How much will global sea level rise this century?

By: Dr. Jeff Masters , 02:49 PM GMT am 13. Juli 2009

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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

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Quoting weathermanwannabe:


Latest CMISS has 20 knots of sheer just to the North, a small gap of 10 knows between 40 & 50 W, then it picks up again...I think it's either going to dissipate or get sheared apart if it gains more latitute over the next two days.....And, no rotation at the surface levels...


And? That is deadly shear? I tend to disagree there
My Local Weather:
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I'm good!

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183. IKE
Quoting TheWeatherMan504:


Schwartz was one of the Best. After they let us go TWC rating's have drastically fallen.


I can see why...they ticked off a number of viewers.
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Quoting IKE:


When NBC took over it seemed to change TWC. I saw Abrams and Bettis on in the morning..and Stephanie was not there that day...nice looking blond lady was subbing...the one that use to be on in the mornings with Marshall Seese...she's good on the air...a lot better than Abrams.


Heather Tesch I think
Quoting BurnedAfterPosting:


Deadly shear? Um where?

Also the system is definitely high enough for coreolis to take effect


Latest CMISS has 20 knots of sheer just to the North, a small gap of 10 knows between 40 & 50 W, then it picks up again...I think it's either going to dissipate or get sheared apart if it gains more latitute over the next two days.....And, no rotation at the surface levels...
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Quoting CaneWarning:


I couldn't stand watching Schwartz. I don't watch TWC anymore either. It's become a joke most of the time. Now that most places have their own cable news network 24/7, I'm not sure there is a need for TWC so much.


Schwartz was one of the Best. After they let us go TWC rating's have drastically fallen.
Member Since: Mai 18, 2008 Posts: 2 Comments: 1042
178. IKE
Quoting TheWeatherMan504:


I got a Federal Grant and I'm heading back to college in August.


When NBC took over it seemed to change TWC. I saw Abrams and Bettis on in the morning..and Stephanie was not there that day...nice looking blond lady was subbing...the one that use to be on in the mornings with Marshall Seese...she's good on the air...a lot better than Abrams.
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Quoting BigTuna:

I can't even post here once per season without getting trolled! *sigh*


?
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Quoting IKE:


Mancuso and Schwartz are both good on-air. I didn't like it when I found that out.

Sorry they laid you off.


I couldn't stand watching Schwartz. I don't watch TWC anymore either. It's become a joke most of the time. Now that most places have their own cable news network 24/7, I'm not sure there is a need for TWC so much.
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shear is 5 knots over the wave
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Quoting IKE:


Mancuso and Schwartz are both good on-air. I didn't like it when I found that out.

Sorry they laid you off.


It was a really depressing. But we knew there was trouble when NBC bought TWC.

Luckily, I got a Federal Grant and I'm heading back to college in August.
Member Since: Mai 18, 2008 Posts: 2 Comments: 1042
12z Tropical Formation Probability has come out and has increased greatly for the wave

http://www.ssd.noaa.gov/PS/TROP/TCFP/data/current/gexyrfpr.png
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Only a 40% chance of weather being a go at the cape

link
Member Since: Mai 16, 2009 Posts: 1 Comments: 1231
170. IKE
Quoting TheWeatherMan504:


They also let go Mark Mancuso, Dave Schwartz, Cheryl Lemke and Eboni Deon. Just name a few on air Mets. They also layed off many employees on the field. Including me.... They blamed the economy. So expect less TWC reporters on the field and more NBC This Hurricane Season. I don't even watch them anymore.


Mancuso and Schwartz are both good on-air. I didn't like it when I found that out.

Sorry they laid you off.
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Quoting futuremet:


One thing I hate about TWC is the fact they continue to promote fallacious propaganda such as GW to make more money

I can't even post here once per season without getting trolled! *sigh*
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Quoting IKE:


Link


They also let go Mark Mancuso, Dave Schwartz, Cheryl Lemke and Eboni Deon. Just name a few on air Mets. They also layed off many employees on the field. Including me.... They blamed the economy. So expect less TWC reporters on the field and more NBC reporters This Hurricane Season. But I don't even watch them anymore, Its become a fashion show when their live.
Member Since: Mai 18, 2008 Posts: 2 Comments: 1042
"'tis mute ,the word they went to hear on high dodona Mountain"
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165. IKE
Quoting BigTuna:

Not sure why it's even called TWC anymore, since 'The Commercial Channel' doesn't have a 'W' anywhere in it!


Agree...they do have too many commercials.


Quoting sporteguy03:


it is in HD though now :)


Sorry...I'm on rabbit ears.
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Quoting weathermanwannabe:


I seriously doubt it; not high enough in the latitudes for significant coreolis action and deadly sheer to the north if it does breach 10N IMHO.


Deadly shear? Um where?

Also the system is definitely high enough for coreolis to take effect
Quoting BigTuna:

Not sure why it's even called TWC anymore, since 'The Commercial Channel' doesn't have a 'W' anywhere in it!


One thing I hate about TWC is the fact they continue to promote fallacious propaganda such as GW to make more money
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Quoting IKE:


Yeah, that's right...you worked there.


it is in HD though now :)
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Quoting Cotillion:
Chill guys... if it happens, it happens. Still isn't quite CVS yet, so don't get too hopeful.

Sit and enjoy the view of no imminent danger...

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Quoting IKE:


I can't watch TWC anymore...

Not sure why it's even called TWC anymore, since 'The Commercial Channel' doesn't have a 'W' anywhere in it!
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157. IKE
Quoting TheWeatherMan504:


They also layed off some good producers... cough


Yeah, that's right...you worked there.
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Tropical Update

BBIAW

Also, I would describe the area as a tropical wave. It is more a broad area of low pressure.
Member Since: Juli 24, 2005 Posts: 407 Comments: 19076
155. Skyepony (Mod)
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Quoting IKE:


That's true....juts don't like the way they fired some good mets since NBC took over and that sleeze-ball met that got fired for his sleezy comments to that female met.


They also layed off some good producers... cough
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Quoting alaina1085:
Ike, that song made me feel like a flower child...:p



is this eHarmony??? :o)

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Quoting Acemmett90:

Heres ana jk


I seriously doubt it; not high enough in the latitudes for significant coreolis action and deadly sheer to the north if it does breach 10N IMHO.
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Quoting leftovers:
does gfs have the system centered correctly?


Yes the Coordinates are

999N 999W
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Hey WeatherStudent....

:)
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149. IKE
Quoting futuremet:


Who got fired?


Link
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Ike, that song made me feel like a flower child...:p
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Quoting IKE:


That's true....juts don't like the way they fired some good mets since NBC took over and that sleeze-ball met that got fired for his sleezy comments to that female met.


Who got fired?
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146. IKE
Quoting alaina1085:
I have a really good friend who is a free lance camera guy and he does alot of jobs for TWC and he even says how bad they suck and how unorganized they are. He also says Mike Seidel is a weirdo! LOL.... hes scary to work for.


He's one I enjoy listening to.

That's in front of a camera though. Off camera...?
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Quoting WeatherStudent:


I see why now, thansk for teh data, FM. However, SW said taht if it were to make it into the Carib it wouldn't survive eitehr because of teh destructive wind shear values in tehre right now.


No, by the time it gets to the Caribbean wind shear will become favorable. Keep in mind that the effects of the trough will be weaker if this system moves in the Caribbean, so the recurvature will be postponed. In about two weeks from now, the upper level dynamics should be more favorable for tropical cyclogenesis, as most of the ULLs embedded in the TUTT moves away. The long range GFS is expecting the upper level winds to be more anticyclonic over the next two weeks, which indicates lower shear. However I am reluctant to jump to any conclusions at the moment; I'll remain conservative for the time being.
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I have a really good friend who is a free lance camera guy and he does alot of jobs for TWC and he even says how bad they suck and how unorganized they are. He also says Mike Seidel is a weirdo! LOL.... hes scary to work for.
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143. IKE
Quoting alaina1085:
Ike, you crack me up....LOL.


I get cracked up listening to the classic guitar on this song.

Thanks:)
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Quoting WeatherStudent:


In addition, did you notice how this latest GFS model run eventually mainstains it stationary around the southeast coast until the next through comes around and kicks it off to the northeast. Ain't gonna happen, lol. :)


Um if one trough misses then yes it could easily stall and meander
The TWC have become to reliant on travel companies. They promote good weather down in the Caribbean which in turns favors the cruise ship companies that support the TWC. Things like "Nothing to worry about if your heading down to the islands, so have a great cruz over by Acapulco."

I have been watching the TWC since 1998, when they were good.
Member Since: Juli 24, 2005 Posts: 407 Comments: 19076
Quoting CaribBoy:
Wow at least a post each minute! this thing is the CATL really speed up the blog


And the first official invest will clog and slow down the blog...........
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Ike, you crack me up....LOL.
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136. IKE
Quoting sporteguy03:


Something to watch at least besides it too hot outside to wash a car :)


LOL....
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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