Sea-levels worldwide will likely rise by 50 to 130 centimeters by the end of this century if greenhouse gas emissions are not reduced rapidly. This is shown in a new study led by the Potsdam Institute for Climate Impact Research that, for the first time, combines the two most important estimation methods for future sea-level rise and yields a more robust risk range. A second study, like the first one to be published in the US Proceedings of the National Academy of Sciences, provides the first global analysis of sea-level data for the past 3000 years. It confirms that during the past millennia sea-level has never risen nearly as fast as during the last century.
Together, the two studies give critical information for coastal planning. For expert assessments of future sea-level rise, the authors make the tool available online.
“With all the greenhouse-gases we already emitted, we cannot stop the seas from rising altogether, but we can substantially limit the rate of the rise by ending the use of fossil fuels,” says Anders Levermann, Research Domain Co-Chair for Adaptation at the Potsdam-Institute for Climate Impact Research (PIK), scientist at Columbia University’s Lamont-Doherty Earth Observatory, and co-author of the study on future sea-level rise. “We try to give coastal planners what they need for adaptation planning, be it building dikes, designing insurance schemes for floodings, or mapping long-term settlement retreat.”
+++Even if the Paris Agreement is implemented, adaptation is a challenge+++
The scientists will make the computer simulation code available online so experts can use the information and the estimation tool for risk assessments. Even if ambitious climate policy follows the 2015 Paris Agreement, sea levels are projected to increase by 20 to 60 centimeters by 2100 – hence the relevance for coastal protection. “This is quite a challenge, but less expensive than adaptation to unabated sea-level rise which in some regions is impossible”, Levermann adds. “If the world wants to avoid the greatest losses and damages, it now has to rapidly follow the path laid out by the UN climate summit in Paris a few weeks ago.”
For future sea-level rise, the scientists combine two approaches. To forecast sea-level rise, some scientists use process-based computer simulations that calculate the contribution of melting glaciers, ice sheet mass loss and the thermal expansion of sea-water from physical laws – warmer water takes more space. These simulations are computationally costly and slow. As an alternative, statistical analyses have been used to assess future sea-level rise quickly at low computational cost. “We designed our tool in a way it is consistent both with the past observations of sea-level rise and the long-term physical processes in the different elements of the Earth system,” says lead-author Matthias Mengel from PIK. “Importantly, our calculation method is fast, which makes it easy to reproduce and allows for a lot of simulation runs to provide probabilities of sea-level rise."
The likely future sea-level rise cannot be brought down to just one number, but is represented as a range, which at first sight might seem large. “The range allows for a risk assessment,” says Ben Marzeion from the University of Bremen, Germany. “Coastal Planners need to know how a reasonable worst-case scenario as well as a well-founded best-case scenario look like to weigh chances and costs. The best available science is now converging towards a common uncertainty range of future sea-level rise. Curbing greenhouse gas emissions now gives us the chance to prevent sea level rise to accelerate further.”
+++During past millennia sea-level has never risen as fast as during the last century+++
The study on future sea-level rise turns out to be confirmed by the other one on past sea-level rise: they yield nearly identical sea-level rise estimates for the 21st century. Also, the new estimates overlap with those of the latest IPCC report.
“Our study is for sea level what the now well-confirmed famous ‘hockey stick’ diagram was for global temperature,” says Stefan Rahmstorf, co-author of the paper on past sea-level rise and Co-Chair of PIK’s research domain Earth System Analysis. “We can confirm what earlier, more local sea-level data already suggested: during the past millennia sea-level has never risen nearly as fast as during the last century.” Based on the analysis of the past millennia of natural sea-level variations, the new study was also able to estimate how much human activities have contributed to modern sea-level rise: Almost certainly more than half of the 20th Century rise has been caused by human activity, possibly even all of it.
Confirming previous assumptions, as boring as it might sound, is of key relevance for the progress of science. “We can now show the effect in an unprecedentedly robust way, based upon the statistical analysis of a global database of regional sea-level reconstructions,” says Rahmstorf. “The new sea-level data confirm once again just how unusual the age of modern global warming due to our greenhouse gas emissions is – and they demonstrate that one of the most dangerous impacts of global warming, rising seas, is well underway.”
Article on future sea-level rise: Mengel, M., Levermann, A., Frieler, K., Robinson, A., Marzeion, B., Winkelmann, R. (2016): Future sea-level rise constrained by observations and long-term commitment. Proceedings of the National Academy of Sciences (PNAS) [DOI:10.1073/pnas.1500515113]
Weblink to the article on future sea-level rise once it is published: www.pnas.org/cgi/doi/10.1073/pnas.1500515113
Weblink to source code for future sea-level rise approximation tool: https://github.com/matthiasmengel/sealevel
Article on past sea-level rise: Kopp, R.E., Kemp, A.C., Bittermann, K., Horton, B.P., Donnelly, J.P., Gehrels, W.R., Hay, C.C., Mitrovica, J.X., Morrow, E.D., Rahmstorf, S. (2016): Temperature-driven global sea-level variability in the Common Era. Proceedings of the National Academy of Sciences (PNAS) [DOI:10.1073/pnas.1517056113]
Weblink to the article on past sea-level rise once it is published: http://www.pnas.org/cgi/doi/10.1073/pnas.1517056113
For further information please contact:
PIK press office
Phone: +49 331 288 25 07
Jonas Viering | Potsdam-Institut für Klimafolgenforschung
NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center
Steep rise of the Bernese Alps
24.03.2017 | Universität Bern
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy