How much will global sea level rise this century?

By: Dr. Jeff Masters , 2:49 PM GMT on July 13, 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 Michfan:
My god here we go again. I just wish that some would act like the professionals they profess to be when it comes to the weather. All this wishcasting is getting ridiculous.


Just go with the flow.


Albeit all of us desire an outcome, we should not let our desire detriment our forecast.
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Quoting K8eCane:



who wishcasted? missed it


Beats me lol
MS2 Julie Payette from Canada now getting ready to go into the orbiter.
Member Since: July 8, 2005 Posts: 259 Comments: 25167
Quoting BurnedAfterPosting:


Wishcasting? lol man no one on here can even discuss a possible area of interest without being called a Wishcaster lol. I have seen the term used many times on my sites in my time, never have I see the word thrown around with such reckless abandon as it is on here.

Makes me feel like people can't talk freely about it without being ridiculed by somebody



who wishcasted? missed it
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The basic weather launch commit criteria on the pad at liftoff must be:


Temperature: Prior to external tank propellant loading, tanking will not begin if the 24 hour average temperature has been below 41 degrees.

After tanking begins, the countdown shall not be continued nor the Shuttle launched if:

a.) the temperature exceeds 99 degrees for more than 30 consecutive minutes.

Lightning (and electric fields with triggering potential):

* Tanking will not begin if there is forecast to be greater than a 20% chance of lightning within five nautical miles of the launch pad during the first hour of tanking. The launch director with the concurrence of the safety director may make an exception after consultation with the Shuttle Weather Officer.

* Do not launch if lightning has been detected within 10 nautical miles of the pad or the planned flight path within 30 minutes prior to launch. Launch may occur if the source of lightning has moved more than 10 nautical miles away from the pad or the flight path and a field mill, used to measure electric fields, is located within 5 nautical miles of the lightning flash.

* The one-minute average of the electric field mill network may not exceed -1 or +1 kilovolt per meter within five nautical miles of the launch pad or the lightning flash at any time within 15 minutes prior to launch. This field mill criteria becomes -1.5 or + 1.5 kilovolts per meter if there are no clouds within 10 nautical miles of the flight path except those which are transparent. Also excepted are clouds with tops below the 41 degrees F. temperature level that have not have been previously associated with a thunderstorm, or associated with convective clouds having tops above the 14 degrees F. temperature level during the last three hours.

* Do not launch when lightning is observed and the cloud which produced the lightning is within 10 nautical miles of the flight path. Launch may not occur until 30 minutes has elapsed since the lightning flash, or the cloud has moved more than 10 nautical miles
Member Since: July 3, 2005 Posts: 437 Comments: 134790
380. 0741
i think this could be our first real player in atlantic ocean we could have invest by tonight or tue
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Quoting Michfan:
My god here we go again. I just wish that some would act like the professionals they profess to be when it comes to the weather. All this wishcasting is getting ridiculous.


Wishcasting? lol man no one on here can even discuss a possible area of interest without being called a Wishcaster lol. I have seen the term used many times on many sites in my time, never have I see the word thrown around with such reckless abandon as it is on here.

Makes me feel like people can't talk freely about it without being ridiculed by somebody
Quoting futuremet:


Don't quote him, he did the same thing last year..


lol...

I remember him! He was that cat guy...
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SMG WEATHER FORECAST SHEET


SMG Mission Weather Information

Member Since: July 3, 2005 Posts: 437 Comments: 134790
"Hey Doug"
"Yea Mark?"
"You see the game last night?"
"Nah, Maybe Chris did"
"Well Did ya Chris?"
Member Since: July 8, 2005 Posts: 259 Comments: 25167
My god here we go again. I just wish that some would act like the professionals they profess to be when it comes to the weather. All this wishcasting is getting ridiculous.
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Quoting SavannahStorm:


Not as dry as it looks- most of the dry air is pushing ahead of the wave.



very much agree
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Labeled as Tropical Wave by Ocean Prediction Center.

Link
Member Since: January 14, 2007 Posts: 17 Comments: 4140


Not as dry as it looks- most of the dry air is pushing ahead of the wave.
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There isnt enough information from anyone or anything right now to make a guess 7 days from now, that makes no sense

Think "Hurricane Frances" track for a sec, yes, there was a trough on the east coast, but it was weak and recurved it AFTER it hit the USA. Again, it's too early to call it a done deal when it hasn't even formed. I doubt if it does, it turns out to sea with that monster B/A High. That right there is close to a 2004 High
Member Since: July 1, 2008 Posts: 13 Comments: 7517
Quoting AllStar17:


How could you say that?


Don't quote him, he did the same thing last year..
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Quoting Patrap:


Everyone?

When is it a everyone club?


Nothing out there to watch ,..way to dry.


lol, ok. Anyway, I'm not fussy. Wave or trough, something interesting to watch for the meantime.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
I have a feeling the blog will become very dramatic over the next few days if this wave develops into an invest or anything else. Back to lurking.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting jasoniscoolman09:
tropical wave in the Central Atlantic WILL NOT BE A TRIOPCAL LOW BY TUSEDAY MORNING..


How could you say that?
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Now that we have 2 models on go for development and there not ripping it apart, there's a slim chance for tropical formation with the *surface trough*. I can see how it can recurve WEST of Bermuda which puts the USA in the uncomfortable spot, but east of Bermuda, nope not happening until the pattern actually changes. For the islands, the EURO takes it through the Lesser Antilles, and the GFS takes it north, so the Islands might wanna watch this more because it's closer to them then the USA.
Member Since: July 1, 2008 Posts: 13 Comments: 7517
These are not 200hr+ forecasts

GFS



ECMWF



The GFS is sightly more aggressive than the ECMWF with the trough. However this trough will be in a quasi-stationary state once it reaches the eastern seaboard,and it is expected to rapidly degenerate thereafter. So yes, if this stays south and weak enough, it may miss the trough.
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Quoting Weather456:
Why is everyone saying the convection is a tropical wave? The wave is further east, the convection is a surface trough of low pressure per the 12Z OPC charts and satellite imagery.


I think they see it and assume its a TW.
Member Since: June 9, 2007 Posts: 4 Comments: 16038
Quoting Weather456:
Why is everyone saying the convection is a tropical wave? The wave is further east, the convection is a surface trough of low pressure per the 12Z OPC charts and satellite imagery.


Everyone?

When is it a everyone club?


Nothing out there to watch ,..way to dry.
Member Since: July 3, 2005 Posts: 437 Comments: 134790
Hey WS, the Rockies are good. Nice and cool today in the valley. I managed to spend a lot of time in the mountains last week and should be on vacation at about 8,000-9,000 feet all next week.

This AOI is looking pretty good. Definitely going to be heating up the blog! A lot of people will come out of lurking. As it gets closer it will be interesting to see how all the variables play out!
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Why is everyone saying the convection is a tropical wave? The wave is further east, the convection is a surface trough of low pressure per the 12Z OPC charts and satellite imagery.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
I got a line of nasties heading my way.

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NASA STS-127 Launch Blog


Member Since: July 3, 2005 Posts: 437 Comments: 134790
yea thought so
one bad storm
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Sept 08 IKE Track
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was that Sept 2008 Pat?
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You guys need to understand that calling i a fish storm is foolishness. Give it a week and let it form, then watch the pattern. Right now, I see no recurvatures for another 2 weeks, the B/A High is strong and should force anything to the west and not get recurved out to sea. The NOGAPS makes the high look 2004ish. Again, guys, look at the pattern, not what the GFS says in 200+ hours.
Member Since: July 1, 2008 Posts: 13 Comments: 7517
348

The GFS did expect IKE to go out to sea for a couple of runs.

Anyone has access to the model archives?
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Member Since: July 3, 2005 Posts: 437 Comments: 134790
Quoting futuremet:


You are right...

Ike was expected to be a fishy at first....look where it ended up


Ike was never expected to turn OTS, it was expected to be a Florida storm, then it took the southward trend.
Member Since: July 1, 2008 Posts: 13 Comments: 7517
I started a stir with the trash pile speculation. Honestly, I was half joking. I think it was Popular Science a couple years back had an expose' on hurricane control and one proposed solution had to do with using cooking oil to create a disruptive slick over the water that would hinder the evaporative process of hurricane development. I thought it sounded at least a tad bit plausible that a huge plastic pile of crap clumped together in a pile the size of Texas could possibly achieve similar results. What a quiet season so far...and dry rainy season here in Southwest Florida (north fort myers).
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The CATL AOI has some excellent divergence and some growing convergence. This will help it maintain and grow its convection. Also the 850mb vorticity is growing slowly as well. Should be an interesting 48 hours.

Member Since: June 9, 2007 Posts: 4 Comments: 16038
UNYSIS 10-Day GFSx
Member Since: July 3, 2005 Posts: 437 Comments: 134790
Good afternoon everyone! Just been reading back through all the posts regarding this hype about a strong tropical wave in the Central Atlantic. I will admit that its quite possibly the healthiest tropical wave we've seen emerge into the Atlantic off Africa with noticeable low-level turning. But, its nothing to get excited or worried about just yet since development won't occur until the tropical wave separates itself from the ITCZ and can support its own convection. Not saying that this will be the case, but this could easily be another one of those promising tropical waves that never ends up developing. Nonetheless, I will continue to keep an eye on it.
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Quoting futuremet:


You are right...

Ike was expected to be a fishy at first....look where it ended up


And it was suppose to hit FL too so yeah this far out who knows in a week where it might be.
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well then i suppose according to the NHC the southeast coast should remain on guard
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Quoting Stormchaser2007:
12z ECMWF at 240 hrs:



Don't look like a trough to me, looks like that is heading to New England, now that the EURO shows a storm, this wave needs to be watched.
Member Since: July 1, 2008 Posts: 13 Comments: 7517
GFS with the EMCWF?

Ohhh could get good here in the next 48!
Member Since: January 14, 2007 Posts: 17 Comments: 4140
Quoting Weather456:


Thats why the interests us here.


You are right...

Ike was expected to be a fishy at first....look where it ended up
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Not that accurate, but still interesting.

Member Since: June 9, 2007 Posts: 4 Comments: 16038
Quoting futuremet:


Sorry to say, but I don't think the Islands are spared from this. If it develops, at least one them will be affected before going out to sea (if it ever does).


Thats why the interests us here.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Troubles looming.

Member Since: June 9, 2007 Posts: 4 Comments: 16038

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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