Sea Level Reconstruction

A sea-level reconstruction is a continuous estimate of past sea level built by combining sparse long records with spatial structure from a denser source. Instrumental reconstructions blend the global tide-gauge network (PSMSL) with the spatial patterns from 1993-onward satellite altimetry, using EOF or Kalman methods to extend a global-mean and regional series back to about 1900. Paleo reconstructions instead use proxies such as salt-marsh foraminifera dated by radiocarbon to recover Common Era sea level. Both are how the rate of rise is shown to have accelerated, and they supply the baseline against which projections and future sea-level allowances are set.