Including decision makers in development of cost-efficient litter monitoring - A three step process

Environmental monitoring data to document levels and sources of macrolitter is important for decision makers to prevent and reduce amounts of this pollution. Here we suggest a structured process in developing national monitoring programs. Given limited resources for monitoring, we highlight the importance of including decision makers in prioritizing monitoring needs. The process involves 1) mapping international obligations and national needs, 2) evaluation of whether these are met by available monitoring data and, 3) assessment of nationally implemented and internationally recommended monitoring methods. Application of this approach when providing advice on a Norwegian monitoring program found that data needs are extensive: amounts, composition and sources of litter should be monitored across environmental compartments to understand entry points, transportation routes and litter loads. Monitoring of items targeted in the EU Single-Use Plastics (SUP) Directive is also needed. Data requirements in Norway are partly met in marine compartments through ongoing monitoring, but data collection is insufficient in time and space. Harmonized monitoring protocols are available, but knowledge on designing representative sampling strategies is lacking. Current monitoring does not meet needs for implementing the SUP Directive, nor to document impacts on biota and litter in non-marine compartments. To meet all needs and obligations, monitoring must be strengthened and extended to all environmental compartments using harmonized protocols with high technical readiness. Improved availability and use of data will allow feedback and secure policy relevance. To facilitate appropriate scientific advice when establishing national monitoring programs decision makers should be engaged in prioritization of monitoring needs.