Review of sl rise along eastern seaboard of us and thoughts on our rapid sl rise data from tide gauges in the sab
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| Incomplete and rapid literature review of SL rise along eastern seaboard of US and thoughts on our rapid SL rise data from tide gauges in the SAB
July 2, 2015 – Jon Martin’s attempt  Many recent papers have pointed out that SL rise is accelerating north of Cape Hatteras (Knight et al., 2005; Boon, 2012; Sallenger Jr et al., 2012), although one dissenting opinion (Houston and Dean, 2011) suggests that SL rise is decelerating. Evidence for deceleration depends on the start time of the analysis and isn’t widely accepted (e.g., Boon 2012). This acceleration has been termed a “hotspot” of SL rise (Sallenger et al., 2012), who point out that the rise occurred between 1950 to 1979 and 1980 to 2009. This 1950 date turns out to be fairly critical as pointed out in a minute. The rise in the hotspot is 1.97 mm/yr faster than the long-term global trend (Sallenger et al., 2012). Similar short term SL rise events have been observed, specifically during 2009 and 2010 north of NYC, when SL jumped 128 mm (Goddard et al., 2015). Goddard (2014) also has long term records of averages from multiple tide gauges from south, mid and northern coast, which show an increase in the southern tide gauges between about 1935 to 1950 (fig. 1).
Causes for the hotspot of sea level rise north of Cape Hatteras are discussed extensively and come down to three possibilities (Woodworth et al., 2010): (1) Wind forcing, (2) changes in Atlantic Meridional Overturning Circulation (3) or vertical divergence of the AMOC (Thompson and Mitchum, 2014). The Thompson and Mitchum (2014) paper suggests that SL variations are coherent from Caribbean to Nova Scotia, which seems to be contrast with much of the other literature that reflects variation in SL rise, usually split at Cape Hatteras (although I’m not sure I understand this paper very well).  In addition to trying to understand causes of changes in SL rise, others (Häkkinen, 2001; McCarthy et al., 2015) work the problem in reverse and say that the SL variations can be used to understand changes in AMOC. I guess this assumes that the AMOC controls sea level and not winds or vertical divergence. Ezer et al., (Ezer et al., 2013) suggest the recent acceleration of SLR in the MAB (ie. the hotspot) results from a change in the Gulf Stream from 6 to 8 year oscillation to continuous weakening since 2004. They suggest this impact is greater in southern than northern MAB. Speculating, perhaps the SL rise hotspot would move south of Cape Hatteras as the Gulf Stream continued to decline, which may be what we’re seeing? This speculation would require understanding a lot better than I do what the link is between the Gulf Stream and SL rise.
Much of the recent work relates the SL rise to AMO through its effects on thermohaline circulation and the AMOC (Knight et al., 2005). Although the work is trying to link the AMO with SL rise, no one that I’ve found (except a web page) discusses the rapid rise shown in figure 1 between 1935 and 1950 and the start of the most recent complete warm phase of the AMO between 1930 and 1960 (Fig. 2). The link between SL and the AMO is important because it provides a model that may be useful for prediction (or at least correlations that may provide predictions) of location and magnitude of SL rise. Some of the predictions so far suggest that declines in the AMOC over the next few decades may increase SL rise north of Cape Hatteras (Knight et al., 2005). Our data of increasing SL south of Cape Hatteras and flattening of the recent rapid rise in this hotspot of the MAB seem to contradict this prediction. A good thing for us is that only one paper we’ve found so far (Park and Sweet, 2015) discusses the recent SL rise south of the Cape Hatteras. That paper focuses on the role of the Florida Current on SL and the impact that SL rise in SE US will have on the Everglades. It does suggest that this large community of people who work on tide gauge data and SL are going to find this increase in SL over the past 5 years in which case we might get scooped. I think that if we talk ourselves into the SE US SL rise as related to warm phase of the AMO, to include that. It seems that the tide gauge records that Arnoldo is working on will be an important contribution to this previous work I’ve sketched out above (which by no means is exhaustive) in several different ways (these are what I see as could be conclusions/discussion points to the work): (1) That there are two periods of faster SL rise (or SL rise acceleration) in SE US than MAB – one 1935 to 1950 and this recent one from 2010 to now (2) The rapid rise in 1935 to 1950 might provide an analogue to the recent one in terms of magnitude and duration. (2) These rises correspond to the AMO cycles (3) If true, and we can figure out causes the rise would be good – no ideas there yet. (4) The link to AMO would suggest that the rapid SL rise in SE US may continue for several more years (although a lot of variability during that time) (5) If the SL rise continues for another decade, difficult time for vulnerable locations along the coast – e.g., Miami. Could we speculate what the SL elevation will be after another decade of increased SL rise? (6) Particularly vulnerable if the cyclicity in SL rise corresponds to cyclicity of increased hurricane activity or frontal storms – another body of literature to go through.
Ezer, T., Atkinson, L.P., Corlett, W.B., Blanco, J.L., 2013. Gulf Stream's induced sea level rise and variability along the US mid‐Atlantic coast. Journal of Geophysical Research: Oceans, 118(2): 685-697. Goddard, P.B., Yin, J., Griffies, S.M., Zhang, S., 2015. An extreme event of sea-level rise along the Northeast coast of North America in 2009–2010. Nature communications, 6. Häkkinen, S., 2001. Variability in sea surface height: A qualitative measure for the meridional overturning in the North Atlantic. Journal of Geophysical Research: Oceans, 106(C7): 13837-13848. Houston, J.R., Dean, R.G., 2011. Sea-level acceleration based on US tide gauges and extensions of previous global-gauge analyses. Journal of Coastal Research, 27(3): 409-417. Knight, J.R., Allan, R.J., Folland, C.K., Vellinga, M., Mann, M.E., 2005. A signature of persistent natural thermohaline circulation cycles in observed climate. Geophysical Research Letters, 32(20). McCarthy, G.D., Haigh, I.D., Hirschi, J.J.-M., Grist, J.P., Smeed, D.A., 2015. Ocean impact on decadal Atlantic climate variability revealed by sea-level observations. Nature, 521(7553): 508-510. Park, J., Sweet, W., 2015. Accelerated sea level rise and Florida Current transport. Ocean Science Discussions, 12(2): 551-572. Sallenger Jr, A.H., Doran, K.S., Howd, P.A., 2012. Hotspot of accelerated sea-level rise on the Atlantic coast of North America. Nature Climate Change, 2(12): 884-888. Thompson, P.R., Mitchum, G.T., 2014. Coherent sea level variability on the North Atlantic western boundary. Journal of Geophysical Research: Oceans, 119(9): 5676-5689. Woodworth, P.L., Church, J.A., Aarup, T., Wilson, W.S., 2010. Introduction in understanding sea-level rise and variability. Wiley-Blackwell, West Sussex, UK. Directory: ~arnoldo -> ftp -> laptop -> documents -> slr slr -> Increase in the rate of sea-level rise in the southeastern United States from 2011 to 2015 Download 95.09 Kb. Share with your friends:
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