How much will global sea level rise this century?
How much will global sea level rise this century? Well, global sea level rise began in the late 1700s, and accelerated to 1.2 inches (3 cm) per decade over the past 25 years (see my post, Sea level rise: what has happened so far). If the conditions that led to this acceleration continue, we can expect sea level will rise an additional 1.1 ft (0.34 m) by 2100 (Jevrejeva et al., 2008). At a minimum, sea level rise during the 21st century should equal that of the 20th century, about seven inches (0.6 ft, 0.18 meters). This is the lower bound given by the IPCC in its 2007 assessment, which projected sea level rise of 0.6 - 1.9 ft (0.18 - 0.59 m) by 2100. However, they cautioned in their report that due to the lack of knowledge about how melting glaciers behave, the actual sea level rise might be higher. There is a growing consensus that the 2007 IPCC sea level rise estimates are much too low.
Figure 1. Observed global sea level from tide gauges (red line, pink color is the uncertainty range) and satellite measurements (green line), with forecasts for the future. The blue colors show the range of projections for three different forecasts (the forecasts overlap, but this overlap is not shown). Image modified from U.S. EPA.
The 2007 IPCC report: too conservative?
Three major sea level rise studies published since the 2007 IPCC report have argued that the IPCC's projections of sea level rise are too conservative. A paper published in 2008 in Science by Pfeffer et al. (2008) concluded that the "most likely" range of sea level rise by 2100 is 2.6 - 6.6 ft (0.8 - 2.0 meters). Their estimates came from a detailed analysis of the processes the IPCC said were understood too poorly to model--the ice flow dynamics of glaciers in Greenland and Antarctica. For example, increased glacial flow may result when water draining from melt water lakes on the surface of the glacier to the base of the glacier, where it acts as a lubricant. The authors cautioned that "substantial uncertainties" exist in their estimates, and that the cost of building higher levees to protect against sea level rise is not trivial.
Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research in Germany looked at the observed relationship between changes in sea level and global temperatures since 1900 (Rahmstorf, 2007). Rahmstorf showed that that there has been a direct relationship between sea level rise and global average temperature: 0.1 - 0.3 meters of sea level rise occurs per °C increase in global temperature. Using this relationship, Rahmstorf predicted 1.6 - 4.6 ft (0.5 - 1.4 m) of sea level rise by 2100, since the IPCC predicts that global temperatures will rise 1.4° to 5.8°C. Rahmstorf concluded, "very low sea-level rise values as reported in the 2007 IPCC report now appear rather implausible in the light of the observational data".
A similar approach was taken by Grinsted et al. (2009), but they extended the relationship between sea level and global average temperature all the way back to 200 A.D. using proxy records. They concluded that ice sheets respond more quickly to temperature changes than the computer models used in the 2007 IPCC assessment. The authors estimated that "IPCC projections of sea level rise 2090 - 2099 are underestimated by roughly a factor of three". The authors predicted that global sea level will be rising 11 mm/year by 2050--four times faster than the 20th century rise. By the last decade of this century, they forecasted that sea level will rise 3.0 - 4.3 feet (0.9 - 1.3 meters), using the IPCC's A1B "business as usual" scenario.
The long-range forecast: using paleohistory to forecast sea level rise
We can also look at times in Earth's past that had similar climate to what we expect by the year 2100. The best time to look at is probably just before the most recent ice age--the Eemian. This interglacial period 130,000 - 114,000 years ago featured temperatures near the poles that were 2°C warmer than present-day temperatures. Tree line lay about 500 miles farther north in the Canadian Arctic, and the hippopotamus ranged as far north as the Thames River in England. A similar climate is expected under some of the more moderate global warming scenarios envisioned by the IPCC. Sea level is believed to have been 4 - 6 meters (13 - 20 feet) higher than at present during the Eemian, but there is at least one unpublished study that presents evidence that global sea level was 6 - 9 meters (20 - 30 feet) higher. If the climate does warm to levels seen in the Eemian, it is widely believed that we would again see sea levels at least 4 - 6 meters higher than the present-day levels. Clearly, sea level rises of this magnitude would be ruinous to society. However, most climate change scientists believe that it would take many centuries for enough ice to melt from the Greenland and West Antarctic ice sheets to create sea level rises of 4 - 6 meters.
However, the scientist who is arguably the most visible and authoritative climate scientist in the world, Dr. James Hansen of NASA, stated (Hansen, 2007) "I find it almost inconceivable that business-as-usual climate change would not yield a sea level change of the order of meters on the century timescale" (IPCC business-as-usual (BAU) scenarios assume that emissions of CO2 and other greenhouse gases will continue to increase year after year). Hansen gave a hypothetical but potentially realistic scenario where the sea level rise due to ice sheet disintegration doubles every decade, leading to a 16 foot (5 meter) sea level increase by 2100. He noted that during the Plio-Pleistocene period 2 - 3 million years ago, CO2 levels were similar to today (350 - 450 ppm), and global temperatures were 2 - 3°C warmer, similar to what we expect by the end of the century. Yet, this Plio-Pleistocene world was "a dramatically different planet, without Arctic sea ice in the warm seasons and with a sea level 25 ± 10 m higher."
Summary
To summarize, here are some predictions of how high global sea level might rise by 2100:
0.6 ft (0.18 m): Constant linear rise, equal to 20th century rise
1.1 ft (0.34 m): Constant acceleration model (Jevrejeva et al., 2008)
0.6 - 1.9 ft (0.18 - 0.59 m): Primitive models of ice sheets (IPCC, 2007)
1.6 - 4.6 ft (0.5 - 1.4 m): Relationship between temperature and sea level rise since 1900 (Rahmstorf, 2007)
3.0 - 4.3 feet (0.9 - 1.3 m): Relationship between temperature and sea level rise since 200 A.D. (Grinsted et al., 2009)
2.6 - 6.6 ft (0.8 - 2.0 meters): Considering glacier ice flow dynamics not included by the IPCC (Pfeffer et al., 2008)
In a 2009 interview with New Scientist magazine, sea level expert Stephan Rahmstorf said, "I sense that now a majority of sea level experts would agree with me that the IPCC projections are much too low." This sentiment was echoed by glaciologist Robert Bindschadler of the NASA Goddard Space Flight Center in Greenbelt, Maryland, who commented, "most of my community is comfortable expecting at least a metre by the end of this century."
In forthcoming posts in this series, I'll explore how a meter (3.28 feet) of sea level rise will affect the U.S. coast, the Caribbean, and other vulnerable locations world-wide. It would be wise to begin preparing now for a potential rise in sea level of a meter this century. In particular, development near the coasts should be severely restricted in low-elevation zones. It will be very expensive to protect or move infrastructure away from rising seas later this century. However, even if the rate of sea level rise doubles every decade, those of us who are over the age of 50 will not live to see sea level rise cause a significant disruption to society. There is time for society to prepare for the rising sea.
References
Jevrejeva, S., J.C. Moore, A. Grinsted,, and P.L. Woodworth, 2008, "Recent global sea level acceleration started over 200 years ago?", Geophysical Research Letters, 35, L08715, doi:10.1029/2008GL033611, 2008.
Grinsted, A., J.C. Moore, and S. Jevrejeva, 2009, "Reconstructing sea level from paleo and projected temperatures 200 to 2100 AD", Climate Dynamics, DOI 10.1007/s00382-008-0507-2, 06 January 2009.
Hansen, J., 2007, "Scientific reticence and sea level rise",, Environ. Res. Lett. 2 (April-June 2007) 024002 doi:10.1088/1748-9326/2/2/024002.
IPCC (Intergovernmental Panel on Climate Change), 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, UK, and New York, 996 pp.
Pfeffer, W.T., J.T. Harper, and S. O'Neel, 2008, "Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise", Science 321 no. 5894, pp. 1340-1343, 5 September 2008. DOI: 10.1126/science.1159099
Rahmstorf, Stefan. "Sea-Level Rise: A Semi-Empirical Approach to Projecting Future." Science 315 (2007): 368–370.
Other posts in this series
Sea level rise: what has happened so far
U.S. vulnerability to sea level rise
Wednesday, I'll take a look at the Atlantic hurricane forecast for the remainder of July. There's currently nothing out there worth discussing--will it stay that way?
Dr. Ricky Rood has some interesting commentary on the new climate change legislation that passed the House last month, and will go to the Senate in September.
Jeff Masters
Reader Comments
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Allan's Tropical Model and Weather Data Page
Curve and Recurve were in a boat....
Baaaa nevermind lol
Developed by the
Regional and Mesoscale Meteorology Branch at CIRA
Thanks Patrap! Let's have a quiet season...I won't have to make any trips to LA and you won't have to make any to TX :)
Dave Schwartz, Cheryl Lemke, Eboni Deon: Weather Channel fired staff
.."I gotta tell ya Folks,Im devasted by the news"..
.."Back to you in the Studio"..
If someone had to be fired, those people were the right choice. I didn't like any of them really. But then again, Stephanie Abrams doesn't do it for me either and she's their golden child it seems.
Lower Level Convergence
and
Upper Level Divergence
seven days or more?
...TROPICAL LOW...
LOW 14N112W 1008 MB MOVE WEST NORTHWEST 10 KT. THE CONVECTION IS
HIGHLY ASYMMETRIC WITH MOST OF THE CONVECTION EAST OF THE CENTER
AND NOT WELL ORGANIZED. MODEL GUIDANCE MOVES THE SYSTEM
NORTHWEST AT ABOUT 12 KNOTS AND WEAKENS THE CIRCULATION AFTER
ABOUT 36 HOURS. SCATTERED MODERATE TO STRONG CONVECTION IS
WITHIN THE AREA FROM 109.5W TO 112W FROM 11N TO 16N. PRES
GRADIENT N OF CENTER RESULTS IN LARGE AREA FRESH WINDS WITHIN
330 NM OF CENTER. TROPICAL CYCLONE FORMATION REMAINS A
POSSIBILITY AS BROAD TROUGH MOVES INTO A LESS ADVERSE WINDS
ALOFT.
You must be getting government money to continually espouse this AGW scam.There are many scientists who would readily dispute your storms and sea level rise predictions. Ever check out WUWT blog?
Thanks
Jack
ABNT20 KNHC 142340
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT TUE JUL 14 2009
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE NEXT 48 HOURS.
$$
FORECASTER BROWN
Couldnt have said it better myself.
LOL ah well.
Everything you hear on the radio dosent need to be repeated word for word.
It's not aimed that way, it will likely not make landfall.
While I believe Global Warming was a scam for money and is not real, it was wrong to accuse Dr. Masters.
http://cimss.ssec.wisc.edu/tropic2/real-time/windmain.php?&basin=europe&sat=wm7&prod=shr&zoom=&time=
maybe the circulation has gotten better organized, but it has no convection over its center lol
No, I want to make him carry ceses and cases and cases of water and hundreds of cots and set up five RedCross shelters and supplying them while driving around in 40mph winds for eighteen hours.
In torrential rain.
With crappy windsheild wipers.
And No defrost.
AND HUNGRY.
LOL you are getting antsy, have you applied for the hurricane center yet? There is nothing there yet to warrant any circles.
All that did for you was make me get a bowl of popcorn and laugh at the funny you got me. By the way, I don't drive.
can't believe we've re-visited the curve-recurve discussion, we went thru about four days of that arguement here last year...
How much curve could a re-curve curve...
Anyone who can read can see the Global evidence of the warming.
Most dont know what to think cuz they never have put forth the effort to see whats occurring, But most I bet Know who the Last Dancing with the Stars winner,or American Idol top dog was I bet.
Thus the confusion..
LOL
"A NEW ATLANTIC OCEAN TROPICAL WAVE IS ALONG 21W TO THE SOUTH
OF 16N. STRONG SHOWERS AND THUNDERSTORMS ARE FROM 10N TO 11.5N
BETWEEN 24W AND 26W."
http://www.nhc.noaa.gov/text/refresh/MIATWDAT+shtml/141734.shtml?
Hmmm... Quickscat shows a near closed surface low, there is a well-defined midlevel low with textbook outflow, and there has been persistant convection near the center for the past 24+ hours. And thats all it gets?
Ah so if someone doesnt agree with that point of view, we are all airheads who havent bothered to look into the debate? Please LOL
I would be helping people, and I really like to do that. About the seat maybe I had to go to the bathroom real bad and then it had a leak on it! LOL Anyways stop ridiculing me.
The NHC isnt around to satisfy some blogger's criteria for a invest, Thats why they have their criteria,...for it to be met.
Anyhoot,,whats the rush ?
I have a right to speak my mind, It's my opinion and I am subject to it.
Cuz in the near future,they wont be a Glacier in it.
I could give a rats butt what anyone thinks on the subject.
My opines as valid as any.
If ya want,..you can do a Blog on all you expound in Knowledge on the subject.
I'm a RedCross Disaster worker. Sometimes we gotta drag our kids around with us for short jobs. Like you, they help too, and are proud of being able to help.
Have one of Patrap's Frescas. I'm gonna have one too. :)
your opinion is your opinion, thats fine, but you are the one that assumed those who dont believe in Global Warming also watch American Idol and things like that. Nice assumption there, because they have everything to do with each other lol
There are many brillant people who dont buy into the GW speculation, does that mean they are airheads too?
Life is good.
Meet "Nola Roux"..our newest Fam member.
Now that is a cute puppy lol, Did he find what he was looking for in the grass?
Okay, I'll take it more easy, just that I think this tropical wave will last a long time.
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