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
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Don't be surprised if I check in from the chilly North .
And we just lost Lorenz in the last year or so.
I remember having to write code to numerically solve and graphically display that at A&M. Was neat.
Au revoir, Kman
Au revoir
However, I'm with Ike on the no formation for the rest of this month. I don't think we'll see the different elements converge sufficiently before then.
It is already about 3am in the area of that wave, it has passed DMIN, coming up on DMAX in a few hours
Reflector site for those at work, which includes Weather456, daily updates
AOI
AOI
How did it miss? I thought it was supposed to go right over it. And i saw a quickscat linked here that showed an on open low... N winds on the west, W winds on the south, but weak north winds on the northeast of the storm.
Also that graphic is cool. thanks.
Go figure an insurance company would capitalize on the theory. LoL -- Night all
a bit puzzling to me.
I know 90L should have been classified, but I'm still skeptical about 92L. Even though it had an eye and stuff, I dunno, stranger things have happened. Btw, I see our CV wave still looks pretty good, a ball of convection near the suspected circulation. If this can last till tomorrow, I see a yellow, maybe orange code coming up, and even if I dare mention INVEST 95L :O lol
In season and actually a threat to become something.
No it has not, remember D-MAX usually enhances convection
13N 27W is that area
Looks like could form one instead of being two seperate, imo.
http://www.nrlmry.navy.mil/nexsat-bin/nexsat.cgi?BASIN=CONUS®ION=AFRICA&SECTOR=Overview&AGE=Prev &SIZE=Full&PRODUCT=vis_ir_background&PATH=CONUS/focus_regions/AFRICA/Overview/vis_ir_background/mete o8&SUB_BASIN=Region/Sector&ANIM_TYPE=Instant&DISPLAY=Single&INTERVAL=Most_Recent&SUB_PRODUCT=meteo8
Meteosat 4 km IR4 Floater
(CIRA Personnel Only)
Soon as they get away from the coast and surrounded by the easterlies they seem to look a little less than spectacular. I think there was a consensus here a few days ago that any wave crossing the ATL would have a less than perfect enviroment.
Not much convection but still some structure.
SSD Unenhanced IR Loop
Dr. Lyons said tonight that the CV Wave have "no chance of developing".
I guess we better believe him, since he has a ''Ph.D'' in tropical meteorology. :)
He's just one resource. I do listen to what he says but I don't take his word to the bank. He can be wrong just like everyone else.
Having said that, I think we are still a week or two away from our first storm. That is just my opinion and I would not take it to the bank either:)
Sounds good, and likely accurate, to me.
B.S., M.S. and Ph.D. in Meteorology, University of Hawaii
Awards & Accreditations
Fellow of the American Meteorological Society
Adjunct Professor Texas A&M University
Published more than 20 papers in scientific journals
Written more than 40 technical reports and articles for the National Weather Service and the Navy
Steve Lyons isn't allowed to be wrong, he is a former aggie prof. (j/k)
Like beell is saying. Do not be surprised if they both look like a patch of cloud, nothingmore, in 24 hours.
Tropical Depression "ISANG" has accelerated as it continues to move northwestward.
Tropical Cyclone Bulletin #3
===================================
At 11:00 AM PhST, Tropical Depression Isang located at 14.7°N 127.4°E or420 kms east of Guiuan, Eastern Samar has 10 minute sustained winds of 55 km/h (30 knots).
Additional Information
=======================
Meanwhile, the Low Pressure Area (LPA) was estimated at 440 kms West of Dagupan, Pangasinan (16.0°N, 116.6°E). This disturbance will continue to enhance the Southwest Monsoon and bring occasional rains over the western section of Southern Luzon.
The public and the disaster coordinating councils concerned are advised to take appropriate actions and watch for the next bulletin to be issued at 11 p.m. today.
wake up * NASA
Extremely impossible, due to orbital mechanics. Now if it was a non-ISS mission like the last one, they have a launch window of 3 hours or more. NASA knows what their doing. And it was supposet to launch in the early morning back in June before the GUCP scrubs.
"Several forecast models do now suggest that some development will take place with the wave over the next few days. The bottom line is that while conditions are not ideal, this is the first wave in a couple weeks that has had any chance of developing," Stephen Strum, Frontier Weather Inc's president and lead meteorologist, said in a morning report.
Strum added that a long-term track was pure speculation at this point.
"Once you get to the middle of July, you start to see the wave activity become a little more active, and the waves that come off Africa have a better chance to develop because the water is now warm enough between the Atlantic and the Caribbean to support the waves. Prior to mid-July the water is just too cool there, so they all just sputter and die," Strum told Reuters.
"These waves start to come off about every three days now. We'll start to see more activity going forward from this point on, which is normal, just from a climatologically typical pattern," Strum said.
Forecaster AccuWeather.com said there were currently no tropical systems across the Atlantic basin and no development expected at least through Wednesday.
The forecaster said, however, it was also tracking three tropical waves.
A tropical wave moving over the Lesser Antilles Tuesday was moving into warmer water, but strong wind shear over the Caribbean would likely prevent the wave from becoming better organized beyond Wednesday, it said.
A wave located over Guatemala and southeastern Mexico was likely to move into the eastern Pacific over the next day or two, AccuWeather.com said.
Natural gas traders linked part of a rise in prices early Tuesday to the stir in tropical activity. Natural gas futures on the New York Mercantile Exchange rose 5 percent early Tuesday to as high as $3.44 per million British thermal units.
The Atlantic hurricane season runs from June 1 to November 30.
There has been one tropical depression so far this season.
The first named storm of the season will be Ana.
Tropical storms pack maximum sustained winds ranging from 39 to 73 miles per hour.
(Reporting by Eileen Moustakis; Additional reporting by Scott DiSavino; Editing by Walter Bagley)
© Thomson Reuters 2009 All rights reserved
Tropical Atlantic
Steve Lyons said that? Yeah he probably did, he's pretty old
Updates?
Longtime no see Mel...
Tropical Update
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