Rapid Sea Level Changes and Surface Temperature Change
- The preservation of the relic shellcrusts up to 2.5m above present in Australia, southeast Asia, southeast Africa and southern Brazil indicates that sea level fell ~ 1 metre rapidly at least once (and possibly rose ~ 1 metre at ~4500 cal yr BP) in a time- frame of less than 50 years.
- The coincidence in time-elevation change in these continents suggest fluctuations in the ocean current conveyor belt rather than tectonic or hydro-isostatic uplift.
- Sea-levels were higher (~ 1 metre) but cooler than present over periods of the mid- to late-Holocene.
- The invasion and disappearance of tropical and/or temperate species coincide with changes in time-elevations of relic inter-tidal zones. Delta oxygen 18 measurements also support sudden changes in sea surface temperatures and sea-levels in near-shore environments
Sea levels were higher (~1m) but air temperatures were cooler than present (from 3500 to 1500 yrs BP). Note the warmer phases 4300 to 3800 and 5500 yrs cal BP (see below).
A coincidence of change in southern hemisphere far-field sites?
(Source: Baker et al. 2001)