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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+1, fantastic!
Oh yes, I read that article. Back then they blamed Ye Olde NH of C for being even more conservative.
James K. Polk started it all...
If it makes it, it won't be until the afternoon that they make it an invest. If it makes it.
LMAO, post of the day right there
Ye Olde Literalle Guy
Have patience, no it shouldnt be an invest already
It needs to persist longer since its a CV wave. Be patient.
1. Carlos is rapidly strengthening
2. CV wave should be an invest now, and a TD within 24 hours.
Ummm...Why?
No need to laugh Sir; I was just making an observation of "current" conditions in the E-Pac regardless of the average (it has been a very slow start to the E-Pac season as well)..
LOL,..J/K
Severe thunderstorms have winds of 58mph and Hail present. A thunderstorm can make the sky dark and still not issue a warning, it happens all the time.
As far as running from them when they approach, that's a different story.
It seems to be establishing pretty good outflow-if it still looks like this this time tommorow it may be named a tropical depression or tropical storm. But, I've seen so many come off the coast of Africa, looking very healthy, and then all but disappear by the time they are halfway between the Cape Verde and Lesser Antilles islands. We will have to be patient and wait and see.
Oh. Something to look forward to when it moves up my way (St Johns County). We haven't had enough rain already the past couple of weeks? Sorry, I forgot. We Floridians refer to it as "heavy humidity"... :-)
Nola Roux is the one with the Black Collar.
Seems carlos is in a rather unique situation. It's being surpressed by a high to the north, so it's sitting on the ITCZ, which is just far enough north to support a storm. It's in a perfect environment for strengthening and moving just barely enough to avoid cold water upwelling. This could be a record breaking long lasting storm, and small storm.
How do you know when one of these warnings should be issued if the storm is at night? Wouldn't all thunderstorms then require a "Really Dark Thunderstorm Warning" to be issued?
Shall we use the EPAC as our main source of Crow this season?
Even that isn't that active though.
Carlos is nearly their - however the moment its visible presentation improves, the ADT goes down.
In the past few years at least, I have not seen a storm look this good over water. They usually die instantly or look sick (like the wave ahead of it) as soon as it hits water. This one, however, actually blew up convection and organized when it hit water. And if not this one, the next wave over land has a very significant rotation.
Tropical Depression "ISANG" has maintained its strength as it continues to move northwestward.
Tropical Cyclone Bulletin #2
===================================
At 11:00 PM PhST, Tropical Depression Isang located at 10.7°N 130.0°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 280 kms West Southwest of Iba, Zambales (14.5°N, 117.3°E). This disturbance will continue to enhance the Southwest Monsoon and bring occasional to frequent rains over the western section of Luzon and Visayas.
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 a.m. tomorrow.
There are still many unknowns about the exact factor El Nino(or La Nina) plays in the hurricane season. The only thing that seems certain is that the moderate to strong El Nino's like 1982, 1987, 1990-1994, 1997 significantly decrease the chances of development in the tropical Atlantic. The weaker El Nino's are still unknowns to even the most experienced climatoligists. Right now El Nino is weak, much weaker than even the moderate 1990-1994 seasons according to the SOI numbers. The tropics HAVE been very quiet thus far, which is not unusual at all. In my opinion around July 20th is the true start of hurricane season anyway. Typically about 70-80% of the storms form between July 20th and October 20th and these are almost always the most dangerous. I am not predicting a 2004 type season, which was an anomaly, but an average season is still the safe bet...UNLESS El Nino strengthens very quickly through August and September which will definitely bring below average activity.
Well said and I agree with you
Well it was quite windy out there to, there was a special weather statement showing a strong storm in the area. It was close but not severe.
LOL,..thanx
How freakin adorable!! Beautiful dogs. What kind are they? I love there color.
I have a bull dog named Lola. Shes bad..lol.
To my very untrained eye that looks very impresive coming off of Africa. Is it in the ITCZ? I heard someone say thats what gives them the convection.
That's very good! I believe the El Nino will not get deeper and bring 4-7 named storms like most our predicting. I think 12-14 is reasonable, a slightly above average season. Of course a 2006 (average) season is not out of the question, just not anything below that I think. A personal opinion of mine.. I still believe we already had 1 named system which was in May right before making landfall in Alabama.
Observations showed 35 knot sustained winds near the center and a blow up of convection. Even some METS believe this should have been named. It's a HUGE debate over that right now, but that's what I believe. So in my books we already had 1 storm which makes it average so far.
Can you narrow it down a little more?
music lives 4-ever....
No.. I can do it as well!
Before:
After:
Or with Tropical Cyclones:
Before:
After:
*basks in glory*
Yes, I am back right now. Carlos looks like it is a category three, and CV storm is strengthening as well.
She was 14 .
UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm
----- Current Analysis -----
Date : 14 JUL 2009 Time : 180000 UTC
Lat : 9:56:00 N Lon : 127:51:02 W
CI# /Pressure/ Vmax
4.6 / 981.5mb/ 79.6kt
Final T# Adj T# Raw T#
(3hr avg)
4.6 4.8 4.8
Latitude bias adjustment to MSLP : +4.3mb
Estimated radius of max. wind based on IR :N/A km
Center Temp : -10.1C Cloud Region Temp : -53.2C
Scene Type : EYE
Positioning Method : RING/SPIRAL COMBINATION
Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC
Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
****************************************************
Now seeing as ADT has always been off with Carlos.... ALOT, I'd say that this puts him at Cat 2/3
The previous wave was embedded in the ITCZ. This one however, is not. It was a rotating storm that came off africa and now the rotation appears to be going from the mid to the low levels, the outflow is just perfect, and the COC is right under the deepest convection. I just wonder what the wave behind it will do when it hits. There's a cluster of storms moving about 5 times faster than it and it's going to collide with the Storm over water tonight.
Ugh. This site doesnt accept long links, so i'm just going to keep this handy instead:
http://tinyurl.com/eatlloopnrl(click full sized, most recent_)
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