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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Africa NEXSAT Loop
Yep....and lets hope this is not a sign of things to come.
My bathtub was spinning up this morning when I was taking a shower. Does that count?
000
WTPZ34 KNHC 141431
TCPEP4
BULLETIN
HURRICANE CARLOS ADVISORY NUMBER 19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP042009
800 AM PDT TUE JUL 14 2009
...CARLOS STRENGTHENS FURTHER...
AT 800 AM PDT...1500 UTC...THE CENTER OF HURRICANE CARLOS WAS
LOCATED NEAR LATITUDE 10.0 NORTH...LONGITUDE 127.5 WEST OR ABOUT
1465 MILES...2360 KM...SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA.
CARLOS IS MOVING TOWARD THE WEST NEAR 7 MPH...11 KM/HR. A GENERAL
MOTION TOWARD THE WEST OR WEST-NORTHWEST IS EXPECTED DURING THE
NEXT DAY OR TWO.
MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 90 MPH...150 KM/HR...
WITH HIGHER GUSTS. SOME ADDITIONAL STRENGTHENING IS POSSIBLE
DURING THE NEXT 24 HOURS.
HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 10 MILES...20 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO
45 MILES...75 KM.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 978 MB...28.88 INCHES.
...SUMMARY OF 800 AM PDT INFORMATION...
LOCATION...10.0N 127.5W
MAXIMUM SUSTAINED WINDS...90 MPH
PRESENT MOVEMENT...WEST OR 280 DEGREES AT 7 MPH
MINIMUM CENTRAL PRESSURE...978 MB
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
200 PM PDT.
$$
FORECASTER BEVEN
My toilet had a cyclonic turn to the water as well... hmmmm SCARY! lol!:)
la verdad... but this is the most activity we have seen out there in a while... with "possible" and I repeat "possible" areas where storms could form...
Great link as to the Jacksonville area and interesting tie in to the general location of the a-b high relative to Jax; I'm actually wondering "what" is a possible factor keeping the area from Tampa to the Big Bend region relatively clear from direct strikes....According to Leon County officials (Tallahassee), a worst case scenario for this region is not a direct strike per se, but, a hurricane "crossing" from the Atlantic side and emerging into the extreme NE Gulf where the Big Bend would be in the NE quadrant.....In terms of a storm approaching from the Gulf, a worst case scenario for the Big Bend area would probably be a major cane making landfall near Apalachicola God Forbid.
Also notice the "9" shape to the eyewall. Would not surprise me now if Carlos got to a major hurricane....more likely a Cat 2, though.
Yep.
yes! summer vacation is over for J.M. I think. I'm sick to death of global warming and sea level rise bickering.
that is true
Link
Isn't shear expected to decrease over the next couple of days?
Carlos is looking pretty good! I agree with ya Allstar.. it may hit cat3 status before it is all said and done, especially if it keeps intensifying at the speed it is doing so now. ;)
Really like this satellite view. Thanks for posting!
There is some IMPRESSIVE surface convergence with the recently emerged low off of Africa. That satellite shows a convergence band well to the northwest of the low being strongly pulled into the low...AGAINST the ambient trade wind flow!
Theres another one behind that that has good circulation, but it's still on land.
And hello Carlos lol
Has a nice, green sound to it, dontcha think?!
Any time science becomes split along political grounds, watch out.
Big Red Flag.
Or when filthy rich people are bored and think they can control the weather, another Big Red Flag
yh
So now we can have bickering over if a tropical system should be named, why the NHC is so "stupid", and other joyous inanities.
the CATL area of disturbed weather has two mid level circulations. one is 8n 41w and the other at 13n 35w. they both look the same way. eventually the stroger of the two will prevail. evetually the westward moving area near 8n 41w i believe will dominant. having said that i do not expect any imminent development from the catl disturbance. however the area south west of the cape verdes looks promising at this time
at least it would be about tropical weather lol
Yeah, but sometimes, there are pearls of wisdom buried in the tropical weather bickering, so I actually have to read them. I can just block out the GW/CC bickering.
Quoting Chicklit:
There should be a truly independent Global Climate Ruling Body that tells governments and people what to do... The Environmental Ruling Body. ERB
Has a nice, green sound to it, dontcha think?!
Any time science becomes split along political grounds, watch out.
Big Red Flag.
Or when filthy rich people are bored and think they can control the weather, another Big Red Flag
Or just when Al Gore decides he needs a bit more money...Burning Red Flag
No. Check out Cyclone Tracy on wikipedia.
Welcome! I know I have learned alot on here... hope you will too.
I should expect he can post whatever the ell he wants.
And on topics some consider dismissive,well..go start
ya own frigging blog on the current tropics.
Well you came here at the right time. With hurricane season about a month and a half in, theres plenty to learn. Welcome to Wunderground.
Case in point. (sigh) Seeya later.
The dust may make it to the states.
thx
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