Human activities are increasingly contributing to the proliferation of eutrophication, which results in significant negative impacts on coastal ecosystems. The appearance of red tides and dead zones or the decline in fishery products can be a manifestation of the effects of eutrophication. Therefore, eutrophication monitoring activities can provide valuable information for preventive eutrophication management efforts. Since eutrophication is an emerging global issue, the United Nations Environment Programme (UNEP) has introduced an index of coastal eutrophication through Sustainable Development Goal (SDG) 14.1.1a. This index links the global reporting system to each country’s national eutrophication monitoring programme.
In 2021, an international team consisting of scientists from the Northwest Pacific Action Plan (NOWPAP) member states, Google, JAXA, and UNEP, and led by Dr. Joji Ishizaka of Nagoya University, Dr. Elígio de Raús Maúre and Dr. Genki Terauchi of the Northwest Pacific Region Environment Cooperation Centre (NPEC), Japan, worked on the development of the first global tool for interactive assessment of coastal eutrophication potential (CEP), the Global Eutrophication Watch, using Google Earth Engine (GEE). The tool uses a regional eutrophication assessment methodology, the NOWPAP Eutrophication Assessment Tool (NEAT), designed for coastal eutrophication assessment based on satellite-derived chlorophyll-a. Thus, the Global Eutrophication Watch provides the means for any user worldwide to conduct a cost-effective assessment of CEP using remotely sensed data on the cloud.
The Global Eutrophication Watch was developed as part of the Marine Coastal Eutrophication project, sponsored by the Group on Earth Observations and GEE, to tackle some of the world's greatest challenges using open Earth data. On February 2, 2023, the team developing the Global Eutrophication Watch organised the final project meeting to review its progress. The reporter updated the team on the current status of the app, the data set included, as well as planned dissemination activities conducted in 2021 and 2022, such as the North Pacific Marine Science Organisation (PICES) annual meeting, UNEP Forum Tokyo, and the Intergovernmental Oceanographic Commission of UNESCO Sub-Commission for the Western Pacific (IOC/WESTPAC) Webinar Series, where the presenters got positive feedback from the audience. Overall, all members joining the meeting were satisfied with the achievement of the project.
Participants of the meeting encouraged further dissemination of the tool in different fora. These fora include the annual meeting of the Regional Seas Programmes scheduled for autumn 2023 in Barbados; and the next PICES annual meeting in October 2023. At the same time, a representative of the Coordinating Body on the Seas of East Asia (COBSEA) also showed interest in the tool and asked for support in preparing a data set for the COBSEA region. One of the challenges faced by this project was the lack of high-quality ocean colour data in the GEE data catalogue. NPEC completed the ingestion of Level 2 data in the NOWPAP region in collaboration with Google. The value of the lessons learned through data ingestion activities was recognised in the meeting, and the need to expand the procedure to a global scale was also emphasised. Meeting participants suggested that space agencies should lead the Level 2 data ingestion.
Global Eutrophication Watch has promising potential in monitoring SDGs and using Earth Observations to support SDGs. One of the major successes of the Global Eutrophication Watch rests in adaptability. For the NOWPAP region, it includes a regionally tuned long-term consistent data set of chlorophyll-a (CHL). For other regions, a simple link to an asset (data set) in GEE can be provided for the tool to run the assessment. In the case of the NOWPAP region, the regional data set spans a 24-year period and overcomes the limitations associated with the shorter lifespans of an individual sensor as it combines data from a different ocean colour sensor. This means that this data set should be continuously updated to allow a sustained CEP assessment. The Global Eutrophication Watch currently includes data set from MODIS/Aqua (Level 3, Global), SeaWiFS (Level 2, West Pacific), SGLI (Level 2, Northwest Pacific), YOC (Level 2 blended, Regional) and a combination of the YOC and SGLI (YOC+SGLI).
