What causes sea level rise?The report warns that one leg will rise within 30 years and floods will occur more frequently.

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How thermal expansion and melting of land ice combine to cause sea level rise over time. The black line is the sea level observed since the start of satellite altimeter recording in 1993. credit: NOAA

Sea levels are rising, which will pose a serious flood risk to most of the Gulf and Atlantic coasts over the next 30 years.

A new report led by scientists from the US National Oceanic and Atmospheric Administration warns that the United States should do it. 10-12 inch preparation Percentage of average sea level rise over the next 30 years.The rise is the subsidence of the land global warming..And given Greenhouse gas Countries released so far may not be able to avoid it.

Significant rises in sea level mean that cities like Miami, where annoying floods occur at high tide today, will have even more damaging floods by the middle of the century. Nationally, the report predicts that moderate coastal floods will occur 10 times more frequently by 2050. Without significant adaptation, high tides flow into the streets more often, disrupting coastal infrastructure, including ports that are essential to the supply chain and economy.

Higher seas also bring seawater further inland. By the end of the century, sea levels are expected to rise by an average of more than two feet, depending on how much the world reduces greenhouse gas emissions.

As Earth scientist, I am studying sea level rise And the effects of climate change.Here is a brief description of the two main ways global warming is affecting Sea level And their threat to the coast.

Thermal expansion of the ocean

The accumulation of greenhouse gases in the atmosphere from the use of fossil fuels and other human activities traps energy that would otherwise escape into space. That energy raises the world’s average surface temperature, especially the upper layers of the ocean.

Thermal expansion occurs when the sea heats up. The heat causes seawater molecules to move slightly apart, occupying more space. As a result, the sea rises higher and floods more land.

Over the last few decades About 40% The cause of global sea level rise is due to the effects of thermal expansion.The ocean, which covers about two-thirds of the Earth’s surface, is absorbed and stored. More than 90 Excessive heat added to the climate system by greenhouse gas emissions

What causes sea level rise?U.S. report warns that floods will rise more often, rising one foot within 30 years

Credit: NOAA

Melt land ice

Another major factor in sea level rise is melting. Land ice.. Mountain glaciers and polar ice sheets are declining at a faster rate than natural systems can replace them.

When land ice melts, the meltwater eventually flows into the ocean, adding new amounts of water to the ocean and increasing total ocean mass.About 50% The rise in world sea levels has been caused by the melting of land ice over the last few decades.

Currently, the ice sheets of Greenland and the polar regions of Antarctica hold sufficient frozen water, so when completely thawed, the world’s sea level will rise as follows. Up to 200 feetOr 60-70 meters-about the height of the Statue of Liberty.

Climate change is also melting sea ice. However, this melting does not contribute to sea level rise, as the ice is already floating on the surface of the sea, pushing away a certain amount of liquid water beneath it.

Risks continue to rise even after emissions stabilize

While Sea surface height It rises globally as the Earth warms, but its impact is not the same in all coastal regions. In some places, the rate of increase can be several times faster due to unique regional conditions such as shift-ins. Ocean Circulation or subsidence of land.

For example, the East Coast and Gulf of the United States Above average riskThe West Coast and Hawaii are projected to be below average, according to a new report.

Nearly four out of every ten residents of the United States live near the coastline, and much of the US economy is also there.

Even if greenhouse gas emissions eventually decrease Sea level The huge ice sheets of Greenland and Antarctica will continue to melt and will continue to rise for centuries as it will take so long to reach a new equilibrium. A 2021 report from the Intergovernmental Panel on Climate Change states that excess heat already present in the climate system is trapped in current thermal expansion rates and melting of land ice for at least the next few decades. Is shown.

The United States was able to see a century’s worth of sea level rise in just 30 years

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Quote: What promotes sea level rise? The report reports that within 30 years there will be a one-foot rise and more frequent floods (February 16, 2022) on February 16, 2022 It warns that it was obtained from one-foot-decades-frequent.html.

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What causes sea level rise?The report warns that one leg will rise within 30 years and floods will occur more frequently.

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