Jumat, 20 November 2020

New NASA Mission To Map Sea Level Rise May Help California Adapt To Changing Coastline - Capital Public Radio News


This story was originally published Dec. 26, 2019, and updated with new reporting about the satellite’s launch Nov. 19, 2020.

NASA has collected data on how seas are rising across the planet for more than 25 years. A new mission is launching this weekend, which will extend that data for five years and may help places like California adapt as seas rise. But the data also poses some major concerns.

“The sea level rise we see today is unlikely to ever be reversed in our lifetimes,” said Josh Willis, the mission’s project scientist at NASA’s Jet Propulsion Laboratory in Pasadena. “Right now, we have about one inch per decade of sea level rise, but it’s widely predicted that this rate of rise will increase.”

The satellite launches Saturday at 9:17 a.m. and can be watched live here. The satellite has a radar altimeter to measure the distance between it and the ocean’s surface within a few centimeters of accuracy. It will do this everywhere across the world every 10 days. 

Willis says tracking sea level rise is important because “two-thirds of the Earth's surface are literally growing because of climate change. We are literally reshaping the Earth.”

The satellite, called Sentinel-6 Michael Freilich/Jason-CS, short for Jason-Continuity of Service, is the fifth iteration of a satellite that tracks sea level rise and is the longest-running mission working on the issue. The first satellite was launched in 1992

As the satellite orbits about 800 miles above Earth the goal is to answer this question: How much will Earth's oceans rise by 2030? Ice melt has caused oceans to rise about 8 inches since 1880 and by 2100 they’re expected to rise between 1 and 4 feet, according to the National Oceanic and Atmospheric Administration. 

“By averaging all that data together, we hope to be able to see the rising of the oceans to within an accuracy of a millimeter or so within a year,” Willis said. 

One week's worth of data from NASA's Earth observing satellites show the rising sea level on Earth between Oct. 29 and Nov. 7, 2019. Areas in red show higher levels, while blue show the lowest.NASA/JPL-Caltech

Data from the other missions have helped agencies learn about El Niño and La Niña, weather systems that have a huge impact on California. 

“Today, we have 27 years of data and having that long time series allows us to detect time signals, but we couldn’t do that without the early data,” said Steve Nerem, a professor in the Department of Aerospace Engineering Sciences at the University of Colorado.

“It’s really one of the most valuable climate data records that we have today,” Nerem said. “We would just be blind without the satellites.”

The data from the satellites also help better predict hurricane intensity and how ocean currents change.

“The satellites just completely change our understanding of sea level rise, what the variability is, and it gives us this complete picture because the measurements are global,” Nerem said.

This satellite is named after the former director of NASA's Earth Science division, and will measure sea level around the globe for the next five years. At that point an identical satellite will replace Sentinel-6/Jason-CS. The mission is a collaboration between NASA and the European Space Agency.

The satellite was developed by the European Space Agency, the European Organization for the Exploitation of Meteorological Satellite, NASA and the National Oceanic and Atmospheric Administration with some funding from the European Commission and from France's National Centre for Space Studies.

“We all share the same oceans … and when a place like Greenland starts losing its ice, sea level all around the world increases and coastlines all around the world are already battling the rising tide of the oceans caused by global warming,” Willis said. 

How Will The Mission Help California? 

People love the Golden State because of the coastline. There are all sorts of songs about the vibe California embodies — think “California Gurls” by Katy Perry, “Californication” by the Red Hot Chili Peppers and “California Love” by 2Pac.

But the ocean's response to climate change is threatening that very identity. 

"It's part of what you often hear described as being Californian,” said Christine Whitcraft, director of Cal State Long Beach's Environmental Science and Policy program. “Threats from sea level rise are important for economics, but they're also important for the intrinsic value they have to us as Californians."

The sea could rise by half a foot by 2030 and as much as 7 feet by the end of the century, according to a high-level report from the state's Legislative Analyst’s Office from 2019. That could have a huge impact on the millions of Californians who live along the coast.

“We could lose two-thirds of our beaches absent any action,” said Rachel Ehlers, a principal fiscal and policy analyst with the LAO. She is also the lead author of the report intended to guide lawmakers as they create legislation. 

“There are many communities around the state that are planning, but very few that have moved on to the phase of taking action,” Ehlers said. “We need to do that both because the water is coming, but also this is a key time to test out strategies.”

This animation shows the radar pulse from the Sentinel-6 Michael Freilich satellite's altimeter bouncing off the sea surface in order to measure the height of the ocean.NASA/JPL-Caltech

To understand how future sea level rise will alter California there needs to be an understanding of how oceans around the world are dealing with warming temperatures, says Ben Hamlington, a research scientist at the NASA Jet Propulsion Laboratory who studies sea level rise.

“Sea level rise is a global problem, but the impacts are local,” he said. “If I'm trying to understand sea level at the coast of California, I don't want a snapshot of what's happened in California, I want a broad view of the Pacific and the broader climate system.”

The data the satellite collects will help with building that understanding, and compared to other satellites this one has the capability to more accurately measure sea level variation near coastlines. That means researchers on the project will be able to help give insights to how rising seas may directly impact communities and businesses. 

Hamlington says there are many variables to factor in along the California coast, including the influence of weather patterns like El Niño and La Niña

“We know sea level is going up off the coast of California,” he said. “Scientifically the coast of California is a really interesting scientific problem because there are a number of processes at play. And really, you have to bring so many different observations to bear to try to understand sea level here.”

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November 20, 2020 at 09:37AM

New NASA Mission To Map Sea Level Rise May Help California Adapt To Changing Coastline - Capital Public Radio News



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