a taxonomy of six inter-related forms of invisibility (social marginalization, forced invisibility by migrants, spatial marginalization, neglected diseases, mental health, uneven climatic monitoring and forecasting) which underlie systematic biases in current understanding of these risks in Latin America, and advocate an approach to climate-health research that draws on intersectionality theory to address these inter-relations. We propose that these invisibilities should be understood as outcomes of structural imbalances in power and resources rather than as haphazard blindspots in scientific and state knowledge. Our thesis, drawing on theories of governmentality, is that context-dependent tensions condition whether or not benefits of making vulnerable populations legible to the state outweigh costs. To be seen is to be politically counted and eligible for rights, yet evidence demonstrates the perils of visibility to disempowered people. For example, flood-relief efforts in remote Amazonia expose marginalized urban river-dwellers to the traumatic prospect of forced relocation and social and economic upheaval. Finally, drawing on research on citizenship in post-colonial settings, we conceptualize climate change as an ‘open moment’ of political rupture, and propose strategies of social accountability, empowerment and trans-disciplinary research which encourage the marginalized to reach out for greater power. These achievements could reduce drawbacks of state legibility and facilitate socially-just governmental action on climate change adaptation that promotes health for all.

Anecdotal evidence suggests that the timing and intensity of the Central American Midsummer Drought (MSD) may be changing, while observations from limited meteorological station data and paleoclimate reconstructions show neither significant nor consistent trends in seasonal rainfall. Climate model simulations project robust future drying across the region, but internal variability is expected to dominate until the end of the century. Here we use a high-resolution gridded precipitation dataset to investigate these apparent discrepancies and to quantify the spatiotemporal complexities of the MSD. We detect spatially variable trends in MSD timing, the amount of rainy season precipitation, the number of consecutive and total dry days, and extreme wet events at the local scale. At the regional scale, we find a positive trend in the duration, but not the magnitude of the MSD, which is dominated by spatially heterogeneous trends and interannual variability linked to large-scale modes of ocean-atmosphere circulation. Although the current climate still reflects predominantly internal variability, some Central American communities are already experiencing significant changes in local characteristics of the MSD. A detailed spatiotemporal understanding of MSD trends and variability can contribute to evidence-based adaptation planning and help reduce the vulnerability of Central American communities to both natural rainfall variability and anthropogenic change.

Agroforestry systems maintain intermediate levels of biodiversity between natural forests and purely agricultural land-uses and may therefore increase connectivity or sustain biodiversity in fragmented forest landscapes. This hypothesis is tested by comparing the species richness and similarity in species composition between forest fragments and agroforestry systems in two landscapes in Guatemala. Connectivity indices were calculated based on the similarity of biodiversity held between forest and agroforestry. Tree and ant species richness was significantly higher for forest than agroforestry land-uses. Conversely, species richness of leaf hoppers (Cicadellidae) was lower in forests compared to agroforests. Chao-Sorensen estimates indicated a high proportion of ant species were shared (0.78–0.99) between different agroforestry land-uses and forest fragments, but lower proportions of tree (0.39–0.55) and leaf hopper species (0.42–0.65). Including the contribution of agroforestry systems in estimates of forest connectivity, based on their biodiversity relative to forest, substantially increased the land area rated with high connectivity (by 100–300%) and forest edge connectivity (by 70–170%), but had negligible impact on land area rated as dense forest. The major forest fragments in the two landscapes were linked by land rated as medium connectivity for forest biodiversity. Thus, agroforestry contributes to the capacity of the landscape to support biodiversity, but only partially increases connectivity between forest fragments in the two landscapes studied. If these benefits are to be sustained, consideration needs to be given to the incentives for land-owners to maintain agroforestry systems.

Drought in Guatemala has negative consequences for agriculture and potable water supplies, particularly in regions of the country with highly seasonal rainfall. General circulation models suggest that a decrease in both winter and summer rainfall over Central America is likely and imminent as a consequence of anthropogenic influences on the climate system. However, precipitation observations over the last several decades are equivocal. Here, we use an Abies guatemalensis tree-ring chronology from the Sierra de los Cuchumatanes to estimate January through March rainfall since the late seventeenth century. Our reconstruction shows that recent winter–spring rainfall from the region is not yet exceptional in the context of the last several centuries, has a significant yet variable decadal component, is associated with large-scale modes of ocean–atmosphere variability, and reveals evidence of past multiyear droughts.

The continued expansion of dendroclimatology into Mesoamerica requires the identification and evaluation of species whose rings can be precisely dated and then statistically compared with precipitation and temperature variability in order to make inferences about past climate. Here, we establish the basis for using Abies guatemalensis Rehder (Pinaceae) for climate reconstruction in Central America. Annual crossdating in this montane species is demonstrated at high-elevation sites in the Sierra de los Cuchumatanes in western Guatemala. We find that ring width is most strongly influenced by early growing season moisture conditions, controlled by late dry season rainfall, and negatively correlated with growing season temperature. Our chronology is also significantly negatively correlated with eastern tropical Pacific sea surface temperature anomalies. Our confirmation of annual chronology and the identification of a climatic signal in this species now allow its use in local and regional paleoclimate reconstructions, as well as ecological studies.

Non-point source water pollution is a key question in rural watersheds and it needs to be studied in order to prevent damages to ground and surface water quality. The main goal of this study is to analyze nutrient and chemical loads in groundwater and streams in Pampa region, Argentina. For studying groundwater loads, a set of 19 observation wells were installed in 2011, in western Buenos Aires. The wells were located at three landscape positions (upper, middle and lower hill) in seven agricultural fields and groundwater samples were monthly collected. As for surface water, two watersheds located in southeastern Buenos Aires, were chosen: Napaleofu creek Watershed (34.000 hectares) and Quequen Grande River watershed (938.000 hectares). Daily water samples were taken from the main stream from October 2011 to May 2013, at both watersheds. Water Samples collected from wells and streams, were analyzed to determine N, and chemical loads. A group of 11 herbicides and one insecticide frequently used by farmers in the watershed were chosen for the study. Nitrogen and chemical concentrations were analyzed considering rainfall events and also compared to critical limits. Preliminary results are presented from a subset of samples since remaining samples are currently being processed in laboratory. As for NO 3 -N concentration, most of wells presented variable concentration depending on monthly precipitation and landscape position. Considering 10 mg/L NO 3 -N as a standard limit, 52% of the observations exceed this value mostly related to unusual precipitations events at winter 2012. Nitrate-N concentration in streamflow at Quequen Grande River and Napaleofu creek were on average 5 ppm. NPS Pollution modeling is a second goal of this on-going research. SWAT validation results are also presented for one of the watersheds under study.