NASA provides key insights into sea-level rise

NASA provides key insights into sea-level rise. Since the launch of its first major oceanographic research satellite in 1992, NASA has collected a record of sea-level rise that spans nearly three decades. Other missions like the U.S.-German Gravity Recovery and Climate Experiment (GRACE) have provided valuable insight into the evolution of sea ice, particularly at the poles.

NASA scientists have determined that Greenland lost 600 billion tons of ice last summer, which is enough to raise global sea levels by a tenth of an inch. Both Greenland and Antarctica are losing ice six times faster today compared to the 1990s.

According to NASA, these measurements are important because the Earth’s glaciers and ice sheets contain enough water to raise global sea levels by more than 195 feet, or 60 meters.

Ice losses in Greenland and Antarctica can lead to sea-level rise that causes coastal flooding far from where the ice melts, even in communities that are on the other side of the world.

Beyond satellite observations, scientists need a closer view to monitor sea levels and sea ice loss. Josh Willis is an expert in the NASA Jet Propulsion Laboratory in Southern California.

“The satellites tell us it’s happening. But we want to know why – what’s causing it?” said Willis. “Generally speaking, it’s global warming. But in a specific sense, how much is it the melting of polar ice sheets as opposed to glaciers? And how much is it ocean warming and thermal expansion? Most importantly, what’s going to happen in the future?”

Willis is the lead investigator for Oceans Melting Greenland (OMG), a mission that was designed to answer some of these questions. OMG maps glaciers, measures the temperature and salinity of the water, and obtains precise maps of the seafloor along the coastline of Greenland. The datasets can be combined to study how Greenland’s glaciers are responding to rising ocean and atmospheric temperatures.

“The satellites are telling us how much global sea level is rising, but the airborne and shipborne data are really telling us how much Greenland is contributing to it, and what’s causing Greenland to contribute to it,” said Willis. “It’s a piece of a much bigger puzzle, but it’s an important piece because Greenland alone has enough ice to raise global sea levels by 25 feet.”

NASA reports that high-tide flooding has doubled in the last 30 years across low-lying communities. There are also other factors, such as sinking land and ocean currents, that can make an area more susceptible to flooding. 

NASA scientists are working with land and resource managers to help mitigate coastal flooding risks.

Ben Hamlington is the head of the Sea Level Change Science Team at the Jet Propulsion Lab.

“A lot of coastal communities are working to identify particular parts of their towns where there have been flooding issues, and they are trying to adopt strategies to lessen the impact of sea level rise and flooding in those areas,” said Hamlington.

“We’re often able to provide the high-resolution information that they need to make important decisions, particularly in terms of subsidence, which can differ quite a bit over even short distances.”

Flooding is one of the most common natural disasters in the United States, causing billions of dollars in damage each year. While global warming is threatening coastal communities with more frequent flooding, the intense storms and excessive rainfall associated with climate change could impact nearly every region of the country.

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By Chrissy Sexton, Earth.com Staff Writer