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Journal ArticleDOI

On the glacial-interglacial variability of the Asian monsoon in speleothem δ18O records.

TL;DR: It is found that the records close to the monsoon moisture source show large glacial-interglacial variability, which then decreases landward, the moisture transport pathway effect, which counteracts the forcing of glacial boundary conditions.
Abstract: While Asian monsoon (AM) changes have been clearly captured in Chinese speleothem oxygen isotope (δ18O) records, the lack of glacial-interglacial variability in the records remains puzzling. Here, we report speleothem δ18O records from three locations along the trajectory of the Indian summer monsoon (ISM), a major branch of the AM, and characterize AM rainfall over the past 180,000 years. We have found that the records close to the monsoon moisture source show large glacial-interglacial variability, which then decreases landward. These changes likely reflect a stronger oxygen isotope fractionation associated with progressive rainout of AM moisture during glacial periods, possibly due to a larger temperature gradient and suppressed plant transpiration. We term this effect, which counteracts the forcing of glacial boundary conditions, the moisture transport pathway effect.
Citations
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Journal ArticleDOI
TL;DR: In this article, Wang et al. reconcile the Chinese 100 kyr problem and the sea-land precession phase paradox by comparing the results of different hydroclimatic proxies.
Abstract: The Asian summer monsoon (ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM. (1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated ~100 kyr (thousand years) periodicity, while the cave oxygen-isotope (δ18O) records reveal periodicity in an almost pure precession band (~20 kyr periodicity)—the “Chinese 100 kyr problem”. (2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8–10 kyr to Northern Hemisphere summer insolation (NHSI), whereas the Asian cave δ18O records follow NHSI without a significant lag—a discrepancy termed the “sea-land precession-phase paradox”. How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the “Chinese 100 kyr problem“ and “sea-land precession-phase paradox”.

50 citations

Journal ArticleDOI
TL;DR: In this article, the authors present new pollen data and mean annual temperature reconstruction from the annually laminated sediments of Lake Suigetsu, Japan, which is an integral component of the IntCal20 radiocarbon calibration model, in which the absolute age scale is established to the highest standard.

18 citations

Journal ArticleDOI
01 Feb 2021-Catena
TL;DR: In this paper, the authors presented a high-resolution EASM precipitation record reconstructed from the loess redness in North China over the past 720 kyr, showing that the average precipitation for interglacials is 420mm/yr, higher than present (~280 mm/yr).
Abstract: The periodicity and forcing mechanism of the past East Asian summer monsoon (EASM) precipitation are the natural background for predicting future precipitation changes, but they are controversial and intensely debated. Here, we present a high-resolution EASM precipitation record reconstructed from the loess redness in North China over the past 720 kyr. The average precipitation for interglacials is 420 mm/yr, higher than present (~280 mm/yr). Combing through our EASM records and previously published data exhibits a dominated periodicity of 100 kyr on the orbital timescale, and thus supports the hypothesis of high-latitude climate forcing. More importantly, we found the precession cycle appears only after the Mid-Brunhes Transition (MBT, ~430 ka) in the EASM records and it follows the global ice volume prior to the MBT in the interglacials interiors. We argue that during the post-MBT interglacials, abruptly appearing Arctic perennial sea ice resulted southward shift of the Northern Hemisphere Westerlies jet, thereby decreasing the EASM precipitation in North China. This suggests that the precession rhythm in the EASM possibly is a result of Arctic perennial sea ice or Northern Hemisphere ice sheets changes. In the warm Marine Isotope Stages (MIS) 5e and 11e, the strongest EASM precipitation may be related to the strengthening of the moisture transport from the warming tropical ocean. Therefore, the variation of the mid-latitude EASM precipitation intensity during the interglacial interiors is the integrated effect between the North Hemisphere high latitude ice volume and low latitude climate changes.

15 citations

Journal ArticleDOI
TL;DR: In this article, the authors quantitatively deconvolve these parameters affecting δ18OCc by applying three geochemical techniques in speleothems covering the penultimate glacial termination, and reveal that the different modes of the AMOC produced distinct impacts on the monsoon system.
Abstract: During glacial terminations, massive iceberg discharges and meltwater pulses in the North Atlantic triggered a shutdown of the Atlantic Meridional Overturning Circulation (AMOC). Speleothem calcium carbonate oxygen isotope records (δ18OCc) indicate that the collapse of the AMOC caused dramatic changes in the distribution and variability of the East Asian and Indian monsoon rainfall. However, the mechanisms linking changes in the intensity of the AMOC and Asian monsoon δ18OCc are not fully understood. Part of the challenge arises from the fact that speleothem δ18OCc depends on not only the δ18O of precipitation but also temperature and kinetic isotope effects. Here we quantitatively deconvolve these parameters affecting δ18OCc by applying three geochemical techniques in speleothems covering the penultimate glacial termination. Our data suggest that the weakening of the AMOC during meltwater pulse 2A caused substantial cooling in East Asia and a shortening of the summer monsoon season, whereas the collapse of the AMOC during meltwater pulse 2B (133,000 years ago) also caused a dramatic decrease in the intensity of the Indian summer monsoon. These results reveal that the different modes of the AMOC produced distinct impacts on the monsoon system. The influence of meltwater pulse events on Asian monsoon systems varied in line with the degree of AMOC weakening, according to a multi-proxy analysis of speleothems from China covering the penultimate glacial termination.

11 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the saturation vapor pressure and temperature for moist air were derived for the meteorologically interesting region of −80 to +50°C. The equations are designed to be easily implemented on a calculator or computer and can be used to convert in either direction.
Abstract: Equations are presented which relate saturation vapor pressure to temperature for moist air. The equations are designed to be easily implemented on a calculator or computer and can be used to convert in either direction. They are more accurate than the commonly used Goff-Gratch equations for the meteorologically interesting region of −80 to +50°C. Equations also are given for the enhancement factor.

1,310 citations

Journal ArticleDOI
TL;DR: In this paper, a theoretical model is derived to account for the deuterium-oxygen 18 relationship measured in meteoric waters, where a steady state regime is assumed for the evaporation of water at the ocean surface and the subsequent formation of precipitation.
Abstract: A theoretical model is derived to account for the deuterium-oxygen 18 relationship measured in meteoric waters. A steady state regime is assumed for the evaporation of water at the ocean surface and the subsequent formation of precipitation. The calculations show that the deuterium and oxygen 18 content in precipitation can be taken as linearly related. From the slope and the intercept (known as the deuterium excess) of the δD-δ18O linear relationship for precipitation we compute the mean values on a global scale of the evaporating ocean surface temperature and the relative humidity of the air masses overlying the oceans. The deuterium excess is primarly dependent on the mean relative humidity of the air masses formed above the ocean surface. Paleoclimatic data may be obtained by this isotopic method from the analysis of old water and ice samples. A moisture deficit of the air over the ocean, equal to only 10%, in comparison to 20% for modern conditions, is deduced from the deuterium-oxygen 18 distribution measured in groundwater samples older than 20,000 years.

1,216 citations

Journal ArticleDOI
TL;DR: In this article, the authors used high precision thermal ionization mass spectrometric (TIMS) methods to determine the half-life of zircons with concordant 238 U/ 238 U and 230 Th / 238 U atomic ratios.

1,171 citations

Journal ArticleDOI
05 Apr 2012-Nature
TL;DR: A record of global surface temperature from 80 proxy records is constructed and it is shown that temperature is correlated with and generally lags CO2 during the last deglaciation, supporting the conclusion that an antiphased hemispheric temperature response to ocean circulation changes superimposed on globally in-phase warming driven by increasing CO2 concentrations is an explanation for much of the temperature change at the end of the most recent ice age.
Abstract: The covariation of carbon dioxide (CO2) concentration and temperature in Antarctic ice-core records suggests a close link between CO2 and climate during the Pleistocene ice ages. The role and relative importance of CO2 in producing these climate changes remains unclear, however, in part because the ice-core deuterium record reflects local rather than global temperature. Here we construct a record of global surface temperature from 80 proxy records and show that temperature is correlated with and generally lags CO2 during the last (that is, the most recent) deglaciation. Differences between the respective temperature changes of the Northern Hemisphere and Southern Hemisphere parallel variations in the strength of the Atlantic meridional overturning circulation recorded in marine sediments. These observations, together with transient global climate model simulations, support the conclusion that an antiphased hemispheric temperature response to ocean circulation changes superimposed on globally in-phase warming driven by increasing CO2 concentrations is an explanation for much of the temperature change at the end of the most recent ice age. Understanding the causes of the Pleistocene ice ages has been a significant question in climate dynamics since they were discovered in the mid-nineteenth century. The identification of orbital frequencies

1,119 citations

Journal ArticleDOI
23 Apr 2004-Science
TL;DR: Thorium-230 ages and oxygen isotope ratios of stalagmites from Dongge Cave, China, characterize the Asian Monsoon and low-latitude precipitation over the past 160,000 years, indicating that insolation triggered the final rise to full interglacial conditions.
Abstract: Thorium-230 ages and oxygen isotope ratios of stalagmites from Dongge Cave, China, characterize the Asian Monsoon and low-latitude precipitation over the past 160,000 years. Numerous abrupt changes in 18O/16O values result from changes in tropical and subtropical precipitation driven by insolation and millennial-scale circulation shifts. The Last Interglacial Monsoon lasted 9.7 +/- 1.1 thousand years, beginning with an abrupt (less than 200 years) drop in 18O/16O values 129.3 +/- 0.9 thousand years ago and ending with an abrupt (less than 300 years) rise in 18O/16O values 119.6 +/- 0.6 thousand years ago. The start coincides with insolation rise and measures of full interglacial conditions, indicating that insolation triggered the final rise to full interglacial conditions.

1,061 citations