I was among the first and have been among the most persistent scientific advocates for addressing climate change in our efforts to restore the Bay. Even so, I think that the recent decision of the Bay Program's Principal Staff Committee not to increase, at this time, the nutrient loads that must be reduced by 2025 to accommodate the effects of climate change is appropriate.
The Bay Program’s computer model estimates of reductions needed to offset the effects of climate change on water quality are, at this point, more exploratory than robust, nor have they been peer-reviewed. Estimates of increased river flows are based on the extrapolation of precipitation trends, and climate model projections of future precipitation vary widely. Unlike weather forecasts, climate models are more reliable for estimating conditions for the mid– and late 21st century, when impacts associated with precipitation, temperature and sea level are expected to increase, than in the near term.
In any case, the Bay Program model currently estimates only a 0.6 percent increase in nitrogen load but a 1 percent decrease in phosphorous load resulting from changing climate between the 1990s and 2025, although nitrate and dissolved phosphate loads might increase by about 2 percent.
To be sure, warmer temperatures on land and in the Bay, increases the amount and intensity of precipitation, and rising sea level will change the total maximum daily load equation and will likely require more pollutant load reductions to sustain water quality improvements beyond 2025. But the interaction of these factors is complex and requires strategic resolution by the scientific community to guide the most effective actions.
The Principal Staff Committee decided that the jurisdictions should begin to take climate change into account in their Phase III watershed implementation plan strategies, while addressing critical scientific uncertainties so that the quantitative load reductions required can be incorporated beginning in 2022. Meanwhile, it seems prudent and effective to:
- Insist on achieving the nutrient and sediment load reductions needed to meet or exceed the present TMDL. There should be no excuses in 2024 like there were in 1999 and 2009.
- Achieve these reductions by implementing best management practices for agriculture and stormwater sources that are climate-ready in that they remain effective in the face of climate variability and weather extremes.
- Invest in and organize the science needed to inform smart climate offset strategies over the coming decades.
- Follow the lead of Maryland and adopt legally required, ambitious reductions of greenhouse gas emissions and follow these commitments with the effective policies and programs needed to achieve those reductions.
The views of columnists are not necessarily those of the Bay Journal.