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New predictions for sea level rise
July 27, 2009Fossil coral data and temperature records derived from ice-core measurements have been used to place better constraints on future sea level rise, and to test sea level projections.
The results are published today in Nature Geoscience and predict that the amount of sea level rise by the end of this century will be between 7- 82 cm - depending on the amount of warming that occurs - a figure similar to that projected by the IPCC report of 2007.
Placing limits on the amount of sea level rise over the next century is one of the most pressing challenges for climate scientists. The uncertainties around different methods to achieve accurate predictions are highly contentious because the response of the Greenland and Antarctic ice sheets to warming is not well understood.
Dr Mark Siddall from the University of Bristol, together with colleagues from Switzerland and the US, used fossil coral data and temperature records derived from ice-core measurements to reconstruct sea level fluctuations in response to changing climate for the past 22,000 years, a period that covers the transition from glacial maximum to the warm Holocene interglacial period.
By considering how sea level has responded to temperature since the end of the last glacial period, Siddall and colleagues predict that the amount of sea level rise by the end of this century will be similar to that projected by the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).
Dr Siddall said: "Given that the two approaches are entirely independent of each other, this result strengthens the confidence with which one may interpret the IPCC results. It is of vital importance that this semi-empirical result, based on a wealth of data from fossil corals, converges so closely with the IPCC estimates.
"Furthermore, as the time constant of the sea level response is 2,900 years, our model indicates that the impact of twentieth-century warming on sea level will continue for many centuries into the future. It will therefore constitute an important component of climate change in the future."
The IPCC used sophisticated climate models to carry out their analysis, whereas Siddall and colleagues used a simple, conceptual model which is trained to match the sea level changes that have occurred since the end of the last ice age.
The new model explains much of the variability observed over the past 22,000 years and, in response to the minimum (1.1 oC) and maximum (6.4 oC) warming projected for AD 2100 by the IPCC model, this new model predicts, respectively, 7 and 82 cm of sea-level rise by the end of this century. The IPCC model predicted a slightly narrower range of sea level rise - between 18 and 76 cm.
The researchers emphasise that because we will be at least 200 years into a perturbed climate state by the end of this century, the lessons of long-term change in the past may be key to understanding future change.
University of Bristol
Dr Mark Siddall from the University of Bristol, together with colleagues from Switzerland and the US, used fossil coral data and temperature records derived from ice-core measurements to reconstruct sea level fluctuations in response to changing climate for the past 22,000 years, a period that covers the transition from glacial maximum to the warm Holocene interglacial period.
By considering how sea level has responded to temperature since the end of the last glacial period, Siddall and colleagues predict that the amount of sea level rise by the end of this century will be similar to that projected by the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).
Dr Siddall said: "Given that the two approaches are entirely independent of each other, this result strengthens the confidence with which one may interpret the IPCC results. It is of vital importance that this semi-empirical result, based on a wealth of data from fossil corals, converges so closely with the IPCC estimates.
"Furthermore, as the time constant of the sea level response is 2,900 years, our model indicates that the impact of twentieth-century warming on sea level will continue for many centuries into the future. It will therefore constitute an important component of climate change in the future."
The IPCC used sophisticated climate models to carry out their analysis, whereas Siddall and colleagues used a simple, conceptual model which is trained to match the sea level changes that have occurred since the end of the last ice age.
The new model explains much of the variability observed over the past 22,000 years and, in response to the minimum (1.1 oC) and maximum (6.4 oC) warming projected for AD 2100 by the IPCC model, this new model predicts, respectively, 7 and 82 cm of sea-level rise by the end of this century. The IPCC model predicted a slightly narrower range of sea level rise - between 18 and 76 cm.
The researchers emphasise that because we will be at least 200 years into a perturbed climate state by the end of this century, the lessons of long-term change in the past may be key to understanding future change.
University of Bristol
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Cuts to Mississippi levees could build new land in sinking delta
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NASA flies to Antarctica for largest airborne polar ice survey
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World's river deltas sinking due to human activity, says new study led by CU-Boulder
A new study led by the University of Colorado at Boulder indicates most of the world's low-lying river deltas are sinking from human activity, making them increasingly vulnerable to flooding from rivers and ocean storms and putting tens of millions of people at risk.
Carnegie Institution
The future of the Earth could rest on potentially dangerous and unproven geoengineering technologies unless emissions of carbon dioxide can be greatly reduced, a new study has found.
Antarctic glacier thinning at alarming rate
The thinning of a gigantic glacier in Antarctica is accelerating, scientists warned today. The Pine Island Glacier in West Antarctica, which is around twice the size of Scotland, is losing ice four times as fast as it was a decade years ago.
Study: Greenland ice sheet larger contributor to sea-level rise
The Greenland ice sheet is melting faster than expected according to a new study led by a University of Alaska Fairbanks researcher and published in the journal Hydrological Processes.
Lesson from the past for surviving climate change
Research led by the University of Leicester suggests people today and in future generations should look to the past in order to mitigate the worst effects of climate change.
Melting Greenland Ice Sheets May Threaten Northeast United States, Canada
Melting of the Greenland ice sheet this century may drive more water than previously thought toward the already threatened coastlines of New York, Boston, Halifax, and other cities in the northeastern United States and Canada.
Melting threat from West Antarctic Ice Sheet may be less than expected, could hit US hardest
While a total or partial collapse of the West Antarctic Ice Sheet as a result of warming would not raise global sea levels as high as some predict, levels on the U.S. seaboards would rise 25 percent more than the global average and threaten cities like New York, Washington, D.C., and San Francisco, according to a new study.
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