Climate Exchange

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ealth

Cross-cutting partnerships

Water management is a good example of the benefits of seasonal

forecasting in Africa, and no doubt similar applications can be

found elsewhere or in other domains such as crop yields or health

management. Interesting investigations are underway in that field,

which covers a large spectrum of potential application. Tackling

vector-borne diseases is one of the biggest challenges, but of

vital interest because of the high impact on human and animal

health, and the economy. Rift Valley Fever (RVF), chikungunya,

dengue and malaria, among other diseases, share a common factor:

mosquitoes. The lifecycle of mosquitoes is a subtle balance between

temperature and rainfall, and suitable sequences are necessary for

the development of the larvae. Being able to better characterize the

role and relationship between vector, virus and climate variability

could lead to better adaptation strategies across the tropical belt,

both for cattle management (in the case of RVF) and for humans.

This has been addressed in several projects tackling diseases and

species with input from Météo-France, in French overseas territo-

ries (for example, dengue in New-Caledonia) or Africa. The main

input to risk mapping is precipitation: a project carried out with the

Centre National d’Études Spatiales (CNES), the Pasteur Institute,

Météo-France and local sanitary agencies in Senegal, taking advan-

tage of satellite images to capture risk areas, has focused on the

contribution of seasonal forecasting for reducing the exposure to

RVF vector risk. One result was a proposition for adapted strategies

for cattle management, an area where many factors play a role. This

clearly implies that local actors take part in the adaptation process

and enrich the climate service with downstream real-life constraints

in order to create a valuable service. It was proven that seasonal fore-

casting can contribute to an early warning system, taking advantage

of various sources of information, and of a partnership between all

stakeholders and experts able to deliver that information.

Another project is dealing with malaria – different disease,

mosquito, and mechanisms to understand. It aims to use seasonal

forecasting for shaping a departmental early warning system. It also

follows the ‘tele-epidemiology’ conceptual framework built by CNES,

based on the use of satellite images. Burkina Faso is at the interface

between Northern Guinea and the Southern part of the Sahel. It has

a temporally limited rainfall season. The climatology shows high

seasonality (with important annual differences in terms of precipi-

tation and temperature), causing mosquito populations to fall each

year to levels that prevent transmission. For a malaria season to

occur, the mosquito population must grow rapidly after the onset of

the monsoon, with the right temperature, precipitation and relative

humidity in place for at least three months.

These factors are the

basis for a warning system taking advantage of climate information.

A field campaign has enabled the NMHS to deliver meteorologi-

cal parameters for 11 villages of the Nouna area. The observations

were employed to validate high-resolution meteorological prod-

ucts used with the remote sensing and entomological data in

order to calibrate a mosquito environment malaria risk model and

evaluate zones potentially occupied by mosquitoes. The second

contribution of climatologists qualitatively evaluated the poten-

tial of departmental seasonal forecasts. The focus was on the

meteorological parameters that are important for the mosquito

environmental malaria risk model: temperature, rainfall and

relative humidity. These are the same as the ones of the ‘fuzzy

logic’ model for the distribution of stable malaria in sub-Saharan

Africa.

This kind of approach is an extension of the Boolean

ones, enabling the evaluation of meteorological

conditions not only as fully suitable or not-suitable,

but also to obtain a gradient of suitability. Climate

information refines the assessment of the situation.

These types of model were first designed to esti-

mate transmission potential and extrapolations were

attempted to evaluate disease outcome. The results

showed that there is no real direct possible extrapo-

lation between transmission potential and disease

outcome. Moreover, there is often no direct link

between meteorological parameters and even trans-

mission potential. This explains the additional use of

remote sensing data in the mosquito environmental

risk model to convert the meteorological parameters,

not only as suitability gradients but also as produc-

tive suitability gradient information. Such studies

illustrate how complicated the application of related

climate information can be, and of course how critical

interaction between various scientific communities is

for solving such issues, as well as the implication of

all existing information resources – satellite, epide-

miological, climatological information etc.

Capacity building in Africa

One key issue when tackling societal application of

seasonal forecasting is the knowledge available in

both the climate and the user communities. From

this perspective, capacity building becomes crucial.

The Climate Outlook Forums (COFs) provide very

good example of capacity building to the benefit of

both communities, especially in West Africa with the

Presao, one of the first COFs. During the pre-forum

workshops, climate knowledge is built or improved

thanks to the presence of regional and international

climate experts. Such meetings can be tailored to the

user domain (like for the water resource domain in