One of the outstanding scientific challenges highlighted by the Global Climate Observing System (GCOS) is the closure of the Earth’s water cycle (as well as the energy balance and the carbon cycles) through satellite Earth Observation (EO). To this end, a suite of essential climate variables (ECvs) has been defined to understand the evolution of climate and to assess the potential derived risks. In this context, the definition of a new ECV, including the information on anthropogenic water use (AWU) can help in advancing the proper closure of the water cycle at higher spatial and temporal scales. The main data source identified by GCOS for tracking AWU is from FAO’s AQUASTAT. However, AQUASTAT provides survey-based irrigation estimates which do not meet the GCOS requirements, i.e., data are provided on a 5-years interval instead of yearly, and are available every 2-3 years.


The overarching objective of Climate Change Initiative – Anthropogenic Water Use (CCI-AWU) precursor project is to derive long-term (at least over twenty years, since early 2000s) AWU time series for selected regions using several approaches exploiting remote sensing observations, as a proof-of- concept of the feasibility towards a proper AWU ECV product. In particular, in this proposal AWU is more specifically intended as agricultural water allocated for irrigation, which represents the largest anthropogenic water use, thus making irrigation the most impactful human activity on the hydrological cycle.