Sea level rise: what has happened so far
Sea level has been rising globally since the late 1700s. This rise has accelerated in recent decades, thanks to increased melting of glaciers and ice sheets due to a warmer climate, plus the fact that warmer oceans are less dense and expand, further increasing sea level. Though sea level rise appears to have slowed over the past five years, it will significantly accelerate if the climate warms the 2 - 3°C it is expected to this century. If these forecasts of a warmer world prove accurate, higher sea levels will be a formidable challenge for millions of people world-wide during the last half of this century. Sea level rise represents one of my personal top two climate change concerns (drought is the other). I'll present a series of blog posts over the coming months focusing on at-risk areas in the U.S., Caribbean, and world-wide. Today, I focus on the observed sea level rise since the Ice Age.
What's at stake
Higher sea levels mean increased storm surge inundation, coastal erosion, loss of low-lying land areas, and salt water contamination of underground drinking water supplies. About 44% of the Earth's 6.7 billion people live within 150 km (93 miles) of the coast, and 600 million people live at an elevation less than ten meters (33 feet). Eight of the ten largest cities in the world are sited on the ocean coast. In the U.S., the coastal population has doubled over the past 50 years. Fourteen of the twenty largest urban centers are located within 100 km of the coast, and are less than ten meters above sea level (McGranahan et al., 2007). The population of many vulnerable coastal regions are expected to double by 2050, according to the U.S. Census Bureau.
Sea level rise since the Ice Age
Before the most recent Ice Age, sea level was about 4 - 6 meters (13 - 20 feet) higher than at present. Then, during the Ice Age, sea level dropped 120 meters (395 ft) as water evaporated from the oceans precipitated out onto the great land-based ice sheets. The former ocean water remained frozen in those ice sheets during the Ice Age, but began being released 12,000 - 15,000 years ago as the Ice Age ended and the climate warmed. Sea level increased about 115 meters over a several thousand year period, rising 40 mm/year (1.6"/yr) during one 500-year pulse of melting 14,600 years ago. The rate of sea level rise slowed to 11 mm/year (0.43"/yr) during the period 7,000 - 14,000 years ago (Bard et al., 1996), then further slowed to 0.5 mm/yr 6,000 - 3,000 years ago. About 2,000 - 3,000 years ago, the sea level stopped rising, and remained fairly steady until the late 1700s (IPCC 2007). One exception to this occurred during the Medieval Warm Period of 1100 - 1200 A.D., when warm conditions similar to today's climate caused the sea level to rise 5 - 8" (12 - 21 cm) higher than present (Grinsted et al., 2008). This was probably the highest the sea has been since the beginning of the Ice Age, 110,000 years ago. There is a fair bit of uncertainty in all these estimates, since we don't have direct measurements of the sea level.
Figure 1. Global sea level from 200 A.D. to 2000, as reconstructed from proxy records of sea level by Moberg et al. 2005. The thick black line is reconstructed sea level using tide gauges (Jevrejeva, 2006). The lightest gray shading shows the 5 - 95% uncertainty in the estimates, and the medium gray shading denotes the one standard deviation error estimate. The highest global sea level of the past 110,000 years likely occurred during the Medieval Warm Period of 1100 - 1200 A.D., when warm conditions similar to today's climate caused the sea level to rise 5 - 8" (12 - 21 cm) higher than present. Image credit: 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.
Sea level rise over the past 300 years
Direct measurements of sea level using tide gauges began in Amsterdam in 1700. Additional tide gauges began recording data in Liverpool, England in 1768 and in Stockholm, Sweden in 1774. These gauges suggest that a steady acceleration of sea rise of 0.01 mm per year squared began in the late 1700s, resulting in a rise in sea level of 2.4" (6 cm, 0.6 mm/yr) during the 19th century and 7.5" (19 cm, 1.9 mm/yr) during the 20th century (Jevrejeva et al., 2008). There is considerable uncertainty in just how much sea level rise has occurred over the past few centuries, though. Measuring global average sea level rise is a very tricky business. For starters, one must account for the tides, which depend on the positions of the Earth and Moon on a cycle that repeats itself once every 18.6 years. Tide gauges are scattered, with varying lengths of record. The data must be corrected since land is sinking in some regions, due to pumping of ground water, oil and gas extraction, and natural compaction of sediments. Also, the land is rising in other regions, such as Northern Europe, where it is rebounding from the lost weight of the melted glaciers that covered the region during the last Ice Age. Ocean currents, precipitation, and evaporation can cause a 20 inch (50 cm) difference in sea level in different portions of the ocean. As a result of all this uncertainty, the 1996 Intergovernmental Panel on Climate Change (IPCC) report gave a range of 4 - 10" (10 - 25 cm) for the observed sea level rise of the 20th century. The 2007 IPCC report narrowed this range a bit, to 5 - 9" (12 - 22 cm), or 1.2 - 2.2 mm/year. Rates of sea level rise are much higher in many regions. In the U.S., the highest rates of sea-level rise are along the Mississippi Delta region--over 10 mm/yr, or 1 inch/2.5 years (USGS, 2006). This large relative rise is due, in large part, to the fact that the land is sinking.
Figure 2. Absolute sea level rise between 1955 and 2003 as computed from tide gauges and satellite imagery data. The data has been corrected for the rising or sinking of land due to crustal motions or subsidence of the land, so the relative sea level rise along the coast will be different than this. The total rise (in inches) for the 48-year period is given in the top scale, and the rate in mm/year is given in the bottom scale. The regional sea level variations shown here resulted not only from the input of additional water from melting of glaciers and ice caps, but also from changes in ocean temperature and density, as well as changes in precipitation, ocean currents, and river discharge. Image credit: IPCC, 2007
Sea level rise over the past 15 years
According to the Intergovernmental Panel on Climate Change (IPCC) 2007 report, sea level accelerated from the 1.2 - 2.2 mm/yr observed during the 20th century to 3.1 mm/year during the period 1993 - 2003. These estimates come from high resolution measurements from satellite radar altimeters, which began in 1992. Tide gauges showed a similar level of sea level rise during that ten-year period. The IPCC attributed more than half of this rise (1.6 mm/yr) to the fact that the ocean expanded in size due to increased temperatures. Another 1.2 mm/yr rise came from melting of Greenland, West Antarctica, and other land-based ice, and about 10% of the rise was unaccounted for. However, during the period 2003 - 2008, sea level rise slowed to 2.5 mm/year, according to measurements of Earth's gravity from the GRACE satellites (Cazenave et al., 2008). This reduction in sea level rise probably occurred because ocean sea surface temperatures have not warmed since 2003 (Figure 3). The authors concluded that sea level rise due to ocean warming decreased more than a factor of five from 2003 - 2008, compared to 1993 - 2003, contributing only 0.3 mm/yr vs. the 1.6 mm/yr previously.
Figure 3. Global average sea surface temperatures (SSTs) from 1990-2008. SSTs have not increased in the past seven years. Image credit: NASA/GISS.
For more information
The best source of information I found while compiling my sea level pages was the Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region report by the U.S. Climate Science Program. It has a huge number of references to all the latest science being done on sea level rise.
References
Bard, E., et al., 1996, "Sea level record from Tahiti corals and the timing of deglacial meltwater discharge", Nature 382, pp241-244, doi:10.1038/382241a0.
Cazenave et al., 2008, "Sea level budget over 2003-2008: A reevaluation from satellite altimetry and Argo", Global and Planetary Change, 2008; DOI:10.1016/j.gloplacha.2008.10.004
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.
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.
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.
McGranahan, G., D. Balk, and B. Anderson, 2007, "The rising tide: assessing the risks of climate change and human settlements in low elevation coastal zones", Environment & Urbanization, 19(1), 17-37.
Moberg, A., et al., 2005, "Highly variable northern hemisphere temperature reconstructed from low- and high-resolution proxy data", Nature 433, pp613-617, doi:10.1038/nature03265.
United States Geological Survey (USGS), 2006, National Assessment of Coastal Vulnerability to Sea-Level Rise: Preliminary Results for the U.S. Gulf of Mexico Coast, U.S. Geological Survey Open-File Report 00-179.
Tropical update
The tropical Atlantic is quiet, and the only region worth watching is the Western Caribbean, which could see formation of a tropical disturbance with heavy thunderstorm activity this weekend.
Jeff Masters
Reader Comments
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Latest NHC map has removed the low. The low the HPC forecasts to develop isnt supposed to develop for another 48-60 hours or so.
Shear in 24 hours (for June 12)
In 48 hours
Loop (up to 96 hours - Java)
Problem is, those same models had a trough split in that mess in the western Caribbean and it didn't happen. The ULL is still there. Nothing will form with it there.
Not close to the heavy convection, and again no low. See my other post about the HPC forecast.
The odds of anything forming appear to have diminished significantly.
I don't expect to really have to watch this area for another 48 hours for this supposed low pressure system. Got a couple of tropical waves in the area and with favorable conditions expected by then we might have something to watch.
Agree.
"Caribbean Sea...
a tropical wave is over the far NW Caribbean...see above. The
surface low in the SW Caribbean is now a surface trough extending
from 17n74w to off the Colombia/Panama coast near 9n77w.
However...the activity in the Caribbean is due to upper level
features. An upper low is along the N coast of Cuba extending an
upper trough over the NW Caribbean to Honduras. A broad upper ridge
dominates the remainder of the Caribbean providing diffluence aloft
to generate scattered showers/thunderstorms from 11n-17n between
71w-78w with scattered showers/isolated thunderstorms N of 18n
across Haiti and far E Cuba between 71w-76w and S of 12n between
76w-82w. The tropical wave will exit the Caribbean later today while
a second wave will move into the E Caribbean on Sat."..........
Nothing is going to form with that ULL there.
This could be a quiet June, which is normal.
there isnt a low
there is a low
there isnt a low
there might not be anything to watch in the tropics but at least someone is heating it up in here
Probably.
Goes back to the old adage...if you want to know the weather, look out the window.
What I see is sunshine....
Here's my forecast highs for the next 7 days....
94
93
92
94
95
96
96
Throw in some humidity and......oppressive. No end in sight.
Maybe September.
Aaaah!
Yep Ike - tis the season - HOT, HOT, HOT!
Well, we begin today the same way we did yesterday : shear rules the Caribbean.
Having said that a couple of things of interest to note. The high over Florida is building East and squeezing the trough over Cuba that is producing all the shear over the SW Caribbean. The trough will likely not last into the weekend.
The 850 vorticity signature over the area of thunderstorms is much improved today and any easing of shear may well see a fairly quick response towards a surface feature. Finally, shear tendency has been decreasing once more so let's see if that continues or reverses.
In summary, don't expect much to change until possibly the weeekend.
Quikscat will likely miss some or all of the area just N of Panama when the pass downloads this morning but it will be interesting to see if we still have the surface low or whether it has degenerated into a trough as analysed by the NHC.
000
WHXX01 KMIA 111235
CHGE77
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1235 UTC THU JUN 11 2009
DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.
EAST PACIFIC OBJECTIVE AIDS FOR
DISTURBANCE INVEST (EP912009) 20090611 1200 UTC
...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090611 1200 090612 0000 090612 1200 090613 0000
LAT LON LAT LON LAT LON LAT LON
BAMS 12.0N 118.2W 13.3N 119.5W 14.7N 120.1W 15.8N 120.1W
BAMD 12.0N 118.2W 13.1N 119.6W 14.3N 120.5W 15.8N 120.7W
BAMM 12.0N 118.2W 13.2N 119.6W 14.5N 120.3W 15.9N 120.6W
LBAR 12.0N 118.2W 13.1N 119.2W 14.8N 120.1W 16.9N 120.9W
SHIP 25KTS 28KTS 32KTS 31KTS
DSHP 25KTS 28KTS 32KTS 31KTS
...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090613 1200 090614 1200 090615 1200 090616 1200
LAT LON LAT LON LAT LON LAT LON
BAMS 16.7N 119.7W 17.8N 119.9W 19.1N 121.1W 19.4N 122.4W
BAMD 17.7N 120.5W 22.0N 119.6W 26.4N 115.8W 31.8N 106.5W
BAMM 17.4N 120.4W 20.5N 120.0W 23.5N 118.8W 26.7N 113.0W
LBAR 19.4N 121.0W 26.3N 118.6W 33.9N 107.2W 36.0N 92.7W
SHIP 30KTS 16KTS 0KTS 0KTS
DSHP 30KTS 16KTS 0KTS 0KTS
...INITIAL CONDITIONS...
LATCUR = 12.0N LONCUR = 118.2W DIRCUR = 320DEG SPDCUR = 4KT
LATM12 = 11.5N LONM12 = 117.7W DIRM12 = 320DEG SPDM12 = 5KT
LATM24 = 10.5N LONM24 = 117.0W
WNDCUR = 25KT RMAXWD = 50NM WNDM12 = 25KT
CENPRS = 1007MB OUTPRS = 1012MB OUTRAD = 200NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
i think it fell a part some
Reflector site for those at work, which now also includes Weather456, daily updates
AOI #1
AOI #2
Its all good Ike, after being evacuated from my apartment last night because another tenant dropped a halogen lamp and started a fire I had my excitement for one day! Lol.
Very little chance through tomorrow. If the trough lifts out over the weekend that may change things, assuming we still have some activity in the area. Remember that June is not a traditionally active month so the odds of development are not high to begin with.
Let's see how it looks Saturday morning.
I agree.
This is not toward you, but it's been "3 to 5 days", for the last 3 to 5 days.
These same models that can't forecast reliably beyond so many hours, also can't forecast shear reliably beyond so many hours.
In other words, it's a guessing game.
It does seem like a record skipping (for the older folks reading the blog.)
What do the numbers mean on this graphic?
(click on image for full size)
MODIFIED - oops... I see some numbers above 360
El Nino is comeing EL Nino is comeing
yay yay yay yay
El Nino is comeing EL Nino is comeing !!!!!!!!
The header on the graphic says [dBZ] which is a measurement of power or power lose, or more appropriately attenuation of power or received signal strength.
Read the link, it explains it, and what it is :)
On this particular graphic, these are Severe and Tornado Watch Boxes, watch number and the time the watch expires in UTC-the "Z" time.
Hint, hint-check the graphic label at upper left.
Insects! We are talking insects?
Will pour myself a cupa joe, and read the article - thanks (I think) big fish.
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