Letters

Science has unequivocally established that human emissions of carbon dioxide trap heat in the earth’s atmosphere, warming the land and oceans. But those CO2 emissions also directly affect the health of our local waters.

Currently, the oceans absorb about 25 percent of carbon dioxide emissions each year, changing the ocean’s chemistry and impacting marine environments. Local marine ecosystems face three problems from CO2 emissions: warming, acidification and deoxygenation.

Sea surface temperatures rise in lockstep with increased concentrations of atmospheric carbon dioxide. 2021 saw the warmest sea surface temperature ever recorded, and ocean temperatures are increasing eight times faster than in decades before 1980.

Warming stresses marine species, increasing their risk of mortality, destroying habitats, interrupting food supplies and disrupting entire ecosystems. Intense marine heat waves can create local, disastrous die-offs, and they are occurring more frequently. On Long Island, our relatively shallow bays and sounds are especially vulnerable to ocean warming and marine heat waves.

Scientists call ocean acidification “climate change’s equally evil twin,” and for shellfish, acidification poses a serious problem. Absorbed CO2 reacts chemically with seawater, making the oceans more acidic. Acidity can dissolve calcium carbonate, the building block of all marine shells, and any increase in acidity makes these shells susceptible to thinning.

In the past 200 years, Earth’s oceans have become 30 percent more acidic, faster than any known change in ocean chemistry in the last 50 million years. But the shell problem gets worse. CO2 also reacts chemically with sea water to reduce the amount of carbonate ions, which shellfish use to construct their calcium carbonate shells. Increased acidity plus depleted carbonate ions makes shell building challenging, especially for newly hatched shellfish.

Because warm water can hold less dissolved oxygen than colder water, global warming leads to deoxygenation of the world’s oceans, increasing the likelihood of localized areas of severe oxygen depletion (hypoxia) that create dead zones. Marine animals must leave, if they can, or die.

For organisms living in littoral regions, the situation is even worse. Deoxygenation in coastal waters is intensified by eutrophication — algal blooms created by nutrient runoff from fertilizers and sewage leakage. The blooms eventually decay from bacterial action that consumes oxygen causing hypoxic dead zones. The frequency, intensity, and duration of these eutrophic dead zones are increasing worldwide and pose a direct threat to Long Island waters.

By 2100, earth’s temperature is projected to rise another 2 degrees Fahrenheit, intensifying all of these problems. We must reduce CO2 emissions to prevent both disastrous global warming and devastation of our local marine ecosystems.

If we fail, global temperatures rise, ocean acidity increases, carbonate ions decrease, hypoxic dead zones expand, and our coastal waters deteriorate. Indefinitely.

John Gibbons

Assistant Professor of Education

Long Island University, C.W. Post