Climate Change, Ocean Acidification, and You

Climate Change Science and Data

• The climate is changing faster than expected. Greenhouse gases, such as carbon dioxide and methane, are the culprits. The burning of fossil fuels for homes, industry, and transportation releases almost 10,000 million metric tons of carbon dioxide into the atmosphere every year. ¹

• Carbon dioxide is changing not only our climate, but also the chemistry of the ocean. About 30% of the carbon dioxide we release into the atmosphere is absorbed by the ocean. ² In marine water, carbon dioxide decreases pH and increases acidity through a process known as ocean acidification.

• Excess nitrogen from sewage treatment plants, polluted stormwater, and fertilizers, is also adding carbon dioxide into nearshore waters through a process known as coastal acidification. ³
• Nitrogen can fertilize massive algal growth in our waters. When the algal blooms die, decomposition depletes the area of life-giving oxygen and releases carbon dioxide, acidifying the water.

The impacts of climate change are evident right here in Casco Bay

Warmer Waters

Friends of Casco Bay has been tracking water temperatures for over 25 years. On average, our data show a 2.5° F increase in water temperatures since 1993.

Sea Level Rise

As water warms, it expands, and the sea encroaches on our coastline. Coastal observers and property owners are reporting an increase in erosion.

Increasing Precipitation

Maine has seen a six-inch average increase in annual precipitation since 1895, further threatening coastal properties. ⁴

Threats to the Ocean Food Web

More carbon dioxide in our waters means there is less shell-building material (calcium carbonate) for clams, mussels and oysters, as well as for tiny critters at the base of the ocean food chain. The saturation state of calcium carbonate is a key measurement of shell-building material for many organisms. Shell formation becomes more difficult when the amount of available calcium carbonate falls below a 1.5 saturation state. ⁵ Our recent data indicate that for nearly half the year, levels of calcium carbonate in Casco Bay are not sufficient for shell-building.

What do these changes mean for Casco Bay?

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  As marine waters become more acidic, we can anticipate more pitting or dissolution of the shells of many commercially viable species in Casco Bay.

• Rising water temperatures are linked with shell disease, directly impacting our lobster fishery and tourism industries.

• Climate change is bad news for clams because green crabs — which eat juvenile shellfish — thrive in warming waters. ⁶

• The distribution and populations of marine species in the Gulf of Maine are shifting. Scientists and lobstermen are documenting the shift in distribution of Maine’s iconic lobsters north and east.

• Copepods are tiny crustaceans that are the main food source for juvenile lobsters. In laboratory experiments, copepods raised in conditions that simulate the climate changes occurring in the Gulf of Maine were less fatty. With a less healthful diet, young lobsters must divert energy from growth and resisting disease to finding enough food to survive. ⁷

What is Friends of Casco Bay doing?

• We helped form the Maine Ocean and Coastal Acidification Partnership (MOCA) to coordinate climate change research and policy change work. MOCA is a diverse coalition of researchers, policy experts, lawmakers, aquaculturalists, and seafood harvesters. We are working to create an action plan for Maine to protect the health of our coastal waters.

• We have worked with Representative Lydia Blume to introduce a bill, LD 1284, Science and Policy Council on the Impact of Climate Change on Maine’s Marine Species, which is making its way through the current legislative session. The bill will create a science and advisory policy council with a mission to evaluate ocean and coastal acidification and the impacts of climate change on Maine’s marine species and to make statewide policy recommendations.

• LD 1284 has been selected by the Environmental Priorities Coalition, a group of 34 environmental organizations, as one of its five priority bills to address climate change in Maine.

• Our Water Reporter volunteers are recording observations of how the Bay is changing. These observations strengthen our advocacy efforts as these reports are shared with regulators, legislators, and other decision makers, alerting them to conditions in the Bay.

What can you do?

• Tell your legislators to support LD 1284 to create a science and policy advisory council to address the impacts of climate change on Maine’s marine species.

• Sign up to get updates on the bill and other efforts of Friends of Casco Bay.

• Join Water Reporter. Your observations combined with those of other volunteers around the Bay will provide a better understanding of changing conditions.

• You can help improve and protect Casco Bay by maintaining a healthy yard without pesticides and fertilizers. Learn more at cascobay.org/bayscaping.

• Volunteer with Friends of Casco Bay. Sign up at cascobay.org/volunteer.

• Support our work at cascobay.org/donate.

• Find more ways to help at cascobay.org/help-casco-bay

References

1. T.A. Boden, R.J. Andres, G. Marland, Global, Regional, and National Fossil-Fuel CO2 Emissions, Research Institute for Environment, Energy, and Economics, Appalachian State University, 2017. https://cdiac.ess-dive.lbl.gov/trends/emis/overview_2014.html
2. N. Gruber, D. Clement, R. Feely, et al., The oceanic sink for anthropogenic CO2 from 1994 to 2007, Science, 2019. http://science.sciencemag.org/content/363/6432/1193
3. J. Weiss, Marine Pollution: What Everyone Needs to Know, Oxford University Press, 2015.
4. I. Fernandez, C. Schmitt, E. Stancioff, et al., Maine’s Climate Future: 2015 Update, The University of Maine, 2015. https://mco.umaine.edu/pubs/pdf/mcf-2015.pdf
5. J. Ekstrom, L. Suatoni, S. Cooley, et al., Vulnerability and adaptation of US shellfisheries to ocean acidification, Nature, 2015. http://pacshell.org/pdf/Ekstrom_etal2015.pdf
6. E. Tan, B, Beal, Interactions between the invasive European green crab, Carcinus maenas, and juveniles of the soft-shell clam, Mya arenaria, in eastern Maine, USA, Journal of Experimental Marine Biology and Ecology, 2015. https://downeastinstitute.org/wp-content/uploads/2018/08/tan-beal-2015.pdf
7. Copepods cope with acidification, Bigelow Laboratory for Ocean Sciences, 2018. https://www.bigelow.org/news/articles/2018-04-10.html