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Sea levels are rising, whether people are ready or unprepared. They will cause severe flood risks to large portions of the Gulf coast and Atlantic coasts, as well the U.S. economic system over the next three decade.
A new report by scientists from the National Oceanic and Atmospheric Administration warns the U.S. to be more careful. Expect to see 10-12 inchesrelative sea level rise in the next 30 year. Global warming and sinking lands are both contributing to the rise. Given the amount of greenhouse gases released so far, it is unlikely that the country can avoid it.
This much sea level rise can lead to cities like MiamiBy midcentury, areas that experience nuisance flooding due to high tides will see more severe floods. The report predicts that moderate coastal flooding will be 10 times more common by 2050. Without significant adaptations, high tides are likely to cause flooding in the streets and disrupt coastal infrastructure, including ports essential for supply chains.
The oceans will be higher. Seawater can be brought inland. Depending on the world’s reductions in greenhouse gas emissions, sea level will rise by an average of 2 feet per century.
As a geoscientist, I study sea level riseand the impacts of climate change. Here’s a quick explanation of two main ways global warming is affecting ocean levels and their threat to the coasts.
Ocean thermal expansion
The atmosphere traps energy that would otherwise escape into space as a result of greenhouse gases resulting from human activities and fossil fuel use. This energy causes global average surface temperatures to rise, particularly in the upper layers of oceans.
The ocean heats up and causes thermal expansion. Sea water molecules move closer together due to heat, taking up more space. The ocean rises higher and floods more land.
Over the past few decades, Around 40%Thermal expansion is responsible for the rise in global sea levels. The ocean, which covers about two-thirds of the Earth’s surface, has been absorbing and storing More than 90%a result of greenhouse gas emissions, which adds heat to the climate system.
NOAA Climate.gov
Ice melting from land
Melting land ice is another major factor in rising sea level. The rate at which mountain glaciers and polar Ice Sheets are melting faster than natural systems can replace is alarming.
Land ice melts into meltwater that eventually flows into the ocean. This adds new water to the ocean and increases the ocean’s total mass.
About 50%Global sea level rise was caused by land ice melt over the past several years.
Currently, the Greenland and Antarctica polar ice sheet hold enough frozen water that if they melt completely it would raise the global ocean level. Up to 200 feet, or 60-70 meters – about the height of the Statue of Liberty.
Sea ice is also melting due to climate change. However, because this ice already floats at the ocean’s surface and displaces a certain amount of liquid water below, this melting does not contribute to sea level rise.
NOAA
Even after emissions stabilize, risk will continue to rise
While the The ocean’s surface heightAlthough global temperature rises as the planet heats, the effects are not the same for all coastal regions. Due to unique local conditions such as changes in ocean circulation and subsidence, the rate of rise in certain places can be several times faster than others.
For example, the U.S. East Coast or Gulf Coast face Risks that exceed the averageAccording to the new report, the West Coast and Hawaii are expected to be lower than the average.
Nearly 4/10 Americans live near a coast. A large part of the U.S. Economy is also located there.
Even if greenhouse gas emissions fall, sea level will continue rising for centuries. This is because the huge ice sheets in Greenland & Antarctica will continue melting and it will take a long time to find a new equilibrium. A 2021 report from Intergovernmental Panel on Climate ChangeThe excess heat in the climate system has locked the current rates for thermal expansion and land-ice melt for at most the next few decades.
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