Tracking 30 Years of Sea Level Rise Around the World

Tracking 30 Years of Sea Level Rise

1992 – 2022

Global mean sea level has risen 101 millimeters (3.98 inches) since 1992, and it continues to do so at 3.9 mm (0.15 inches) per year.

A new satellite was launched by scientists and engineers thirty years ago to examine how the waters rise and decrease over time, a job that was previously only possible from the coast. On August 10, 1992, TOPEX/Poseidon launched into orbit and began a 30-year record of ocean surface height all across the globe. The findings have verified what scientists had previously seen from the shorelines: the seas are rising, and the rate is accelerating.

Researchers have found that global mean sea level—shown in the line plot above and below—has risen 10.1 centimeters (3.98 inches) since 1992. Over the past 140 years, satellites and tide gauges together show that global sea level has risen 21 to 24 centimeters (8 to 9 inches).

Beginning with TOPEX/Poseidon, NASA and partner space agencies have flown a continuous series of satellites that use radar altimeters to monitor ocean surface topography. Essentially, the satellites monitor the vertical shape and height of the ocean. Radar altimeters continually emit pulses of radio waves (microwaves), which are reflected back toward the satellite by the ocean’s surface. The instruments calculate the time it takes for the signal to return, while also tracking the precise location of the satellite in space. From this, scientists can calculate the height of the sea surface directly underneath the satellite.

Since 1992, five missions with similar altimeters have repeated the same orbit every 10 days: TOPEX/Poseidon (1992 to 2006), Jason-1 (2001 to 2013), the Ocean Surface Topography Mission/Jason-2 (2008 to 2019), Jason-3 (2016 to present), and Sentinel-6 Michael Freilich (2020 to present). The missions were built through various partnerships between NASA, France’s Centre National d’Etudes Spatiales (CNES), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), the European Space Agency (ESA), and the U.S. National Oceanic and Atmospheric Administration (NOAA).

Combined, the mission teams have assembled a unified, standardized ocean topography record that is equivalent to the work of a half-million tide gauges. The researchers accumulated and corroborated a data record that is now long enough and sensitive enough to detect global and regional sea level changes beyond the seasonal, yearly, and decadal cycles that naturally occur.

“With 30 years of data, we can finally see what a huge impact we have on the Earth’s climate,” said Josh Willis, an oceanographer at the Jet Propulsion Laboratory (JPL) and NASA’s project scientist for Sentinel-6 Michael Freilich. “The rise of sea level caused by human interference with the climate now dwarfs the natural cycles. And it is happening faster and faster every decade.”

The map at the top of this page shows global trends in sea level as observed from 1993 to 2022 by TOPEX/Poseidon, the three Jason missions, and Sentinel-6 Michael Freilich. Note the spatial variations in the rate of sea level rise, with some parts of the ocean rising faster (depicted in red and deep orange) than the global rate. Many of the anomalies reflect long-term shifts in ocean currents and heat distribution.

Global Sea Level Change Since TOPEX/Poseidon Launched 30 Years Ago

1992 – 2022

The altimetry data also show that the rate of sea level rise is accelerating. Over the course of the 20th century, global mean sea level rose at about 1.5 millimeters (0.06 inches) per year. By the early 1990s, it was about 2.5 mm (0.1 inches) per year. Over the past decade, the rate has increased to 3.9 mm (0.15 inches) per year.

In the line plot, the highs and lows each year are caused by the exchange of water between the land and sea. “Winter rain and snowfall in the northern hemisphere shifts water from ocean to land, and it takes some time for this to runoff back into the oceans,” Willis noted. “This effect usually causes about 1 centimeter of rise and fall each year, with a bit more or less during El Niño and La Niña years. It’s literally like the heartbeat of the planet.”

While a few millimeters of sea level rise per year may seem small, scientists estimate that every 2.5 centimeters (1 inch) of sea level rise translates into 2.5 meters (8.5 feet) of beachfront lost along the average coast. It also means that high tides and storm surges can rise even higher, bringing more coastal flooding, even on sunny days. In a report issued in February 2022, U.S. scientists concluded that by 2050 sea level along U.S. coastlines could rise between 25 to 30 centimeters (10 to 12 inches) above today’s levels.

“What stands out from the satellite altimetry record is that the rise over 30 years is about ten times bigger than the natural exchange of water between ocean and land in a year,” Willis said. “In other words, the human-caused rise in global sea level is now ten times bigger than the natural cycles.”

NASA Earth Observatory video and image by Joshua Stevens, using TOPEX/Poseidon data courtesy of Josh Willis/JPL-Caltech.

21 Comments on "Tracking 30 Years of Sea Level Rise Around the World"

  1. “In other words, the human-caused rise in global sea level is now ten times bigger than the natural cycles.”

    Where is the evidence presented that the long-term rise in sea level is all “human-caused?” In order for all the rise in sea level to be attributed to humans, it is necessary to demonstrate that all the global temperature increase is itself human caused. While estimates vary, it is commonly claimed that humans are responsible for 50-110% of the temperature increase. The latter figure would suggest the improbable situation of natural warming that started 20,000 years ago shut down at the beginning of the Industrial Revolution. It should be noted that the change in sea level is of the same order of magnitude as tectonic plate motion. As the tectonic plates move over the surface of Earth, the volumes of the ocean basins similarly change.

  2. Gordon Jenkins | August 19, 2022 at 5:24 pm | Reply

    The seiðrspel according to Josh Willis/JPL-Caltech. Subsidence and shore erosion is caused by humans only. Nature is nothing. Coincidence IS causation. Amen. Can I get an “amen” from the true believers of the most powerful new religion of the 21st century? Belcher Islands in Hudson Bay? Not sinking? Not Subsiding? Not eroding? Outliers! Ignore those blasphemous outliers sent to test your faith!

  3. HMM, AVERAGE SEA LEVEL RISE FOR A ONE HUNDRED YEAR PERIOD IS 36″. YOUR CALCULATIONS SHOWED ONLY A 4″ OCEAN RISE BY 2050,”Over the past decade, the rate has increased to 3.9 mm (0.15 inches) per year.” MY SIMPLE MATH X 28 YEARS = 4″.

    SO I AM WITNESSING AVERAGE OCEAN RISE. YOUR COMMENTS ON THE 2-2.5 METER OCEAN RISE WERE VAGUE IN TERMS OF HOW CENTIMETERS/MILIMETERS TURN INTI 8.5 FEET OF OCEAN RISE. SO, THE PANIC IS THE OCEAN IS RISING, OKAY. DO YOU WANT TO STOP IT, IF SO, HOW POSSIBLY CAN YOU? IT IS NATURE AT WORK FOR THE LAST 140+ YEARS AND BEYOND.

  4. Gee apparently some have the view that humans can pump vast amounts of CO2 into the atmosphere and have no impact on the climate, or this is small compared to natural cycles! Well the natural cycles are the ups and downs each year as indicated on the graph, the steady increase across these cycles is what is believed to be human induced sea level rise consequential to global warming and increased ice melt. Global warming, via higher levels of CO2 is old, and one would have thought settled science; it was first put forward in 1859.

    I note the rate of sea level rise is increasing, you can also see this on the graph. This means averages projected forward are inadequate, step up the maths and go to curve fitting then see where it goes 🙂

    • “… humans can pump vast amounts of CO2 into the atmosphere …”

      The human annual CO2 flux is about 3-4% of the total flux. I guess you could call that “vast amounts.” However, the known human contribution is less than the uncertainty in all the natural fluxes.

      The last continental glaciation peaked about 20,000 years ago, and melting glaciers have been contributing water to the oceans since then. The post-glacial warming causes the surface ocean water to expand. Besides the thermosteric increase in ocean volume, there are sediments pouring into the oceans from all the rivers in the world, and the northern land that is rebounding, from the melted ice formerly depressing it, is causing a decrease in the ocean basin volume.

      The recent ‘acceleration’ may or may not be a long-term effect. We will just have to wait and see. It wouldn’t be the first time that an increase in sea level rise was followed by a decrease.

  5. It is slightly amusing to read the denier’s ongoing comments. At least, if nothing else, I look forward to when they drown, burn, or starve.

    Meanwhile the positive feed backs loops have begun. Why are some people so opposed to stopping pollution? Because they love looking at the smoke blowing out their car exhaust? and bodily tailpipes?

    • Thank you for your well wishes.

      I haven’t seen smoke pouring out of tailpipes of gasoline-powered internal combustion engines since about the 1960s. Now, diesel engines are something else. One sometimes still sees soot coming from trucks.

  6. Geoff Monohan | August 21, 2022 at 5:42 am | Reply

    Considering CO2 makes up 0.04% of the atmosphere, 97% of that figure occur’s naturally. Humans contribute 3% of what’s less than half of .1% of the atmosphere. You may wish to reconsider the humans pumping vast amounts of CO2 line, no matter how you spin it CO2 is still a minor trace gas. So you would be more correct saying humans pump a minute amount of CO2 into the atmosphere, adding to the minute amount that’s already there. But follow the religion without question as you will.

  7. I’m a former environmental scientist because of the current lies. That being said. If oceanic rise is of such concern, then what bank in the world would lend money for ocean front property knowing that it may be underwater soon and no way to recoup their investment in it. Follow the money and you will find the truth. Also what about continental rebound rise from glacial offloading? It’s a known geological fact that North America has lifted after glacial offloading and offset oceanic rise of the melted ice shields. Lastly who in their abosulte expert knowledge can predict only doom and gloom coming out of the quartarnary ice age? It may wind up being the best thing to happen to humans existence on our planet. This year we have wide spread drought in the summer northern hemisphere and the nut bags are screaming its humans climate change. Actually it’s the big light bulb in our sky. This year is the highest recorded energy output of our sun ever. That’s why we are having a hard drought northern hemisphere summer and it may continue to be through the southern hemisphere summer ahead. We just don’t know. Co2 climate change is garbage science and that’s why I left the field. Like I said follow the money you will find the truth

  8. Interesting how climate change deniers are so passionate that they always post the first comments on articles like this.

    The reason for the sea level change is already known and widely validated by climate science. This project is about precision measurement, not about root cause analysis.

    • “Interesting how climate change deniers are so passionate that they always post the first comments on articles like this.”

      Not really a correlation between passion and timeliness. I read SciTechDaily every day, and I live in the eastern US time zone. I’m often the first commenter on other topics as well. You are projecting.

  9. Bill Williamson | August 21, 2022 at 10:16 am | Reply

    It’s amazing people are allowed to buy homes near there coast anymore…

  10. Interesting look at the last 30 years. What is the measured rate of sea level increase before 1992 (w/o satellites)…. say in the 40s? Also what has been the rate of temperature increase in the last 30 years as also measured, (now accurately) by satellites? Answers…..the rate of sea rise now is the same as the 40s and the heat of temperature increase is much lower than predicted based on modelling.

  11. Scientists agree that the Ice Age came on suddenly (circa 120k years ago). Before then, there were NO ICE CAPS, and thus seas would have been much higher, perhaps 400-500 feet higher. This actually suggests Atlantis residing in the now dry valley (Richat Structure) in Mauritania, which would have been a lush estuary during its heyday. So are we about to be bombed into another long nuclear winter in order to prevent global warming?

  12. Past measurements of prior interglacial periods demonstrated ocean level swings of 120+ meters (~400 feet). The last interglacial period experienced higher sea levels than presently. So saying human activity is the cause of climatic warming and sea level changes might be an exaggeration – unless one wants to speculate that similar civilizations arose during past interglacial periods and cause prior changes in temperatures and sea levels.

  13. Maurice Butler | August 21, 2022 at 10:26 pm | Reply

    This didn’t seem to be supported by Fort Dorset, Sydney, Australia with has over 100 years of tide records from the same place. Like wise Plymouth Rock should be under water.

  14. Yes, well these findings will confound the oceanographer at the University of Auckland who found most Pacific islands had INCREASED their surface area.

  15. Its not merely mean sea level that rises. Atmosphere sits on top, so on average the air masses would be pushed farther from center of earth.

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