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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WRONG ANSWER...Actually quasi is a VERY bright dude...and has a met degree if memory serves.
We find that a total sea-level rise of about 2 meters by 2100 could occur under physically possible glaciological conditions but only if all variables are quickly accelerated to extremely high limits. More plausible but still accelerated conditions lead to total sea-level rise by 2100 of about 0.8 meter.
So the 2 meters shown in the graph is an outlier. 0.8 meters is their "best fit" prediction, which brings it more in line with the IPCC and Rhamstorf studies. The Pfeffer study merely showed that such a rise was physically possible, but only if glacial melting accelerated to an implausibly high level. That graph is a sensationalist spin on a more moderate prediction.
The Low Pressure Area East of Northern Mindanao has developed into a Tropical Depression and was named "ISANG".
Tropical Cyclone Bulletin #1
===================================
At 5:00 PM PhST, Tropical Depression Isang located at 9.4°N 131.0°E or 555 kms east of Northern Mindanao has 10 minute sustained winds of 55 km/h (30 knots).
Additional Information
=======================
Meanwhile, a Low Pressure Area (LPA) was estimated at 285 kms West of Iba, Zambales (15.5°N, 117.0°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 p.m. today.
Another weak storm (so far)....
Tropical Cyclone Advisory #18
SEVERE TROPICAL CYCLONE CARLOS (EP042009)
10:00 AM UTC July 14 2009
====================================
At 9:00 AM UTC, Hurricane Carlos (987 hPa) located at 9.7N 127.2W or 1280 NM southwest of the southern tip of Baja California Peninsula has sustained winds of 65 knots with gusts of 80 knots. The cyclone is reported as moving west at 8 knots.
Hurricane Force Winds
======================
10 NM from the center
Gale Force Winds
================
30 NM from the center
Forecast and Intensity
=====================
12 HRS: 9.8N 128.6W - 70 knots (SHSH-1 Cyclone)
24 HRS: 10.0N 130.3W - 70 knots (SHSH-1 Cyclone)
48 HRS: 10.4N 134.4W - 55 knots (Tropical Storm)
72 HRS: 11.0N 139.0W - 50 knots (Tropical Storm)
---
Where is Taz for that saying...
A nibble from my local NWS, they must be bored..
EVEN LATEST 00Z GFS TRIES TO DEVELOP A DISTURBANCE ON
THE FRONT IN THE GOMEX AND TRACKS IT INTO THE FORECAST AREA EITHER
MON OR TUE.
Like most, no mention of CATL waves, but yeah I think the first one and the second one need to sweep the area of dust before anything can awaken out there...otherwise my guys just like to keep things close to home.
Happy Tuesday ya'll!
Carlos is now a hurricane again.
It's beginning to intensify, raw #T 4.8 with a CI of 3.2.. beginning to get its act together.
Not expected to remain a hurricane for long.. 2 days tops it seems. But we don't know with this storm, do we?
Muuuch better than this time yesterday... likkle storm though.
Pinhole eye!! ^_^
quite interesting EATL. it looks like the CATL wave is moituring the atmosphere for the two good looking waves behind. (1) The one to it"s east and the other over Africa.
be back later with my thoughts and analysis of the tropics
Not a lot going on.
Chances of depression higher
1021. Tropicsweatherpr 6:42 AM EDT on July 14, 2009
Ah. This is the one I was looking at over Ghana on the weekend. It's looking relatively fit.... seems the wave train is finally picking up a bit of steam.
TROPICAL WAVE...CURRENTLY ALONG 31W...WILL TRACK WESTWARD AT
15-20 KT DURING THE NEXT FEW DAYS...PRECEDED BY A
LEADING...ALBEIT WEAK...VORTICITY MAXIMUM. THE WAVE WILL LIKELY
ENTER THE TROPICAL N ATLC BY THE END OF THE WEEK. WHILE THE GFS
SHOWS THE POTENTIAL FOR TROPICAL CYCLOGENESIS ALONG THIS
WAVE...THIS APPEARS TO BE A GRIDSCALE FEEDBACK ISSUE...AS LITTLE
GLOBAL MODEL GUIDANCE OR CLIMATOLOGY BACK UP THIS SOLUTION.
WINDS OF 20 KT...HOWEVER...WILL LIKELY ACCOMPANY THE WAVE.
I think you can go wash your car, still a few days before something develops if it even does.
For the moment, the waves do have a bit of breathing space.
Interesting... CMC is starting to develop this system ala FAY... will be interesting if this development will carry over on the 12Z run.
As SLU has stated... NHC believes GFS has been having "GRIDSCALE FEEDBACK ISSUES", interesting that if that's the case that it has been having it for so long and parameters haven't been updated accordingly to minimize these feedbacks.
Gridscale feedback issue.
What's the sense in even following the GFS for tropical development?
Yup....
44 days down...
139 to go....
558 GFS model runs...
and......it's over.............
Link To This Discussion
I am still watching a feature in the eastern Atlantic that some of the model guidance is latching onto for
possible development later this week. This feature is a monsoon trough of low pressure near 41 West Longitude.
The GFS model has been forecasting this possibility for at least the last week and has been alone in its development
forecast. Now, some of the other model guidance like the Canadian and European models have also jumped onboard that
development will occur later this week. Now, the question now becomes, will this actually occur or are the models
just playing games??
The latest satellite imagery is showing a large and somewhat disorganized area of shower and thunderstorm activity
around this monsoon trough, although there is some organization in the thunderstorm activity near 8 North Latitude,
43 West Longitude. Environmental conditions around this trough are somewhat favorable for development and they are
forecast to remain somewhat favorable for the next few days.
Out of all of the model guidance, the Canadian model in the end is the most aggressive and forecasts a track into
the Caribbean as a weak system by Saturday and then turns it northwest between Cuba and Hispaniola early next week
where it bombs out near the Bahamas next Tuesday before racing up the coast. I am throwing out this solution as
anything that gets into the Caribbean will be torn to shreds by wind shear. The GFS and European models both forecast
weak development with a track north of the Leeward Islands late this weekend into early next week. In the end, the
GFS model keeps this system east of the United States while the European model forecasts a closer approach to the US,
although it keeps it a open trough of low pressure.
Here is my overall thinking: Some development seems possible over the next few days as the enviornment ahead of this
trough is somewhat favorable. A west to west-northwest track seems reasonable for the next few days and this system
should near the northern Leeward Islands by late this weekend where heavy rain and gusty winds should be expected
by Sunday. After this weekend, there are two possible track scenarios: (1) Is a due west track into the Caribbean next
week like the Canadian model is forecasting. If it followed this track, it would be torn to shreds due to strong wind
shear. (2) A track west-northwest to slightly northwest north of the Leeward Islands next week where it would need to
be monitored very closely to see how close it tracks to the United States, although the persistent trough of low
pressure over the eastern United States should deflect any approaching system away from the US coastline. So all-in-
all, I give this system a 25 to at most 35 percent chance of developing into a tropical depression over the next 3 to
5 days. Obviously, I will be watching this system closely and will keep you all updated.
Something else that caught my interest this morning is the GFS model%u2019s forecast of an area of low pressure
briefly developing in the northeast Gulf of Mexico on Monday and tracking inland into northern Florida and southern
Georgia by next Tuesday. I found it interesting as this low pressure system would be forming at the tail end of a
frontal system that will be moving offshore of the US coastline early next week and there are some indications that
there may be a trough split next week off of the southeast US coast or northern Gulf of Mexico as that frontal system
departs. This trough split may try to pop a tropical system in these areas (off of US Southeast coast or northern Gulf
of Mexico) next week, so this is something to watch for. None of the other model guidance is forecasting this and the
GFS model forecast of a low pressure system on Monday may be caused by convective feedback, but since a trough split may
occur next week, it is something to keep in the back of your mind.
LOL Ike. Are you bored? Did you get much rain yesterday? I had .02 in my gauge. Heard it was very spotty, and very heavy in places close by though.
Maybe just watch the CMC and ECMWF runs then lol :)
Link To This Discussion
I am still watching a feature in the eastern Atlantic that some of the model guidance is latching onto for
possible development later this week. This feature is a monsoon trough of low pressure near 41 West Longitude.
The GFS model has been forecasting this possibility for at least the last week and has been alone in its development
forecast. Now, some of the other model guidance like the Canadian and European models have also jumped onboard that
development will occur later this week. Now, the question now becomes, will this actually occur or are the models
just playing games??
The latest satellite imagery is showing a large and somewhat disorganized area of shower and thunderstorm activity
around this monsoon trough, although there is some organization in the thunderstorm activity near 8 North Latitude,
43 West Longitude. Environmental conditions around this trough are somewhat favorable for development and they are
forecast to remain somewhat favorable for the next few days.
Out of all of the model guidance, the Canadian model in the end is the most aggressive and forecasts a track into
the Caribbean as a weak system by Saturday and then turns it northwest between Cuba and Hispaniola early next week
where it bombs out near the Bahamas next Tuesday before racing up the coast. I am throwing out this solution as
anything that gets into the Caribbean will be torn to shreds by wind shear. The GFS and European models both forecast
weak development with a track north of the Leeward Islands late this weekend into early next week. In the end, the
GFS model keeps this system east of the United States while the European model forecasts a closer approach to the US,
although it keeps it a open trough of low pressure.
Here is my overall thinking: Some development seems possible over the next few days as the enviornment ahead of this
trough is somewhat favorable. A west to west-northwest track seems reasonable for the next few days and this system
should near the northern Leeward Islands by late this weekend where heavy rain and gusty winds should be expected
by Sunday. After this weekend, there are two possible track scenarios: (1) Is a due west track into the Caribbean next
week like the Canadian model is forecasting. If it followed this track, it would be torn to shreds due to strong wind
shear. (2) A track west-northwest to slightly northwest north of the Leeward Islands next week where it would need to
be monitored very closely to see how close it tracks to the United States, although the persistent trough of low
pressure over the eastern United States should deflect any approaching system away from the US coastline. So all-in-
all, I give this system a 25 to at most 35 percent chance of developing into a tropical depression over the next 3 to
5 days. Obviously, I will be watching this system closely and will keep you all updated.
Something else that caught my interest this morning is the GFS model%u2019s forecast of an area of low pressure
briefly developing in the northeast Gulf of Mexico on Monday and tracking inland into northern Florida and southern
Georgia by next Tuesday. I found it interesting as this low pressure system would be forming at the tail end of a
frontal system that will be moving offshore of the US coastline early next week and there are some indications that
there may be a trough split next week off of the southeast US coast or northern Gulf of Mexico as that frontal system
departs. This trough split may try to pop a tropical system in these areas (off of US Southeast coast or northern Gulf
of Mexico) next week, so this is something to watch for. None of the other model guidance is forecasting this and the
GFS model forecast of a low pressure system on Monday may be caused by convective feedback, but since a trough split may
occur next week, it is something to keep in the back of your mind.
Bored? No....I just got up...my coffee is brewing as I type.
It was spotty here too. Between Mossy Head and Crestview got dumped on...I just had a trace to under a tenth at my house.
Thanks for the update!
ECMWF does the best job. It's not right all of the time, but it doesn't spin up ghost-storms as much as the GFS.
L8R...have a nice day........
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM 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 ROBERTS/BEVEN
35w
Link
see u later
[It equalled a record set 7 years earlier in 1986.. same pressure reading, though in '86 some say it hit perhaps 912, or even lower. Quite remarkable.]
If it does actually come our way, it'll be the first genuinely tropical anything we've had here this year.
Definitely showing a bit more character today.
Link
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