Is Sea Level Rising?

The above chart shows the average global sea level rise since 1880.

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COURT HOUSE - Sea level rise is a reality and one that will not change anytime soon. Cape May County, with its close proximity to seawater and reliance on the ocean for much of its economy, will feel the effects of climate change and the ensuing seawater rise more heavily than most of the nation.

Cities like Wildwood sit at zero feet above sea level. Much of the county sits at 10 feet or less above sea level.

Between 1993 and 2020, NASA satellites reported a 4-inch change in sea level. National Oceanic and Atmospheric Administration (NOAA) reports that “global mean sea level has risen about 8-9 inches (21–24 centimeters) since 1880, with about a third of that coming in the last two and a half decades.” Many proposed projects to protect the county’s seaside towns are, as reported in a Feb. 18 Herald article (https://bit.ly/2ZlKHqc), in the billions.

How do we know that sea levels are rising? Here, in Cape May County, it is more obvious than in many places.

Various towns had to do extensive, costly construction work to offset rising waters and more frequent flooding. NASA uses satellites, as well as “satellite laser altimeters,” to measure the changes in the ocean’s height, as measured from space.

NOAA’s Laboratory for Satellite Altimetry describes this process: “Satellite radar altimeters measure the ocean surface height (sea level) by measuring the time it takes a radar pulse to make a roundtrip from the satellite to the sea surface and back.” Trends from this, and other satellite measurements, have shown a clear upwards trend line in overall ocean height.

The global rise in average sea level means that hurricanes and other weather events have a greater impact on Cape May County's towns and communities. In a panel last year, Dr. Lenore Tedesco, executive director for the Wetlands Institute, said that “the rate of rise over the past 25 years or so is more than double what it was earlier, compared to the first 100 years or so of this record. Since 1965, we are at a rise rate of 1.5 feet per century.”

She also noted the county is likely to see an “additional 1 to 1.8 feet of rise from where we are now through 2050.” Rises like this greatly contributed to the severe damage that Hurricane Sandy caused throughout the Jersey Shore; 27 additional miles were impacted by Sandy that might have been spared were it not for exacerbated ocean rise.

The primary cause of ocean level rise is the melting Antarctic and Greenland freshwater icecaps. NASA’s GRACE satellites monitor the weight of these monolithically large bodies of ice and show that they lose mass at an average of 147 gigatons per year; more than 2,500 gigatons of ice melted from both locations since monitoring began in 2002.

Melting ice caps is not the only factor that contributes to ocean level rise. NASA attributes much of the ocean level rise to the physical expansion of ocean water. As greenhouse gasses are trapped by the Earth’s atmosphere, the ocean is the primary absorption agent that absorbs the ensuing heat.

A NASA explanation of this phenomenon said that “as this heat is absorbed, ocean temperatures rise and water expands. This thermal expansion (https://go.nasa.gov/2Ziwdap) contributes to an increase in global sea level (https://go.nasa.gov/2NGZ9nk).”

A study published by the Intergovernmental Climate on Climate Change (IPCC) titled, “Sea Level Rise and the Implications for Low-Lying Island Coasts and Communities,” outlines the social, ecological, and other various effects that rising seas will have in the decades and centuries to come.

According to the study, “As a consequence of natural and anthropogenic changes in the climate system, sea-level changes are occurring on temporal and spatial scales that threaten coastal communities, cities, and low-lying islands.”

The study goes on to list “six main concerns for low-lying coasts... permanent submergence of land by mean sea levels or mean high tides; more frequent or intense flooding; enhanced erosion; loss and change of ecosystems; salinization of soils, ground and surface water; and impeded drainage.”

The study echoes sentiments expressed by Tedesco, that many of the negative consequences related to ocean level rise will come from events exacerbated by the rise, such as storms, hurricanes, and high tides. Storms and hurricanes that might not otherwise be deadly or damaging will continue to increase in intensity and intrusiveness as a result of a higher average ocean height.

The IPCC study says that “overall, while the literature suggests that it is still too early to attribute coastal impacts to SLR (sea level rise) in most of the world’s coastal areas, there is very high confidence that as sea level continues to rise, the frequency, severity, and duration of hazards and related impacts increases.”

A conservative estimate, outlined in a 2013 IPCC study, predicts that the ocean will rise just under a meter by 2100. Yet, more recent studies predict that, if current emission levels remain unchecked, a 5 degree Celsius increase in global temperatures will melt Antarctic and Greenland ice caps such that the ocean level rise could exceed 70 inches.

What is sure; however, is that a higher average ocean level is bad news for Cape May County. The county is already experiencing the consequences of a sea-level rise of 8-9 inches. Increases based on several predictive models will have more severe consequences if they hold true.

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