Welcome to the sea level pages of PIK
We love the sea and the coast. And
we want to better understand the interplay of sea level, climate
and coasts, as part of our integrated Earth system science. The
Potsdam Institute is home to one of the world's leading sea level
Our research is publically funded and the insights should be of
use to all. On these pages we thus provide comprehensive information
about our sea level research. You will not only find the results,
scientific papers and popular articles, but also input data and
computer codes which allow colleagues to reproduce our calculations,
verify them or develop them further.
Global ocean water volume shown as one
Adam Nieman, Carbon Visuals
Sea level in Earth's history. At the
height of the last Ice Age huge ice sheets covered the northern
continents. When the Ice Age came to a close, global temperature
rose by 5 ºC and two thirds of the ice melted. Sea level rose
by 120 meters - a rise that only came to a close around 4,000 years
ago. The remaining third of the ice is still around today on Greenland
and Antarctica - enough to raise global sea level by a further 60
meters. With our climate models we simulate
complete glacial cycles and the waxing and waning of the ice.
Together with US colleagues we work towards reconstructing
sea level changes over the past millennia from proxy data.
Projections of future sea level rise. In
our research group the "semi-empirical
method" was developed to estimate future sea level rise
following from a specified global warming scenario. This method
uses a simple, physics-based relationship between global temperature
and sea level, which is calibrated using data from the past. In
addition we work on regional sea level projections which take into
account regional differences in sea level rise, caused e.g. by the
gravity effect of shrinking ice sheets.
Ocean currents and thermal expansion.
We work with global ocean circulation models to understand issues
like the thermal
expansion of ocean waters due to global warming or the effect
of changing ocean currents on regional sea levels.
Dynamics of continental ice masses.
Together with the University of Alaska, PIK develops the Parallel
Ice Sheet Model (PISM), an innovative computer model of continental
ice sheet dynamics. We use this model to study the stability of
the Antarctic ice sheet. In addition we have coupled the ice
model Sicopolis to our Earth System model CLIMBER-2 to study
the stability of the Greenland ice sheet in past and future climate
Coastal impacts. Jointly with the European
Climate Forum and the universities of Kiel and Southampton we are
developing the integrated model DIVA.
DIVA is a global model to estimate impacts of sea level rise on
all coastal nations as well as the costs and benefits of possible
adaptation measures. The model covers a multitude of social, ecological
and economic effects, e.g. beach erosion, inundation of coasts,
storm surge damages, migration of affected people, changes in coastal
ecosystems and the penetration of salt water into the lower reaches
Our current global sea level projections
Future sea level rise primarily depends
on our future greenhouse gas emissions. Depending on the
emissions scenario (B1, A2, A1FI) our semi-empirical estimates (central
estimates published 2009) range between ca. 1.0 and 1.4 meters for
the period 1990-2100. This is significantly more than corresponding
estimates of the 2007 IPCC report ("AR4") based on process-based
models. The red line shows tide gauge data (Church & White 2006).
Graph taken from Vermeer
& Rahmstorf 2009. Data download here.
Worldwide cooperation and recognition
Oceans and climate know no national frontiers. Hence we cooperate
with leading sea level researchers from around the world, for example
in joint studies published with Anny Cazenave (CNES, France), John
Church (CSIRO, Australia), Ben Horton (Univ. of Pennsylvania) and
Bob Nicholls (Univ. of Southampton). Our publications are amongst
the most-cited in the community: out of the over 9,000 sea level
studies published in the past five years, our papers rank #1, #2
and #3 (*). Broadly based assessments have endorsed our projections,
e.g. the Antarctic
Science Report, the Copenhagen
Diagnosis, the Arctic Report
of AMAP and the 2012 World
Bank Climate Report.
A number of states uses our semi-empirical method in coastal planning,
e.g. the Netherlands and the US states California
Carolina, and our results have entered the recommendations
of the US Army Corps of Engineers. The unique DIVA model is
used in a number of global and continental-scale studies, e.g. Economics
of Adaptation to Climate Change (World Bank, 2010) and the state
of environment report of the European Environment Agency.
Prof. Levermann was appointed lead author of the sea level chapter
of the IPCC. Prof. Rahmstorf served
in the Delta Commission
of the Dutch government. Graphs from our work are used e.g. by the
government and in the Garnaut-Review
for the Australian government.
Media interest is likewise high: BBC and CNN reported in their
TV news broadcasts about our research, the weekly magazine of the
british Financial Times in 2009 had a cover
portrait of Prof. Rahmstorf as "Mr sea level rise",
and the New York Times prominently presented our results in a major
cover story on sea level rise.
(*) According to a search of the publications
data base ISI Web of Science
for the term "sea level" since publication year 2007.
Search conducted on 21 November 2011.