The ESA Climate Change Initiative (CCI): A European contribution to the generation of the Global Climate Observing System

The Earth System behaves as a highly coupled system comprising physical, chemical, biological, and anthropogenic components and processes with complex interactions and feedbacks between them. Climate change is arguably the greatest challenge to balance in the Earth system. The Paris Agreement (UNFCCC, 2016) recognised the need to reduce the risks from and impacts of climate change and called for the increase in the global average temperature to be held well below 2 °C above pre-industrial levels, with the ideal aim being to limit it to 1.5 °C. The UN Framework Convention on Climate Change (UNFCCC) agreement is based on the evidence for, and likely causes of, climate change synthesised by the Intergovernmental Panel on Climate Change (IPCC) and is supported, for climate, by the Global Climate Observing System (GCOS). GCOS has defined a set of Essential Climate Variables (ECV), established the requirements for their systematic observation, and the development of data archives, needed to support the study the climate system. The Climate Change Initiative (CCI), represents the contribution by the European Space Agency (ESA) to GCOS. CCI is a programme designed to bring together European expertise in Earth Observation with that from the climate research community to address those ECV that can be generated using satellite observations. Specifically the objective is 'to realise the full potential of the long-term global Earth Observation archives that ESA together with its Member States have established over the last thirty years, as a significant and timely contribution to the ECV databases required by the United Nations Framework Convention on Climate Change (UNFCCC)'. In doing so the intended legacy of the programme is to put in place mechanisms capable of providing long term, fully traceable, and transparent access to its records. This paper provides an overview of the CCI Programme and highlights a few of its achievements to date.