Significant progress in the understanding and projection of climate change has been made over the last decade. However, large uncertainties remain, particularly in the determination of the rate of climate change, impacts on regional scales where society and environment are most vulnerable and occurrence of extremes (e.g. sea-level rise). Reduction of these uncertainties requires the filling of significant gaps in observational programmes and understanding, and improved models for projection of climate change, both globally and regionally. The WCRP has a number of activities (see UNFCCC SBSTA webcasts) directed towards research on questions such as: how is climate changing; what is driving the changes; how to deliver more useful projections of future climate; and how to better inform management of climate-related risks? To meet the scientific challenges associated with climate change, nations will need to increase their support for the research described here and exemplified by the World Climate Research Programme Task Team on Anthropogenic Climate Change (see Climate Change brochure). The team's most important focus to reduce uncertainty in climate change projections remains model improvement, which is spear-headed by the WCRP Group on Coupled Models (WGCM). WCRP is also now engaged with the Intergovernmental Panel on Climate Change (IPCC), and the wider Earth System Science Partnership (ESSP) in a dialogue on specification of new and standard emission scenarios. It is essential that future research efforts be focussed, which may include limiting the number of greenhouse gas scenarios used in climate change projections and ensuring continuity of a limited set of scenarios between IPCC Assessments.

Dr H. Le Treut
Laboratoire de Météorologie Dynamique, IPSL Paris, France
E-mail: letreut@lmd.jussieu.fr

Professor V. Ramaswamy
NOAA Geophysical Fluid Dynamics Laboratory, Princeton University, USA
E-mail: v.ramaswamy@noaa.gov

Dr D. Griggs
Met Office, Hadley Centre, UK
E-mail: dave.griggs@metoffice.gov.uk

Dr G. Flato
Environment Canada
E-mail: greg.flato@ec.gc.ca

Dr J. Church
Antarctic CRC and CSIRO Marine Research, Australia
E-mail: john.church@csiro.au

Professor J. Mitchell (Co-chair, WGCM-ACC)
Met Office, Exeter, UK
E-mail: john.f.mitchell@metoffice.gov.uk

Dr G. Meehl (Co-chair, WGCM-ACC)
National Center for Atmospheric Research (NCAR), USA
E-mail: meehl@ncar.ucar.edu