Synergies and complementarities between ecosystem accounting and the Red List of Ecosystems.

Safeguarding biodiversity and human well-being depends on sustaining ecosystems. Two global standards for quantifying ecosystem change, the International Union for Conservation of Nature Red List of Ecosystems (RLE) and the United Nations System of Environmental-Economic Accounting Ecosystem Accounting (EA), underpin headline indicators for the Kunming-Montreal Global Biodiversity Framework. We analyse similarities and differences between the standards to understand their complementary roles in environmental policy and decision-making. The standards share key concepts, definitions of ecosystems and spatial data needs, meaning that similar data can be used in both. Their complementarities stem from their differing purposes and thus how data are analysed and interpreted. Although both record changes in ecosystem extent and condition, the RLE analyses the magnitude of change in terms of risk of ecosystem collapse and biodiversity loss, whereas EA links ecosystem change with the ecosystem's contributions to people and the economy. We recommend that the RLE and EA should not be treated as unrelated nor undertaken in isolation. Developing them in concert can exploit their complementarities while ensuring consistency in foundational data, in particular ecosystem classifications, maps and condition variables. Finding pathways for co-investment in foundational data, and for knowledge-sharing between people and organizations who undertake RLE assessments and accounting, will improve both processes and outcomes for biodiversity, ecosystems and people.