How much will global sea level rise this century?

By: Dr. Jeff Masters , 2:49 PM GMT en Julio 13, 2009

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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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Problem solved. Anyways cyclonic turning still evident.

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1734. WAHA
Quoting CaneWarning:


You can use your debit card. I know I did.

No, I don't have that either. I pay for things in cash, but maybe I'll get a debit card.

How is Carlos doing?
Member Since: Posts: Comments:
Quoting DestinJeff:
"i think we should wait and see a trend in the models before we call anything for sure"

"this is going to be a loooooong CV season at this rate"

"has the first named storm of the season ever been a CV storm before?"

"NHC should designate this, but they are being too conservative because of how far away it is"

"look at the wave behind it ... who said this season was a bust?"

"i don't know, but i have a feeling anywhere from jacksonville to new england should keep their eyes on this one"

"this might just a pull a Dean and go straight west"



Classic!

Take a look at this:


UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 14 JUL 2009 Time : 183000 UTC
Lat : 9:56:44 N Lon : 127:54:37 W


CI# /Pressure/ Vmax
4.7 / 979.7mb/ 82.2kt


Final T# Adj T# Raw T#
(3hr avg)
4.7 4.8 4.8

Latitude bias adjustment to MSLP : +4.3mb

Estimated radius of max. wind based on IR : 10 km

Center Temp : -4.3C Cloud Region Temp : -52.5C

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

****************************************************
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Quoting WAHA:

NOOOO! I don't have a credit card, and i probably will decide to not have one in the future. As for debut card, different story (private story, too).


You can use your debit card. I know I did.
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Quoting WAHA:

NOOOO! I don't have a credit card, and i probably will decide to not have one in the future. As for debut card, different story (private story, too).


Lol,

Has anyone posted something from the ORIGINAL NHC site. My browser says their is something from it, I just can't find it.
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Six European volunteers have emerged from a simulated space capsule in Moscow after spending more than three months locked inside.

They were part of an experiment into how astronauts might deal with the very cramped conditions and prolonged isolation of a journey to Mars.

Link

Any volunteers...?
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Ring side seats! Get em now, before they are gone. The blog is filling up fast. It won't be long till and all out verbal knock down starts to form. Once it does it could rapidly intensify into a strong farce!
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I will admit that as the season ramps up (before it really gets cooking), the blogs get way overheated. It is kinda like watching Jerry Springer or Cops. You know whats going to happen, you know its going to be messy, but you just can't take your eyes off it - its like a train wreck.
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1725. WAHA
Quoting IKE:


We should charge admission....I'm just waiting...I know it's gonna happen...

NOOOO! I don't have a credit card, and i probably will decide to not have one in the future. As for debut card, different story (private story, too).
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1724. Ossqss
Quoting Cotillion:
A sociologist would have a field day on here.

Perhaps an Endocrinologist also :)
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Quoting Ossqss:


It is already there in the picture you posted. It does not require any password to access it.


Ossqss, Mail.
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Quoting IKE:


We should charge admission....I'm just waiting...I know it's gonna happen...


It's the WUFC!!!
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Quoting IKE:


We should charge admission....I'm just waiting...I know it's gonna happen...


I wouldn't mind. It might stop some of the mess.
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Quoting jeffs713:


I have my popcorn waiting. Between the GW bickering (well, lately, its been arguing and screaming), and the OMG-WILL-THIS-BE-A-CAT-5-IN-SOUTH-FLORIDA??? messages... it will be grand entertainment tonight.


It is a hoot! I just sit back and watch sometimes...
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1719. IKE
Quoting seminolesfan:

Fights?....On Jeff's blog??...Whaaat???


We should charge admission....I'm just waiting...I know it's gonna happen...
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Quoting WAHA:

I have a few questions.
1; how many people visit that site?
2; why is for every visit on a site it costs more?

1. Dunno.
2. Ask your ISP. Bandwidth is leased from the backbone carriers (AT&T is a major one), and the more bandwidth the ISP leases, the more it costs. The more the ISP pays, the more the customer pays.
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Quoting WAHA:

I have a few questions.
1; how many people visit that site?
2; why is for every visit on a site it costs more?


1. The site admin would be the one with that info.
2. All those 'magic internet tubes' that connect us aren't really magic at all.
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The Earliest Satellite Image of a Hurricane From Space


Hurricane Carla - 1961 - Category 5 TC
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1715. IKE
Quoting DestinJeff:
"i think we should wait and see a trend in the models before we call anything for sure"

"this is going to be a loooooong CV season at this rate"

"has the first named storm of the season ever been a CV storm before?"

"NHC should designate this, but they are being too conservative because of how far away it is"

"look at the wave behind it ... who said this season was a bust?"

"i don't know, but i have a feeling anywhere from jacksonville to new england should keep their eyes on this one"

"this might just a pull a Dean and go straight west"



LOL....:)
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1713. WAHA
Quoting Stormchaser2007:

Exactly.

I have a few questions.
1; how many people visit that site?
2; why is for every visit on a site it costs more?
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Yea, seeing as the eye is small than some tornadoes too.
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http://en.wikipedia.org/wiki/File:TD_Four_21_aug_2006_1435Z.jpg

TD 4 soon to be Debby (2006)
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Quoting IKE:


It does...God help us all when a cat 2 is floating around...admin will be banning em left and right...fights will break out on here....

Fights?....On Jeff's blog??...Whaaat???
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A sociologist would have a field day on here.
Member Since: Posts: Comments:
1707. Ossqss
Quoting Stormchaser2007:


Do not give that link out in a public blog! We will not be able to use it anymore.


It is already there in the picture you posted. It does not require any password to access it.
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Accuweather has a nice satellite feed that loads the West coast of Africa every 3 hours.

Accuweather
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1705. IKE
Quoting Stormchaser2007:


Depends on what you find funny.


Some of it's funny....enjoyable....better than CNN...MSNBC or FOX noise...
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Stare at the pretty cyclone and forget...

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Quoting Stormchaser2007:


I mean in terms of the amount of convective rebuild that has occurred.


Oh I know, heck wasn't expecting anything like this at all today. Pretty interesting day.
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1702. IKE
Quoting reedzone:


Do you see it IKE? You got to really follow it closely, shows a tiny L moving north of the Islands then up the Carolinas to New England.


I see it. ECMWF has been pretty consistent with it.
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Quoting jeffs713:

Bandwidth is expensive.

Exactly.
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Quoting IKE:
This blog is hilarious....


Depends on what you find funny.
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Quoting WAHA:

Why?

Bandwidth is expensive.
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1698. IKE
Quoting seminolesfan:

Gets better every year, doesn't it?


It does...God help us all when a cat 2 is floating around...admin will be banning em left and right...fights will break out on here....
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Quoting IKE:


12Z ECMWF


Do you see it IKE? You got to really follow it closely, shows a tiny L moving north of the Islands then up the Carolinas to New England.
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Quoting IKE:
This blog is hilarious....

Gets better every year, doesn't it?
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1695. WAHA
Quoting Stormchaser2007:


If it becomes too widely used then RAMSDIS will shut it down.

Why?
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Quoting WAHA:

What's terrible about showing it?


If it becomes too widely used then RAMSDIS will shut it down.
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1693. IKE
This blog is hilarious....
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1692. WAHA
Quoting Stormchaser2007:


Do not give that link out in a public blog! We will not be able to use it anymore.

What's terrible about showing it?
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1691. IKE
Quoting reedzone:
New EURO takes the wave and tracks it just north of the Islands, then heads up the east coast, as a very weak low the whole time, but there is something on there.


12Z ECMWF
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Quoting SomeRandomTexan:
The firework show is scheduled, and I am pulling up a chair as we speak. Wouldn't wanna miss out on any of the action thats going to take place tonight... Blog should be popping...


I have my popcorn waiting. Between the GW bickering (well, lately, its been arguing and screaming), and the OMG-WILL-THIS-BE-A-CAT-5-IN-SOUTH-FLORIDA??? messages... it will be grand entertainment tonight.
Member Since: Posts: Comments:
1689. WAHA
Quoting IpswichWeatherCenter:


Don't Waha - he is a very useful resource to my predictions!

KEEP going!

Energizer
keep going
I use those for my wii
Quoting Ossqss:


I will show ya ! Here are the properties if you wanted them .

http://rammb.cira.colostate.edu/ramsdis/online/images/tropical/250.JPG

Thanks
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Quoting Ossqss:


I will show ya. Here are the properties if you wanted them .

http://rammb.cira.colostate.edu/ramsdis/online/images/tropical/250.JPG


Do not give that link out in a public blog! We will not be able to use it anymore.
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Quoting kmanislander:
Very cold cloud tops developing in the latest wave to leave the coast. That, combined with a more symmetrical appearance to the cloud field may signal development on the way.

Although it is still early in the CV season we saw what happened with Bertha so nothing is out of the realm of possibility. Quikscat this evening will be interesting.



When is quickscat out?
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Quoting reedzone:


I think we all weren't expecting this ;)


I mean in terms of the amount of convective rebuild that has occurred.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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