David R. Kanter1,2, Jeffrey D. Sachs3
1 Department of Environmental Studies, New York University, 285 Mercer Street, New York, NY, 10003, USA
2 Agriculture and Food Security Center, Columbia University, 61 Route 9w, Palisades, NY, 10964, USA
3 The Earth Institute, Columbia University, Hogan Hall, 2910 Broadway, New York, NY, 10025, USA
Nitrogen pollution is one of the most important environmental issues of the 21st century, contributing to air and water pollution, biodiversity loss, climate change and stratospheric ozone depletion. While the planetary boundary for nitrogen is one of two that humanity has exceeded, it has yet to garner the attention from the policy community that it deserves. Moreover, emerging calls for a coordinated international response to nitrogen pollution need to be reconciled with the reality that solutions, particularly in the agricultural sector, are often locally specific. This is the goal of the new “Pathways to Nitrogen’s Planetary Boundary” project (PNPB): disaggregating nitrogen’s planetary boundary into several regional boundaries, and developing pathways to reach these boundaries using regionally-tailored nitrogen use efficiency strategies. This new form of regional integrated assessment aims to provide a roadmap for policy-makers to better address nitrogen pollution. It also adopts a form of scenario development seldom used in environmental modeling: “backcasting” technical pathways to achieve a future goal (nitrogen’s planetary boundary), instead of forecasting multiple futures from a common present. The regional teams (East Asia, South Asia, East Africa, Eastern Europe, Latin America and North America) have already been formed as part of the International Nitrogen Management System initiative. Their focus on improving understanding of regional nitrogen flows is a crucial first step for developing the regional boundaries and pathways. PNPB would provide a forum for sharing methods, tools, data, and results among the teams, and ultimately aggregate the pathways to determine the extent to which they meet nitrogen’s planetary boundary.