The ESA Climate Change Initiative: satellite data records for essential climate variables

Observations of the Earth from space have been made for over 40 years and have contributed to advances in many aspects of climate science. However, attempts to exploit this wealth of data are often hampered by a lack of homogeneity 30 and continuity, and by insufficient understanding of the products and their uncertainties. There is, therefore, a need to reassess and reprocess satellite datasets to maximise their usefulness for climate science. The European Space Agency (ESA) has responded to this need by establishing the Climate Change Initiative (CCI). The CCI will create new climate data records for (currently) thirteen essential climate variables (ECVs) and make these open and easily accessible to all. Each ECV project works closely with users to produce time series from the available satellite observations relevant to users’ needs. A Climate Modelling Users’ Group provides a climate system perspective and a forum to bring the data and modelling communities together. This paper presents the CCI programme. It outlines its benefit and presents approaches and challenges for each ECV project, covering clouds, aerosols, ozone, greenhouse gases, sea surface temperature, ocean colour, sea level, sea ice, land cover, fire, glaciers, soil moisture and ice sheets. It also discusses how the CCI approach may contribute to defining and shaping future developments in Earth observation for climate science