Ocean Conditions
Key Finding: Sea surface temperature, sea level, and coastal flooding are increasing along New York State’s coast. Sea surface temperatures are rising more rapidly in the state than the global average. Sea level along New York’s coastline has risen almost 1 foot in the past century and is projected to increase by another 1 to 2 feet by mid-century, making chronic flooding more common in low-lying coastal neighborhoods. Ocean water is also becoming more acidic as it absorbs excess carbon dioxide from the atmosphere, although stormwater runoff currently has a larger effect on acidity in New York’s coastal waters.
Climate Projections and Our Actions
Projections of future climate change depend on the world’s future emissions of heat-trapping greenhouse gases. Some of the projections discussed here present a range of numbers, based on those future emissions. If global emissions are reduced, it would decrease future warming and some of the associated impacts, and the resulting climate changes could be closer to the lower numbers presented here—or even lower.
Sea Level and Coastal Flooding
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As the world gets warmer, sea level rises. This happens for two main reasons. One is that water expands as it gets warmer. The other is because ice sheets—like those in Antarctica and Greenland—and glaciers are melting, and the extra water ends up in the ocean. Higher sea levels lead to more flooding along the coast. Coastal areas like the Long Island, New York City, and South Hudson assessment regions are especially at risk. Sea level is rising in New York:
- Historical observations: Over the past 100 years, sea level has risen in New York City by almost 1 foot. Due to rising sea levels, “high-tide flooding”—or chronic flooding caused by high water levels even on sunny days—has become more common along New York’s coast. For example, floods that happened twice a year on average at Kings Point on Long Island Sound in the 1950s and 1960s now occur about 10 times a year.
- Projections for the future: Sea level is projected to rise along the state’s coastline and in the tidal Hudson by about 2 to 3 feet by the end of the century. However, there is a chance of a more dramatic change if part of the Antarctic ice sheet collapses, for example. Such a change is impossible to predict with any certainty, and scientists consider it a “low probability but high impact” event. If it happens, New York could experience sea level rise of about 7 to 10 feet by the end of the century. In any case, as sea level rises, coastal floods are expected to happen more often and be more intense. Chronic flooding could affect New York City’s low-lying coastal neighborhoods as often as 49 to 71 days per year by the 2040s—in other words, once a week or more. Rising sea levels will also make flooding more severe during coastal storms.
The Link Between Sea Level
and Storms
Rising sea levels can make flooding from coastal storms more dangerous. Storm surge is an abnormally high water level caused by a storm as its heavy winds push water toward the coast. Higher sea levels combined with storm surge will make coastal flooding during these storms more frequent and severe.
Coastal floods from higher sea levels can cause direct harm to people, such as injuries, illnesses, and mental health impacts. They can also cause power outages; contaminate drinking water; and prevent people from accessing health care, transportation, and other needs. On Long Island, coastal floods risk damaging culturally significant Shinnecock Nation sites. People in some low-lying coastal areas may have to temporarily or permanently leave their homes as sea level continues to rise. Sea level rise also increases coastal erosion, which threatens coastal habitats.
Sea Surface Temperature
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The temperature of the water at the ocean’s surface is a key indicator of climate change. Changes in sea surface temperature affect ocean currents, weather, and marine life. Sea surface temperature is rising around New York State:
- Historical observations: Global average sea surface temperature has risen from 1901 to 2020, with changes varying regionally. Waters near New York warmed more than the global average from 1982 to 2018. Sea surface temperatures near the state have risen since the 1980s in all four seasons, with the largest increases in summer and fall. Marine heat waves, which are periods of several days with water temperatures much higher than normal, have also increased in recent years.
- Projections for the future: Global and regional sea surface temperatures are expected to continue rising. Waters along the U.S. East Coast are projected to continue warming more than other parts of the world’s oceans.
Higher water temperatures can have major impacts on marine and coastal ecosystems. Fish species are especially sensitive to changes in temperature, and warmer oceans have less oxygen supply than colder waters. This causes some species to shift their ranges to colder waters. While new fisheries could arise, some existing fisheries are expected to struggle due to declining populations of certain fish.
Ocean Acidification
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Oceans absorb some of the carbon dioxide produced by human activities. Carbon dioxide reacts with sea water to produce carbonic acid, so an increase in dissolved carbon dioxide leads to an increase in acidity (lower pH). Ocean acidity is changing in waters near New York State:
- Historical observations: The ocean has already become more acidic as it absorbs more atmospheric carbon dioxide. In the ocean waters around New York, high amounts of dissolved carbon dioxide suggest increased acidity. Stormwater runoff—water from precipitation that flows over land and buildings—is also a driver of acidification. When runoff flows into waterways, it adds sediments and pollutants that affect the water’s pH level.
- Projections for the future: Globally, oceans are expected to continue becoming more acidic during the 21st century. The northeastern U.S. coast is expected to experience some of the earliest impacts of acidification as more precipitation adds more runoff to coastal waters.
Higher acidity changes water chemistry, which affects the habitats of many ocean species. For example, it is harder for shellfish to create shells in more acidic water. Declines in shellfish populations affect ecosystems, people’s health, and the economy: shellfish help filter pollutants from water, are a traditional food source for some Indigenous Peoples, and contribute to New York’s fishing industry.
Explore Other Signs of Climate Change
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