What was done
The authors conducted a critical review of paleo-sea-level assessments made along the eastern coast of Brazil over the past 35 years based on more than a thousand radiocarbon-dated sea-level indicator samples from fourteen coastal sectors.

What was learned
In the postglacial transgression, sea level reached present mean sea level approximately 6600 years ago (years before present, yr BP). Thereafter, a mid-Holocene highstand with sea levels varying from a minimum of 2.1 to a maximum of 5.0 meters above current sea level was established somewhere between 5410 and 5195 yr BP. Still later, Angulo et al. say that "sea level apparently withstood an elevation between 2 and 3 m [above current sea level] until about 2000 yr BP," during "a progressive decline, with uneven rates, of the relative sea-level since the mid-Holocene highstand."

What it means
Sea level appears to have been slowly dropping along the eastern coast of Brazil for several thousand years; but Angulo et al. say "it cannot be ruled out, however, that the late Holocene sea-level fall in Brazil underwent small-scale (few decimeters) oscillations, such as those proposed by Baker et al. (2001) for southeast Australia." This possibility takes on increased importance in view of claims of possible sea-level rise associated with human-induced global warming. If, for example, sea-level has oscillated somewhat over this period, it is possible that the sea-level's current modest rising mode may be nothing more than a small portion of a natural oscillation having nothing to do with the ongoing rise in the air's CO2 content, which casts a pall of suspicion over climate-alarmist claims that the continued burning of fossil fuels will lead to the inundation of low-lying coastal areas and islands.

Reference
Baker, R.G.V, Haworth, R.J. and Flood, P.G. 2001. Warmer or cooler late Holocene marine palaeoenvironments? Interpreting southeast Australian and Brazilian sea-level changes using fixed biological indicators and their δ¹⁸O composition. Palaeogeography, Palaeoclimatology, Palaeoecology 168: 249-272.