Wednesday, September 1, 2010

{#7b}Appendix to {email #7} Church et al. 2006, highlights

I received an email this morning, short and sweet, but worth sharing:

Church, J.A., N.J. White and J.R. Hunter. 2006. Sea level rise at tropical Pacific and Indian Ocean islands. Global and Planetary Change, 53, 155-168, doi:10.1016/j.glopacha.2006.04.001.
( the definitive rebuttal of Mörner.

Keep up the good work!
I did include Church et al. 2006 in my previous email to SPPI - but, this email has inspired me to share some of its content:

1. Introduction

The islands in the tropical oceans are some of the regions most vulnerable to sea-level rise and the associated impacts of climate change. These impacts include changes in weather patterns (temperature, winds, precipitation etc.), sea-level rise, coastal erosion, changes in the frequency of extreme events including potential increases in the intensity of tropical cyclones/hurricanes, reduced resilence of coastal ecosystems (including bleaching and changed calcification rates of coral reefs) and saltwater intrusion into freshwater resources. Mörner et al. (2004) and Mörner (2004) recently drew attention to the potential vulnerability of the Maldives.

However, Mörner et al. (2004) argued that there had been a 30 cm fall in sea-level at the Maldives over the last 50 yrs while Mörner (2004) argued that there had been no global averaged sea-level rise over the decade of the 1990s. Mörner's conclusions concerning a sea-level fall at the Maldives have been firmly rebutted by Woodworth (2005), Woodroffe (2005) and Kench et al. (2005). The impacts of sea-level rise on Tuvalu have also been a subject of considerable controversy (Eschenbach, 2004a,b; Hunter, 2004).

The tropical Pacific and Indian Ocean regions have considerable interannual and decadal sea-level variability associated with the El Niño-Southern Oscillation (ENSO), the Asian–Australian monsoon and phenomena like the North Pacific Decadal Oscillation (Trenberth and Hurrell, 1994; Chambers et al., 2002; Han and Webster, 2002; Church et al., 2004). In short tide-gauge records, this variability may obscure any longer-term sea-level change, or the variability may be misinterpreted as a regional change. For example, annual mean sea-level at some locations can change by as much as 20–30 cm on interannual time scales.

The availability of improved data sets over recent decades should allow more effective separation of the short-term variability from the longer-term sea-level rise. Of particular importance is the high quality data from the TOPEX/Poseidon and Jason-1 satellite altimeter missions (January 1993 to present) that allows the basin-wide scales of sea-level variability to be examined.

Also important are the sea-level records from high quality tide gauges at a number of islands in the tropical Pacific Ocean. Many of these were installed in the 1970s or early 1980s to study the evolution of ENSO events and were important elements of the Tropical Ocean Global Atmosphere project (World Climate Research Program, 1985; McPhaden et al., 1998). With an increasing focus on sea-level rise in the late 1980s, the quality of individual gauges, and of the network as a whole, has been improved using modern instrumentation with rigorous datum
control (most recently using continuous GPS instruments) and the extension of the network to more locations. For many of these sites, there are now more than 20 yrs of data. However, there are only a few Pacific island records extending over the full 52 yrs examined here.

Modern statistical techniques have also been developed to combine the best attributes of the in situ and satellite data sets; i.e. the longer in situ records and the broad (essentially global ocean) coverage from satellites. These techniques, modeled on approaches used to estimate global surface temperatures over the last century (e.g. Kaplan et al., 1998, 2000; Rayner et al., 2003), use tide-gauge data to estimate the amplitude of empirical orthogonal functions (EOFs) whose spatial structure has been estimated from the satellite altimeter data. Importantly, this technique takes account of the spatial patterns of sea-level variability, rather than regarding variations from the global mean as “noise”. For example, the anti-phase sea-level movements on either side of the Pacific Ocean are attributed to ENSO, rather than being regarded as unexplained random variations. The technique provides estimates of monthly averaged sea level on a near global (65°S–65°N) 1° × 1° ocean grid (essentially the ice free regions; Chambers et al., 2002; Church et al., 2004; Church and White, 2006).

Given the potential vulnerability of the Maldives, Tuvalu and other island states in the Pacific and Indian oceans, we assemble the sea-level data sets described above to provide the best possible estimates of sea-level rise for the latter half of the 20th century for these islands. We also test the veracity of assertions (Mörner, 2004; Mörner et al.,2004) that no significant sea-level rise is occurring. The data sets and techniques used are described briefly in Section 2. The results (Section 3) indicate large interannual variability of the tropical Pacific and Indian ocean region and clear evidence that global average sea level has been rising both over the last decade and the last half of the 20th century. We find no evidence for the 30 cm fall in sea level “in the 1970s to early 1980s” for the Maldives as postulated by Mörner et al. (2004).

Of course the report is too long for me to copy it here - to link to the report click

c2. The data sets and methods
2.1. Preliminaries
2.2. The tide-gauge data set
2.3. The TOPEX/Poseidon satellite altimeter data set
2.4. The reconstructed global sea-level fields
2.5. Uncertainties

3. Results
3.1. Pacific Ocean
3.2. Indian Ocean
3.3. Sea level at Funafuti, Tuvalu
3.4. Pattern of sea-level rise for 1950 to 2001

4. Conclusions

For 1993 to 2001, the altimeter data and the reconstructed sea levels show the average sea level in the region covered by Fig. 1 rising at about 4.3 mm yr− 1, similar to but slightly larger than the regional TOPEX/Poseidon trend of about 3.6 mm yr− 1. A number of recent studies (Leuliette et al., 2004; Church et al., 2004; Holgate and Woodworth, 2004; Cazenave and Nerem, 2004) also confirm the global average sea-level rise from altimeter studies, with estimates varying over a small range depending on the details of the calculation. In direct contrast, Mörner (2004) shows a plot (his Fig. 2) of sea-level variations from October 1992 to April 2000, based on TOPEX/Poseidon data, ostensibly showing that there is no rise in GMSL.

This is described as being “raw data”, and appears to be cycle-by-cycle (10 day) averages of global mean sea-level. Unfortunately, there is neither a description of the data that were used to produce this figure, nor a reference to its source. In order to be a meaningful estimate of global mean sea-level, a number of corrections would have been necessary, including wet tropospheric path delay, dry tropospheric path delay, ionospheric path delay, sea-state bias and tides, but it is unclear which, if any, of these well-known and understood corrections have been applied.

The altimeter data and the reconstructions reveal a large-scale pattern of sea-level change over this period — sea-level falling in the eastern Pacific and the western Indian Ocean and rising in the western Pacific and eastern Indian Ocean. The rates of change are large and are characteristic of interannual climate variability. There is in general a good agreement between the tide-gauge data, the altimeter data and the reconstructions for the period of overlap. In the Indian Ocean, the tide-gauge records at the Maldives indicate large rates of relative sea-level rise in agreement with Singh et al. (2001) and Woodworth (2005), and in disagreement with Mörner et al. (2004).

For the 1950 to 2001 period, there is a good agreement between the observed and the reconstructed sea-level variability in the equatorial region. However, there are only six complete island tide-gauge records, all in the Pacific Ocean. The average trend for these records gives a relative sea-level rise of 1.4 mm yr− 1 (1.6 mm yr− 1 from the reconstructed sea-level at these locations). Corrected for GIA and changes in atmospheric pressure, the average tide-gauge trend is 2.0 mm yr− 1. Even for the longest records, particularly those within 15° of the equator in the
Pacific Ocean, the large ENSO related interannual variability means that there is considerable uncertainty in the trends from individual gauges.

One of the unprincipled tactics of the AGW is a Hoax industry is that they never acknowledge how many smart, dedicated people are involved in these studies. Therefore, I am including this article’s references since they represent yet more detailed publications from which the above study could draw from.

To claim that an Indian Jones’ type renegade knows more than the collective knowledge listed below seem egotistic to the extreme. Especially, when the objects and critiques to Mörner’s work are never seriously acknowledged or discussed by Mörner, SPPI, or Mr. Monckton.
References :
Benada, J.R., 1997. PO.DAAC Merged GDR (TOPEX/POSEIDON) Generation B User's Handbook, Version 2.0. JPL PO.DAAC D-11007. Jet
Propulsion Laboratory, California Institute of Technology, Pasadena.

Caccamise, Dana J., Merrifield, Mark A., Bevis, Michael, Foster, James, Firing, Yvonne L., Schenewerk, Mark S., Taylor, Frederick
W., Thomas, Donald A., 2005. Sea level rise at Honolulu and Hilo, Hawaii: GPS estimates of differential land motion. Geophysical Research Letters 32, L03607. doi:10.1029/2004GL021380.

Cazenave, A., Nerem, R.S., 2004. Present-day sea level change: observations and causes. Review of Geophysics 42, RG3001. doi:10.1029/2003RG000139.

Chambers, D.P., Melhaff, C.A., Urban, T.J., Fuji, D., Nerem, R.S., 2002. Low-frequency variations in global mean sea level: 1950–2000.
Journal of Geophysi cal Research 107, 3026. doi:10.1029/ 2001JC001089.

Church, J.A., White, N.J., 2006. A 20th century acceleration in global sea- level rise. Geophysical Research Letters 33, L01602. doi:10.1029/ 2005GL024826.

Church, J.A., White, N.J., Coleman, R., Lambeck, K., Mitrovica, J.X., 2004. Estimates of the regional distribution of sea-level rise over the 1950 to 2000 period. Journal of Climate 17, 2609–2625.

Douglas, B.C., 1991. Global sea level rise. Journal of Geophysical Research 96, 6981–6992.

Douglas, B.C., 1997. Global sea rise: a redetermination. Surveys in Geophysics 18, 279–292.

Emery, W.J., Thompson, R.E., 1998. Data analysis methods in physical oceanography. Pergamon. 634 pp.

Eschenbach, Willis, 2004a. Tuvalu not experiencing increased sea level rise. Energy and Environment 15, 527–543.

Eschenbach, Willis, 2004b. Response to John Hunter's review. Energy and Environment 15, 931–935.

Firing, Y.I., Merrifield, M.A., Schroeder, T.A., Qiu, B., 2004. Interdecadal sea level fluctuations at Hawaii. Journal of Physical Oceanography 34, 2514–2524.

Folland, C.K., Karl, T.R., Christy, J.R., Clarke, R.A., Gruza, G.V., Jouzel, J., Mann, M.E., Oerlemans, J., Salinger, M.J., Wang, S.-W.,
2001. Observed climate variability and change. In: Houghton, J.T.,

Ding, Y., Griggs, D.J., Noguer, M., van der Linden, P., Dai, X., Maskell and, K., Johnson, C.I. (Eds.), Climate Change 2001: The Scientific Basis. Contribution of Working Group 1 to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, pp. 99–181.

Fu, L.-L., Chelton, D.B., 2001. Large-scale ocean circulation. In: Fu, L.-L., Cazenave, A. (Eds.), Satellite Altimetry and Earth Sciences: A Hand-
book for Techniques and Applications. Academic Press, San Diego, pp. 133–169. 423 pp.

Han, W., Webster, P.J., 2002. Forcing mechanisms of sea level interannual variability in the Bay of Bengal. Journal of Physical Oceanography 32, 216–239.

Holgate, S.J., Woodworth, P.L., 2004. Evidence for enhanced coastal sea level rise during the 1990s. Geophysical Research Letters 31, L07305. doi:10.1029/2004GL019626.

Hunter, J.R., 2004. Comments on: ‘Tuvalu not experiencing increased sea level rise.’. Energy and Environment 15, 925–930.

Kaplan, A., Cane, M.A., Kushnir, Y., Clement, A.C., Blumenthal, M.B., Rajagopalan, B., 1998. Analyses of global sea surface temperature 1856–1991. Journal of Geophysical Research 103, 18567–18589.

Kaplan, A., Kushir, Y., Cane, M.A., 2000. Reduced space optimal interpolation of historical marine sea level pressure. Journal of Climate 13, 2987–3002.

Keihm, S., Zlotnicki, V., Ruf, C., 2000. TOPEX microwave radiometer performance evaluation. IEEE Transactions on Geoscience and Remote Sensing 38, 1379–1386.

Kench, P.S., Nichol, S.L., McLean, R.F., 2005. Comment on “New perspectives for the future of the Maldives” by Morner, N.A., et al. [Global Planet. Change 40 (2004), 177–182]. Global and Planetary Change 47, 67–69.

Kilonsky, B., University of Hawaii Sea Level Centre, personal communication.

Kistler, R., et al., 2001. The NCEP-NCAR 50-year reanalysis: monthly means CD-ROM and documentation. Bulletin of the American Meteorological Society 82, 247–267.

Leuliette, E.W., Nerem, R.S., Mitchum, G.T., 2004. Calibration of TOPEX/Poseidon and Jason Altimeter Data to construct a continuous record of mean sea level change. Marine Geodesy 27, 79–94.

Lombard, Alix, Cazenave, Anny, Le Traon, Pierre-Yves, Ishii, Masayoshi, 2005. Contribution of thermal expansion to present-day sea-level change revisited. Global and Planetary Change 48, 303–312.

McPhaden, M.J., Busalacchi, A.J., Cheney, R., Donguy, J.R., Gage, K.S., Halpern, D., Ji, M., Julian, P., Meyers, G., Mitchum, G.T., Niiler, P.P., Picaut, J., Reynolds, R.W., Smith, N., Takeuchi, K., 1998. The Tropical Ocean Global Atmosphere (TOGA) observing system: a decade of progress. Journal of Geophysical Research 103, 14,169–14,240.

Mitchell, W., 2004. Monthly data report no 144 (December 2004), the South Pacific sea level and climate monitoring project. Bureau of Meteorology. Available from

Mitchell, W., Chittleborough, J., Ronai, B., Lennon, G.W., 2001. Sea Level Rise in Australia and the Pacific. Proceedings of the Pacific Islands Conference on Climate Change, Climate Variability and Sea Level Rise published by National Tidal Facility Australia. Flinders Press. ISBN: 0-9579264-0-5, pp. 47–57.

Mitchum, G.T., 1998. Monitoring the stability of satellite altimeters with tide gauges. Journal of Atmospheric and Oceanic Technology 15, 721–730.

Mitchum, G.T., 2000. An improved calibration of satellite altimetric height using tide gauge sea levels with adjustment for land motion. Marine Geodesy 23, 145–166.

Mitrovica, J.X., Milne, G.A., Davis, J.L., 2001. Glacial isostatic adjustment on a rotating earth. Geophysical Journal International 147, 562–578.

Mörner, N.-A., 2004. Estimating future sea level changes from past records. Global and Planetary Change 40, 49–54.

Mörner, N.-A., Tooley, M., Possnert, G., 2004. New perspectives for the future of the Maldives. Global and Planetary Change 40, 177–182.

Ostrom, C.W., 1990. Time series analysis, regression techniques. Second Edition: Quantitative Applications in the Social Sciences, vol. 9. Sage Publications, Newbury Park, California.

Ponte, R.M., 2006. Low frequency sea level variability and the inverted barometer effect. Journal of Atmospheric and Oceanic Technology 23, 619–629.

Rayner, N.A., Parker, D.E., Horton, E.B., Folland, C.K., Alexander, L.V., Rowell, D.P., Kent, E.C., Kaplan, A., 2003. Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. Journal of Geophysical Research 108, 4407.doi:10.1029/2002JD002670.

Singh, O.P., Khan, Tariq Masood Ali, Aktar, Fahmida, Sarker, Majajul Alam, 2001. Recent sea level and sea surface temperature changes along the Maldives Coast. Marine Geodesy 24, 209–218.

Tamisiea, M.E., Mitrovica, J.X., Nerem, R.S., Leuliette, E.W., Milne, G.A., 2006. Correcting satellite-derived estimates of global mean sea level change for global isostatic adjustment. Personal communication.

Torrence, C., Webster, P.J., 1999. Interdecadal changes in the ENSO- Monsoon System. Journal of Climate 12, 1679–2690.

Trenberth, K.E., Hurrell, J.W., 1994. Decadal atmosphere-ocean variations in the Pacific. Climate Dynamics 9, 303–319.

Von Storch, H., Zwiers, F.W., 1999. Statistical analysis in climate research. Cambridge University Press. 484 pp.

Woodroffe, C.D., 2005. Late Quaternary sea-level highstands in the central and eastern Indian Ocean: a review. Global and Planetary Change 49, 121–138.

Woodworth, P.L., 2005. Have there been large recent sea level changes in the Maldive Islands? Global and Planetary Change 49, 1–18.

Woodworth, P.L., Player, R., 2003. The permanent service for mean sea level: an update to the 21st century. J. Coastal Res. 19, 287–295.

World Climate Research Program, 1985. Scientific Plan for the Tropical

Ocean and Global Atmosphere Program, Tech. Doc. WMO/TD-64.

World Meteorological Organisation, Geneva. 146 pp.

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