…John A. Church of Australia, and his collaborator Neil J. White analyze records from instruments called tide gauges, starting in the 19th century and running into the 21st, and they also incorporate the satellite measurements of sea level that have been available since 1993.
The satellite record gives far more complete coverage of the ocean than the tide-gauge record, but of course it is much shorter and can reveal nothing about sea level through most of the 20th century. Additional techniques are being developed, like surveys of changes in salt marshes that closely track sea level, but the data from these methods are still sparse.
The new paper makes considerable efforts to compensate for these difficulties, putting the available data through rigorous tests to extract the trends. That said, the findings won’t be startling to anybody who is following this field; they are consistent with Dr. Church’s previous work, and they broadly match the bulk of the published science on sea level, like this paper and this one.
The paper confirms that the ocean has been rising in fits and starts since the 19th century. And both the tide gauges and satellites show that the rate of sea-level rise appears to have accelerated in the early 1990s, so that the ocean is now rising at about a foot per century, perhaps slightly less. That is almost twice the rate of increase that prevailed through most of the 20th century.
They are consistent with scientific work from glaciologists, whose calculations show an accelerating loss of ice from Greenland and Antarctica, as well as from many of the world’s mountain glaciers.
Many of the glaciologists expect a further increase in the rate of sea-level rise in the 21st century and fear that the ocean could rise as much three to six feet by century’s end.
The source article A Fresh Take on Sea-Level Rise - NYTimes.com .