The rising tide

Sea levels may rise five feet by 2100

Posted by Joseph Romm (Guest Contributor) at 3:56 PM on 31 Dec 2007

Read more about: climate | climate science | climate change impacts | oceans

A recent Nature Geoscience study, "High rates of sea-level rise during the last interglacial period," ($ubs. req'd) finds that sea levels could rise twice what the IPCC had project for 2100. This confirms what many scientists have recently warned (also see here), and it matches the conclusion of a study (PDF) earlier this year in Science.

[As an aside, in one debate with a denier -- can't remember who, they all kind of merge together -- I was challenged: "Name one peer-reviewed study projecting sea-level rise this century beyond the IPCC." Well, now there are two from this year alone!]

For the record, five feet (PDF) of sea level rise would submerge some 22,000 square miles of U.S. land just on the Atlantic and Gulf Coasts (farewell, southern Louisiana and Florida) -- and displace more than 100 million people worldwide. And, of course, sea levels would just keep rising some six inches a decade -- or, more likely, even faster next century than this century.

The researchers base their finding on their analysis of the rate of sea-level rise during the last warm or interglacial period (the Eemian, about 120,000 years ago), when seas rose 1.6 meters (five feet) per century. Why look at the rate of Eemian sea level rise? Becaause that's the last time the planet was as warm as it soon will be again: "such rates of sea-level rise occurred when the global mean temperature was 2 �C higher than today, as expected again by AD 2100."

Indeed, if we don't reverse emissions trends very soon (and stay below 450 ppm of carbon dioxide), the planet might well warm 3�C or more by 2100. The Eemian warming was driven by "changes in orbital parameters from today (greater obliquity and eccentricity, and perihelion), known as the Milankovitch cycle." Current warming is driven by human emissions of greenhouse gases.

Here is the entire abstract from the article -- note that the Eemian is also called "Marine Isotope Stage 5":

The last interglacial period, Marine Isotope Stage (MIS) 5e, was characterized by global mean surface temperatures that were at least 2 �C warmer than present. Mean sea level stood 4-6 m higher than modern sea level, with an important contribution from a reduction of the Greenland ice sheet. Although some fossil reef data indicate sea-level fluctuations of up to 10 m around the mean, so far it has not been possible to constrain the duration and rates of change of these shorter-term variations. Here, we use a combination of a continuous high-resolution sea-level record, based on the stable oxygen isotopes of planktonic foraminifera from the central Red Sea and age constraints from coral data to estimate rates of sea-level change during MIS-5e. We find average rates of sea-level rise of 1.6 m per century. As global mean temperatures during MIS-5e were comparable to projections for future climate change under the influence of anthropogenic greenhouse-gas emissions, these observed rates of sea-level change inform the ongoing debate about high versus low rates of sea-level rise in the coming century.

If we don't act now, we are clearly risking catastrophic sea level rise for many, many generations to come.

For story: The rising tide
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Looking on the Bright Side

Continuing a New Year Resolution to try to see the bright side of EVERYTHING...

The broad coastal plains inundated by the rise in sea level will become excellent habitat for marine life. Vast shallow areas will serve as buffers from storm surges, protecting new coastal wetlands for birds, mammals, reptiles, amphibians, et cetera. The unpredictable circumstances will drive humans inland, permitting establishment of new natural areas. Fisheries will rebound. Abandoned cities will be the foundations of new reefs.

Perhaps God is firing a shot over the bow. Rather than punish us for our sins by wiping out most of humanity with one enormous flood, He/She is giving Europe back to Arctic wildlife (no more Gulf Stream) and the coasts back to other wildlife. I wonder what He/She will do if we ignore THIS warning.

by wiscidea at 6:07 PM on 31 Dec 2007

Rising Tide needs Detergent

Senor Romm, We need to wash the minds of all of you folks who do not understand Earth Science.We will get more water,but that will all be over in a few short years and we will get cooler for a few years,then stabilise.Us old senior scientists from Earth Service have informed and informed folks about the anomalous energies that visit our galaxy on a periodical basis and revv the grid system(and not the power companys grid system,by the way,as I have had some folks giggle when they were unable to process my taskings)The 10.5 solar cycle we all know about is just an example of the energy that visits us.This anomaly period that has a 1050 year periodicity(Do yo get the connection between the 10.5 I spoke to and the 1050 I am speaking to now??) has been affecting us now for over 20 years and ebbs and flows until the main body that rides on that oxygen line passes us by,we will get belted with weather just as the biblical story has taught some,as that was a story of the experiencing of the 1050,the glaciers will return,life will go back to somewhat normal,although extra water will inhabit the earth.Carbon components do not cause warming and plants do not make the oxygen on our earth or any other.Hydrogen and oxygen come into this planet as a gas frequency just as ozone is produced by just a blue uv light in many peoples hot tubs and your favorite beauty/barber shop for years and most folks just dont put it together that the light frequency demonstration is telling them something,just as we science men from earth service have been trying to tell some of you folks something about how their earth actually works.The other planets in our solar system make the gases we need for human/animal/plant survival.We spin at the same frequency as Mars and that planet has a 24 hour day and was previously inhabited. All of our solar system planets have been perturbed by this anomaly,of which I can completely explain,very simply in fact.But the bottom line is that the damage being done with ill informed science /media is creating economics problems and political problems everywhere and those that propagate the hysteria of carbon based man made global warming are tantamount to treasonous action against all of this earths citizens when they fail to just look about them when Earth Service science men show them the planetary science information that is necessary for their properness as science men.Tell me Mr. Romm ,just what does open the stomata on a leaf? Just for openers and tell me Mr. Romm how you would process if this old Papa told you we have a crystalline core on this planet and that that fact gives anyone who can process the secret of gravity along with grid science giving all of the clues necessary for proper understanding of climate science,every single one and the other planets in our system work on the same EXACT scientific principles.I would choose to wash you Mr. Romm ,so you might start anew,but Im afraid from my experience with earlier taskings with you that you will remain in the spin cycle. Ta for now.

Earth Shaman

by Earth Shaman at 10:46 PM on 31 Dec 2007

Some interesting comments

We posted something similar a couple of weeks previously and received some interesting comments:

http://www.talkclimatechange.com/2007/12/18/is-sea-level- ...

TalkClimateChange - news, opinion, talk.

by mseall at 2:30 AM on 01 Jan 2008

Nobody knows anything, maybe?

Five feet over a century sounds reasonable, although we really don't know where, when, or exactly why.

Where: the Earth is not perfectly round and water will flow at different rates from the poles towards the Equator in a "lumpy" manner perhaps, is my understanding. So maybe that is why some islands in the Indian Ocean and South Asia seem to have a more pronounced sea level rise that other places? I haven't a clue.

When: this depends on the release of a whole bunch of land-based ice being melted into water. Think glaciers. Sea ice already displaces water in the ocean (ice actually expands compared to a liquid state, right?). But our predictions of land ice melt possibly require more investigation. That could be catastrophic, a "Noah event."

Why: well let's say heat trapping gases in the lower atmosphere are strongly correlated, although as Earth Shaman points out, Circadian cycles may be present as well - with unknown effects IMHO.

But as a sort of modern-day "beach man," the impacts on coastal communities could be felt even with a rise of a foot or so. Now that is serious, because with erosion and land subsidence, and the fact that many communities on the Gulf and Atlantic coasts were built with a 300-foot beach, the beach would simply disappear! No more beaches. Some of the best Pacific surf breaks will be lost as well. Wow, surfing of all kinds is really going to suffer.

Yep, 12 inches would be a total disaster for many of us living on what is a sand spit. /sam

Onward through the fog

by Sam Wells at 11:02 AM on 01 Jan 2008

Anybody's guess is good. Why not 20 ft?

Because we are already off the bad side of any global warming model that wasn't calculated on an xbox by the deniers. Anybody, anywhere who says they have a good model for climate change is full of it at this point because last summers arctic ice melt took everybody by surprise.

Exactly how much methane is coming out of the siberian permafrost is also a product of pure speculation. We know that there is more biologically available carbon in those permafrosts than every chunk of coal and drop of oil ever burnt but we don't know how to estimate the eventual release or what the feedback mechanisms will be.

All we are really sure of is that events are off the bad side of the charts.

All us backyard Noahs better get to building. How long is a cubit anyway? It's the Waterworld baby. TEOTWAWKI (sing along now..)

Put the Carbon Back

by Pangolin at 3:22 PM on 01 Jan 2008

Conclusions Matching Conclusions

I'm so glad your conclusion matched their conclusion. Which was also the result of a summary of a brief. That summary is now being used to distill a policy into an action statement. The outcome of which will be that of their conclusion.

We're still waiting on the data.

But that will come.

Or else we'll make some up.

by jabailo at 10:38 PM on 01 Jan 2008

ADVERTISING POLICY

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