Improvements to the Wetland Extent Trends (WET) index as a tool for monitoring natural and human-made wetlands

Abstract Indicators of status and trends in wetland extent are essential for monitoring progress towards the environmental targets set by the Convention on Biological Diversity (CBD), the United Nations Sustainable Development Goals (SDGs) and the Ramsar Convention on Wetlands. Here, we test the value of the Wetland Extent Trends (WET) index as an updatable indicator of trends in wetland area and its application to global and regional scale assessments and national reporting. We expand the indicator to include a regional trend for Latin America and the Caribbean and a global human-made WET index. Based on a sample of over 2000 wetland records, natural wetland extent declined on average by 35% globally, at an increasing rate from 1970 to 2015. Human-made wetlands, however, increased by 233% from 1970 to 2014. The continuing decline in natural wetland extent suggests that global targets will not be achieved without significant further efforts.