Climate service derived indicators to assess the impact of climate change on local river assimilative capacity

Abstract Continental climate services provide information on essential climate variables and indicators, which can further be used to address challenges at the local scale. Climate impact indicators are the core data for evaluating the change of the assimilative capacity of the river systems under future projection scenarios. Here, the indicators from the Copernicus pan-European climate service are used to develop and showcase a water management information service for the Asopos River, Greece. River flow indicators are incorporated in the estimation of emission limit values which serve as environmental pressure indicators, for the reference and two future periods (early- and mid-century). Assimilative capacity is evaluated for six heavy metals, namely Cr, Cd, Cu, Pb, Ni and Zn. Socioeconomic indicators are also utilized to incorporate changes of economic activities in the assessment. Results from the large ensemble of 209 scenarios, consisting of different global circulation, regional climatic and impact model combinations as well as industrial activity evolution, indicate that a decrease (up to 33% of 209 scenarios) of assimilative capacity is more probable than an increase (up to 18% of the scenarios) in a future climate. Local industrial activity evolution also has an effect on the uncertainty of the results for the early-century period. We conclude that although climate impact indicators are free of the need for laborious processing, they cannot cover all requirements for local analyses. Consequently information from continental climate services and local data should be used for climate change impact investigations.