What’s causing sea-level rise? It’s expected to increase by 10-12 inches between now and midcentury

Sea levels are rising regardless of whether people are ready. This will bring flood risks to large areas of the Gulf coast and Atlantic coasts, as well as the U.S. economy.

A new report by scientists from the National Oceanic and Atmospheric Administration warns the U.S. to be more careful. Prepare for 10-12 inchesrelative sea level rise in the next 30 year. Sinking land and global warming are the main causes of the rise. There are enough greenhouse gases already released from fossil fuel use and other activities to make it impossible to avoid it.

This much sea level rise can lead to cities like MiamiBy midcentury, areas that experience nuisance flooding from high tides will see more devastating floods. High tides without significant adaptations will cause more flooding to streets and disrupt coastal infrastructure, including ports essential for supply chains.

The report predicts that moderate coastal flooding in the United States will occur 10x more often by 2050. The ocean will be higher Bring seawater further inland. 2 feet of sea level will likely be reached by the end of the century. This depends on how well countries reduce their greenhouse gas emissions.

As a geoscientist, I study sea level riseClimate change and its effects. Here’s a quick explanation of two main ways climate change 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. The average global surface temperature rises due to this energy, particularly in the upper ocean layers.

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 last several decades, Around 40%The effect of thermal expansion has caused global sea level rise. 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.

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 and the meltwater eventually flows into oceans, increasing ocean volume and adding water to it.
About 50%The past several decades of land ice melting caused the global sea level rise.

The Greenland and Antarctica polar ice sheet hold enough frozen waters at the moment that if they melt completely, it will raise the global sea-level. Maximum 200 feet, or 60-70 meters – about the height of the Statue of Liberty.

Climate change is also melting sea ice. 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.

Even after emissions stabilize, the risk of an explosion will continue to increase

While the The ocean’s surface heightWhile global warming causes global rises, the impact on each coastal area is different. 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 & Gulf Coast are both facing Risks that exceed the averageAccording to the report, Hawaii and the West Coast are projected to be lower that the average.

Nearly 4 out 10 Americans live near the coast, and a large portion of the U.S. economic activity is also there.

Even though greenhouse gas emissions eventually decline, sea levels will continue to rise for centuries. The massive ice sheets of Greenland and Antarctica will continue their melting and it will take quite a while to reach a new equilibrium. A 2021 report of the Intergovernmental Panel on Climate ChangeThis shows that the climate system’s excess heat has locked in current rates of thermal expansion, and land ice melting for at least the next few years.