On the origin of multidecadal to centennial Greenland temperature anomalies over the past 800 yr

Kobashi, Takuro; Shindell, D. T.; Kodera, Kunihiko; Box, Jason E.; Nakaegawa, Tosiyuki; Kawamura, Kenji

doi:10.5194/cp-9-583-2013

Cited by 39 publications

(44 citation statements)

References 52 publications

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“…Consistent with this theory, Greenland temperatures have deviated negatively (positively) from the NH temperature trend when solar activity was stronger (weaker) over the past 800 yr (Kobashi et al, 2013). Climate modelling also indicates that the Atlantic meridional overturning circulation (AMOC) reduces (increases) during weaker (stronger) solar activity (Cubasch et al, 1997;Waple et al, 2002), contributing to negative Greenland temperature responses to solar variability (Kobashi et al, 2013). Currently, the past variations of NAO and/or AMOC (e.g.…”

Section: T Kobashi Et Al: Causes Of Greenland Temperature Variabilisupporting

confidence: 57%

“…Therefore, it can be expected that stronger (weaker) solar activity induces warming (cooling) in NH temperature, and relative cooling (warming) in Greenland through positive (negative) NAO. Consistent with this theory, Greenland temperatures have deviated negatively (positively) from the NH temperature trend when solar activity was stronger (weaker) over the past 800 yr (Kobashi et al, 2013). Climate modelling also indicates that the Atlantic meridional overturning circulation (AMOC) reduces (increases) during weaker (stronger) solar activity (Cubasch et al, 1997;Waple et al, 2002), contributing to negative Greenland temperature responses to solar variability (Kobashi et al, 2013).…”

Section: T Kobashi Et Al: Causes Of Greenland Temperature Variabilimentioning

confidence: 53%

“…In our earlier study, we found that Greenland temperature deviated negatively (positively) from northern hemispheric (NH) temperature trend during stronger (weaker) solar activity owing to changes in atmospheric/oceanic changes (e.g. NAO/AO) over the past 800 yr (Kobashi et al, 2013). Therefore, a precise Greenland temperature record can provide important constraints on the past atmospheric/oceanic circulation in the region and beyond.…”

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confidence: 99%

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Causes of Greenland temperature variability over the past 4000 yr: implications for northern hemispheric temperature changes

et al. 2013

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Abstract. Precise understanding of Greenland temperature variability is important in two ways. First, Greenland ice sheet melting associated with rising temperature is a major global sea level forcing, potentially affecting large populations in coming centuries. Second, Greenland temperatures are highly affected by North Atlantic Oscillation/Arctic Oscillation (NAO/AO) and Atlantic multidecadal oscillation (AMO). In our earlier study, we found that Greenland temperature deviated negatively (positively) from northern hemispheric (NH) temperature trend during stronger (weaker) solar activity owing to changes in atmospheric/oceanic changes (e.g. NAO/AO) over the past 800 yr (Kobashi et al., 2013). Therefore, a precise Greenland temperature record can provide important constraints on the past atmospheric/oceanic circulation in the region and beyond. Here, we investigated Greenland temperature variability over the past 4000 yr reconstructed from argon and nitrogen isotopes from trapped air in a GISP2 ice core, using a one-dimensional energy balance model with orbital, solar, volcanic, greenhouse gas, and aerosol forcings. The modelled northern Northern Hemisphere (NH) temperature exhibits a cooling trend over the past 4000 yr as observed for the reconstructed Greenland temperature through decreasing annual average insolation. With consideration of the negative influence of solar variability, the modelled and observed Greenland temperatures agree with correlation coefficients of r = 0.34-0.36 (p = 0.1-0.04) in 21 yr running means (RMs) and r = 0.38-0.45 (p = 0.1-0.05) on a centennial timescale (101 yr RMs). Thus, the model can explain 14 to 20 % of variance of the observed Greenland temperature in multidecadal to centennial timescales with a 90-96 % confidence interval, suggesting that a weak but persistent negative solar influence on Greenland temperature continued over the past 4000 yr. Then, we estimated the distribution of multidecadal NH and northern high-latitude temperatures over the past 4000 yr constrained by the climate model and Greenland temperatures. Estimated northern NH temperature and NH average temperature from the model and the Greenland temperature agree with published multi-proxy temperature records with r = 0.35-0.60 in a 92-99 % confidence interval over the past 2000 yr. We found that greenhouse gases played two important roles over the past 4000 yr for the rapid warming during the 20th century and slightly cooler temperature during the early period of the past 4000 yr. Lastly, our analysis indicated that the current average temperature or higher temperatures occurred at a frequency of 1.3 times per 1000 yr for northern high latitudes and 0.36 times per 4000 yr for NH temperatures, respectively, indicating that the current multidecadal NH temperature ) is more likely unprecedented than not (p = 0.36) for the past 4000 yr.

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Section: T Kobashi Et Al: Causes Of Greenland Temperature Variabilisupporting

confidence: 57%

Section: T Kobashi Et Al: Causes Of Greenland Temperature Variabilimentioning

confidence: 53%

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confidence: 99%

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Causes of Greenland temperature variability over the past 4000 yr: implications for northern hemispheric temperature changes

et al. 2013

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“…However, regional climate may further deviate from the hemispheric trend owing to regional atmospheric and oceanic circulation changes induced by forcing (e.g., solar activity). For example, stronger (weaker) solar activity produced negative (positive) temperature anomalies from the hemispheric temperature trend in Greenland (Figures 3b and 3c) [Kobashi et al, 2013a[Kobashi et al, , 2013b.…”

Section: Resultsmentioning

confidence: 99%

Modern solar maximum forced late twentieth century Greenland cooling

Kobashi

Box

Vinther

et al. 2015

Geophysical Research Letters

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The abrupt Northern Hemispheric warming at the end of the twentieth century has been attributed to an enhanced greenhouse effect. Yet Greenland and surrounding subpolar North Atlantic remained anomalously cold in 1970s to early 1990s. Here we reconstructed robust Greenland temperature records (North Greenland Ice Core Project and Greenland Ice Sheet Project 2) over the past 2100 years using argon and nitrogen isotopes in air trapped within ice cores and show that this cold anomaly was part of a recursive pattern of antiphase Greenland temperature responses to solar variability with a possible multidecadal lag. We hypothesize that high solar activity during the modern solar maximum (approximately 1950s–1980s) resulted in a cooling over Greenland and surrounding subpolar North Atlantic through the slowdown of Atlantic Meridional Overturning Circulation with atmospheric feedback processes.

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“…We also note that the standard deviation (0.07 ‰) of δ 15 N × 11 in GISP2 is much smaller than standard deviation of raw δAr/N 2 (1.33 ‰) over the past 6000 years, indicating that the variations of δAr/N 2corr mostly originate from the raw δAr/N 2 and not from δ 15 N. For the sake of simplicity, we denote all the δAr/N 2corr as δAr/N 2 in later sections. The significance of correlations were calculated considering the autocorrelation of time series (Ito and Minobe, 2010;Kobashi et al, 2013). We consider > 95 % confidence as significant, unless otherwise noted.…”

Section: Data Descriptionmentioning

confidence: 99%

Post-bubble close-off fractionation of gases in polar firn and ice cores: effects of accumulation rate on permeation through overloading pressure

et al. 2015

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Abstract. Gases in ice cores are invaluable archives of past environmental changes (e.g., the past atmosphere). However, gas fractionation processes after bubble closure in the firn are poorly understood, although increasing evidence indicates preferential leakages of smaller molecules (e.g., neon, oxygen, and argon) from the closed bubbles through the ice matrix. These fractionation processes are believed to be responsible for the observed millennial δO 2

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On the origin of multidecadal to centennial Greenland temperature anomalies over the past 800 yr

Cited by 39 publications

References 52 publications

Causes of Greenland temperature variability over the past 4000 yr: implications for northern hemispheric temperature changes

Causes of Greenland temperature variability over the past 4000 yr: implications for northern hemispheric temperature changes

Modern solar maximum forced late twentieth century Greenland cooling

Post-bubble close-off fractionation of gases in polar firn and ice cores: effects of accumulation rate on permeation through overloading pressure

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