Sea level rise over past century unmatched in 6,000 years
The sea level rise seen over the past century is unmatched by any period in the past 6,000 years. The reconstruction of 35,000 years of sea level fluctuations finds that there is no evidence that levels changed by more than 20cm in a relatively steady period that lasted between 6,000 years ago and about 150 years ago.
This makes the past century extremely unusual in the historical record, with about a 20cm rise in global sea levels since the start of the 20th century. Scientists have identified rising temperatures, which have caused polar ice to melt and thermal expansion of the sea, as a primary cause of the sea level increase.
A two-decade-long collection of about 1,000 ancient sediment samples off Britain, north America, Greenland and the Seychelles formed the basis of the research, led by the Australian National University and published in PNAS.
The 35,000-year span of the study was chosen as this comprises an interglacial period. Researchers could pick submerged sediments that may include tree roots, suggesting a previously lower sea level, or mollusks, which can be measured against the fossil record to determine the previous sea level.