A scientific program to anticipate the future climate
Guyaclimat is a benchmark study that analyzes the climatic transformations expected in French Guiana up to 2100. Carried out by Météo-France and the Bureau de recherches géologiques et minières (BRGM), this program is based on detailed regional projections to be released in 2022. The results provide a basis for action by local authorities, developers and economic players.
A response to targeted local demand
Specific needs in the face of the limitations of global models
For a number of years, Guyanese decision-makers have been calling for projections tailored to the realities of the territory. Although the IPCC’s global climate models are accurate on a planetary scale, they are not sufficient for effective planning on a local scale. Guyaclimat meets this need by providing analyses of five parameters: temperature, precipitation, wind, waves and sea level.
Multi-stakeholder financing
This project is supported by the Direction Générale des Territoires et de la Mer (DGTM), the Agence Française de Développement (AFD), the Agence de la Transition Ecologique (ADEME), the Office de l’Eau de Guyane, Météo-France and BRGM.
An adapted scientific methodology
Local data and advanced modeling
Guyaclimat teams combined field surveys, local observation data and global climate simulations from the sixth CMIP6 exercise. Downscaling of the global models was carried out with quantile-quantile bias correction, using the long series of observations from Guyana’s weather stations.
Climate scenarios
For atmospheric variables, two socio-economic scenarios were used: SSP2-4.5 (moderate emissions) and SSP5-8.5 (high emissions). For sea-level rise, the study uses the RCP2.6, RCP4.5 and RCP8.5 scenarios, as well as a scenario high-end for extreme cases.
Temperatures: a sustained and marked rise
According to Guyaclimat, warming between now and 2100 will be between +1.5°C and +4°C, depending on emissions trajectories. Maximum temperatures could rise by +2.5 to +4.1°C, especially between August and November. In the Cayenne-Matoury area, afternoons would regularly exceed 34°C in the SSP5-8.5 scenario.
Minimums are expected to rise from +3.2 to +4.2°C, leading to more frequent hot nights throughout the year, with direct implications for public health and energy consumption.
Precipitation: more intense dry seasons
Guyaclimat simulations indicate an annual fall in precipitation of between -3% and -26%, depending on the scenario. This decrease would be particularly marked during the “little summer of March” and the long dry season. In September, the drop could reach -75% in some areas.
These trends would accentuate water stress and put pressure on forest ecosystems, whose equilibrium depends on regular water supplies.
Sea level: the growing risk of chronic submersions
Guyaclimat forecasts a mean sea-level rise of +0.84 m by 2100 in the RCP8.5 scenario, with an uncertainty of between 0.59 and 1.17 m. This rise favors chronic submersions: temporary flooding occurring during high tides, even in calm weather.
The maps produced by the study identify vulnerable areas, in particular Cayenne, Kourou and Mana, and provide essential tools for guiding coastal development policies.
The Amazon rainforest, an ecological pillar under pressure
Covering around 97% of the country, Guiana’s forests are a major carbon sink. Guyaclimat points out that rising temperatures can reduce this capacity: in hot weather, trees close their stomata, slowing down photosynthesis and growth, thus limiting the absorption of carbon dioxide.
A strategic tool for adaptation
Guyaclimat is not limited to scientific analysis: it provides public and private players with a basis for decision-making. Projections can be integrated into development, resource management and risk prevention plans. The water, agriculture and energy sectors thus have reliable data with which to adapt their strategies.
Guyaclimat’s forecasts for 2100 highlight profound transformations: marked warming, reduced rainfall, rising sea levels and increased pressure on biodiversity. These findings call for swift, coordinated, science-based action to preserve the region and its inhabitants in the face of the century’s climatic challenges.
