the Earth’s climate warms, a melting ice sheet produces a distinct and
highly non-uniform pattern of sea-level change, with sea level falling
close to the melting ice sheet and rising progressively farther away.
The pattern for each ice sheet is unique and is known as its sea level
fingerprint. Now, a group of geophysicists from the University of
Toronto, Harvard and Rutgers Universities have found a way to identify
the sea level fingerprint left by a particular ice sheet, and possibly
enable a more precise estimate of its impact on global sea levels.
findings provide a new method to distinguish sea-level fingerprints in
historical records of sea levels, from other processes such as ocean
waves, tides, changes in ocean circulation, and thermal expansion of the
ocean,” says Carling Hay, a Ph D candidate in the Department of Physics
at the University of Toronto and lead author of a study published in Proceedings of the National Academy of Sciences (PNAS). “It may indeed allow us to estimate the contributions of individual ice sheets to rising global sea levels.”
around the world are trying to estimate both the current rate of sea
level rise and the rates of ice sheet melting, and yet little work has
been done to combine the two problems and answer these questions
and colleagues Jerry Mitrovica and Eric Morow of Harvard University,
and Robert E. Kopp of Rutgers University sought out statistical
techniques that had not previously been applied to this problem, and
began developing the new method using data analysis techniques common in
other fields such as engineering science, economics, and meteorology.
The researchers then tested and refined the method by applying it to
synthetic data sets—i.e., data sets with the same amount of noise as
real data, but with known melting signals. The tests provide important
guidance for the application of the method to actual sea-level records.
are now applying our methodology to historical sea level records to
provide a new estimate of total sea level rise and the melt rates of the
Greenland and West Antarctic ice sheets, over the 20th century,” says
Hay. “Preliminary results show intriguing evidence for acceleration of
globally averaged sea-level rise in the second half of the period, along
with a simultaneous rise in temperature. Once our study of historical
records is complete, the next step will be to incorporate
satellite-based measurements of sea-level changes.”
findings are reported in the paper “Estimating the sources of global
sea level rise with data assimilation techniques.” The research is
supported by funding from the Canadian Institute for Advanced Research,
Harvard University, and the US Department of Energy American Association
for the Advancement of Science Fellowship Program.
Source: University of Toronto