The US Global Change Research Program just released Volume II of the Fourth National Climate Assessment (NCA4-II). News stories on this report have focused on the report’s “dire” and “grim” predictions. Problem is, NCA4-II did not predict anything. Rather, the report explores possible futures based on different “scenarios”, which it says “are never predictions nor forecasts”. Depending on what scenario is used, the effects of climate change range from the manageable to the awful. Take the case of rising sea levels:
Source: NCA4-II https://nca2018.globalchange.gov/chapter/appendix-3/#section-2
Two things stand out to me in the above chart. One is that global sea levels haven’t risen all that much yet. And, two, the range of sea rise between best- and worst-case scenarios is about seven feet. Plus, I once again want to point out: the worst-case scenario used in NCA4-II is only within the realm of the plausible if you assume a reversal of current mitigation and adaptation trends.
Enough of implausible scenarios! Onward to the hopeful parts of NCA4II - namely, what is being done and what can be done to adapt to the potential effects of climate change.
Chapter 9: Oceans and Marine Resources-Excerpts
Warming, acidification, and reduced oxygen conditions will interact with other non-climate-related stressors such as pollution or overfishing. Conservation measures such as efforts to protect older individuals within species, maintain healthy fish stocks, and establish marine protected areas can increase resilience to climate impacts.
Continued monitoring to measure the effects of warming, acidification, and deoxygenation on marine ecosystems, combined with laboratory and field experiments to understand the mechanisms of change, will enable improved projections of future change and identification of effective conservation strategies for changing ocean ecosystems.
Modeling studies show that climate-ready, ecosystem-based fisheries management can help reduce the impacts of some anticipated changes and increase resilience under changing conditions. There is now a national strategy for integrating climate information into fishery decision-making, and the North Pacific Fishery Management Council is now directly incorporating ocean conditions and climate projections in its planning and decision-making.
Several corrosive events along the Pacific Northwest coast prompted the Pacific Coast Shellfish Growers Association to work with scientists to test new observing instruments and develop management procedures. The hatcheries now monitor pH and pCO2 (partial pressure of carbon dioxide) in real time and adjust seawater intake to reduce acidity. Similar practices are being employed on the East Coast to adapt shellfish hatcheries to the increasing frequency of low-pH events associated with increased precipitation and runoff.
Current modeling systems make it possible to forecast temperature, pH, and oxygen conditions several months into the future. Operational forecasts are also being developed for harmful algal blooms and for the timing of Maine’s lobster fishery. Further engagement with users would improve the utility of these emerging forecasts.
Next: Adapting to Climate Change, per NCA4-II/Agriculture