NASA assessment finds sea level has risen more than 9 centimeters in just 30 years: ScienceAlert

It probably comes as no surprise to people living in low-lying coastal regions, but the waters of the sea are rising significantly and measurably. This assessment comes from NASA, which analyzed 30 years of satellite sea level measurements.

The news is not good. Since 1993, the seas have risen by a total of 9.1 centimeters. Two years ago, it had increased by 0.27 centimeters. This one-year increase from 2021 to 2022 may seem small in comparison, but it’s a warning sign.

And it adds up over time.

Even taking into account slight changes due to natural influences like La Niña (which periodically cools the oceans), the height of the seas continues to rise. Based on continuous long-term satellite measurements, the projected rate of sea level rise will reach 0.66 centimeters per year by 2050.

To bring this idea home, NASA estimated last year that levels along US coasts could rise up to 30 centimeters above their current level by 2050. It could get worse in other parts of the world.

We cause this sea level rise

The culprit of all this is human-caused climate change. It is driven by the excessive amounts of greenhouse gases like carbon dioxide that humans pump into the atmosphere. Climate change is having a number of effects across the globe, but it’s particularly evident in Earth’s ice caps and glaciers.

In the past year alone, the Antarctic ice sheet has seen above-average melting, even taking summer temperatures into account.

Image of Earth showing sea level measured by the Sentinel-6 Michael Freilich satellite in 2021. Red areas are regions where sea level is above normal while blue indicates where it is below normal. normal. The satellite collects measurements for about 90% of the Earth’s oceans. (NASA Earth Observatory)

The stability of the Greenland ice sheet has changed a lot, and today the Greenland ice sheet is a major contributor to sea level rise. This is because its runoff and Antarctic ice water add more fresh water to the ocean as warming causes the ocean to expand. seawater. The result is rising seas that cancel out other natural effects on the height of the sea surface.

Sea level tracking from space

The best and most accurate way to track the rise in ocean height is by using space-based instruments on satellites.

The American-French TOPEX/Poseidon mission began measuring the height of the sea surface in 1993. Since then, sea level observations have continued through missions led by NASA, ESA and the United States National Oceanic and Atmospheric Administration (NOAA).

Scientific and technical innovations such as radar altimeters make it possible to produce ever more precise measurements of sea level around the world. To calculate the height of the sea, they bounce microwave signals off the surface of the ocean. Then they record the time it takes for the signal to travel from a satellite to Earth and back, as well as the strength of the return signal.

An illustration of the Sentinel-6 Michael Freilich satellite. Launched in November 2020, it is one of the latest in a series of spacecraft – beginning with TOPEX/Poseidon in 1992 and continuing with the Jason series of satellites – that have been collecting ocean height measurements for nearly 30 years. (NASA/JPL-Caltech)

“We have this clear view of recent sea level rise – and can better predict how much and how fast the oceans will continue to rise – because NASA and the Center National d’Etudes Spatiales (CNES) have brought together decades of ocean observations.

“By combining this data with measurements from the rest of NASA’s fleet, we can also understand why the ocean is rising,” said Karen St. Germain, director of NASA’s Earth Sciences Division in Washington.

The 30-year-old satellite record not only shows long-term trends, but allows scientists to see through short-term natural changes.

“It helps us identify trends that tell us where sea level is heading,” said JPL’s Ben Hamlington, a researcher who leads NASA’s Sea Level Change Science Team.

These measurements are coupled with almost a century of terrestrial observations and long-term measurements of greenhouse gases in the atmosphere. Data from measurements of ice mass and land motion give scientists a better idea of ​​how and why the seas are rising.

Ground level effects of sea level rise

All of these fundamental observations are important for understanding the effects of climate change. But they also help shape the kinds of services that federal and international agencies provide to coastal communities. These are the front-line places that must prepare for rising waters.

An aerial view of icebergs near Kulusuk Island, off the southeast coast of Greenland, an area that is experiencing an accelerating rate of ice loss. Water runs off into the ocean and contributes to sea level rise. (NASA Goddard Space Flight Center)

As this rise continues, at least 800 million people will face a rise of at least half a meter in water levels. Concretely, places like Miami, New York, Bangkok, Shanghai, Lima (Peru), Cape Town and many others will suffer continual marine incursions.

The coastal regions of the United States alone are home to more than half of the country’s population. They contain major shipping ports, as well as recreation areas and other facilities. The major physical impacts of sea level rise also threaten wildlife populations, delta regions, marshes and wetlands.

These are just some of the effects of climate change and how it is causing sea levels to rise. That’s why fleets of satellites not only track rising sea water, but also atmospheric concentrations of gases such as carbon dioxide.

“Tracking the greenhouse gases we’re adding to the atmosphere tells us how much we’re pushing the climate, but sea level shows us how much it’s responding,” said Jet Propulsion oceanographer Josh Willis. NASA laboratory in Southern California.

“These measurements are a critical yardstick for determining how much humans are reshaping the climate.”

This article was originally published by Universe Today. Read the original article.

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