Investigating Sea Level Trends in the United States

Introduction

The problem of rising sea levels isn’t a singular country’s issue, or a West or East Coast issue; it’s a global issue. Rising sea levels have created monumental problems, such as storm surges becoming deadlier and excessive flooding occurring further inland. These may seem like issues that already occur, but rising water levels intensify them. The biggest factors in the increasing sea levels are thermal expansion caused by warming oceans and the significant melting of ice from glaciers and ice sheets, such as Greenland.

This runoff must go somewhere, and when it enters the ocean, levels rise. When heat from our emissions enters the ocean, the water absorbs the majority of the emissions, which warms it. From an economic perspective, the coasts harbor large populations affected by tropical storms, hurricanes, and rising sea levels. All of these factors are interconnected, and rebuilding what has been destroyed by these surges is very costly.

Investigating the problem: Sea level trends for the East, West, and Gulf coast

The following table presents a visual representation of the trend in sea-level rise over the past 100 years, with fifteen different locations from the East Coast, West Coast, and Gulf Coast of the United States.

In summary, this table shows the relative trend, the timeframe of data, and the change in 100 years. For the East Coast, we see an average relative trend of 3.56 mm per year, with an average increase of 1.17 feet over 100 years. The West Coast varied from north to south, with some locations, such as Crescent City, CA, actually decreasing. However, North Spit had a 4.81 mm relative trend. What shocked me the most was the Gulf Coast, especially with the 9.08 mm relative trend for Grand Isle, LA. The average relative trend for the Gulf Coast was a total of 4.608 mm per year. As we can see from these numbers, rising sea levels are a reality and pose a serious challenge. The data doesn’t lie, and for places such as Grand Isle, LA, and our own area of Sewell’s Point, VA, it’s an issue we must strive to address.

Data Interpretation

Why are there differences in sea levels from coast to coast? On the East Coast, there are three major factors in the rise of sea levels: the slowing of the Gulf Stream, the El Nino cycle, and changes in the North Atlantic weather patterns. Scientists refer to some flooding as “sunny day” flooding. One scientist in particular, William Sweet— an NOAA oceanographer— investigated what is causing this issue. He used data from buoys to track the speed of the Gulf Stream and found that northeasterly wind and the slowing of the stream are actually causing these sunny day floods.

Another researcher, Tal Ezer, an oceanographer at ODU, also examined the currents and weather patterns to explain the rise in sea level on the East Coast. Using satellites, he discovered that the sea surface elevation across the Gulf Stream has a slope. This slope on the coastal side can be a few feet lower than on the east side. When the Gulf Stream’s current is stronger, it causes the slope to be steeper, which is brought about by the Earth’s rotation. When the stream slows, the slope decreases, pushing more water against the land and causing flooding during high tides.

The second and third factors are the El Nino years, which we also learned about in class. While El Nino occurs in the Pacific Ocean, its effects span our continent, causing a change in wind patterns and rising water levels along the East Coast. The change in weather affects the jet stream; more wind comes with storms, altering the distribution of water in the North Atlantic Ocean and, in turn, increasing sea levels along the East Coast. Scientists discovered that El Nino actually controls the increases and decreases of water on the coast.

The sea level trends on the Gulf Coast are among the highest and the worst in the United States. With the warm waters of the Gulf Coast, any hurricane that enters them will intensify, becoming even more dangerous and deadly, as we saw with Hurricane Katrina and Hurricane Harvey. The factors that influence the East Coast also affect the Gulf Coast. However, summer tides are now higher and winter tides lower due to more acute temperature differences between the seasons. This pattern, along with changes in air temperature and air pressure, play crucial roles in the rise of sea levels. Even small changes in the tides can lead to more storm surges and flooding, as seen in our own communities of Norfolk and Virginia Beach.

The East Coast is affected by the melting ice sheets of Greenland, but the West Coast suffers in the same way, just from Antarctica. Both continents are melting, and the rates are increasing, which isn’t merely a United States issue but a global issue. Warming waters and melting glaciers are the most significant factors in the global sea level rise. The El Nino years affect the West Coast even more than the East and Gulf because they occur right in the Pacific Ocean. This can instigate even stronger storms and, due to the sea level rise, lead to more landslides and floods. Plate tectonics also plays a role due to the uplift of land along the West Coast. Where the Pacific and North American plates slide past each other on the San Andreas fault line, there is a change in sediment and water. This causes areas to gradually sink lower and lower every year, while the sea levels increase. Over time, these will eventually converge, leaving parts of California underwater.

Implications of Changing Sea Levels on the Local Level

I personally live in the area code 23507, which is very close to the Chelsea district of Ghent. I know we are in Zone A, which speaks for itself; considering we would be the first to be told to evacuate. If we are the first to evacuate, then it doesn’t take much research to know we are the most at risk for flooding issues. According to the risk finder website, there are 2,900 people in this area code that live on exposed land below 6 ft. In this part of Zone A, 2,900 people live here and 1,869 of them are in the low social vulnerability population. Older residents and residents with mental disabilities are common in my area. Not only that, but we also live right near the tunnel and the shipyard.

That’s tons of transportation and movement which puts a lot of people at risk in the case of a deadly flood, not to mention the destruction of homes which, according to the website, was an average of $367 million! I feel like there doesn’t need to be that much argument for the mitigation of this issue in this area. It seems like a no-brainer to me that if any number of people live somewhere, especially in a high-risk zone, then something should be done to protect them and the city’s land. Not only would there be large impacts on personal property, but economically, it could result in loss of jobs in trade due to the shipyard and rail system close to my house, and the tunnel tolls.

Adapting and Mitigating to Sea Level Changes

In the area where I live, every single time it rains hard, the streets flood. During a single rainstorm – not even a hurricane, just a storm – the street next to us actually flooded enough to go over the hood of cars parked there. In that historic district, there are a few streets with brick that do not have drainage on them. If a street is going to flood in a storm, imagine what would happen to the entire area during a hurricane! One of the strategies I think would help to mitigate flooding issues would be more federal grants to assist people in lifting their homes. On Hampton Blvd in Norfolk, there are a few who have actually done so, but I don’t think as many people know about this possibility as they should.

Perhaps we could hold meetings in the city to distribute more information, maybe send out pamphlets in the mail from the city, but information needs to be provided to take advantage of this opportunity and potentially save your home from flood damage. Another strategy for this area would be to not build in areas that are prone to flooding. Build higher and in smarter locations where you can control rain runoff. This could be combined with a rule or law that requires new builders of any kind to raise their buildings a certain number of feet. This prevents them from building low and potentially claiming large numbers on their insurance and/or losing their property to flood and damages. Lastly, the mitigation strategies we could benefit from could include a seawall, like Galveston, TX, implemented on their coast. This would not only cost a lot of money to make, but it would provide a lot of jobs in the time it took to create. It’s a long-term solution, but one that comes at a high cost.

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