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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It used to have no chance of fizzling, but right now I deny you. It looks much like it is starting to peter out.
The yellow areas in the eastern caribbean are mostly 27C water. Not prohibitively cooler. The colors and contours are in 2C increments.
These images are primarily for use in tropical storm monitoring. There are several areas to choose from providing a large-scale view of the Atlantic, down to the Gulf of Mexico. During hurricane season, the hurricanes page provides a variety of GOES atmospheric products to help monitor the active storms.
I still got that CROW on stand by for no storms in july.
Order:
Medium Well, Hold the A1..
11PM to 4 AM Local Time..
cause it too far away for them.
pardon the ignorance, what is CROW?
Also, I'm hoping JM posts about this CVwave soon.
CROW is just another sad attempt to be funny...
Yes, Carlos has made a rather impressive comeback. Such a small storm now, too. Hurricane force winds extend out 10 miles, and tropical storm winds only 45 miles.
TTAA00 KNHC DDHHMM
BULLETIN
HURRICANE CARLOS ADVISORY NUMBER 19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP042009
800 AM PDT TUE JUL 14 2009
...CARLOS STRENGTHENS FURTHER...
AT 800 AM PDT...1500 UTC...THE CENTER OF HURRICANE CARLOS WAS
LOCATED NEAR LATITUDE 10.0 NORTH...LONGITUDE 127.5 WEST OR ABOUT
1465 MILES...2360 KM...SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA.
CARLOS IS MOVING TOWARD THE WEST NEAR 7 MPH...11 KM/HR. A GENERAL
MOTION TOWARD THE WEST OR WEST-NORTHWEST IS EXPECTED DURING THE
NEXT DAY OR TWO.
MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 90 MPH...150 KM/HR...
WITH HIGHER GUSTS. SOME ADDITIONAL STRENGTHENING IS POSSIBLE
DURING THE NEXT 24 HOURS.
HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 10 MILES...20 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO
45 MILES...75 KM.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 978 MB...28.88 INCHES.
...SUMMARY OF 800 AM PDT INFORMATION...
LOCATION...10.0N 127.5W
MAXIMUM SUSTAINED WINDS...90 MPH
PRESENT MOVEMENT...WEST OR 280 DEGREES AT 7 MPH
MINIMUM CENTRAL PRESSURE...978 MB
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
200 PM PDT.
$$
FORECASTER BEVEN
Wouldn't that make it the smallest Hurricane on record? Or does TC Tracy still hold it?
14/1800 UTC 10.0N 127.9W T5.0/5.0 CARLOS
Thanks......As you note, the wave looks very impressive at the moment but it is still a long way away from tropical disturbance status...The next 24 hours will be very interesting to see if it can sustain convective activity.
Marco has the record.
6-10 precip outlook...
WTPZ34 KNHC 142033
TCPEP4
BULLETIN
HURRICANE CARLOS ADVISORY NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP042009
200 PM PDT TUE JUL 14 2009
...CARLOS MAINTAINING DISTINCT SMALL EYE FEATURE...
AT 200 PM PDT...2100 UTC...THE CENTER OF HURRICANE CARLOS WAS
LOCATED NEAR LATITUDE 10.0 NORTH...LONGITUDE 128.2 WEST OR ABOUT
1500 MILES...2415 KM...WEST-SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA.
CARLOS IS MOVING TOWARD THE WEST NEAR 8 MPH...13 KM/HR. A GENERAL
MOTION TOWARD THE WEST OR WEST-NORTHWEST IS EXPECTED DURING THE
NEXT DAY OR TWO.
MAXIMUM SUSTAINED WINDS ARE NEAR 100 MPH...160 KM/HR...WITH HIGHER
GUSTS. SOME ADDITIONAL STRENGTHENING IS POSSIBLE WITHIN THE NEXT 24
HOURS.
HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 10 MILES...20 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 45
MILES...75 KM.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 978 MB...28.88 INCHES.
...SUMMARY OF 200 PM PDT INFORMATION...
LOCATION...10.0N 128.2W
MAXIMUM SUSTAINED WINDS...100 MPH
PRESENT MOVEMENT...WEST OR 280 DEGREES AT 8 MPH
MINIMUM CENTRAL PRESSURE...978 MB
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
800 PM PDT.
$$
FORECASTER ROBERTS/BEVEN
EUMESAT- Western Africa + Cape Verdes
Tracy still holds it, but I think Carlos is second.
Expected. The DMIN should greatly weaken the AEW.
WTPZ44 KNHC 142036
TCDEP4
HURRICANE CARLOS DISCUSSION NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP042009
200 PM PDT TUE JUL 14 2009
VISIBLE SATELLITE IMAGERY DEPICTS A CLOUD-FREE PINHOLE EYE FEATURE.
ENHANCE BD INFRARED IMAGERY INDICATES THAT THE EYE HAS WARMED
CONSIDERABLY SINCE THIS MORNING WITH COOLING CLOUD TOP TEMPERATURES
ASSOCIATED WITH THE INNER CORE EYEWALL CONVECTION. BASED ON THIS
RECENT CLOUD PATTERN DEVELOPMENT...AND AN INCREASING ADVANCED DVORAK
TECHNIQUE T-NUMBER...THE INITIAL INTENSITY IS RAISED TO 85 KT.
THE INTENSITY FORECAST IS QUITE SIMILAR TO THE PREVIOUS ADVISORY...
AND FOLLOWS THE ICON INTENSITY CONSENSUS GUIDANCE. ALTHOUGH THE
OFFICIAL FORECAST CALLS FOR THE SYSTEM TO MAINTAIN ITS CURRENT
STRENGTH THROUGH THE 24 HOUR PERIOD...SLIGHT FLUCTUATIONS ARE
POSSIBLE IN THE SHORT TERM. THROUGH THE REMAINING PORTION OF
THE FORECAST...A GRADUAL WEAKENING IS EXPECTED DUE TO INCREASING
VERTICAL SHEAR.
THE INITIAL MOTION IS 280/7. CARLOS REMAINS SOUTH OF A LOW/MID-LEVEL
RIDGE...WITH A LARGE AREA OF LOW PRESSURE AT THE LOW/MID-LEVELS TO
THE EAST OF THE HURRICANE. THE TRACK GUIDANCE MODELS GENERALLY
AGREE ON CARLOS MOVING WESTWARD TO WEST-NORTHWESTWARD WITH SOME
ACCELERATION UNDER THE RIDGE...ALTHOUGH THERE CONTINUES TO BE A
SPREAD IN HOW FAR NORTH THE CYCLONE COULD GET. THE HWRF...GFDL...
AND UKMET ARE STILL ON THE SOUTH SIDE OF THE GUIDANCE ENVELOPE...
WHILE THE NOGAPS AND GFDN ARE STILL ON THE NORTH SIDE. THE NEW
FORECAST TRACK IS AN UPDATE OF THE PREVIOUS PACKAGE...DOWN THE
MIDDLE OF THE GUIDANCE ENVELOPE...AND IN BEST AGREEMENT WITH THE
CORRECTED CONSENSUS MODEL.
FORECAST POSITIONS AND MAX WINDS
INITIAL 14/2100Z 10.0N 128.2W 85 KT
12HR VT 15/0600Z 10.3N 129.3W 85 KT
24HR VT 15/1800Z 10.7N 130.9W 85 KT
36HR VT 16/0600Z 11.1N 132.7W 80 KT
48HR VT 16/1800Z 11.5N 135.0W 75 KT
72HR VT 17/1800Z 12.0N 140.0W 70 KT
96HR VT 18/1800Z 12.0N 145.5W 60 KT
120HR VT 19/1800Z 12.0N 152.0W 50 KT
$$
Not sure, couldn't find Tracy's hurricane radii. But overall gale force winds, Tracy is smaller than Carlos still. I think it's likely Tracy just beats Carlos.
Marco was ***still*** not the smallest hurricane. Because it wasn't one. Smallest tropical cyclone, yup - 12 miles outward only.
Only for the 45th time today...
TTAA00 KNHC DDHHMM
BULLETIN
HURRICANE CARLOS ADVISORY NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP042009
200 PM PDT TUE JUL 14 2009
...CARLOS MAINTAINING DISTINCT SMALL EYE FEATURE...
AT 200 PM PDT...2100 UTC...THE CENTER OF HURRICANE CARLOS WAS
LOCATED NEAR LATITUDE 10.0 NORTH...LONGITUDE 128.2 WEST OR ABOUT
1500 MILES...2415 KM...WEST-SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA.
CARLOS IS MOVING TOWARD THE WEST NEAR 8 MPH...13 KM/HR. A GENERAL
MOTION TOWARD THE WEST OR WEST-NORTHWEST IS EXPECTED DURING THE
NEXT DAY OR TWO.
MAXIMUM SUSTAINED WINDS ARE NEAR 100 MPH...160 KM/HR...WITH HIGHER
GUSTS. SOME ADDITIONAL STRENGTHENING IS POSSIBLE WITHIN THE NEXT 24
HOURS.
HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 10 MILES...20 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 45
MILES...75 KM.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 978 MB...28.88 INCHES.
...SUMMARY OF 200 PM PDT INFORMATION...
LOCATION...10.0N 128.2W
MAXIMUM SUSTAINED WINDS...100 MPH
PRESENT MOVEMENT...WEST OR 280 DEGREES AT 8 MPH
MINIMUM CENTRAL PRESSURE...978 MB
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
800 PM PDT.
$$
FORECASTER ROBERTS/BEVEN
CLUSTER...ABOUT THE SIZE OF THE STATE OF DELAWARE...OVER THE
LOW-LEVEL CENTER. THEREFORE...THE INITIAL INTENSITY IS BEING KEPT
AT 55 KT IN LINE WITH THE LAST AIR FORCE RECON DATA...EVEN THOUGH
DVORAK SATELLITE CLASSIFICATIONS ARE T2.0/30 KT FROM BOTH TAFB AND
SAB. I HAVE WORKED SOME TINY TYPHOONS IN THE WESTERN PACIFIC
BEFORE...BUT HORIZONTALLY-CHALLENGED MARCO COULD BE THE SMALLEST
TROPICAL CYCLONE ON RECORD."
Its 8PM Local... this is the last of the DMIN... All uphill from here till 4 AM Local.
Carlos is very small, but is a cat.2 hurricane. Impressive.
ok...thanks
Looks better than some TD's I've seen..
Convection is weakening a bit. We'll see soon what happens.
Thanks Wx!
Dying? What are you looking at. The convection is a bit west of the COC but it is intensifying, and more is developing on the south and east sides. During the diurnal min! (By the way, why is sunset the min and the middle of the night the max? I'm confused)
Viewing: 1801 - 1851
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