Mapping the effects of climate change on bluetongue transmission in Europe

Conference in Bangkok (Thailand) and Paris

Helene Guis123, Cyril Caminade4, Andy Morse4, François Roger2, Matthew Baylis1

1 Lucinda (Liverpool University Climate and Infectious Diseases of Animals Group), Liverpool University, UK
2 AGIRs (Animal and Integrated Risk Management Unit), Cirad, France
3 TETIS (Territories, Environment, Remote Sensing and Spatial Information Unit), Cirad, Cemagref, Engref, France
4 Department of Geography, Liverpool University, UK

Bluetongue (BT) is an arboviral disease of ruminants which emerged in Europe in 1998 and has, since then, caused an unprecedented series of epizootics of major economic consequence. Two distinct epidemiological events underlie this emergence: the northward expansion of the Afro-asian midge Culicoides imicola, probably under the influence of climate change; and the involvement of indigenous European Culicoides of the Obsoletus and Pulicaris groups.
In order to assess the effects of climate change in the distribution of BT in Europe, the basic reproduction number R0 of BT was modelled by a unique integration of epidemiological models with state-of-the-art climate models. This approach allows us to map R0 throughout Europe on an annual basis under past, present and future conditions simulated using several different climate models, with outputs in terms of model means and uncertainties
R0 was computed for a population of two hosts as sheep and cattle have different epidemiological roles in the transmission of BT (the latter being less affected by the disease but presenting a long viraemia) and for both the exotic (C. imicola) and indigenous vectors.
Climatic data for recent past (1961-2000) and future (1950-2050) periods was provided by the ENSEMBLES European project at a spatial scale of 25*25 km. For the recent past, improved regional climate simulations were produced by running a subset of four regional climatic models with the most realistic boundary conditions (ERA40 reanalysis) and external forcing. For the future conditions, simulations were carried out by running three regional climate models forced at their boundaries by a general circulation models forced by the IPCC’s (Intergovernmental Panel on Climate Change) Special Report on Emissions Scenario (SRES) A1B (integrated world with a balanced emphasis on all energy sources).
This modelling approach was carried out in three steps to assess the effects of climate change on each of the components of the BT epidemiological cycle: i) viral replication only, ii) viral transmission taking into account host distribution and iii) the combination of the viral, host and vector components. Results show the coherence between past anomalies in R0 and past incursions of Culicoides-borne diseases in Europe and highlight the fact that the vector component is both the most critical and yet the least well-defined one.

Here is the associated presentation:
HG_ClimateBT_BangkokSept2008v3.pdf

20th century Sahel rainfall variability as simulated by the ARPEGE AGCM and future changes (2)

Here is the submitted draft version to climate dynamics concerning the links between SST/Tropospheric temperatures and the Sahelian drought for the ARPEGE model, and an highlight concerning the IPCC simulations

update (09/07/08)

clim_dyn_paper_caminade_terray_2008.pdf

Blue tongue disease and climate change over Europe

The blue tongue disease (catarrhal fever) is a non contagious, insect-borne viral disease of ruminants, affecting mainly sheep and less frequently the cattle. It is caused by the the bluetongue virus, transmitted by different culicoides (fly). A significant increase of the disease has been seen since the last decade over Northern Europe. This work is a first attempt to relate climate change (as the virus is temperature driven) and the possible change in the affected areas over Europe for the next upcoming decades, based on the ENSEMBLES RCM simulations.
Here is a short report concerning preliminary results:
Blue_tongue_results.pdf

Validation Atlas for ENSEMBLES RCMs runs over Europe

This is a link to a short document including few validation maps (climatology, variance) for 4 models of the ENSEMBLES RCM database. The recent climate linear trends are also highlighted, and few climate projections are shown (2030-2050 minus 1961-2000).
This is done for the summer (JJA) and winter (DJF) seasons and for 4 impact variables:

Rainfall
2meter temperature
Minimum and maximum temperatures.

Other analyses would be updated later (time series....)

The link: Valid_RCM.doc

Presentation Niamey, AMMA-ENSEMBLES meeting

Submitted Abstract:

As a consequence of the severe drought that occurs from 1970 to 2000, forecasting rainfall over the Sahel at seasonal time scales became a priority regarding to impacts in terms of food, health and security managements since the 1970’s. Improving the prediction of the West African Monsoon (WAM) system and its impacts on health, water resources and food security is one of the main aims of the AMMA (African Monsoon Multidisciplinary Analysis) project. In parallel, within the European DEMETER and ENSEMBLES projects framework, a well-validated European coupled multi-model ensemble forecast system for reliable seasonal to interannual prediction has been developed, and maintained at ECMWF. Using the model forecasts performed in ENSEMBLES and DEMETER projects in order to highlight their performance and their reliability over West Africa appeared to be essential, from the first cross AMMA/ENSEMBLES meeting that took place in Bamako, Mali.

Within this framework, we propose to highlight the performance of the different models participating in the ENSEMBLES and DEMETER projects in capturing the mean features of the WAM, as well as of the multi-model hindcasts, during the rainy season (from July to September) over the [1991-2001] common period. Different reference observation data sets are used (CRU, GPCP, NCEP....) to validate the model forecasts. This task is achieved using common validation tools, namely typical indices and maps to determine the model biases (mean/variability) and determinist/probabilistic scores (Correlation/Brier/ROC) to highlight the forecasts performance. A perfect model approach is also used to determine the potential predictability (PP) of the main impact variables (this analysis provides an idea about the upper limit of forecasting probabilities).

Preliminary results highlight common precipitation biases as simulated by coarse resolution GCM used in climate studies, namely overestimation of rainfall over the high mountains (Ethiopia plateau) and underestimation over the low ones (Cameroon mounts, Senegal coast). These biases are relatively similar for both the mean and the variance. Other common (well-known) biases are depicted for relevant SST areas, namely a warm bias over the Gulf of Guinea and the Eastern Pacific region (ENSO). The rainfall potential predictability is relatively high over the Guinea Coast whereas it is relatively weak over the Sahel. Moreover, the model rainfall forecasts seem to be more skilful over the Guinea Coast and the tropical Atlantic Ocean than the Sahel.

Similarities and differences between DEMETER and ENSEMBLES hindcasts systems over sub-Saharan Africa will then be given in the conclusion. A discussion will also be done about the limiting selected common period (1991-2001). Namely, is 10 year model climate enough to have significant statistical results (mean, variance, etc) over the Sahel? Strategies and methods to improve the model forecast performance will then be highlighted as perspectives.

Presentation link:
caminade_morse_Niamey.ppt

Guideline (few comments slide by slide):
guideline_Niamey.ppt

Validation ENSEMBLES/DEMETER v1.2

An updated version of the validation Atlas of DEMETER/ENSEMBLES seasonal forecast over Africa. ROCSS and Brier Scores have been added for rainfall and 2m temperature.
Few results are discussed:

Atlas_ENSEMBLES_DEMETER_Africa.v1.2.pdf

The figures have also been updated on the flickr site:
http://flickr.com/photos/25358757@N06/sets/72157605087475214/

20th century Sahel rainfall variability as simulated by the ARPEGE AGCM and future changes

Here is a first paper draft concerning the links between SST/Tropospheric temperatures and the Sahelian drought for the ARPEGE-climat model, and an highlight concerning the IPCC simulations:

clim_dyn_paper_caminade_terray_2008.pdf