P., the temperature kept rising at a rate of 3.7 ± 0.1 °C per 1,000 years (Figs 2 and 3). P., Greenland experienced a rapid cooling (9.2 ka event). (b) Reconstructed and modeled Greenland temperatures over the Holocene from various climate model experiments.We used the Greenland ice core chronology (GICC05), which is based on annual layer counting from multiple cores, synchronized with common volcanic layers with a 51-year cutoff period (Fig. Then, the data were again resampled for the sampling ages and used for the following calculations. The reconstructed Greenland temperature exhibits significant millennial correlations with KO of Oman and Chinese Dongge cave stalagmites (proxies for monsoon activity), indicating that the reconstructed temperature contains hemispheric signals. 4), suggesting that the Holocene climate was mostly under the persistent influence of volcanic activity that is consistent with our earlier studies for the past 4000 years, and model results indicate that solar variability did not play a persistent role in driving millennial-scale variability in Greenland.Climate model simulations forced with the volcanic forcing further suggest that a series of large volcanic eruptions induced hemispheric-wide centennial to millennial-scale variability through ocean/sea-ice feedbacks. Nevertheless, solar variability had significant negative imprints on centennial temperature changes especially during the colder periods of the early and late Holocene (stronger solar activities induced colder temperatures in Greenland, or vice versa; Fig. Notably, periods of stronger solar activity in the early Holocene coincide with several rapid cooling periods (e.g., the Preboreal Oscillation and the 8.2 ka event; Fig.(a) Reconstructed temperature from argon and nitrogen isotopes with 2σ error bands. Z-score is a measure of a time series having mean zero and standard deviation of one. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material.
The names are given according to the Greenland temperature changes or common usages if available. Afterwards, the temperature gradually decreased with occasional large drops (Figs 2 and 3). Experiments without volcanic and solar forcing that exhibit long-term trends similar to that of full forcing are not shown for the sake of simplicity.We circumvented the drifts by allowing slight constant shifts in ΔT by minimizing the difference between the observed and modeled δ) to minimize the drift. to take a memory effect of temperature in the ice-sheet. We tested different sections and found little differences in the calculated surface temperatures. For both periods, slight constant shifts for prescribed temperatures were allowed to fit with borehole temperatures during the following minimization procedure. Observed and modelled ΔTs agree within their uncertainties (Fig. Surface temperature calculations are conducted automatically to minimize the differences between the modelled and observed δ. For one realization, about 360 runs from 50,000 years B. to present were necessary with different values for each parameter.