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Sea Level Rise: What is Happening?

EcologyGlobal Warming

Level

Ines Gendre

updated May 3, 2023

Copywriter specializing in environmental thematics at Greenly

As you’ve maybe heard, sea levels are rising.

Like many changes happening to our natural world, sea level rise can be explained by global warming. As humans continue to burn fossil fuels, we are adding more greenhouse gases to the atmosphere and making climate change worse.

As our planet heats up due to global warming, its oceans do as well.

So how do warmer oceans result in higher sea levels? What are the consequences of current sea levels rising and future sea level rise for humans and for the environment?

What causes sea level rise?

“ Our oceans are filled with ice, contained in massive ice sheets. As these bodies of ice melt into the water due to global warming, sea levels rise because H2O molecules expand as ice melts into water. ”

If you put ice in your beverage and let it sit, the water level will be higher after the ice melts. The same is what is happening to our oceans – rising seas are occurring each decade our planet experiences global warming.

And over several decades, those tiny changes can compound to a foot of sea level change – similar to what is happening with the West Antarctic Ice Sheet.

How will Greenland and Antartica affect sea level rise?

Greenland and Antartica are two of the biggest ice bodies on the planet. They also happen to be shrinking rapidly as our oceans warm.

Greenland is contributing the most to global sea-level rise among other large ice bodies. This is primarily due to it being in the Arctic Ocean – The Arctic has warmed nearly four times faster than the global average in recent decades.

Like Greenland’s ice sheet, the Florida-sized Thwaites Glacier in Antartica is also retreating quickly. It is nicknamed the “Doomsday Glacier” because it holds a significant amount of the world’s glaciated ice, and is contributing to a substantial amount of rising sea level.

Even if we were to stop emitting greenhouse gases right now, there are some results of human-induced climate change that are guaranteed to happen. For example, regardless of how soon we can stop climate change, over 3% of the Greenland ice sheet will melt. This will cause almost a foot of global sea level rise.

While it is unclear how long it will take for this ice to melt, it is imperative that governments begin to plan for this rise.

Effects of sea level rise

Sea level rise is a serious risk to coastal wildlife and plants. Life systems in these areas can be fragile and need frequent changes in soil saturation in order to survive and thrive.

With more intense weather patterns and a higher coastline expected with global warming, coastal life around the world is and will be threatened by lost habitat, soil contamination with salt, and erosion. As many as 233 animal species in 23 U.S. states that are already on the endangered species list are threatened by sea level rise.

“ In fact, the effects of rising seas and relative sea level rise are already happening: with local sea level rise resulting in gulf coast cities like Miami and the rest of Florida to be mostly underwater by 2100. It isn't just ice sheets or melting mountain glaciers that are a cause of concern for rising sea levels, but sea level rising is resulting in worse natural disasters spurred by climate change like hurricanes. ”

For example, after Hurricane Katrina, National Oceanic determined that Lake Pontchartrain in New Orleans was a whopping eight inches taller than it was before. Areas that remain most impacted by this observed sea level rise include the Gulf Coast and South East Coast in the United States.

This is all due to global average temperatures continuing to rise, thermal expansion as oceans get warmer, and major ice sheets continuing to melt and contribute to global sea levels rising.

How does sea level rise affect humans?

Sea level rise will have several direct and indirect effects on humans.

As you might expect, sea level rise will affect humans by threatening them with displacement. Rising sea levels will shrink our land masses and surface mass balance will be implicated as well... Intensifying natural disasters and seasonal flooding will further make living by the ocean dangerous, as ocean warming will continue to impact local sea levels in conjunction with rising global temperatures.

Sea level rise is only getting worse, with natural disasters like Hurricane Ian breaking records for how much sea level was a result of a storm surge. It isn't just Florida that needs to remain aware of the changes sea surface levels – but states like Louisiana and Texas are sinking even more rapidly than other Gulf Coast cities.

Many large American population centers, such as Miami, New York, and New Orleans, are located right on the shoreline. These cities are also very flat, low lying coastal areas – making them susceptible to the consequences of sea level rise.

In fact, almost 30% of the total U.S. population lived in densely populated coastal areas in 2017.

“ Outside of the U.S., major coastal cities under threat due to sea level rise include Mumbai, Tokyo, Shanghai, Bangkok, and Amsterdam. ”

Inland cities and ecosystems will also be affected by sea level rise. This conclusion comes from decades of data, as many scientists have had trouble agreeing on the factors that have resulted in the current global mean sea level and overall rising seas.

However, one conclusion has been made surefire – some of the more recent natural disasters have spurred some of the highest sea level rises in the shortest amount of time. This makes rising ocean temperatures, antarctic ice sheets melting, and rising sea levels more threatening than ever before.

As coastal cities around the world try to protect themselves from sea level rise, it is inevitable that many people will choose to leave their homes to look for a more stable life in a place not located next to the sea. This could stress urban systems of other nearby cities that may see an influx of new inhabitants.

Ultimately, sea level rise will impact the daily lives of thousands of people – and it will only get worse as the global mean temperature continues to rise and atmospheric warming persists.

Rapid and unplanned urbanization influences the local flora and fauna, too. For example:

Streams, rivers, and lakes tend to get dirtier.
The air becomes more polluted.
Highways are built that fracture ecosystems.

Based on the above effects, more and more ecosystems will be threatened by not only climate change, but also the displacement of humans.

Seasonal and rare floods will reach higher on land than ever before, changing the salinity of bodies of water further inland.

Economic impact of sea level rise

“ Coastal towns and cities everywhere will be faced with tough decisions as they slowly lose land to the ocean. Wealthier areas, like many places in the U.S., may choose to spend to try to keep the ocean at bay. Others will be forced to retreat inland, as construction will become impossible with the projected rise of local seas and major flooding to come. ”

The city of Norfolk, Virginia plans to spend $1.8 billion to protect itself with flood walls and storm-surge barriers. New York City has already approved a similar $1.45 billion project that will include elevating parts of the city by nearly 10 feet.

Some areas of the country are choosing to spend on natural methods of defense. New Jersey, for example, is spending over $30 million to buy land near its coasts to convert urban areas back into swamps and marshes. These aquatic areas act as natural buffers from the ocean and as natural disaster mitigators.

American cities have a lot to lose. Miami, New York, and New Orleans are the top three cities in the world for current economic assets exposed to coastal flooding. Miami is the number one city in the world for potential exposed economic assets in 50 years. New York is the third, and New Orleans is the 12th.

What will be the extent of sea level rise?

How much will sea levels rise by 2050?

According to NOAA, the National Oceanic and Atmospheric Administration, American coastlines are projected to rise an average of 10-12 inches by 2050.This sea level rise is about the same rise seen over the past 100 years.

The NOAA sea level rise report says the gulf coast, which includes Florida and Louisiana, will likely be hit the worst – they should expect 14-18 inches of sea level increase by 2050. Compare this to the 4-8 inches likely to impact the West coast.

This difference is down to geography - the extent of erosion is determined by the shape of the land. Human activity can accelerate sea level increase by excavating resources like oil and groundwater, exacerbating subsidence.

Based on current projections, we can expect at least two feet of sea level rise by 2100. However, if we can reduce our greenhouse gas emissions in the coming years, our future risk will be lower, too.

How much have sea levels risen already?

Since 1880, the earth has seen a slow increase of 8-9 inches of global sea level rise on average. However, in just the last 30 years, we have seen 3.8 inches of sea level rise.

How will sea level rise affect natural disasters?

Sea level rise can have significant impacts on the frequency and intensity of natural disasters such as hurricanes and cyclones.

For example, it is likely that by 2050, on average, the U.S. will see intense floods occur five times as often and moderate floods 10 times as often as they currently do.

Outside of the U.S., countries that are most vulnerable to sea level rise are low-lying island nations who risk losing much of their land mass.

“ Consider the Maldives – most of the country’s islands are about 3.5 feet above sea level. Their current president says “The difference between 1.5° Celcius (2.7° Fahrenheit) and 2° Celcius (3.6° Fahrenheit) is a death sentence for the Maldives.” Their former president starred in a 2011 documentary. The movie, titled “The Island President”, detailed the country’s fight to stay afloat in the coming climate catastrophe. ”

With less area of our planet covered in ice, it will lower earth’s global albedo. This, along with warmer oceans, will contribute to a positive feedback loop that will continue to raise earth’s temperature.

How can Greenly help?

Although some changes to our world may feel inevitable due to climate change, it is still up to us to make a difference. If we are able to stop global warming at or near 1.5° Celcius (2.7° Fahrenheit), we can keep sea level rise from reaching predicted levels.

If your business needs help to understand its impact on the environment, contact Greenly. We can give you a life-cycle analysis of your product to find ways to limit your carbon footprint. We can then connect you with certified carbon offset projects.