Source: press release for Myers et al., 2015
Sea Levels 2-4 m Higher Until ~5,000 Years Ago
Imply Surface Temps Were At Least 5°C Warmer
According to the accepted (IPCC) formula for calculating the contribution of ocean warming (thermal expansion) to sea level rise upon reaching equilibrium, every additional degrees Celsius of surface warmth yields about 0.4 meter (0.2 to 0.6) to global sea levels.
Moore et al., 2013 “The equilibrium sea level change from thermal expansion alone has been estimated to be ~0.2–0.6 m/°C” (Meehl et al., 2007b).
IPCC AR5: “The amount of ocean thermal expansion increases with global warming (0.2 to 0.6 m/°C–1)”
Considering that much of the globe had sea levels that reached or exceeded 2 to 4 meters above present during the Early to Mid Holocene (~10,000 to ~5,000 years ago), a conversion of 0.4 m/°C (from thermal expansion alone) would indicate that surface temperatures were at minimum 5°C warmer than now during the first half of the Holocene. There are many paleoclimate reconstructions of surface temperatures that substantiate such high levels of warming during this period (illustrated below).
It should be noted that during the Early to Middle Holocene, when sea levels were 2-4 meters higher than now and surface temperatures can be inferred to have been at least 5°C warmer, Earth’s CO2 concentrations were only hovering around 260 ppm to 265 ppm – about 140 ppm lower than today’s values (over 400 ppm).
When we consider that 93% of the Earth’s heat is contained in the oceans, which is symbiotically connected to sea level rise and fall via thermal expansion, we can affirm that both surface temperatures and sea levels can and do rise and fall without any meaningful contribution from the atmospheric CO2 concentration. Therefore, it can be concluded that other internal mechanisms, and not CO2 concentrations, are the driving influence impacting both surface temperatures and sea levels.
Argentina, 3-5 meters higher than present, Bini et al., 2017
“The main conclusion is that the relative sea-level between c. 7000 and 5300 cal. yr BP was in the range of c. 2–4 m a.s.l. [above present mean sea level], with a mean value of c. 3.5 m a.s.l. … Initial glacio-hydro-isostatic models of the Patagonian coast [Argentina] suggested that the shoreline could be characterized by currently raised beaches, which started to form as soon as ice-sheet melting ceased (Clark et al., 1978). A more recent model (Milne and Mitrovica, 2008) predicted that RSLs might have exceeded present by c. 5 m at 6000 cal. yr BP. [T]he altimetric and chronological data of the valleymouth terraces show a highstand between c. 7000 and 6600 cal. yr BP at c. 4 m a.s.l. [4 meters above present mean sea level], followed by a progressive fall to c. 2–2.5 m between 6200 and 5300 cal. yr BP.”
Antarctic Peninsula, 15.5 meters higher than present, Watcham et al., 2011
“The curve shows a mid-Holocene RSL highstand on Fildes Peninsula at 15.5 m above mean sea level between 8000 and 7000 cal a BP.”
South Africa, 3.5 meters higher than present, Lecea et al., 2017
“Ramsay (1995) produced a 9 kyr BP record of sea-level changes from the South African east coast, that showed sea levels reached a high stand of +3.5 m [above present] at 4.65 kyr BP [4,650 years ago]. … In Mozambique, Norström et al., (2012) identified a sea-level highstand ~3 m above present at ~ 6.6 kyr BP.”
Western India, 2 meters higher than present, Das et al., 2017
“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.”
Western Sumatra, Indonesia, 2-6 meters higher than present, Dura et al., 2011
“A prominent feature of southeast Asia Holocene sea level records is the mid-Holocene highstand [Geyh et al., 1979; Tjia, 1996; Scoffin and Le Tissier, 1998; Hanebuth et al., 2000], which in Western Sumatra, varies in timing and magnitude from 3000 to 5000 cal years B.P., and +6 to +2 m above present-day sea levels [Horton et al., 2005].”
Denmark, 2.2 meters higher than present, Sander et al., 2016
“The data show a period of RSL [relative sea level] highstand at c. 2.2 m above present MSL [mean sea level] between c. 5.0 and 4.0 ka BP [5,000 to 4,000 years before present].”
Africa, 3.5 meters higher than present, Accordi and Carbone, 2016
“Then, the skeletal carbonate storage on the shelf reached its maximum 5 to 4 ka BP [5000 to 4000 years before present] (Ramsay, 1995) during a highstand about 3.5 m above the present sea level, when shallow marine accommodation space was greater than at present.”
Brazil, 4 meters higher than present, Spotorno-Oliveira et al., 2016
“The transgressing sea rapidly rose until reaching the ~ +4 m highstand [above present] level around 5000 years BP.”
Bangladesh, 4.5-5 meters higher than present, Rashid et al., 2012
“The abundant marine diatoms and mangrove pollens indicate the highest RSL [relative sea level] transgression in Bangladesh at approximately 6000 cal BP, being at least 4.5 to 5 m higher than the modern m.s.l. [mean sea level]. … [T]he present shoreline of Bangladesh was established at approximately 1500 cal BP and has not noticeably migrated inland since.”
China, 2-4 meters higher than present, Bradley et al., 2016
“In general, the data indicate a marked slowdown between 7 and 8 kyr BP, with sea level rising steadily to form a highstand of ~2-4 m [above present sea level] between 6 and 4 kyr BP [6000 and 4000 years before present]. This is followed by a steady fall, reaching present day levels by ~1 kyr BP.”
East Antarctica, 8 meters higher than present, Hodgson et al., 2016
“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].”
Argentina, Uruguay, 4 – 6.5 meters higher than present, 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.”
Brazil, 2.7 meters higher than present, Fontes et al., 2017
Vancouver, 1-3 meters higher than present, Dura et al., 2016
“RSL [relative sea level] highstand of <1 m (northern Sumatra) and ∼3 m (western Sumatra) between 6 and 3 ka [6,000-3,000 years ago].”
Thailand-Malaysia, 4-5 meters higher than present, Marwick et al., 2017
“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). … 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.”
Japan, 2.7 meters higher than present, Yokoyama et al., 2016
“The Holocene-high-stand (HHS) inferred from oyster fossils (Saccostrea echinata and Saccostrea malaboensis) is 2.7 m [above present sea level] at ca. 3500 years ago, after which sea level gradually fell to present level.”
Uruguay, 3-4 meters higher than present, Bracco et al., 2014
“We present a sea level change curve for mid Holocene in Uruguay. Sea level reached 4 m amsl [above present mean sea level] between 6000 and 5500 yr BP [before present]. A rapid sea level fall to about 1 m amsl [above present mean sea level] was inferred for 4700-4300 yr BP. A further sea level increase to about 3 m amsl [above present mean sea level] was inferred after 4300 yr BP. After 4300 yr BP there was a constant sea level a decline.”
New Zealand, 2.75 – 3 meters higher than present, Clement et al., 2016
“In North Island locations the early-Holocene sea-level highstand was quite pronounced, with RSL [relative sea level] up to 2.75 m higher than present. In the South Island the onset of highstand conditions was later, with the first attainment of PMSL being between 7000–6400 cal yr BP. In the mid-Holocene the northern North Island experienced the largest sea-level highstand, with RSL up to 3.00 m higher than present.”
Eastern Australia, 2 meters higher than present, Macreadie et al., 2015
“[R]esults from other studies … suggest that high-stand, at perhaps 2 m above present msl[mean sea level] was achieved as early as 7000 radiocarbon years BP [before present](7800 cal. years BP) and that sea-level has exceeded the present value for much of the mid- to late-Holocene [~7000 to ~1000 years ago].”
Thailand, 1.5-3.0 meters higher than present, Scheffers et al., 2012
“Nevertheless, those from the Laem Son coral profile, as well as those from oysters in the Phang-nga Bay show the same trend and maximum altitude lower than +3 m compared with modern RSL (Figure 6a); the maximum of +2.5–3.0 m was timed to c. 5700 cal. BP. … [W]e tentatively deduce a highstand around 5300 BP in the order of +1.5–2.5 m above [present] RSL [relative sea level]”
Kuwait, Qatar, Abu Dhabi, Arabian Gulf, 2-4 meters higher than present, Reinink-Smith, 2015
“[A]ssuming the tidal ranges were similar in the middle Holocene, a rough estimate of the MSL [mean sea level] during the middle Holocene highstand is 5.2 m − 1.7 m = +3.5 m above the present MSL [mean sea level]. … The +3.5 m highstand estimate in northeastern Kuwait derived in this study is also higher than the previously reported maximum estimates of +2 to +2.5 m responsible for other Holocene beach ridges in the Arabian Gulf (Gunatilaka, 1986; Lambeck, 1996; Kennett and Kennett, 2007; Jameson and Strohmenger, 2012). Some beach ridges in Qatar and Abu Dhabi are at elevations of 2–4 m above MSL [present mean sea level] as far as 5-15 km inland (Alsharhan and Kendall, 2003).”
Singapore, 2.5 meters higher than present, Bird et al., 2010
“The sea-level curve, corroborated by the indpendent proxy records, suggests rapid rise at a rate of 1.8 m/100 yr until 8100 cal (calibrated) yr B.P., a near cessation in the rate of sea level rise between 7800 and 7400 cal yr B.P., followed by a renewed rise of 4–5 m that was complete by 6500 cal yr B.P [0.5 m/100 yr]. … A mid-Holocene highstand of ~+2.5 m [above present] was reached after 6500 cal yr B.P., followed by a lowering, with mangroves prograding over the core site by ca. 1000 cal yr B.P.”
South Africa, 3 meters higher than present, Strachan et al., 2014
“The mid-Holocene highstands culminated in a sea-level maximum of approximately 3 m above mean sea level (MSL) from 7300 to 6500 cal years BP [calendar years before present] and of 2 m above MSL at around 4000 cal years BP.”
Brazil, 1-4 meters higher than present, Hein et al., 2014
“Along the eastern and southern Brazilian coasts of South America, 6000 years of sea-level fall have preserved late-stage transgressive and sea-level highstand features 1–4 m above present mean sea level and several kilometers landward of modern shorelines.”
Reconstructions Of 4 – 6° C Warmer
Temps During The Last 10,000 Years
Svalbard, Arctic, 4-6°C Warmer Than Present, Mangerud and Svendsen, 2017
“August temperatures on Svalbard were 6°C warmer at around 10.2–9.2 cal. ka BP … 4°C warmer than present between 8.2 and 6 cal. ka BP”
East China, 3-4°C warmer than present, Li et al., 2017
Northern Japan, 3-4°C warmer than present, Kawahat et al., 2017
“SST [sea surface temperatures] dropped by 3.5 °C [15.1 to 11.6 °C] within two centuries. Several peaks fluctuate by 2°C over a few centuries.”
Tibetan Plateau, 4-5°C warmer than present, Saini et al., 2017
Fan Lake, Antarctica, 8°C warmer than present, Foster et al., 2016
Arctic Ocean, 3-4 °C warmer than present, Bonnet et al., 2010
North Iceland, 5 °C warmer than present, Andersen et al., 2004
Northwest Greenland, 2.5-4 °C warmer than present, Lasher et al., 2017
“This paper presents a multi proxy lake record of NW Greenland Holocene climate. … Summer temperatures (2.5–4 °C warmer than present) persisted until ∼4 ka [4,000 years ago]
Antarctic Peninsula, 4-5°C warmer than present (1,000 years ago), Browne et al., 2017
NW Pacific, 4 °C warmer than present, Yamamoto et al., 2016
North Atlantic, 6°C warmer than present, Mark, 2016
Mediterranean Sea, 4°C warmer than present, Jalali et al., 2016
Alberta, Canada, 8°C warmer than present, Demezhko et al., 2017
British Columbia (Canada), 3-4°C warmer than present, Rosenberg et al., 2004
East Greenland, 3-6 °C warmer than present, Lusas et al., 2017
“Air temperatures in Milne Land, west of our study area, based on preliminary estimates from chironomids, may have been 3–6°C warmer than at present (Axford et al. 2013)”
Russia, 2.5° to 7.0°C warmer than present, MacDonald et al., 2000
“Over most of Russia, forest advanced to or near the current arctic coastline between 9000 and 7000 yr B.P. and retreated to its present position by between 4000 and 3000 yr B.P. … During the period of maximum forest extension, the mean July temperatures along the northern coastline of Russia may have been 2.5° to 7.0°C warmer than modern.”
Antarctic Peninsula, 3.5 °C warmer than present, Mulvaney et al., 2012
“A marine sediment record from offshore of the western Antarctic Peninsula also shows an early Holocene optimum where surface ocean temperatures were determined to be ~3.5 °C warmer than present, while the George VI ice shelf on the southwestern Antarctic Peninsula was absent during this early Holocene warm interval before reforming in the mid Holocene.”
via NoTricksZone
August 21, 2017 at 05:23AM
Iowa Climate Science Education 