The GISP2 δ18O Climate Record of the Past 16,500 Years and the Role of the Sun, Ocean, and Volcanoes

Abstract

Measured 18O/16O ratios from the Greenland Ice Sheet Project 2 (GISP2) ice core extending back to 16,500 cal yr B.P. provide a continuous record of climate change since the last glaciation. High-resolution annual 18O/16O results were obtained for most of the current millennium (A.D. 818-1985) and record the Medieval Warm Period, the Little Ice Age, and a distinct 11-yr 18O/16O cycle. Volcanic aerosols depress central Greenland annual temperature (∼1.5°C maximally) and annual 18O/16O for about 4 yr after each major eruptive event. On a bidecadal to millennial time scale, the contribution of solar variability to Holocene Greenlandic temperature change is ∼0.4°C. The role of thermohaline circulation change on climate, problematic during the Holocene, is more distinct for the 16,500-10,000 cal yr B.P. interval. (Analogous to 14C age calibration terminology, we express time in calibrated (cal) yr B.P. (A.D. 1950 = 0 cal yr B.P.)). The Oldest Dryas/Bølling/Older Dryas/Allerød/Younger Dryas sequence appears in great detail. Bidecadal variance in 18O/16O, but not necessarily in temperature, is enhanced during the last phase of lateglacial time and the Younger Dryas interval, suggesting switches of air mass transport between jet stream branches. The branched system is nearly instantaneously replaced at the beginning of the Bølling and Holocene (at ∼14,670 and ∼11,650 cal yr B.P., respectively) by an atmospheric circulation system in which 18O/16O and annual accumulation initially track each other closely. Thermodynamic considerations of the accumulation rate-temperature relationship can be used to evaluate the 18 O/16O-temperature relationship. The GISP2 ice-layer-count years of major GISP2 climate transitions also support the use of coral 14C ages for age calibration.

Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/234U/238U and 14C dates on pristine corals

“…Over the radiocarbon calibration interval, there are generally fewer than thirty tie points correlating deep sea core ocean/climate proxies to ice core proxies, thereby assigning calendar age estimates to most calibration points by interpolation. Differences between the various Greenland ice core chronologies are due to age model assumptions, inherent subjectivity in discerning annual bands in ice or layered sediments in general, the fidelity of proxies to record an annual signal, occasional wind erosion or scouring of some snow layers, and compacting and degrading annual signals deeper in the ice cores (Dansgaard et al, 1989(Dansgaard et al, , 1993Johnsen et al, 1992Johnsen et al, , 1995Johnsen et al, , 1997Johnsen et al, , 2001Meese et al, 1994Meese et al, , 1997Taylor et al, 1993;Stuiver et al, 1995;Andersen et al, 2004). Intervals where the annual signal is weak or missing entirely would not be counted by any of the proxies and therefore not included in Meese et al's (1997) error assessment.…”

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

“…Based on a marine sediment record from the Arabian Sea, the Indian monsoon varied in intra-Holocene cycles of about 1050, 1500, and 3000 years (Sirocko et al, 1996), i.e. periods similar to the climate cycles found in ice cores from Greenland (Stuiver et al, 1995;Grootes and Stuiver, 1997). One may, therefore, expect that analogous events of enhanced precipitation and fluvial runoff in South China may lead to an enlarged plume of low sea-surface salinity (SSS) offshore Hongkong ( Fig.…”

Human responses to the Younger Dryas in Japan

“…His analysis of varved layers from the Lake Suigetsu has demonstrated that the cooling event at approximately 11,320 B.P. (Kitagawa and van der Plicht, 1998) may corresponds with the 100 year cooling event from 11,300 to 11,400 years ago recorded in the Greenland ice core (GISP 2) (Stuiver et al, 1995).…”

“…In correlating the oxygen isotope ratios in the GISP 2 (Stuiver et al, 1995), an abrupt increase of quartz flux that suggests the onset of dry and cold climate in inner Asia is 350 years earlier than the onset of Younger Dryas (Fukusawa, 1999: 241). This estimate is further supported by reconstructed changes in mean annual temperatures recorded in the pollen stratigraphy of Lake Suigetsu, western Japan (Nakagawa et al, 2005).…”

“…Following the records in the Greenland ice cores (Stuiver et al, 1995), we employ as dates for Younger Dryas, beginning at 12,900 cal. B.P.…”