The Intergovernmental Panel on Climate Change and climate scientists the world over have warned that sea levels would rise as global warming continued. Recent research in the Falkland Islands has found evidence of that, with data from 1842 helping to corroborate what many had already firmly believed.
“We have been fortunate in being able to compare modern sea-level measurements obtained from tide gauges and from satellite radar altimeters with historical measurements made at Port Louis in the Falkland Islands in 1842,” explained researcher Prof. Philip Woodworth of the National Oceanography Centre.
James Clark Ross
In 1839 James Clark Ross (later knighted), on his way to the Antarctic to search for the magnetic south pole, having already discovered the magnetic north pole in an expedition to the Arctic, made a stop at Port Louis, the first settlement on the Falkland Islands founded almost a century earlier. His ships – the HMS Erebus and HMS Terror – had taken damage passing through the Drake Passage, and he set up a winter base on the island.
As a result, Ross took careful measurements of the sea level relative to two benchmarks that were cut into the cliffs and marked with brass plaques that remain in good condition today.
These measurements have allowed Woodworth’s team to compare the sea level in 1842 to current day levels, along with measurements taken in the interim in 1981, 1983 and 2009. Combined with data from nearby Port Stanley, where a permanent tide gauge was operated between the 1960s and 1970s and then again from 1992, and with correction for air pressure effects and vertical land movement, the researchers were able to arrive at conclusive measurements that show a rising sea.
The data show that sea levels have risen by an average of approximately 0.75 millimetres a year between 1842 and the early 1980s, figures similar to other estimates for long-term sea level rise at Port Arthur, Tasmania, Australia, measurements with which Ross was also associated, as well as other locations in the Northern and Southern hemispheres.
Unsurprisingly the data show that sea-level rise has accelerated over recent decades, with estimates suggesting that sea levels around the Falkland Islands have risen by an average of approximately 2.5 millimetres a year since 1992, a figure once again consistent with separate data, measurements made by satellite radar altimeters over the same period.
“The benchmarks left by James Clark Ross on the cliffs of Port Louis will facilitate future studies of sea-level change – just as Ross intended,” said Woodworth.
Image Source: Strange Ones