Climate Benefits of Reducing Nutrient Pollution in Aquatic Ecosystems
Beaulieu, J., E. Kopits, Chris Moore, AND B. Parthum. Climate Benefits of Reducing Nutrient Pollution in Aquatic Ecosystems. 2021 Social Cost of Water Pollution Workshop, Virtual, April 21 - 23, 2021.
Climate change, driven by the accumulation of greenhouse gases (GHG) in the atmosphere, imparts considerable costs to the US taxpayers through storm damage, real estate losses, and energy costs, among others. Recent studies demonstrate 1) that lakes and reservoirs impacted by nutrient pollution are an important source of greenhouse gases (GHG) to the atmosphere, and 2) GHG emissions can be reduced through water quality improvements. This study monetizes the avoided climate change costs by improving water quality and reducing greenhouse gas emissions.
Recent research shows that limiting nutrient pollution in lakes and reservoirs not only improves water quality but also reduces greenhouse gas (GHG) emissions that contribute to climate change (Del Sontro et al. 2018, Beaulieu et al. 2019). The over-enrichment of waters with anthropogenic sources of nitrogen and phosphorus leads to excessive growth of algae and aquatic vegetation which can restrict the use of water for fisheries, recreation, industry, and drinking. Excessive nutrient inputs to surface waters can also stimulate the biological production of the greenhouse gases carbon dioxide, methane, and nitrous oxide. Quantifying and monetizing the climate impacts of eutrophication from nutrient pollution will provide a more complete assessment of the benefits of nutrient management policies. This paper estimates the reduction in GHG emissions from waterbodies in the Chesapeake Bay watershed that could result from the implementation of nutrient management plans developed to achieve U.S. Environmental Protection Agency (EPA) recommended limits on nitrogen and phosphorus loading to aquatic ecosystems. The EPA and U.S. Geological Survey (USGS) used hydrological and nutrient retention models to estimate nitrogen, phosphorus, and chlorophyll a (an index for algae abundance) concentrations in over 4,500 lakes in the Chesapeake Bay watershed under various management scenarios. Using predicted changes in daily GHG emissions rates resulting from changes in lake phosphorous and chlorophyll concentrations (Beaulieu et al. 2019) we monetize the climate benefits associated with these emissions reductions using estimates of the social cost of carbon dioxide, methane, and nitrous oxide (e.g., Greenstone et al. 2013, Marten et al. 2015). This study provides a roadmap for estimating economic benefits from nutrient management policies that have not been included in previous regulatory benefit-cost analyses.