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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NCEP/EMC Cyclogenesis Tracking Page
ABPZ20 KNHC 142341
TWOEP
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
500 PM PDT TUE JUL 14 2009
FOR THE EASTERN NORTH PACIFIC...EAST OF 140 DEGREES WEST LONGITUDE..
THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
CARLOS...LOCATED ABOUT 1500 MILES SOUTHWEST OF THE SOUTHERN TIP OF
BAJA CALIFORNIA.
THE LOW PRESSURE AREA LOCATED ABOUT 700 MILES SOUTH-SOUTHWEST OF THE
SOUTHERN TIP OF BAJA CALIFORNIA HAS BECOME A LITTLE BETTER DEFINED
TODAY. SHOWER AND THUNDERSTORM ACTIVITY IS CURRENTLY DISPLACED
FROM THE CENTER...BUT ONLY A SLIGHT INCREASE IN ORGANIZATION WOULD
RESULT IN THE FORMATION OF A TROPICAL CYCLONE. THERE IS A HIGH
CHANCE...GREATER THAN 50 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
US temp reading accuracy report
No one can claim anything after reading how manipulated these records are now. We really have no idea of the truth at this point because of this type of bad science. For those of you hard and fast on the GW item, read it and tell me how you feel about how accurate our records and the global surface observations are now. To use information like this to push any agenda is just wrong. Can you poke a hole in that report?
its all ready a runaway train now we sit back and witness the changes
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
yup a few were
Patrap, I think you know me better than that. Nothing I like less than having to lay eyeballs on that sort of tube drivel...bad enough to have to hear it from time to time should someone else be watching.
And cooling, warming, or neither can cause a glacier to shrink, be it unnaturally or naturally. Far more important is the regional jet stream patterns and precip (just like tree rings, Mr Mann). Lots of glaciers still generally shrinking since the last ice age, too.
I think you also what sort of data hound I am, too. I'll stop there, friend.
LOL...figures....
No I think some are losing the idea of what that yellow circle means. Nothing will be posted in the TWO and no circles show up if there is nothing out there that will develop in 48 hours. That wave may look good, but it doesnt mean its going to develop in 48 hours. NHC has called it right by not doing anything
hehe....
Sockpuppets are fun, boys and girls.
As an aside: That Ice Core Data provides data proving warming, as it reads from right to left in terms of time.
Great detective work there, though.
If the organization is still there tomorrow, we could see the NHC notice it
We don't need any canes :)
just my opinion , I ain't going argue about it, I'm no expert and don't claim to be, anyway lets wait and see what happens, fact is no one really knows.
OF 16N. STRONG SHOWERS AND THUNDERSTORMS ARE FROM 10N TO 11.5N
BETWEEN 24W AND 26W.
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 37W/38W TO THE SOUTH
OF 17N MOVING WEST ABOUT 20 KT. SOME CELLS OF SHOWERS AND
POSSIBLE THUNDERSTORMS ARE FROM 13N TO 13.5N BETWEEN 37W AND 38W.
CLOUDS AND OTHER POSSIBLE PRECIPITATION COVER THE AREA
FROM 10N TO 17N BETWEEN 33W AND 40W.
VERY good image there!
This is soooo very far off of the NHC forecasts for Carlos (maybe the NHC has just gotten bashful about expecting Carlos to do much after the weekend's forecasts):
REQUIREMENTS FOR Tropical Cyclone Formation Alert
If a system gets 35 to 38 points, a TCFA may be issued depending on Dvorak trends, and if a system gets 39 points or more a TCFA should be issued.
Surface
Condition Points
A circulation is evident using visible satellite, shortwave infrared, microwave imagery or QuikSCAT/Windsat ambiguities 3 points
A circulation has been evident for at least 24 hours 5 points
A westerly surface- or gradient-level wind of 5 kt that is within 200 nm (370 km, 230 mi) south of the centre of the disturbance 5 points
Any wind associated with the system is at least 20 kt 2 points
Any wind associated with the system is at least 25 kt 3 points
Any wind associated with the system is at least 30 kt 4 points
A weather station within 200 nm of the system has reported had a pressure drop of 2 mb over 24 hours 3 points
A weather station within 200 nm of the system has had a pressure drop of 3 mb over 24 hours 4 points
The estimated MSLP of the system is less than 1010 to 1009 mb 3 points
The estimated MSLP of the system is 1008 mb or less 4 points
500 mb height
Condition Points
There is evidence of at least an inverted trough 2 points
There is evidence of a closed circulation in the system 4 points
200 mb height
Condition Points
Westerly flow of at least 15 kt over the disturbance -4 points
There is evidence of anticyclonic outflow over the centre of the disturbance 4 points
Easterly flow of at most 20 kt over the disturbance 3 points
Sea surface temperature
Condition Points
The sea surface temperature is 26 Celsius (78.8 Fahrenheit) or higher 3 points
Satellite data
Condition Points
The system has persisted for at least 24 hours 3 points
The system has persisted for at least 48 hours 4 points
The system has persisted for at least 72 hours 5 points
The system has a Dvorak classification of T1.0 to T1.5 from all three agencies (TAFB, SAB, AFWA) 3 points
The system has a Dvorak classification of T1.5 to T2.0 from all three agencies 5 points
The Dvorak final-T number has decreased by T0.5 to T1.0 from two or more agencies -2 points
Miscellaneous
Condition Points
The cloud system is north (or south) of 5 degrees latitude 3 points
The tropical system is within 72 hours of reaching a Department of Defense resource 3 points
The cloud system center and the satellite centre fixes for the system are within 2 degrees of each other 2 points
**********************************************************
Personally contrary to what some might think, I personally don't care if I ever see a yellow circle or red one for that matter, after going through Ivan in 2004 and come near losing everything you ever worked for I even hate to hear the word hurricane, I tell you some here got it all wrong or get the wrong impression, this site is becoming a bashing gotcha game, I don't think I'll be posting here much anymore!
Been through to many to count, moved to the wrong states in the wrong years. Isabel and Charley stick out the most for me. Isabel to me though was way worse than Charley. And I was in Charley as a weakening Category 3/2.
Even pointing this out in a generous way is still bashing those people, there is unfortunately no way around it sometimes.
I will agree that it has been less that titillating to be in this particular room since the season started.
You just put some in one ear and out the other or put them on ignore or take a break from blogging on here.
Some times it is unnerving.
To be honest I wasn't directing my post to you, it was a general comment of what I been seeing here lately by a few, I only picked the post by wunderkidcayman regarding the yellow circle to express my feelings in general, personally I don't get that offended as everyone will have an opinion one way or the other, of course most will think their opinion is the best, just human nature, I'm just speaking about the blog in general.
Are we witnessing the chain reaction of residual energy, or what could be the creation of the first cyclone from the wave that is now coming off of the coast of Africa? Just making an observation based question up :)
Isabel is the only storm I've been through and even as a TS it managed to flip my life up-side-down.
I still have a crow order (medium-well , Hold the A1) for you if there is one named storm in july.
LOL...keep it on hold. I may be wrong....soon.....
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