There is no sign of a storm on this clear afternoon in Norfolk, Virginia, as seawater collects along the curb. The wind is calm and the sky is bright. However, the tide seems to be trying the city’s patience as it creeps across the asphalt. “Sunny day flooding,” as the locals refer to it, has become oddly commonplace.
Something subtle but significant appears to be taking place beneath these serene scenes, according to recent NASA data. Global sea levels increased by 0.59 centimeters in 2024, which is much more than the 0.43 centimeters that scientists had predicted. It may seem like a little difference. It isn’t. From approximately 0.21 centimeters per year in the early 1990s to approximately 0.45 centimeters in recent years, the annual rate of sea level rise has more than doubled over the course of three decades of satellite records.
| Category | Details |
|---|---|
| Agency | NASA |
| Key Data Source | NASA Sea Level Change Team |
| 2024 Global Sea Level Rise | 0.59 cm (higher than projected 0.43 cm) |
| Total Rise Since 1993 | ~10 cm (4 inches) |
| Main 2024 Driver | Thermal expansion (warming ocean water) |
| Arctic Monitoring | Landsat satellite program |
| Official Sea Level Portal | https://sealevel.nasa.gov |
| Earth Science Data Access | https://earthdata.nasa.gov |
Researchers were taken aback by the driver as well as the acceleration. For many years, the main topic of discussion was melting ice sheets and glaciers. Thermal expansion, or the warming and physical swelling of oceans due to heat absorption, was responsible for almost two-thirds of the rise in 2024. Over 90% of the excess planetary heat is absorbed by the ocean, which seems to be subtly changing shape.
This change seemed to have been concealed in plain sight. There is evidence of ice melt, including retreating glaciers and collapsing shelves. Warming water isn’t. It lifts coastlines inch by inch as it grows invisibly. The color gradients travel the world like a slow pulse when viewing satellite animations from NASA’s Sea Level Change portal. There is no significant surge in the ocean. It builds up.
Landsat imagery has been used to map erosion hotspots in the Arctic, where coastlines retreat by over a meter annually. At Point Hope, Alaska, sediment accumulates on one side of a settlement while erosion eats away at the other. These regional differences might be a cover for a more widespread instability. Sea levels are rising, waves are getting stronger, and permafrost is thawing in unpredictable ways.
The data paints a more comprehensive picture. Sea levels have increased by about 10 centimeters since 1993. That’s roughly four inches, which is sufficient to alter the baseline for each high tide. Whether the 2024 spike is a particularly warm anomaly or the beginning of a steeper trend is still unknown. However, scientists are wary. The ocean’s heat content keeps increasing.
Within the next 30 years, an additional 15 centimeters are predicted to arrive in the Pacific Islands. That isn’t abstract for atolls that are low in the sky. It means that crops and wells are contaminated by saltwater seeping into freshwater lenses. It indicates that in some areas, high tide flooding is increasing tenfold. Coastal real estate markets are expected to adjust, according to investors. How fast adaptation can surpass physics is a mystery.
Other layers exist. Damage is increased by storm surges that ride on top of higher seas. Changes in water density cause subtle shifts in tidal cycles. Researchers predict clusters of high-tide flooding events, rather than isolated occurrences, to start occurring in coastal areas of the United States in the mid-2030s. It’s difficult not to sense the future quietly approaching as Miami Beach locals navigate flooded intersections on otherwise serene mornings.
There is some sudden change along the coast. Overnight, hurricanes redraw coastlines. The more disturbing change, however, is statistically slow. Without underlying sea level rise, the great majority of nuisance floods observed over the last 20 years would not have happened. The statement isn’t dramatic. It’s math.
Despite global water rise, post-glacial rebound is lifting land in some places in Greenland and parts of Canada. In some places, the coast gets bigger, and in others, it gets smaller. Perception is complicated by this unevenness. While some beaches disappear, it enables skeptics to identify stable ones. Rarely does climate change occur in a uniform manner.
It seems as though satellites, which are millimeters in size and orbit silently, have taken on the role of our distant witnesses. Satellite altimetry creates a planetary perspective, in contrast to tide gauges that are fixed to particular ports. It is hard to ignore the acceleration shown by the data, which spans more than 30 years.
But there is still uncertainty. Ocean rise in early 2025 was slowed by a recent La Niña pattern that temporarily stored more rainfall on land. For some, it was a sign of relief. It was dubbed a pause by scientists. Water has the ability to regain its equilibrium.
Subtlety, rather than secrecy, is what makes this climate change “hidden.” The ocean is warming beneath the surface, reshaping coastlines without much fanfare, and expanding without spectacle. Not a siren. No press until a certain threshold is reached.
After a winter storm, one can observe dunes moving and hooks forming along barrier beaches while standing along Cape Cod. This is what storms have always done. However, the starting line has shifted due to higher seas. Every surge extends a little further inland. The baseline rises a bit every year.
According to NASA data, the end of the world is not imminent. They show momentum. compounding momentum. momentum that increases the cost of severe storms and the frequency of minor floods. There is a silent realization as you watch this happen: the coastline is not a permanent boundary. The terms of the negotiation between land and water are evolving.
