 |
|
Close relationship between past warming and sea-level rise
June 23, 2009In a paper in Nature Geoscience, a team from the National Oceanography Centre, Southampton (NOCS), along with colleagues from Tübingen (Germany) and Bristol presents a novel continuous reconstruction of sea level fluctuations over the last 520 thousand years. Comparison of this record with data on global climate and carbon dioxide (CO2) levels from Antarctic ice cores suggests that even stabilisation at today's CO2 levels may commit us to sea-level rise over the next couple of millennia, to a level much higher than long-term projections from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).
Little is known about the total amount of possible sea-level rise in equilibrium with a given amount of global warming. This is because the melting of ice sheets is slow, even when temperature rises rapidly. As a consequence, current predictions of sea-level rise for the next century consider only the amount of ice sheet melt that will occur until that time. The total amount of ice sheet melting that will occur over millennia, given the current climate trends, remains poorly understood.
The new record reveals a systematic equilibrium relationship between global temperature and CO2 concentrations and sea-level changes over the last five glacial cycles. Projection of this relationship to today's CO2 concentrations results in a sea-level at 25 (±5) metres above the present. This is in close agreement with independent sea-level data from the Middle Pliocene epoch, 3-3.5 million years ago, when atmospheric CO2 concentrations were similar to the present-day value. This suggests that the identified relationship accurately records the fundamental long-term equilibrium behaviour of the climate system over the last 3.5 Million years.
Lead author Professor Eelco Rohling of the University of Southampton's School of Ocean and Earth Science based at NOCS, said: "Let's assume that our observed natural relationship between CO2 and temperature, and sea level, offers a reasonable 'model' for a future with sustained global warming. Then our result gives a statistically sound expectation of a potential total long-term sea-level rise. Even if we would curb all CO2 emissions today, and stabilise at the modern level (387 parts per million by volume), then our natural relationship suggests that sea level would continue to rise to about 25 m above the present. That is, it would rise to a level similar to that measured for the Middle Pliocene."
Project partners Professor Michal Kucera (University of Tübingen) and Dr Mark Siddall (University of Bristol), add: "We emphasise that such equilibration of sea level would take several thousands of years. But one still has to worry about the large difference between the inferred high equilibrium sea level and the level where sea level actually stands today. Recent geological history shows that times with similarly strong disequilibria commonly saw pulses of very rapid sea-level adjustment, at rates of 1-2 metres per century or higher."
The new study's projection of long-term sea-level change, based on the natural relationship of the last 0.5 to 3.5 million years, differs considerably from the IPCC's model-based long-term projection of +7 m. The discrepancy cannot be easily explained, and new work is needed to ensure that the 'gap is closed'.
The observed relationships from the recent geological past can form a test-bed or reality-check for models, to help them achieve improved future projections.
National Oceanography Centre, Southampton (UK)
Lead author Professor Eelco Rohling of the University of Southampton's School of Ocean and Earth Science based at NOCS, said: "Let's assume that our observed natural relationship between CO2 and temperature, and sea level, offers a reasonable 'model' for a future with sustained global warming. Then our result gives a statistically sound expectation of a potential total long-term sea-level rise. Even if we would curb all CO2 emissions today, and stabilise at the modern level (387 parts per million by volume), then our natural relationship suggests that sea level would continue to rise to about 25 m above the present. That is, it would rise to a level similar to that measured for the Middle Pliocene."
Project partners Professor Michal Kucera (University of Tübingen) and Dr Mark Siddall (University of Bristol), add: "We emphasise that such equilibration of sea level would take several thousands of years. But one still has to worry about the large difference between the inferred high equilibrium sea level and the level where sea level actually stands today. Recent geological history shows that times with similarly strong disequilibria commonly saw pulses of very rapid sea-level adjustment, at rates of 1-2 metres per century or higher."
The new study's projection of long-term sea-level change, based on the natural relationship of the last 0.5 to 3.5 million years, differs considerably from the IPCC's model-based long-term projection of +7 m. The discrepancy cannot be easily explained, and new work is needed to ensure that the 'gap is closed'.
The observed relationships from the recent geological past can form a test-bed or reality-check for models, to help them achieve improved future projections.
National Oceanography Centre, Southampton (UK)
Sea-level Current Events and Sea-level News RSSNorth Carolina sea levels rising 3 times faster than in previous 500 years, Penn study says
An international team of environmental scientists led by the University of Pennsylvania has shown that sea-level rise, at least in North Carolina, is accelerating.
Saving Sand: South Carolina Beaches Become a Model for Preservation
While most people head to Myrtle Beach for vacation, a group of scientists have been hitting the famous South Carolina beach for years to figure out how to keep the sand from washing away.
Diverting sediment-rich water below New Orleans could lead to extensive new land
Diverting sediment-rich water from the Mississippi River below New Orleans could generate new land in the river's delta in the next century.
Cuts to Mississippi levees could build new land in sinking delta
Diverting sediment-rich water from the Mississippi River below New Orleans could generate new land in the river's delta in the next century that would equal almost half the acreage otherwise expected to disappear during that period, a new study shows.
Rising sea levels are increasing the risk of flooding along the south coast of England
A new study by researchers at the University of Southampton has found that sea levels have been rising across the south coast of England over the past century, substantially increasing the risk of flooding during storms.
Peering under the ice of a collapsing polar coast
Starting this month, a giant NASA DC-8 aircraft loaded with geophysical instruments and scientists will buzz at low level over the coasts of West Antarctica, where ice sheets are collapsing at a pace far beyond what scientists expected a few years ago.
New coastland map could help strengthen sea defenses
The 'Coastland Map' produced by scientists from Durham University and published in the Journal GSA Today, charts the post Ice-Age tilt of the UK and Ireland and current relative sea-level changes.
Climate change triggered dwarfism in soil-dwelling creatures of the past
Ancient soil-inhabiting creatures decreased in body size by nearly half in response to a period of boosted carbon dioxide levels and higher temperatures, scientists have discovered.
How Will Future Sea-Level Rise Linked to Climate Change Affect Coastal Areas?
The anticipated sea-level rise associated with climate change, including increased storminess, over the next 100 years and the impact on the nation's low-lying coastal infrastructure is the focus of a new, interdisciplinary study led by geologists at The Florida State University.
Unlocking the secrets of the seafloor: The future of scientific ocean drilling
Close to 600 scientists from 21 countries met Sept. 23 - 25 2009 in Bremen, Germany, to outline major scientific targets for a new and ambitious ocean drilling research program.
More Sea-level Current Events and Sea-level News Articles
 |
The Best of Sea Level by Sea Level |
 |
Cats on the Coast by Sea Level |
 |
Ball Room by Sea Level Exclusive K2 24-bit remastered pressing comes packaged in a paper sleeve. |
 |
Sea Level by Sea Level |
|
On the Edge by Sea Level | |
 |
Sea Level Sea Level (Primary Contributor) |
 |
Long Walk on a Short Pier by Sea Level |
 |
The Sedimentary Record of Sea-Level Change by Angela L. Coe (Author), Dan W. J. Bosence (Author), Kevin D. Church (Author), Stephen S. Flint (Author), John A. Howell (Author), R. Chris L. Wilson (Author) This illustrated textbook describes how past changes in sea-level can be detected through an analysis of the sedimentary record, and how sequence stratigraphy techniques can provide explanations of how the sedimentary system evolves through geological time. Designed for use in undergraduate and graduate courses, it includes detailed case studies, set-aside focus boxes, and bulleted Questions and Answers interspersed throughout. The book is also supported by a website hosting sample pages. |
 |
Live Below Sea Level Starring: Fred Eaglesmith Recorded during Fred's last tour of Holland in November and December 2006, 13 tracks live in Haarlem and another 4 live in Spijkerboor. |
 |
Twenty Thousand Leagues Under the Sea (Bring the Classics to Life: Level 4) by Jules Verne (Author) Bring The Classics To Life Series - Reading Level 4.0-5.0. This novel has been adapted into 10 short reading chapters. Ages 7+ and English Language Learners of all ages. 8.5""x11"" ""worktext"". Abridged with excersice acitivities built in along with answer keys. |
| © 2009 BrightSurf.com |