Do photos prove that sea levels aren't rising? No, that's not true: Scientists agree that the global sea level is rising, and it is rising at an increasing rate. Photographs of historic landmarks, displayed without any context or explanation, cannot show whether sea levels are rising or falling.
The photos appeared in a Facebook post published on July 17, 2022. It features a video with a series of images, including side-by-side photographs of Fort Denison in Sydney Harbour, Australia, and a photograph of Plymouth Rock. Atop the pictures of Fort Denison, text reads:
Unprecedented climate change has caused sea level at Sydney Harbour to rise approximately 0.0 cm over the past 140 years.
This is what the post looked like on Facebook at the time of writing:
(Source: Facebook screenshot taken on Fri Jul 29 16:13:31 2022 UTC)
Taken by themselves, photographs purporting to show Fort Denison, 140 years apart, do not say anything about sea levels. It's unclear what time of year the photographs were taken, just as it's unclear whether they were taken at high or low tide.
Regardless, the assertion that the sea level in Sydney has not risen over the past 140 years is false. The National Oceanic and Atmospheric Administration (NOAA) reports that the relative sea level trend there is .75 millimeters a year, which works out to be a rise of roughly 3 inches in 100 years. That increase is less than that of the global sea level, which rises at a rate of about one-eighth of an inch a year (or 12½ inches in 100 years), according to NOAA. That rate has increased in recent decades, NOAA says.
The agency explains the difference between global and local sea levels on its website:
Global sea level trends and relative sea level trends are different measurements. Just as the surface of the Earth is not flat, the surface of the ocean is also not flat--in other words, the sea surface is not changing at the same rate globally. Sea level rise at specific locations may be more or less than the global average due to many local factors: subsidence, upstream flood control, erosion, regional ocean currents, variations in land height, and whether the land is still rebounding from the compressive weight of Ice Age glaciers.
The Facebook post also includes a photograph of Plymouth Rock with text that reads: "2022 Still at Sea Level."
Lead Stories has written about this image before and found that the photo does not show that there has been no change in sea level in the past 400 years. Claims to the contrary are based on false assumptions: one, that Plymouth Rock has been in the same place since 1620 (it hasn't), and, two, that a single photograph of a rock in a tidal zone can show the current sea level or prove that there has been no change over time.
