Tracking the Atlantic Multidecadal Oscillation through the last 8,000 years

Knudsen, Mads Faurschou; Seidenkrantz, Marit‐Solveig; Jacobsen, Bo Holm; Kuijpers, Antoon

doi:10.1038/ncomms1186

Cited by 327 publications

(288 citation statements)

References 61 publications

(121 reference statements)

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“…We note, however, that the latter periodicity (~26 years) lies close to the Nyquist period and therefore may be an artefact of the sampling frequency. Notably, the 56-year cycle in our sea-ice record is not associated with any well-known solar cycles, but falls within the range of the 55e70 year spectrum calculated for the Atlantic Multidecadal Oscillation (AMO) over the last 8000 years (Knudsen et al, 2011), although the sea-ice variability linked to solar forcing may also have impacted the AMO cycle .…”

Section: Discussionmentioning

confidence: 98%

Solar forcing as an important trigger for West Greenland sea-ice variability over the last millennium

Sha

Jiang

Seidenkrantz

et al. 2016

Quaternary Science Reviews

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a b s t r a c tArctic sea ice represents an important component of the climate system, and the present reduction of sea ice in the Arctic is of major concern. Despite its importance, little is known about past changes in sea-ice cover and the underlying forcing mechanisms. Here, we use diatom assemblages from a marine sediment core collected from the West Greenland shelf to reconstruct changes in sea-ice cover over the last millennium. The proxy-based reconstruction demonstrates a generally strong link between changes in sea-ice cover and solar variability during the last millennium. Weaker (or stronger) solar forcing may result in the increase (or decrease) in sea-ice cover west of Greenland. In addition, model simulations show that variations in solar activity not only affect local sea-ice formation, but also control the sea-ice transport from the Arctic Ocean through a sea-iceeoceaneatmosphere feedback mechanism. The role of solar forcing, however, appears to have been more ambiguous during an interval around AD 1500, after the transition from the Medieval Climate Anomaly to the Little Ice Age, likely to be driven by a range of factors.

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Section: Discussionmentioning

confidence: 98%

Solar forcing as an important trigger for West Greenland sea-ice variability over the last millennium

Sha

Jiang

Seidenkrantz

et al. 2016

Quaternary Science Reviews

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“…In other words, the AMO cycle behaves closely to that of the global temperature cycle in both the cycle length and extremes occurrence. Knudsen et al (2011) noticed that since the AMO obeys a 60-yr cycle, the Inter-Tropical Convergence Zone also exhibits a similar cycle. The approximately 60-yr cycle is also detected in the Pacific Decadal Oscillation (PDO) given that it goes through warm and cool phases with the duration of about 30 years each (http://jisao.washington.edu/pdo/).…”

Section: Introductionmentioning

confidence: 99%

“…In this context, Knudsen et al (2011) discussed the nature and origin of the Atlantic Multidecadal Oscillation (AMO) suggesting in particular that a quasi-persistent ~55-yr to 70-yr AMO, existed during large parts of the Holocene. This cycle is linked to internal oceanatmosphere variability and its length was found to be approximately 62 years with maxima around 1878, 1943 and 2004, and minima around 1912 and 1974.…”

Section: Introductionmentioning

confidence: 99%

Evidence for two abrupt warming events of SST in the last century

Varotsos

Franzke

Efstathiou

et al. 2013

Theor Appl Climatol

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We have recently suggested that the warming in the sea surface temperature (SST) since 1900, did not occur smoothly and slowly, but with two rapid shifts in 1925/1926 and 1987/1988, which are more obvious over the tropics and the northern midlatitudes. Apart from these shifts most of the remaining SST variability is due to the El-Nino Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Here we provide evidence that the time separation between these two SST shifts (around 60 years) is almost equal to the quasi-periodicity of many natural cycles, like that of the PDO, the global and Northern Hemisphere (NH) annual mean temperature, the Atlantic Multi-decadal Oscillation (AMO), the Inter-Tropical Convergence Zone, the Southwest US Drought data, the length of day, the air surface temperature, the Atlantic meridional overturning circulation, and the change in the location of the centre of mass of the solar system. In addition, we show that there exists a strong seasonal link between SST and ENSO over the tropics and the NH midlatitudes, which becomes stronger in autumn of the Northern Hemisphere. Finally, we found that before and after each SST shift the intrinsic properties of the SST time series obey stochastic dynamics, which is unaffected by the modulation of these two shifts. In particular, the SST fluctuations for the time period between the two SST shifts exhibit 1/f-type long range correlations, which are frequently encountered in a large variety of natural systems. Our results have potential implications for future climate shifts and crossing tipping points due to an interaction of intrinsic climate cycles and anthropogenic greenhouse gas emissions.

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“…Observational data from the instrumental period and paleoproxies show a large decadal-to-multidecadal variability in the North Atlantic Ocean (Kerr 2000;Kilbourne et al 2008;Knudsen et al 2011). The main mode of sea surface temperature (SST) variability is a basin-wide warming or cooling, with the largest SST anomalies over the North Atlantic subpolar basin, commonly referred to as the Atlantic multidecadal oscillation (AMO).…”

Section: Introductionmentioning

confidence: 99%

Mechanisms Determining the Winter Atmospheric Response to the Atlantic Overturning Circulation

et al. 2016

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In climate models, an intensification of the Atlantic meridional overturning circulation (AMOC) precedes a warming in the North Atlantic subpolar basin by a few years. In the IPSL-CM5A-LR model, this warming may explain the atmospheric response to the AMOC observed in winter, which resembles a negative phase of the North Atlantic Oscillation (NAO). To firmly establish the causality links between the ocean and the atmosphere and illustrate the underlying mechanisms in this model, ensembles of atmosphere-only simulations are conducted, prescribing the SST and sea ice anomalies that follow an AMOC intensification. In late winter, the North Atlantic SST and sea ice anomalies drive atmospheric circulation anomalies similar to those found in the coupled model. Simulations only driven by the SST anomalies related to the AMOC show that the largest oceanic influence is due to the warm subpolar SST anomaly, which enhances the oceanic heat release and decreases the lower-tropospheric baroclinicity in the region of maximum eddy growth, resulting in a weaker meridional eddy heat flux in the atmosphere. The transient eddy feedback leads to a negative NAO-like response. An AMOC intensification is also followed by less sea ice over the Labrador Sea and more sea ice over the Nordic seas. The simulations with full boundary forcing suggest that such anomalies act to strengthen both the poleward momentum flux and the upward heat flux into the polar stratosphere and lead to a stratospheric warming, which then reinforces the negative NAO signal in late winter.

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Tracking the Atlantic Multidecadal Oscillation through the last 8,000 years

Cited by 327 publications

References 61 publications

Solar forcing as an important trigger for West Greenland sea-ice variability over the last millennium

Solar forcing as an important trigger for West Greenland sea-ice variability over the last millennium

Evidence for two abrupt warming events of SST in the last century

Mechanisms Determining the Winter Atmospheric Response to the Atlantic Overturning Circulation

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