A Review of Climate Change & Oceans

Boy Throwing Rocks -- Art Set


–From the East Hampton Star. By Judith S. Weiss

While some politicians claim that climate change is a hoax, and climate scientists try to refine their models and forecasts of exactly how much warming will take place in the next few decades, marine scientists can see clearly the evidence of what has already happened.

Everyone has heard about melting glaciers and dying coral reefs, but climate change is doing something else that is equally dangerous. The oceans absorb about a third of the carbon dioxide emitted from burning fossil fuels. In one way that’s good, because it slows down the warming, but it is making the seawater more acidic. CO2 in the ocean combines with water to form carbonic acid and makes the water more acidic — in fact 30 percent more acidic in recent decades.

This affects marine animals; the most severe effect is impairing shell formation in animals with calcium carbonate shells, such as clams and mussels. This has already occurred: In the Pacific Northwest, oyster larvae in hatcheries are unable to make their shells properly. Tiny planktonic snails are showing eroded shells. Acidified water poses an additional stress to corals already suffering from rising temperatures. Another effect is on behavior. Acidified waters impair the sense of smell of fish, causing them to be unable to find their home reef and to move toward, rather than away from, the odor of a predator.

Another reason global warming has not been too bad yet is because the ocean absorbs most of the earth’s excess heat. But oceans are warming due to greenhouse gas emissions. According to the National Oceanic and Atmospheric Administration, half of the increase in ocean heat content since 1865 has occurred over the past two decades. Warmer water holds less oxygen, but the respiration rate of animals (except for marine mammals) increases with temperature, so they need more oxygen at the same time that less is available. A warmer ocean has less turnover (vertical water movements), which normally brings nutrient-rich water up from deep water to the plankton that photosynthesize near the surface. With fewer nutrients, they photosynthesize less and animals can’t get enough food.

Many species are moving north to find more suitable environments, including species of commercial importance. Lobsters are disappearing from Long Island and southern New England, but increasing in the Gulf of Maine and Canada. Commercial catches are regulated by regional management agencies, but now these animals are fewer where they had been, and are increasing in places where they weren’t important before.

The most dramatic responses to warming oceans are in corals. When stressed, corals eject the single-celled symbiotic algae that live in their tissues, which normally photosynthesize and provide the coral with most of its nutrition. When they are ejected, the coral is “bleached” and appears white. While they can still get some nutrition by catching plankton with their tentacles, most species get less than half of their nutrition this way, so if the stress persists and zooxanthellae do not return, corals die. About 30 percent of the Great Barrier Reef of Australia died in 2016-17. This is devastating not only for the corals, but also for the thousands of other species that depend on the reef, including humans, who depend on it for $6 billion in tourism revenue annually. An excellent documentary about this tragedy, called “Chasing Coral,” is available on Netflix.


Major changes are occurring in the polar regions, where the extent of sea ice is diminishing rapidly. As ice melts, the water gets fresher and normal algal blooms diminish, providing less food at the bottom of the food chain on which the rest of the ecosystem depends. Some species that rely on sea ice, like Adelie penguins in Antarctica and polar bears in the Arctic, are in trouble.

Closer to home, sea level rise is one effect that is apparent in coastal regions. Sea level rise results from water expanding when it warms plus addition of new water from melting glaciers. It is happening faster than was predicted. Increased flooding from storms is common, and many areas (e.g., South Florida) have flooded streets even on sunny days. Since much of the world’s population lives in coastal areas, threats to human lives and well-being are becoming apparent.

In Bristol Bay, Alaska, the ability of local communities to access subsistence resources is impaired. Changes in the timing of ice freeze and melt are affecting safety, making it difficult to travel to neighboring villages and in some cases causing loss of life. Residents of some small low-lying Pacific islands have already moved elsewhere, and such “climate refugees” will increase in the future, which can cause political and social problems. Despite this, the Trump administration has recently undone a regulation that required that development near the coast take sea level rise into consideration, to reduce the risk of future damage.

Natural communities are also at risk. Coastal salt marshes in the intertidal zone are very important ecosystems that reduce storm surge and winds, absorb pollutants, and provide habitat for a variety of crabs, shrimp, fishes, birds, and mammals. In the face of rising seas, marshes must either increase their elevation or move inland. Increase in elevation results from new sediments being deposited and organic matter accumulation from marsh plants. Many marshes in the Northeast do not have adequate input of new sediments to increase their elevation, so moving back is the only option. (The marshes in Accabonac Harbor are increasing with sediments but not organic matter from plants, and have not been keeping up with sea level rise over the past decade.)

In developed regions, there are roads, sidewalks, etc., immediately inland, so there is no place for the marshes to go. Subject to “coastal squeeze,” many marshes that protect us from storm surge and winds will disappear. Recently, the East Hampton Town Board very wisely used the community preservation fund to buy some properties adjacent to marshes to allow for migration.

Another component of forecasted climate change is increased rainfall in the Northeast. This will intensify the nitrogen problem in estuaries, since more rain means more runoff and nitrogen going into the water. Much of our local nitrogen problem is due primarily to leaching from septic systems, but the expansive green lawns in the Hamptons suggest there is a lot of fertilizer runoff also. Warmer water in the future will also accelerate algal blooms.

What can be done? We need rapid decreases in emissions of greenhouse gases, especially carbon dioxide. While governmental actions are vital, and it is important to keep up the pressure on elected officials to do more, collectively individuals can make a difference. Examine your “carbon footprint.” Does your car use a lot of gas? Next time, buy a hybrid or electric. Do you drive short distances that you could walk or bike or take public transportation? How high is your electric bill? Could you keep your house a bit warmer in the summer and a bit cooler in the winter to save energy?

I am surprised and saddened to see so few houses around here with solar panels. Solar technology has improved greatly and the price has gone down. Could you eat less meat and more vegetables? Animal agriculture, especially beef, creates a huge amount of greenhouse gases. Studies indicate that the most important thing you can do — if you are still in a position to do this — is reduce the number of children you have.

All these actions will make the quality of life better for the children and grandchildren you do have.

Judith S. Weis is a professor emerita at Rutgers University. She has a house in Springs.

Categories: algae blooms, Coral Reefs, Ocean acidification, Rivers to the Sea, Sea Level Rise, Warming Oceans

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