Objectives:

To diagnose the future impacts of anthropogenic climate change on monsoon climates using existing control/scenario integrations. The application of regional models to monsoon systems will be included since they provide the higher spatial resolution needed for the impact studies involving agriculture and hydrology. The incidence of extreme events will be a particular focus of study.

Work description:

MF: The impact of climate change on Africa will be investigated. Using SSTs from a transient atmosphere-ocean simulation in a greenhouse gas increased scenario for the next century as boundary forcing, `time-slice' integrations will be performed with a state-of-the-art AGCM incorporating a zooming technique to achieve a resolution of about 100 km over Africa.

DMI: High resolution time-slice experiments of the present day and climate change scenarios will be used to assess the changes in the characteristics of the Asian/Indian summer monsoon in terms of the monsoon's seasonality (e.g. onset) and the statistics of extreme events (e.g. wet/dry spells). The potential factors (e.g. ocean warming, reduction in Eurasian snow cover) which give rise to changes in monsoon activity will be investigated.

CNRS-LMD with UB: The response of monsoon systems to climate change will be analysed in coupled integrations. The sensitivity of the response to land surface exchanges will be investigated by comparing the results with an integration which uses a new multi-level model of soil moisture. This model takes into account the different textures in a grid box, the sub grid variability of the soil reservoirs and will be used to study the role of infiltration rate on the response to greenhouse gas forcing.

MPG.IMET: Transient scenario simulations with a coupled atmosphere ocean model show a considerable increase of precipitation over India for the next century, accompanied by enhanced variability. The potential link with increased variability in ENSO needs to be established. The change of monsoon statistics in response to global warming will be investigated in transient coupled model simulations. Under increased CO2 conditions, plants may be able to make more efficient use of soil moisture. This effect, not yet incorporated in climate models, may be important for agriculture, because it may reduce evapo-transpiration.

The Met. Office: The changes in the Indian monsoon simulated by global and regional climate models in response to increases in greenhouse gases will be compared for 2041-2060 relative to pre-industrial conditions. The response of both time-averaged features and intraseasonal variability in the monsoon will be investigated. The impact of using finer resolution in the regional model will be assessed. This will provide important information on the ability of the regional model to provide reliable data at the spatial scales (~100km or less) required for impact studies.

Deliverables:

D2001: Documentation of the impacts of anthropogenic climate change on the characteristics of monsoon climates, including the seasonality, interannual and intraseasonal variability, and the incidence of extreme events.

D2002: Assessment of the value of high resolution regional model simulations for use in impact studies involving agriculture and hydrology.

Milestones:

Year 1: Report on largescale greenhouse-gas driven changes in the African and Indian monsoons using global models.

Year 2: Report on detailed greenhouse-gas driven changes in the Indian monsoon using high resolution time-slice integrations.

Year 3: Assessment of the effect of improved soil hydrology on the water budget response of monsoon systems to anthropogenic climate change