6-8 inches over the last 100 or so yrs is negligible in the grand lifespan of Earth. Even if those two photos were taken during different ride flows, unless you hade very large and legible measuring sticks and the photos were taken at the same place, with the same aspect ratio, magnification, and lighting, you still wouldn't be able to determine whether there is any measurable increase in ocean levels.
6-8 inches over the last 100 or so yrs is negligible in the grand lifespan of Earth. Even if those two photos were taken during different ride flows, unless you hade very large and legible measuring sticks and the photos were taken at the same place, with the same aspect ratio, magnification, and lighting, you still wouldn't be able to determine whether there is any measurable increase in ocean levels.