10 New Papers: Sea Levels 1 – 6 Meters Higher 4,000 – 6,000 Years Ago

atmospheric CO2 concentrations up to 350 ppm have been characterized as climatically “safe”.  However, CO2 concentrations above 350 ppm are thought to be dangerous to the Earth system.  It is believed that such “high” concentrations could lead to rapid warming, glacier and ice sheet melt, and especially catastrophic sea level rise of 10 feet within 50 years. It is interesting to note these prognostications of impending deluge are predicated on the assumption that CO2 concentrations are a driver of sea level fluctuations. Scientists have determined that during the interglacial 400,000 years ago (MIS 11), CO2 peaked at a very safe 280 parts per million (ppm).  Despite such a low and “ideal” CO2 concentration, scientists have determined that sea levels during that interglacial were 20 meters higher than than they are now. Guo et al., 2017

“The upper 250 meter-long sediment core of Site U1391 (1085 m water depth) retrieved from the Portuguese margin in the Northeast Atlantic Ocean was adopted for the benthic foraminiferal analyses to disclose the variations in Mediterranean Outflow Water (MOW) intensity over the last ~ 0.9 Ma [900,000 years]. The strongest MOW [Mediterranean Outflow Water]  intensity during MIS 11 [400,000 years ago] confirms the climatic influence of waving sea level on the MOW current by its +20 m high-stand above the present sea level.”
CO2 graph courtesy of NASA.gov

Sea Levels 6-8 Meters Higher 6-9 Thousand Years Ago (~260 ppm CO2)
Although most scientists have found that the Holocene’s (~11,700 years ago to present) sea level peaks (highstands) were between 1 and 4 meters higher than present, there are some who have found that Early Holocene sea levels reached as high as 6 to 8 meters above mean sea level today.
Prieto et al., 2016
“Analysis of the RSL [relative sea level] database revealed that the RSL [relative sea level] rose to reach the present level at or before c. 7000 cal yr BP, with the peak of the sea-level highstand c. +4 m [above present] between c. 6000 and 5500 cal yr BP [calendar years before present] … This RSL [relative sea level] curve was re-plotted by Gyllencreutz et al. (2010) using the same index points and qualitative approach but using the calibrated ages. It shows rising sea-levels following the Last Glacial Termination (LGT), reaching a RSL [relative sea level] maximum of +6.5 m above present at c. 6500 cal yr BP [calendar years before present], followed by a stepped regressive trend towards the present.”

Hodgson et al., 2016
“Rapid early Holocene sea-level rise in Prydz Bay, East Antarctica … The field data show rapid increases in rates of relative sea level rise of 12–48 mm/yr [+1.2 to 4.8 meters per century] between 10,473 (or 9678) and 9411 cal yr BP in the Vestfold Hills and of 8.8 mm/yr between 8882 and 8563 cal yr BP in the Larsemann Hills. … The geological data imply a regional RSL [relative sea level] high stand of c. 8 m [above present levels], which persisted between 9411 cal yr BP and 7564 cal yr BP [calendar years before present], and was followed by a period when deglacial sea-level rise was almost exactly cancelled out by local rebound.”

Recent Sea Level Rise Undetectable When Viewed In Its Long-Term Context
Despite the surge in anthropogenic CO2 emissions and atmospheric CO2 since the 20th century began, the UN’s Intergovernmental Panel on Climate Change (IPCC) has concluded that global sea levels only rose by an average of 1.7 mm/yr during the entire 1901-2010 period, which is a rate of less than 7 inches (17 cm) per century and an overall rise of just 0.19 of a meter in 110 years. According to Wenzel and Schröter (2014), the acceleration rate for the sea level rise trend since 1900 has been just +0.0042 mm/yr, which is acknowledged by the authors to be “not significant” and well within the larger range of uncertainty (+ or – 0.0092 mm/yr), effectively putting the overall 20th/21st century sea level rise acceleration rate at nearly zero. As mentioned, most scientists have found that sea levels were about 1 – 4 meters higher than they are now between 4,000 and 6,000 years ago (when CO2 concentrations were about 260 to 265 ppm).  It may therefore be enlightening to visualize the overall nineteen hundredths of a meter (0.19) rise in sea levels since 1901 in its long-term (Holocene) context.  Assuming a sea level highstand of about 2.5 meters above present during the Mid-Holocene, notice how modest the recent rise appears.
10 More New Papers Affirm Sea Levels Were Much Higher 4-6 Thousand Years Ago
In the last few years alone (2014 to 2016), there were at least 35 papers published in the peer-reviewed scientific literature indicating that sea levels were substantially higher than they are now just a few thousand years ago…when CO2 concentrations are thought to have been “safe”. In 2017, there have already been another 10 scientific papers published that can be added to this growing list. It is becoming more and more apparent that sea levels rise and fall without any obvious connection to CO2 concentrations.  And if an anthropogenic signal cannot be conspicuously connected to sea level rise (as scientists have increasingly noted), then the greatest perceived threat (rising sea levels) promulgated by advocates of dangerous anthropogenic global warming will have lost its impact.
1.  Das et al., 2017  (India) “In the absence of any evidence of land-level changes, the study suggests that at around 6 ka to 3 ka [6,000 to 3,000 years ago], the sea was approximately 2 m higher than present.”

2.  Fontes et al., 2017   (Brazil) “During the early-middle Holocene there was a rise in RSL [relative sea level] with a highstand at about 5350 cal yr BP [calendar years before present]  of 2.7 ± 1.35 m [higher than present], which caused a marine incursion along the fluvial valley.”
3.  Yoon et al., 2017  (Korea) “Songaksan is the youngest eruptive centre on Jeju Island, Korea, and was produced by a phreatomagmatic eruption in a coastal setting c. 3.7 ka BP [3,700 years before present]. The 1 m thick basal portion of the tuff ring shows an unusually well-preserved transition of facies from intertidal to supratidal, from which palaeo-high-tide level and a total of 13 high-tide events were inferred. Another set of erosion surfaces and reworked deposits in the middle of the tuff ring, as high as 6 m above present mean sea level, is interpreted to be the product of wave reworking during a storm-surge event that lasted approximately three tidal cycles. … The reworked deposits alternate three or four times with the primary tuff beds of Units B and C and occur as high as 6 m above present mean sea level or 4 m above high-tide level (based on land-based Lidar terrain mapping of the outcrop surface).”  
4.  Marwick et al., 2017  (full pdf)  (Thailand) “Sinsakul (1992) has summarised 56 radiocarbon dates of shell and peat from beach and tidal locations to estimate a Holocene sea level curve for peninsula Thailand that starts with a steady rise in sea level until about 6 k BP, reaching a height of +4 m amsl (above [present] mean sea level). Sea levels then regressed until 4.7 k BP, then rising again to 2.5 m amsl at about 4 k BP. From 3.7 k to 2.7 k BP there was a regressive phase, with transgression starting again at 2.7 k BP to a maximum of 2 m amsl at 2.5 k BP. Regression continued from that time until the present sea levels were reached at 1.5 k BP. … Tjia (1996) collected over 130 radiocarbon ages from geological deposits of shell in abrasion platforms, sea-level notches and oyster beds and identified a +5 m [above present] highstand at ca. 5 k BP in the Thai-Malay Peninsula. …  Sathiamurthy and Voris (2006) summarise the evidence described above as indicating that between 6 and 4.2 k BP, the sea level rose from 0 m to +5 m [above present] along the Sunda Shelf [+2.8 mm/yr], marking the regional mid-Holocene highstand. Following this highstand, the sea level fell gradually and reached the modern level at about 1 k BP [1,000 years ago].”
5.  May et al., 2017 (W. Australia) “[T]he mid-Holocene sea-level highstand of Western Australia [was] at least 1–2 m above present mean sea level. … Between approximately 7000 and 6000 years BP, post-glacial RSL [relative sea level] reached a highstand of 1-2 m above the present one, followed by a phase of marine regression (Lambeck and Nakada, 1990; Lewis et al., 2013).”
6.  Kane et al., 2017 (Equatorial Pacific) “The high stand is documented across the equatorial Pacific with peak sea-level values ranging from 0.25 to 3.00 m above present mean sea level (MSL) between 1000 and 5000 yr BP (Fletcher and Jones, 1996; Grossman et al., 1998; Dickinson, 2003; Woodroffe et al., 2012). Woodroffe et al. (2012) argues that Holocene sea-level oscillations of a meter or greater are likely to have been produced by local rather than global processes.”
7.  Khan et al., 2017 (Caribbean) “Only Suriname and Guyana [Caribbean] exhibited higher RSL [relative sea level] than present (82% probability), reaching a maximum height of 1 m [above present] at 5.2 ka [5,200 years ago]. … Because of meltwater input, the rates of RSL change were highest during the early Holocene, with a maximum of 10.9 ± 0.6 m/ka [1.9 meters per century] in Suriname and Guyana and minimum of 7.4 ± 0.7 m/ka [0.74 meters per century] in south Florida from 12 to 8 ka [12,000 to 8,000 years ago].”
8.  Meltzner et al., 2017  (Southeast Asia) “Half-metre sea-level fluctuations on centennial timescales from mid-Holocene corals of Southeast Asia … RSL [relative sea level]  history between 6850 and 6500 cal years BP that includes two 0.6 m fluctuations, with rates of RSL [relative sea level] change reaching 13±4 mm per year. … Here RSL [relative sea level] rose to an initial peak of +1.9 m [above present] at 6,720 cal years BP, then fell rapidly to a lowstand of +1.3 m, remaining at about that level for ∼100 years, before rising to a second peak at +1.7 m shortly after 6,550 cal years BP. Around 6,480 cal years BP, RSL appears to have fallen again to +1.3 m before rising to a third peak at +1.6 m or higher. … The peak rate of RSL rise, averaged over a 20-year running time window over the period of study (6,850–6,500 cal years BP), is +9.6±4.2 mm per year (2σ); the peak rate of RSL fall is −12.6±4.2 mm per year. … To put the ∼0.6 m mid-Holocene fluctuations in context, annual mean sea level in some modern tide-gauge records is seen to change by as much as 0.2–0.3 m on interannual timescales, and the interannual s.d. of sea surface height between 1979 and 2013 approached 0.1 m in some portions of the western Pacific.  The central dome of each microatoll grew during a period when RSL was high; RSL then fell rapidly, killing the upper portions of the corals; RSL then stabilized at a lower elevation, forming a series of low concentric annuli 0.6 m higher than present-day analogues; RSL [relative sea level] then rose 0.6 m in less than a century, allowing the coral to grow upward to 1.2 m higher than modern living corals.” 9.  Leonard, 2017 (Great Barrier Reef) “The resultant palaeo-sea-level reconstruction revealed a rapid lowering of RSL of at least 0.4 m from 5500 to 5300 yBP following a RSL [relative sea level] highstand of ~0.75 m above present from ~6500 to 5500 yBP. RSL then returned to higher levels before a 2000-yr hiatus in reef flat corals after 4600 yBP. The RSL oscillations at 5500 yBP and 4600 yBP coincide with both substantial reduction in reef accretion and wide spread reef “turn-off”, respectively, thereby suggesting that oscillating sea level was the primary driver of reef shut down on the GBR.”
10.  Dechnik et al., 2017 (Tropical Western Pacific) “[I]t is generally accepted that relative sea level reached a maximum of 1–1.5 m above present mean sea level (pmsl) by ~7 ka [7,000 years ago] (Lewis et al., 2013).”   This article appeared on the NoTricksZone website at http://notrickszone.com/2017/05/08/10-new-papers-sea-levels-1-6-meters-higher-4000-6000-years-ago/]]>

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