Institute Catala Of Ciencies Del Clima Ic3

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Institute Catala Of Ciencies Del Clima Ic3

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Lowe R.,Abdus Salam International Center For Theoretical Physics | Lowe R.,Institute Catala Of Ciencies Del Clima Ic3 | Chirombo J.,Ministry of Health | Tompkins A.M.,Abdus Salam International Center For Theoretical Physics
Malaria Journal | Year: 2013

Background: Malaria transmission is influenced by variations in meteorological conditions, which impact the biology of the parasite and its vector, but also socio-economic conditions, such as levels of urbanization, poverty and education, which impact human vulnerability and vector habitat. The many potential drivers of malaria, both extrinsic, such as climate, and intrinsic, such as population immunity are often difficult to disentangle. This presents a challenge for the modelling of malaria risk in space and time. Methods. A statistical mixed model framework is proposed to model malaria risk at the district level in Malawi, using an age-stratified spatio-temporal dataset of malaria cases from July 2004 to June 2011. Several climatic, geographic and socio-economic factors thought to influence malaria incidence were tested in an exploratory model. In order to account for the unobserved confounding factors that influence malaria, which are not accounted for using measured covariates, a generalized linear mixed model was adopted, which included structured and unstructured spatial and temporal random effects. A hierarchical Bayesian framework using Markov chain Monte Carlo simulation was used for model fitting and prediction. Results: Using a stepwise model selection procedure, several explanatory variables were identified to have significant associations with malaria including climatic, cartographic and socio-economic data. Once intervention variations, unobserved confounding factors and spatial correlation were considered in a Bayesian framework, a final model emerged with statistically significant predictor variables limited to average precipitation (quadratic relation) and average temperature during the three months previous to the month of interest. Conclusions: When modelling malaria risk in Malawi it is important to account for spatial and temporal heterogeneity and correlation between districts. Once observed and unobserved confounding factors are allowed for, precipitation and temperature in the months prior to the malaria season of interest are found to significantly determine spatial and temporal variations of malaria incidence. Climate information was found to improve the estimation of malaria relative risk in 41% of the districts in Malawi, particularly at higher altitudes where transmission is irregular. This highlights the potential value of climate-driven seasonal malaria forecasts. © 2013 Lowe et al.; licensee BioMed Central Ltd.

Ballester J.,Institute Catala Of Ciencies Del Clima Ic3 | Rodo X.,Institute Catala Of Ciencies Del Clima Ic3 | Giorgi F.,Abdus Salam International Center For Theoretical Physics
Climate Dynamics | Year: 2010

Daily output from the PRUDENCE ensemble of regional climate simulations for the end of the twentieth and twenty-first centuries over Europe is used to show that the increasing intensity of the most damaging summer heat waves over Central Europe is mostly due to higher base summer temperatures. In this context, base temperature is defined as the mean of the seasonal cycle component for those calendar days when regional heat waves occur and is close, albeit not identical, to the mean temperature for July-August. Although 36-47% of future Central Europe July and August days at the end of the twenty-first century are projected to be extreme according to the present day climatology, specific changes in deseasonalized heat wave anomalies are projected to be relatively small. Instead, changes in summer base temperatures appear much larger, clearly identifiable and of the same order of magnitude as changes in the whole magnitude of heat waves. Our results bear important consequences for the predictability of central European heat wave intensity under global warming conditions. © 2009 Springer-Verlag.

Ballester J.,Institute Catala Of Ciencies Del Clima Ic3 | Robine J.-M.,French Institute of Health and Medical Research | Herrmann F.R.,University of Geneva | Rodo X.,Catalan Institution for Research and Advanced Studies
Nature Communications | Year: 2011

The steady increase in greenhouse gas concentrations is inducing a detectable rise in global temperatures. The sensitivity of human societies to warming temperatures is, however, a transcendental question not comprehensively addressed to date. Here we show the link between temperature, humidity and daily numbers of deaths in nearly 200 European regions, which are subsequently used to infer transient projections of mortality under state-of-the-art high-resolution greenhouse gas scenario simulations. Our analyses point to a change in the seasonality of mortality, with maximum monthly incidence progressively shifting from winter to summer. The results also show that the rise in heat-related mortality will start to completely compensate the reduction of deaths from cold during the second half of the century, amounting to an average drop in human lifespan of up 3-4 months in 2070-2100. Nevertheless, projections suggest that human lifespan might indeed increase if a substantial degree of adaptation to warm temperatures takes place. © 2011 Macmillan Publishers Limited. All rights reserved.

Guemas V.,Institute Catala Of Ciencies Del Clima Ic3 | Guemas V.,French National Center of Weather Research | Doblas-Reyes F.J.,Institute Catala Of Ciencies Del Clima Ic3 | Doblas-Reyes F.J.,Catalan Institution for Research and Advanced Studies | And 2 more authors.
Nature Climate Change | Year: 2013

Despite a sustained production of anthropogenic greenhouse gases, the Earth's mean near-surface temperature paused its rise during the 2000-2010 period. To explain such a pause, an increase in ocean heat uptake below the superficial ocean layer has been proposed to overcompensate for the Earth's heat storage. Contributions have also been suggested from the deep prolonged solar minimum, the stratospheric water vapour, the stratospheric and tropospheric aerosols. However, a robust attribution of this warming slowdown has not been achievable up to now. Here we show successful retrospective predictions of this warming slowdown up to 5 years ahead, the analysis of which allows us to attribute the onset of this slowdown to an increase in ocean heat uptake. Sensitivity experiments accounting only for the external radiative forcings do not reproduce the slowdown. The top-of-atmosphere net energy input remained in the [0.5-1] W m-2 interval during the past decade, which is successfully captured by our predictions. Most of this excess energy was absorbed in the top 700 m of the ocean at the onset of the warming pause, 65% of it in the tropical Pacific and Atlantic oceans. Our results hence point at the key role of the ocean heat uptake in the recent warming slowdown. The ability to predict retrospectively this slowdown not only strengthens our confidence in the robustness of our climate models, but also enhances the socio-economic relevance of operational decadal climate predictions. © 2013 Macmillan Publishers Limited. All rights reserved.

Pueyo S.,Institute Catala Of Ciencies Del Clima Ic3
Landscape Ecology | Year: 2011

There is an ongoing controversy on the use of the patch-size distribution as an early warning signal for abrupt shifts to a desertified state in Mediterranean arid landscapes. This controversy started with Kéfi et al.'s suggestion that, when approaching the transition point to widespread desertification, vegetation patches would switch from a power-law (PL) to a truncated power-law (TPL) distribution. Here I show that, for fundamental reasons, no untruncated power law can be found in this context, irrespective of the level of degradation. This result does not deny the importance of the findings by Kéfi et al., but means that these have to be reinterpreted by moving from the PL/TPL dichotomy to other categorizations of the patch-size distribution. Physical constraints on patch-size distributions have general interest for landscape ecology. © 2011 Springer Science+Business Media B.V.

Pueyo S.,Institute Catala Of Ciencies Del Clima Ic3
Sustainability (Switzerland) | Year: 2014

This paper outlines a synthesis of ecological economics with econophysics and other complexity approaches to economics. Arguably, the resulting "ecological econophysics" will be scientifically sounder than mainstream economics and much better suited to addressing a major challenge of our times: the development of democratically-based policies to reduce economic throughput to an environmentally sustainable level without triggering economic crises and without excluding part of the world's population, i.e., to implement degrowth. Degrowth will need major structural changes, which leads us to question whether there are limits to the malleability of the economic system's architecture. A fundamental limit will be encountered if, as suggested by the physics of complexity, long-lasting complex systems always occur midway between an ordered and a disordered state. There is much evidence that this hypothesis holds and that the current economic system satisfies this condition. However, this does not mean that the problems posed by this system should be unavoidable. Ecological econophysics gives clues to identifying alternative economic systems that would also function between order and chaos, but which would have radically different implications for environmental sustainability and social justice. © 2014 by the author.

Doblas-Reyes F.J.,Catalan Institution for Research and Advanced Studies | Doblas-Reyes F.J.,Institute Catala Of Ciencies Del Clima Ic3 | Garcia-Serrano J.,Institute Catala Of Ciencies Del Clima Ic3 | Lienert F.,Institute Catala Of Ciencies Del Clima Ic3 | And 2 more authors.
Wiley Interdisciplinary Reviews: Climate Change | Year: 2013

Seasonal climate forecasts occupy an intermediate zone between weather forecasting and climate projections. They share with the numerical weather prediction the difficulty of initializing the simulations with a realistic state of the atmosphere and the need to periodically verify different aspects of their quality, while additionally are burdened by uncertainties in feedback processes that also play a central role in constraining climate projections. Seasonal predictions have to deal also with the challenge of initializing all the components of the climate system (ocean, sea ice, and land surface). The value of skilful seasonal forecasts is obvious for many societal sectors and is currently being included in the framework of developing climate services. Seasonal forecasts will in addition be valuable by increasing the acceptance of climate projections among the general public. This advanced-review article presents an overview of the state-of-the-art in global seasonal predictability and forecasting for climate researchers and discusses fundamental advances to increase forecast quality in the near future. The article concludes with a list of challenges where seasonal forecasting is expected to focus on in the near future. WIREs Clim Change 2013, 4:245-268. doi: 10.1002/wcc.217 Conflict of interest: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website. © 2013 John Wiley & Sons, Ltd.

Lowe R.,Institute Catala Of Ciencies Del Clima Ic3
Transactions of the Royal Society of Tropical Medicine and Hygiene | Year: 2015

Dengue is a mosquito-transmitted viral infection of major international public health concern. Global environmental and socio-economic change has created ideal conditions for the global expansion of dengue transmission. Innovative modelling tools help in understanding the global determinants of dengue risk and the relative impact of environmental and socio-economic factors on dengue transmission and spread. While climatic factors may act as a limiting factor on the global scale, other processes may play a dominant role at the local level. Understanding the spatial scales at which environmental and socio-economic factors dominate can help to target appropriate dengue control and prevention strategies. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved.

Garcia-Serrano J.,Institute Catala Of Ciencies Del Clima Ic3 | Doblas-Reyes F.J.,Institute Catala Of Ciencies Del Clima Ic3 | Doblas-Reyes F.J.,Catalan Institution for Research and Advanced Studies
Climate Dynamics | Year: 2012

The ENSEMBLES multi-model and perturbed-parameter decadal re-forecasts are used to assess multi-year forecast quality for global-mean surface air temperature (SAT) and North Atlantic multi-decadal sea surface temperature variability (AMV). Two issues for near-term climate prediction, not discussed so far, are addressed with these two examples: the impact of the choice of the observational reference period, and of the number of years included in the forecast average. Taking into account only years when both observational and model data are available, instead of using the full record, to estimate observed climatologies produces systematically (although not statistically significantly different) higher ensemble-mean correlations and lower root mean square errors in all forecast systems. These differences are more apparent in the second half of the decadal prediction, which suggests an influence of non-stationary long-term trends. Also, as the forecast period averaged increases, the correlation for both global-mean SAT and AMV is generally higher. This also suggests an increasing role for the variable external forcing as when forecast period averaged increases, unpredictable internal variability is smoothed out. The results show that predicting El Niño-Southern Oscillation beyond one year is a hurdle for current global forecast systems, which explains the positive impact of the forecast period averaging. By comparing initialized and uninitialized re-forecasts, the skill assessment confirms that variations of the global-mean SAT are largely controlled by the prescribed variable external forcing. By contrast, the initialization improves the skill of the AMV during the first half of the forecast period. In an operational context, this would lead to improved predictions of the AMV from initializing internal climate fluctuations. The coherence between the multi-model and perturbed-parameter ensemble supports that conclusion for boreal summer and annual means, while the results show less consistency for boreal winter. © 2012 Springer-Verlag.

Pueyo S.,Institute Catala Of Ciencies Del Clima Ic3
Climatic Change | Year: 2012

Most countries endorse a limit of either 2°C or 1. 5°C global warming above pre-industrial levels. However, for several reasons, there is still a significant uncertainty in the climate sensitivity parameter, which relates greenhouse gas concentration (or other forcings) to steady-state temperature. One key source of uncertainty is the disagreement about the appropriate prior for Bayesian estimation. A common choice is the uniform distribution, often thought to contain no information. However, when used to estimate sensitivity it leads to paradoxical results, which have been interpreted as revealing an inherent indeterminacy in the prior of choice. If this were the case, part of the uncertainty would be irreducible. Here I develop an objective Bayesian approach to this problem. I show that both Jaynes' invariant groups criterion and a new criterion based on information theory lead to the conclusion that there is a uniquely defined non-informative prior of climate sensitivity, which is distinct from the uniform and solves the paradox. This prior distribution is the log-uniform. Furthermore, this result is supported empirically by the observation that other comparable non-equilibrium parameters display a scale-invariant, log-uniform-like frequency distribution. Rather than advocating a direct use of this prior, I recommend to refine it with a limited use of expert elicitation or other methods. A sound prior is a key ingredient in the process to reach a consensus low-uncertainty estimate of climate sensitivity to inform climate policy. © 2011 Springer Science+Business Media B.V.

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