Nature study finds many coastal sea-level risk assessments used underestimated baseline water heights

What exactly does the study say was underestimated?

It says many assessments used a baseline coastal water height that was too low—meaning the starting point for estimating flooding and exposure was underestimated, by about 30 cm on average across the reviewed work. Weather Channel Guardian Hindu

Why does the study say this underestimation happens?

Coverage of the study says the error often comes from mismatches in how sea level and land elevation are measured and referenced—using different vertical reference surfaces (datums) or models that don’t align with observed local sea surface heights. Weather Channel DIE WELT as

Where does the study indicate the problem is most pronounced?

Reports say it is more frequent in parts of the Global South—particularly the Pacific and Southeast Asia/Indo-Pacific—while being less common in Europe and along Atlantic coasts. Weather Channel Guardian NBC News