Historical records may underestimate global sea level rise
New research published in Geophysical Research Letters shows that the longest and highest-quality records of historical ocean water levels may underestimate the amount of global average sea level rise that occurred during the 20th century. Dr. Philip Thompson, associate director of the University of Hawai'i Sea Level Center in the School of Ocean and Earth Science and Technology (SOEST), led the study.
A team of earth scientists from the University of Hawai'i at Manoa, Old Dominion University, and the NASA Jet Propulsion Laboratory worked together to evaluate how various processes that cause sea level to change differently in different places may have affected past measurements. One particularly important concept is the existence of "ice melt fingerprints," which are global patterns of sea level change caused by deviations in Earth's rotation and local gravity that occur when a large ice mass melts. Each glacier, ice cap, or ice sheet has a unique melt fingerprint that can be determined using NASA's GRACE satellite measurements of Earth's changing gravitational field.
|The current site of the San Francisco tide gauge operated by NOAA, which is one of the longest and highest-quality records |
of ocean water level in the world. The tide gauge was initially installed in 1854 [Credit: NOAA Tides and Currents]
"This is really important, because it is possible that certain melt fingerprints or the influence of wind on ocean circulation might cause us to overestimate past sea level rise," said Thompson, "but these results suggest that is not likely and allow us to establish the minimum amount of global sea level rose that could have occurred during the last century."
The investigation concludes that it is highly unlikely that global average sea level rose less than 14 centimeters during the 20th century, while the most likely amount was closer to 17 centimeters.
Source: University of Hawaii at Manoa [October 03, 2016]