Holocene periodicity in North Atlantic climate and deep-ocean flow south of Iceland

Bianchi, G. G.; McCave, I Nick

doi:10.1038/17362

Cited by 715 publications

(497 citation statements)

References 33 publications

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“…Similar fluctuations in OMZ intensity have occurred during the Dansgaard-Oeschger (D-O) events (millennial-scale abrupt climate oscillations) during the last glacial period Schmittner et al, 2007). Bottom-water temperature and current velocities have also fluctuated in relation to decadal-millennial scale climatic changes during the last de-glaciation and Holocene (Bianchi and McCave, 1999;Marchitto and deMenocal, 2003;Farmer et al, 2011;Cronin et al, 2012). Finally, deep-sea bottom temperatures have also exhibited systematic glacial-low, interglacial-high patterns during the Plio-Pleistocene (Dwyer et al, 1995;Martin et al, 2002;Sosdian and Rosenthal, 2009;Elderfield et al, 2010).…”

Section: Introductionmentioning

confidence: 81%

Major impacts of climate change on deep-sea benthic ecosystems

Sweetman

Thurber

Smith

et al. 2017

Elementa: Science of the Anthropocene

253

289

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The deep sea encompasses the largest ecosystems on Earth. Although poorly known, deep seafloor ecosystems provide services that are vitally important to the entire ocean and biosphere. Rising atmospheric greenhouse gases are bringing about significant changes in the environmental properties of the ocean realm in terms of water column oxygenation, temperature, pH and food supply, with concomitant impacts on deep-sea ecosystems. Projections suggest that abyssal (3000-6000 m) ocean temperatures could increase by 1°C over the next 84 years, while abyssal seafloor habitats under areas of deep-water formation may experience reductions in water column oxygen concentrations by as much as 0.03 mL L -1 by 2100. Bathyal depths (200-3000 m) worldwide will undergo the most significant reductions in pH in all oceans by the year 2100 (0.29 to 0.37 pH units). O 2 concentrations will also decline in the bathyal NE Pacific and Southern Oceans, with losses up to 3.7% or more, especially at intermediate depths. Another important environmental parameter, the flux of particulate organic matter to the seafloor, is likely to decline significantly in most oceans, most notably in the abyssal and bathyal Indian Ocean where it is predicted to decrease by 40-55% by the end of the century. Unfortunately, how these major changes will affect deep-seafloor ecosystems is, in some cases, very poorly understood. In this paper, we provide a detailed overview of the impacts of these changing environmental parameters on deep-seafloor ecosystems that will most likely be seen by 2100 in continental margin, abyssal and polar settings. We also consider how these changes may combine with other anthropogenic stressors (e.g., fishing, mineral mining, oil and gas extraction) to further impact deep-seafloor ecosystems and discuss the possible societal implications.

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Section: Introductionmentioning

confidence: 81%

Major impacts of climate change on deep-sea benthic ecosystems

Sweetman

Thurber

Smith

et al. 2017

Elementa: Science of the Anthropocene

253

289

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“…Planktonic foraminiferal data north of Iceland indicate surface water cooling of about 3°C, while transfer function calculation based on diatoms indicate a summer sea surface temperature drop of about 2°C (Jiang et al, in prep.). The actual background for the 8200 cal yr BP cooling event is not fully understood, but it has been suggested by many authors that fresh melt water input from the Laurentide ice sheet may have influenced the thermohaline system at that time ( Klitgaard-Kristensen et al, 1998;KlitgaardKristensen et al, 2001;Bianchi andMcCave, 1999 andBauch et al, 2001). …”

Section: Comparison and Discussionmentioning

confidence: 99%

Environmental changes off North Iceland during the deglaciation and the Holocene: foraminifera, diatoms and stable isotopes

Knudsen

Jiang

Jansen

et al. 2004

Marine Micropaleontology

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A combined study of foraminifera, diatoms and stable isotopes in marine sediments off North Iceland records major changes in sea surface conditions since about 15800 cal years (yr) BP. Results are presented from two gravity cores obtained at about 400 m water depth from two separate sedimentary basins on each side of the submarine Kolbeinsey Ridge. The chronology of the sedimentary record is based partly on AMS 14 C dates, partly on the Vedde and the Saksunarvatn tephra markers, as well as the historical Hekla AD 1104 tephra. During the regional deglaciation, the planktonic foraminiferal assemblages are characterised by consistently high percentages of sinistrally coiled Neogloboquadrina pachyderma. However, major environmental variability is reflected by changes in stable isotope values and diatom assemblages. Low 18 O values indicate a strong freshwater peak as well as possible brine formation by sea-ice freezing during a pre-Bølling interval (Greenland Stadial 2), corresponding to the Heinrich 1 event. The foraminifera suggest a strong concurrent influence of relatively warm and saline Atlantic water, and both the foraminifera and the diatoms suggest mixing of cold and warm water masses. Similar but weaker environmental signals are observed during the Younger Dryas (Greenland Stadial 1) around the level of the Vedde Ash. Each freshwater peak is succeeded by an interval of severe cooling both at the beginning of the Bølling-Allerød Interstadial Complex (Greenland Interstadial 1) and during the Preboreal, presumably associated with the onset of intense deep water formatiom in the Nordic Seas. The Holocene thermal optimum, between 10200 and about 7000 cal years (yr) BP, is interrupted by a marked cooling of the surface waters around 8200 cal yr BP. This cold event is clearly expressed by a pronounced increase in the percentages of sinistrally coiled N. pachyderma, corresponding to a temperature decrease of about 3°C. A general cooling in the area is indicated after 7000-6000 cal yr BP, both by the diatom data and by the planktonic foraminiferal data. After a severe cooling around 6000 cal yr BP, the planktonic foraminiferal assemblages suggest a warmer interval between 5500 and 4500 cal yr BP. Minor temperature fluctuations are reflected both in the foraminiferal and in the diatom data in the upper part of the record, but the time resolution of the present data is not high enough to pick up details in environmental changes through the late Holocene.

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“…Other details are as given in Figure 2 and Greenland (Holmgren et al, 1999). Ocean-floor sediment cores south of Greenland suggest the possible existence of pervasive cycles of oceanic variability at around 1500 years, both in surface waters and in the strength of North Atlantic deep water movements that continued over long periods of time extending into the Holocene (Bond et al, 1997(Bond et al, , 1999(Bond et al, , 2001Bianchi and McCave, 1999). A dominant signal in the δ 18 O record for Makapansgat is that induced by variability in the range 600-800 years.…”

Section: Variability Over the Period Of Meteorological Recordmentioning

confidence: 99%

Millennial to multi‐decadal variability in the climate of southern Africa

Tyson

Cooper

McCarthy

2002

Intl Journal of Climatology

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Wavelet analysis has been used to determine changes in the variability of southern Africa climate over the last three millennia. The structure of the variability in a 3000-year δ 18 O record has been compared with that in tree ring data for the last 600 years and both to the variability in annual rainfall and runoff during the 20th century. Preferred modes of variability are shown to have occurred in all the data sets. For overlap periods, the variability modes are in phase where the data are for a common seasonal rainfall regime.From the combined proxy and instrumental data it appears that an ∼1500-year oscillation in rainfall variability may have been present during the late Holocene. Considerable variability in South African climate has been shown to reside in the bands 500-800 and 60-120 years. The latter is manifest in stable isotope and tree ring proxy data and in measured rainfall and runoff, and shows a distinctive latitudinal variation over southern Africa. The ∼80-year variability has been present for at least 600 years in the tree ring data and at least 3000 years in the stable isotope data. During the 20th century, the variability in the 60-120-year range was confined south of 20°S in southern Africa.The existence of considerable multi-decadal climate variability in the range 16-20 years has been confirmed south of 15°S. Tree ring data show that the ∼18-year oscillation in climate has been present for at least 600 years. The 500-800-year, ∼80-year and ∼18-year variability has been both frequency-and amplitude-modulated over time, but never to the extent that the variability bands have lost their integrity. Their persistence is a striking feature of southern African climate.The millennial, centennial and multi-decadal variability in climate over southern Africa finds counterparts with temporal variability in similar time ranges reported elsewhere. Spatial teleconnections in variability likewise have been shown to occur. The changes in climate variability over the subcontinent are part of variability changes affecting the Earth system in many other regions.

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Holocene periodicity in North Atlantic climate and deep-ocean flow south of Iceland

Cited by 715 publications

References 33 publications

Major impacts of climate change on deep-sea benthic ecosystems

Major impacts of climate change on deep-sea benthic ecosystems

Environmental changes off North Iceland during the deglaciation and the Holocene: foraminifera, diatoms and stable isotopes

Millennial to multi‐decadal variability in the climate of southern Africa

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