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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http://www.nhc.noaa.gov/tafb/ATSA_12Z.gif
I doubt the TWO mentions anything...copy and paste...TS formation is not anticipated in the next 48 hours...
Irene?
12Z is 8am, that would coincide with the 8am TWO
in other words, the map is old lol
12z= 8am.
Sorry, this isn't a Modoki El Nino. If you actually read what Dr. Master's posts you would know that this is a classic El Nino. A year like 2002 or 2006 is much more likely than 2004.
I guess you gotta think, could this be a TS in 48 hours? Perhaps not. Invest, maybe, at tops within that timeframe.
It's over 3,000 miles away....
It's called being banned under that handle.
I have no idea on track because there are too many variables. We should focus on development not the track.
Sources:
http://www.examiner.com/x-9111-SF-Environmental-Policy-Examiner~y2009m7d5-Does-global-warming-dimin ish-with-accurate-temperature-measurements-Part-1
Type "Global Cooling" and got to news section.
http://members.shaw.ca/sch25/FOS/Climate_Change_Science.html
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 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 BEVEN
Nuttin'
If I'm wrong....crow me.
LOL ok makes more sense
Link
At 18z there will be a wave on the surface analysis. But there will not be an invest probably for 24 hours at least. If ever.
And oil burbles up from the mantle for us all to burn and enjoy in perpetuity.
Someone needs to get their "facts" in order.
Im going to save your comment and we'll see how you do when the seasons done.
96E has not been able to consolidate
I won't
No it wasn't.
1998 did start the year as an El Nino, but by the time the meat of the season started, it was La Nina.
Link
The El Nino lingered into the beginning of the hurricane season, but changed to La Nina
10
4
2
Just wait it out and you'll see we get at LEAST 12 named storms this year :)
Where did I say El Nino was going to shut everything down? It will at the end of September since it is a typical El Nino though. A NORMAL El Nino, like this one, does mean an average to slow season, especially in terms of ACE. It does not mean you can't get a lot of storms or major hurricanes hitting land. It means overall, based on the Accumulated Cyclone Energy, the season will be average to below average. You may want to go look a few things up before opening your mouth. 2004 is not the TYPICAL El Nino. You can look at maps and see that they are not similar in any way in terms of SST anomalies. It was the topic of one of the blogs which obviously you didn't read. By the way, 1998 was a La Nina year, not an El Nino year smart guy. 1997-1998 was the El Nino, and it weakened and headed to La Nina in 1998. Like I said, do some research and don't just spurt off crap cause you want the season to be like 2004.
I'm not changing it. I belatedly picked mine the last half of June. Take off a point for a late pick.
I'll stick with my totals...
The wave that looked impressive yesterday in the central Atlantic blossomed convection as strong southerly winds increased and provided surface convergence yesterday, and then as the southerlies weakened and the trough elongated there has been a noticeable decrease in thunderstorm activity.
The eastern Atlantic Wave has really been blowing up this afternoon as northwesterly and westerly winds tighten the area of moisture and increase surface convergence.
Both things are readily visible in the loop...but goes to show how hard it is to predict which waves will develop and which won't.
We just have to wait and see on both!
7 Tropical Depressions
5 Tropical Storms
2 Hurricanes
0 Major Hurricanes.
This is from the following:
Revised May 2nd:
12-15 Tropical Depressions
8-12 Tropical Storms
7 - 9 Hurricanes
1 Major Hurricane
0 Cape Verde Cyclones
Original Prediction (Predicted April 15th):
15-17 Tropical Depressions
12-14 Tropical Storms
5-9 Hurricanes
0-1 Major Hurricane
2 Cape Verde Cyclones
Amen to that
Thats Funny ... Best forecasting today ...LOL
11 named storms
6 hurricnes
3 major hurricanes
(1)NHC is conservative.
(2)Is south Florida in the cone?
(3)I think it curves north of the islands.
(4)Could it hamper my Caribbean cruise set for the 21st-27th?
(5)last and certainly not least...season is a bust.
Not unless the El Nino significantly deepens. It's still a weak one for the time being.
It'll be around the normal long-term average (I.e. below average for the current cycle of tropical activity). Seems a reasonable enough projection on current trends.
What about "Fish"?
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