Holocene climate change in southern Oman deciphered by speleothem records and climate model simulations

Tian, Ye; Fleitmann, Dominik; Zhang, Qiong; Sha, Lijuan; Wassenburg, Jasper. A.; Axelsson, Josefine; Zhang, Haiwei; Li, Xianglei; Hu, Jun; Li, Hanying; Zhao, Liang; Cai, Yanjun; Ning, Youfeng; Cheng, Hai

doi:10.1038/s41467-023-40454-z

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Published: 05 August 2023

Holocene climate change in southern Oman deciphered by speleothem records and climate model simulations

Nature Communications volume 14, Article number: 4718 (2023) Cite this article

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Abstract

Qunf Cave oxygen isotope (δ¹⁸O_c) record from southern Oman is one of the most significant of few Holocene Indian summer monsoon cave records. However, the interpretation of the Qunf δ¹⁸O_c remains in dispute. Here we provide a multi-proxy record from Qunf Cave and climate model simulations to reconstruct the Holocene local and regional hydroclimate changes. The results indicate that besides the Indian summer monsoon, the North African summer monsoon also contributes water vapor to southern Oman during the early to middle Holocene. In principle, Qunf δ¹⁸O_c values reflect integrated oxygen-isotope fractionations over a broad moisture transport swath from moisture sources to the cave site, rather than local precipitation amount alone, and thus the Qunf δ¹⁸O_c record characterizes primary changes in the Afro-Asian monsoon regime across the Holocene. In contrast, local climate proxies appear to suggest an overall slightly increased or unchanged wetness over the Holocene at the cave site.

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Introduction

Speleothem oxygen isotope (δ¹⁸O_c) records in the Asian summer monsoon domain are important to understand monsoon variability on a wide range of timescales^1,2,3,4,5. The Asian summer monsoon contains two large monsoon subsystems, the East Asian summer monsoon and the Indian summer monsoon. The speleothem δ¹⁸O_c records from both regions show a broadly similar pattern on the orbital scale, following Northern Hemisphere summer insolation (NHSI), nearly in phase at the precession band (~20-ka cycles, ka: thousand years)^1,6,7,8,9,10, which supports the conventional monsoon hypothesis¹¹—the insolation hypothesis¹². A large number of publications clearly show that the enhanced Asian summer monsoon from the precession minimum (P_min) or NHSI maximum to the precession maximum (P_max) or NHSI minimum, corresponds to the negative δ¹⁸O_c excursions in the speleothem records, and vice versa^{1,3,11,13,14,15,16,17,18,19}. These data-model comparisons validate the interpretation that speleothem δ¹⁸O_c records from the Asian summer monsoon domain reflect regional Asian summer monsoon intensity or the scale of summer monsoon circulations on orbital scales^1,10. However, the relation between the speleothem δ¹⁸O_c records and precipitation amount at the cave site may be complex^1,2,3. A number of studies suggested that δ¹⁸O_c records from the Asian continent may partially reflect changes in moisture source, isotope fractionation at the source area, transport pathways, as well as the isotopic composition of the Bay of Bengal surface water^13,20,21,22. When the Asian summer monsoon is strong, the spatial scale of the summer monsoon circulation expands, and more remote moisture is transported inland, resulting in lower precipitation oxygen isotope (δ¹⁸O_P) values in continental regions and vice versa^{1,2,3,16,23,24,25,26}. Theoretically, speleothem δ¹⁸O_c, as a proxy of the δ¹⁸O_p at the cave site, is related to oxygen-isotope fractionations integrated from tropical oceans to the cave site along the moisture transport trajectory^25,26. Besides, the influence of other factors on speleothem δ¹⁸O_c, such as the mixing of different moisture sources and rainfall amount, should not be precluded.

The Holocene, from ~11.7 ka BP (before present, where present = 1950 CE) to the present, spans about half of a precession cycle, approximately from P_min (NHSI maximum) to P_max (NHSI minimum). While a large set of Holocene speleothem records are available in the East Asian summer monsoon domain^3,27,28, similar records in the Indian summer monsoon domain remain sparse and segmented. The well-known Indian summer monsoon record comes from Qunf Cave in Oman, southeastern Arabian Peninsula²⁹. The Qunf δ¹⁸O_c record covers most of the Holocene and has been widely used as a typical Indian summer monsoon record. It has been highly cited during the past two decades and remains a unique Holocene δ¹⁸O_c record in the area up till now. Previous studies on the Qunf δ¹⁸O_c record, and additional speleothem records from Oman and Yemen, suggested that these records reflect changes in Indian summer monsoon precipitation amount during the Holocene^29,30,31,32. The sharp decrease of the speleothem δ¹⁸O_c from 10.3 to 9.6 ka BP was interpreted to indicate a rapid northward shift of the summer position of the intertropical convergence zone (ITCZ) and the associated Indian summer monsoon rainfall, leading to a rapid increase in summer monsoon precipitation. After ~8 ka BP, the speleothem δ¹⁸O_c record shows an almost linear response to the orbitally-induced variation in NHSI at 30°N, which implies a gradual southward retreat of the ITCZ and gradual weakening of the Indian summer monsoon in response to a decrease in summer insolation²⁹. This interpretation seems to be consistent with the conventional wisdom that increased NHSI enhances the land-sea thermal contrast and, thus, the summer monsoon intensity¹¹. However, this classical notion of monsoon has been challenged by a number of recent modeling studies^33,34,35.

Marine records from the Arabian Sea near Qunf Cave, such as the upwelling-driven biological productivity, foraminifera assemblage, particle size, and oxygen minimum zone records were also interpreted as proxies of the Indian summer monsoon intensity^36,37,38. A few marine upwelling records from the Arabian Sea show a consistent Holocene pattern with the speleothem records³⁹. However, some marine upwelling records in the Arabian Sea suggest intensified Indian summer monsoon winds throughout the entire Holocene and show a significant lag to NHSI and the Indian summer monsoon intensity change inferred by speleothem δ¹⁸O_c records^36,40,41,42. These observations were interpreted to be caused by the latent heat from the southern Indian Ocean and the global ice volume besides insolation^36,42,43. Alternatively, the apparent lag to the NHSI is interpreted as the length of late summer and the effect of the Atlantic Meridional Overturning Circulation^37,38.

Hsu et al.⁴⁴ were the first to show that their climate model actually reproduced this opposite response between land and ocean to NHSI at the precession band. This study was followed by multiple climate model simulations that confirmed the results from refs. ^{3,16,17,45,46,47}. Later, ref. ² coined the term “land-sea precession phase paradox” in the research forefront of the Asian summer monsoon, referring to the contrast between speleothem and marine proxy records. Also, Ruddiman⁴⁸ argued that the Arabian Sea summer monsoon proxies are not tightly coupled to monsoon intensity but are influenced by other processes. Recently, refs. ^45,46 explained the mechanisms for the opposing marine and terrestrial proxy response in the Indian summer monsoon domain. It appears that the upwelling-based proxies in the Arabian Sea are not linked to the Indian monsoon rainfall over India at precession timescales⁴⁷. Changes in the low-level jet could cause a stronger wind stress curl during weaker summer insolation and lead to strong upwelling. This interpretation appears to largely reconcile the so-called “sea-land precession-phase paradox”, as the monsoon wind strength over the oceans is not necessarily coupled with monsoon precipitation over the Asian continent^1,2. However, in light of these recent discussions and data-model comparisons^16,21,25, critical issues remain regarding: (1) What is the hydroclimate significance of Qunf δ¹⁸O_c variation? (2) What is the local hydroclimate variation pattern across the Holocene? (3) What is the relation between the Qunf δ¹⁸O_c record and NHSI? (4) Is precipitation at Qunf Cave sourced from single or multiple moisture sources? These questions call for further investigations, especially with speleothem multi-proxy data.

In this study, we provide multiple proxies in addition to δ¹⁸O_c from the stalagmite Q5 from Qunf Cave, southern Oman, including (²³⁴U/²³⁸U)₀, δ¹³C, trace elements, fluid inclusion δD_fi, and Δ'¹⁷O records to reconstruct the local and regional hydroclimate history across the Holocene. We then compare the Qunf Cave record with climate model simulations to evaluate alternative interpretations of Qunf δ¹⁸O_c values.

Results and discussion

Climate conditions and chronology

Qunf Cave (17°10′N, 54°18′E; 650 m above sea level), from which stalagmite Q5 was collected, is located in southern Oman (Fig. 1), at the northern fringe of the present summer ITCZ and the northern limit of the Indian summer monsoon. At present, summer monsoon rainfall accounts for more than 90% of the total annual rainfall amount (400–500 mm at the cave site)²⁹. The average summer (June, July, and August, JJA) rainfall recorded at the Salalah GNIP station (17°02′N, 54°07′E) is 1.65 mm d⁻¹ (1988–1989), and the JJA rainfall of 1989 is 3.43 mm d⁻¹ at Qairoon Hairiti GNIP station (17°15′N, 54°05′E). The Somali jet brings considerable moisture to the Qunf Cave site during the summer, mainly from the tropical South Indian Ocean across the equator to the western Arabian Sea (Fig. 1). In comparison with the dry years, the wet years in the area have more local moisture contributions, accompanying with less precipitation over South Asia. Meanwhile, the moisture tagging analysis and simulations also indicate that the Red Sea, the Persian Gulf, Mediterranean and Iranian Plateau provide considerable moisture to the Qunf Cave site (Fig. 1 and Supplementary Fig. 1). Q5 grew from 10.8 to 0.4 ka BP with a hiatus from 2374 (±143) to 840 (±56) year BP (Supplementary Fig. 2), i.e., almost the entire Holocene.

**Fig. 1: Qunf Cave (yellow asterisk) June–July–August (JJA) evaporation minus precipitation (E-P) diagnosed from 12-days back trajectories using the FLEXPART.**

Moisture sources revealed by multi-proxy records and climate model simulation

Fluid inclusion δD_fi values provide the isotope composition of the cave drip water from which the speleothem calcite precipitated, and may contain information on the conditions of drip water. Q5 δD_fi data show a distinct trait. During the Holocene Humid Period in Southern Arabia (~10.5 to ~6 ka BP)^30,32,49,50, δD_fi values are more depleted, with a mean δD_fi value of ~2.07‰. After ~6 ka BP, δD_fi shows an increasing trend, with an average value of ~9.46 ‰ (Fig. 2a). Consistently, the δD_fi data from Hoti Cave (northern Oman), which sits close to Qunf, also show a significant change in the moisture source, seasonality, and amount of rainfall above the cave around 6 ka BP⁴⁹. Moreover, the slope of the ln(δ¹⁸O_c + 1)-ln(δ¹⁷O_c + 1) line shifts at ~6 ka BP from 0.510 to 0.523 (Supplementary Fig. 4a, b). δ¹⁸O_c-δ¹⁷O_c data thus suggest that either moisture source conditions or the moisture sources have changed at ~6 ka BP in southern Oman. Although previous studies based on δ¹⁸O_c records (including Q5) consider that the Indian summer monsoon (or the Indian Ocean) was the sole moisture source in southern Oman^29,30,31,51, our new data seem to imply an additional moisture source, yet unknown, that could be involved during the Holocene Humid Period⁴⁹.

Δ'¹⁷O is defined as the deviation of triple oxygen isotope data from a reference relationship between speleothem δ¹⁷O_c and δ¹⁸O_c⁵² (See supplementary text), which is related to distinct hydroclimate dynamics^53,54,55,56. Speleothem Δ'¹⁷O is not sensitive to Rayleigh distillation from the ocean to the continent⁵⁷ (Supplementary Fig. 5a). Therefore, it reflects mainly the original Δ'¹⁷O signal of water vapor, which in turn allows a calculation of the relative humidity at the moisture source^52,58,59,60. In addition, other factors might also contribute to some extent to the Δ'¹⁷O variation, such as the mixing of water vapors (between the original air masses and continental recycling moisture along air-mass trajectories), re-evaporation of precipitation (depending on the re-evaporation rate and downdraft intensity), and convections^61,62. Collectively, the process of stronger continental recycling and re-evaporation of precipitation may cause higher Δ'¹⁷O (Supplementary Fig. 5b). Q5 Δ'¹⁷O data show higher values (−225 per meg) during ~8-6 ka BP compared to early (−259 per meg) and late (−245 per meg) Holocene (Fig. 2b). Between 8 and 6 ka BP, the relative humidity of the moisture source area inferred by Δ'¹⁷O is lower (~60%) (Fig. 2c). From ~6 ka BP to the present, the calculated relative humidity of Q5 moisture source fluctuated around 80%.

To further understand the hydroclimate conditions at Qunf Cave, we compared the EC-Earth simulated summer (JJA) hydrological conditions between 8 K (8 ka BP) and PI (pre-industrial period). Our model simulations indicate that during the 8 K period, the North African summer monsoon—characterized by the southwesterly wind extending across the continent and reaching the southern Arabian Peninsula was considerably stronger (Fig. 3a). Although it is possible that the ~900-m high Dhofar mountain could prevent some of the moisture from the African continent to reach the Qunf Cave area, both the summer monsoon wind from the Arabian Sea in the south and the African continent in the west could have contributed water vapor to southern Oman at 8 K. This is in line with an expansion of the North African summer monsoon across the Red Sea during the high NHSI time^16,63. The model simulations reveal a ~6% increase in relative humidity at the equatorial Atlantic, Arabian Sea and Qunf Cave site from 8 K to PI (Fig. 3b). The ∆'¹⁷O-based reconstruction of relative humidity at the moisture source shows a ~15% increase from middle to late Holocene (Fig. 2c). The direction of these Holocene trends is consistent. Taking into account the uncertainties of the modeled and reconstructed relative humidity, these datasets show strong similarities.

**Fig. 3: EC-Earth simulation results of June–July–August (JJA) hydroclimate difference between 8 ka BP (8 K) and preindustrial period (PI).**

The influence of the Indian summer monsoon and its interaction with the North African summer monsoon may not be ignored as the Arabian Sea is located right in the confluence region between African and Asian summer monsoon systems^13,16,63,64. The North African summer monsoon has effective control over the Eastern Mediterranean deepwater ventilation on orbital time-scales through changing the discharge of the Nile River. This results in density stratification and breakdown of deepwater formation reflected by sapropel layers S1 in Ocean Drilling Program Site 968 from ~10.2 to 6.5 ka BP^65,66,67,68. This strong North African summer monsoon period corresponds precisely with the lowest δ¹⁸O_c period in the Q5 record (Fig. 4). Furthermore, the Soreq and Jeita cave δ¹⁸O_c records from the Levant are also sensitive to changes in δ¹⁸O of the Eastern Mediterranean surface seawater. More negative δ¹⁸O_c values are indicative of higher Nile discharge from the early to middle Holocene^69,70 (Fig. 4). Additionally, δD_wax records from eastern Africa, which reflect North African summer monsoon variations, also exhibit a trend similar to the Q5 δ¹⁸O_c record⁷¹ (Fig. 4). After ~6 ka BP, the North African summer monsoon fringe retreated from the southern Arabian Peninsula/northeastern Africa associated with the termination of the Mediterranean sapropel S1 period and the termination of the Holocene African Humid Period (Fig. 4). The Qunf multi-proxy datasets, combined with a set of model simulations on the Holocene hydroclimate evolution in the region, allow for a thorough comparison between observed and modeled Holocene hydroclimate conditions. We propose that there was a large-scale reorganization of atmospheric circulation in the region. In addition to the water vapor transported by the Indian summer monsoon from the adjacent Arabian Sea, the North African summer monsoon may have contributed remote moisture from the tropical Atlantic via Northeast Africa to Qunf Cave during the early and middle Holocene. This finding offers robust evidence supporting earlier model results^16,17. In this regard, the shift in δD_fi and Δ'¹⁷O data around 6 ka BP could indicate a decrease/withdrawal in the contribution of the North African summer monsoon⁶³.

**Fig. 4: Comparison of the Q5 δ¹⁸O_c record with other North African summer monsoon and Asian summer monsoon proxy records, and 30°N–30°S June–July–August (JJA) insolation.**

Understanding of Qunf δ¹⁸O_c record

δ¹⁸O_c values of stalagmite Q5 show an abrupt decrease (from −0.2 to −2.5‰) that occurred from ~10.8 to 9 ka BP, followed by a relatively stable period (~ −2‰) between 9 and 6 ka BP, and then by a persistent increase of δ¹⁸O_c from −2‰ to ~ 0‰ till a hiatus from ~2.4 to 0.8 ka BP. After the hiatus, δ¹⁸O_c decreased from ~ 0‰ to ~−1‰ over ~400 years (Fig. 2d). δ¹⁸O_c shows the same trends as δD_fi, supporting that the δ¹⁸O_c reflects drip water δ¹⁸O variability. Currently, the effect of the Indian summer monsoon is prevailing over the southern Arabian Peninsula (Fig. 1). The long-term increasing trend of the Qunf δ¹⁸O_c record from ~6 ka BP to the present may indicate an overall Indian summer monsoon (or summer monsoon circulation) waning process^8,49,72. A significant mid-Holocene positive shift of δ¹⁸O_c at ~6 ka BP is also found in Hoti Cave in northern Oman (Fig. 4), marking the southward retreat of the ITCZ and the associated Indian summer monsoon rainfall belt and a change in the seasonality of rainfall^32,49. As aforementioned, water vapor from the equatorial Atlantic could be transported across the African continent by strong North African summer monsoon wind to Qunf Cave during the early to middle Holocene. Thus, from ~10 to ~6 ka BP, southern Oman was likely affected by both the Indian summer monsoon and likely, but to a lesser extent, the North African summer monsoon, both resulting in the more negative δ¹⁸O_p owing to larger-scale summer monsoon circulations and associated remote moisture^1,2,3, as well as the increased local precipitation amount effect (“amount effect”)^29,30,31.

Taking a broader perspective, the monsoons over the African continent and the Indian Ocean exhibit remarkably similar hydroclimate trends during the middle to late Holocene. This suggests that they were sensitive to, or driven by, a common forcing mechanism on suborbital timescales^73,74. More broadly, the entire North African summer monsoon and Asian summer monsoon (Indian summer monsoon and East Asian summer monsoon) may be viewed as a large unified summer monsoon system. In this interpretative framework, the Qunf δ¹⁸O_c record shows the Holocene hydroclimate variation of this “super-monsoon” or Afro-Asian monsoon regime^63,64, since the Qunf δ¹⁸O_c variations appear to follow the overall changes of the Afro-Asian monsoon intensity according to both empirical and model results as aforementioned.

The Qunf δ¹⁸O_c record mostly reflects large-scale monsoon circulation changes, making local hydroclimate proxies an essential complement. Combining the (²³⁴U/²³⁸U)₀, δ¹³C, and trace element records from Q5 (Fig. 2) with the simulation results (Fig. 3 and Supplementary Fig. 7) enables us to reconstruct local precipitation minus evaporation (P-E) over the Holocene. Our simulation results show that both the North African summer monsoon and Indian summer monsoon were much stronger at 8 K than at PI. Notably, the summer precipitation amount at Qunf Cave was higher at 8 K. This may lead to increased water flow rates in Qunf Cave’s epikarst, resulting in lower (²³⁴U/²³⁸U)₀ values, as (²³⁴U/²³⁸U)₀ is influenced by water flow rates and water–rock interaction times^75,76,77.

However, the summer P-E appears to be slightly lower over a large part of the Arabian Peninsula, suggesting a strong evaporation condition (Fig. 3, Supplementary Fig. 7). These results are consistent with Q5 δ¹³C and trace elements ratio data. Lower summer temperature and slightly increased P-E could favor increased organic materials and reduced prior calcite precipitation (PCP), resulting in more negative δ¹³C values in the late Holocene^78,79,80. Q5 δ¹³C values range from -6.4‰ to 1.1‰, with relatively stable values (~ −1‰) from ~10.8 to 6 ka BP and a decreasing trend from~−1‰ to ~−5‰ since ~6 ka BP (Fig. 2), suggesting slightly lower P-E (or effective wetness) in the early and middle Holocene compared to the late Holocene. Trace element ratios (Mg/Ca, Sr/Ca, and Ba/Ca) show a significant decreasing trend from 10.8 to ~6 ka BP, followed by low and stable ratios after ~6 ka BP (Fig. 2). PCP often occurs in the vadose zone of many cave systems, and increases with reduced effective infiltration, affecting trace element ratios in cave drip waters^81,82,83. The slightly lower P-E condition at 8 K (or the early to middle Holocene, Supplementary Fig. 7) suggests increased evaporation under higher summer insolation, promoting PCP and resulting in observed higher trace element ratios. The low and stable trace element ratios after ~6 ka BP could be due to the expected trend of reduced summer evaporation caused by decreased NHSI from the early/middle to late Holocene.

Both model simulation and proxy records show a similar increasing trend in local hydroclimate conditions at the cave site from 8 K to PI, the P-E was lower during the early to middle Holocene compared to the late Holocene (See supplementary text). However, given the variety of factors and multiplicity of proxy interpretations, further studies remain a prerequisite to understanding the Holocene hydroclimate history in the region.

The Indian summer monsoon variations across the Holocene

The understanding of monsoons as an integral component of the global atmospheric circulation and hydroclimate is becoming prevalent^33,35. Of note are three primary theoretical concepts of monsoons: one based on convective quasi-equilibrium (CQE)^84,85, another founded on the moist static energy budget^86,87, and a third that frames the monsoon as an extension of the zonal-mean ITCZ^34,35. While these theoretical frameworks help explain certain aspects of modern monsoon variability, especially regarding monsoon rainfalls and thermodynamics, the interpretations of paleoclimate variations across various timescales are still in development^45,46,88,89.

Physically, the summer barometric differentials and other boundary conditions on a large spatial-scale, regardless of their cause, drive the Asian summer monsoon circulation (e.g., at 850 hPa) (Supplementary Fig. 8) and the associated large-scale vapor flux (Supplementary Fig. 9). In terms of precipitation δ¹⁸O_p at the cave site, prior to the onset of the Asian summer monsoon, the moisture source is relatively proximate, resulting in heavier δ¹⁸O_p. After the summer monsoon onset, the spatial-scale of monsoon circulation and moisture from remote sources increase dramatically (Supplementary Figs. 8 and 9), both leading to lighter precipitation δ¹⁸O_p at the cave site. Consequently, cave δ¹⁸O_c mainly indicates the dynamic aspect of the monsoon circulation⁹⁰, with a small portion of the variability explained by local rainfall amount or thermodynamics. Local rainfall amount or P-E is, however, better reflected by other proxies [e.g., trace elements, (²³⁴U/²³⁸U)₀, and δ¹³C].

As the Indian summer monsoon is an interhemispheric monsoon system, the interhemispheric differential in tropical insolation (or Summer Inter-Tropical Insolation Gradient, SITIG⁹¹) is critical, reflecting both “pull” and “push” forcings from Northern and Southern Hemisphere that propel monsoon changes¹. Thus, we use the interhemispheric differential in tropical insolation (30°N-30°S) as an integrated insolation forcing of the monsoon, consistent with previous evidence, such as the Asian summer monsoon variation pattern over the MIS 3¹. The Qunf δ¹⁸O_c record suggests an Indian summer monsoon waning trend from the middle Holocene to the present, broadly following SITIG. This observation is consistent with many other Indian summer monsoon records, such as the Sahiya and Mawmluh records from northern India^72,92, the Tianmen record from the southern Tibetan Plateau⁹³, and some of the upwelling records from the Arabian Sea and its adjacent area³⁹ (Fig. 4).

In the early 1990s, ref. ³⁶ studied a set of upwelling proxies from marine sediment cores from the Arabian Sea. They raised a hypothesis that changes in the Indian summer monsoon were driven not only by NHSI, but also by the latent heat release of moisture originating from the southern Indian Ocean and the global ice volume affecting the Indian summer monsoon precession phases. Sea surface temperature variation over the south subtropical Indian Ocean controls the latent heat effect on the Indian summer monsoon, which has a significant phase lag to the NHSI maxima at the precession band^{36,40,94,95,96}. Multiple upwelling records indeed show a significant phase lag (up to 8–11 ka) or nearly anti-phase to NHSI at the precession band^40,41,42. Model simulations reveal contrasting hydroclimatic responses between land and ocean to NHSI changes at the precession band^16,17,44. This phenomenon has been referred to as the “land-sea precession phase paradox”². In the Indian summer monsoon regions, Jalihal et al.^46,47,97 investigated the opposing marine and terrestrial responses, both empirically and theoretically. They discovered that, in addition to NHSI, precipitation changes over the ocean are influenced by changes in surface energy fluxes and vertical stability. This view largely reconciles the apparent discrepancy between the Qunf δ¹⁸O_c record and some previous marine upwelling records from the Arabian Sea in terms of the precession phase paradox.

Overall, our speleothem multi-proxy records and modeling results provide valuable insights into the interpretation of the Qunf δ¹⁸O_c record and the Holocene hydroclimate history in the southern Arabian Peninsula. During the early to middle Holocene, corresponding to the Holocene Humid Period in southern Arabia, the North African summer monsoon, in addition to the Indian summer monsoon, may likely contribute water vapor to the Qunf Cave area as well. After ~6 ka BP, Qunf Δ'¹⁷O data suggest a possible reduction in moisture delivered by the North African summer monsoon, higher δ¹⁸O_c values suggest that only the Indian summer monsoon prevails with water vapor mainly derived from the proximate Arabian Sea like today. Our results are consistent with the interpretative framework that in addition to the amount effect, speleothem δ¹⁸O_c values are essentially related to oxygen-isotope fractionations integrated during the moisture transport from the source to the cave site. More broadly, the Qunf δ¹⁸O_c record may be viewed theoretically as an archive indicating the change of the vast monsoon regime, the unified North African summer monsoon - Asian summer monsoon system. Although the Qunf δ¹⁸O_c have lighter values and the precipitation amount might increase from ~10 to ~6 ka BP, Qunf (²³⁴U/²³⁸U)₀, δ¹³C, and trace element ratio records (Mg/Ca, Sr/Ca, Ba/Ca) seem to suggest a lower P-E condition. This requires further investigation.

Methods

Modern source–receptor relationship

To establish a modern source–receptor relationship for moisture transport in the study region, the Lagrangian trajectory model FLEXPART, driven by ERA-Interim reanalysis, was used. Based on ERA-interim precipitation (1979–2019), we created wet and dry composites from the three driest (−1.5σ) and wettest (+1.5σ) June-July-August (JJA) years in our study area (17°N−17.75°N, 54°E-54.75°E). FLEXPART simulations were performed during JJA in these years.

The FLEXPART simulation was driven by ERA-interim through 6-hourly analyzes (at 00.00, 06.00, 12.00, and 18.00 UTC) and 3-hourly forecasts at intermediate times (at 0300, 0900, 1500, and 2100 UTC), with 1° × 1° resolution on 60 model levels⁹⁸. Surface moisture flux is calculated over an area (A), where E-P for the total particles residing over A is given by:

$${{{{{\rm{E}}}}}}-{{{{{\rm{P}}}}}}\approx \frac{{\sum }_{k=1}^{K}\left(e-p\right)}{A}$$

(1)

where e-p is the rate of moisture change along the trajectory⁹⁹. The simulation releases 50,000 particles, and K is the number of N particles that resides over A. This approach divides the whole atmosphere’s mass into small elements distributed homogeneously in the atmosphere according to the atmospheric mass distribution. These are then moved with the mass-consistent winds and are based on mass-consistent turbulence and convection parameterizations^100,101. We calculated the mean net moisture flux based on E-P and backtracked elements that had a loss (E-P < 0) over the Qunf Cave region (17°N−17.75°N, 54°E-54.75°E) for 12 days.

²³⁰Th dating

A total of 50 new ²³⁰Th dates were obtained from stalagmite Q5. Powder sub-samples were hand-drilled parallel to the growth band near the stalagmite axis. The ²³⁰Th dating work was performed at Xi’an Jiaotong University Isotope Laboratory using multi-collector inductively coupled plasma mass spectrometers (Thermo-Finnigan Neptune-plus). We used standard chemistry procedures to separate U and Th for dating¹⁰². A triple-spike (²²⁹Th–²³³U–²³⁶U) isotope dilution method was employed to correct instrumental fractionation and determine U-Th isotopic ratios and concentrations. Details about the instrumental setup are provided by refs. ^103,104. All ages are in stratigraphic order within dating uncertainties. The age model was constructed using the Constructing Proxy Records from Age (COPRA) program¹⁰⁵. Q5 δ¹⁸O_c and δ¹³C records were adjusted to the new age model (Supplementary Fig. 2).

Trace element analysis

The trace elements were measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES) (Thermo Scientific iCAP DUO 6300) in Instituto Pirenaico de Ecologia, Spanish Scientific Research Council (IPE-CSIC). The drilled powder (100–150 mg) was placed in tubes cleaned with 10% HCl, rinsed with MilliQ-filtered water, and dissolved in 1.5 mL of 2% HNO₃ (Tracepur) immediately before analysis. Samples were run at average Ca concentrations of 200 ppm. Calibration was conducted offline using the intensity ratio method described by ref. ¹⁰⁶. The results are shown by molar ratios of Mg, Ba, and Sr relative to Ca.

Triple oxygen isotope analysis

The δ¹⁷O_c of Q5 was measured at Xi’an Jiaotong University Isotope Laboratory. After drilling the carbonate powder of the sample, we add in phosphoric acid (H₃PO₄, 1.92 g/ml, ~104%) at 25 °C to extract CO₂. Then the CO₂ was equilibrated with an equal amount of the O₂ gas for 30 min under 750 °C to reach a Pt-catalyzed equilibrium by an O₂–CO₂ Pt-catalyzed oxygen-isotope equilibration reaction system. In this system, the two post-equilibration gases were separated from each other cryogenically. Finally, δ¹⁷O_c was obtained through measurements of the resultant O₂ and CO₂ by a Thermo Scientific MAT 253 mass spectrometer⁶⁰. The calculation of Δ'¹⁷O and the relative humidity at the moisture source follows the method from ref. ⁶⁰ (See supplementary text).

Fluid inclusion measurements

Q5 δD_fi was analyzed at Xi’an Jiaotong University Isotope Laboratory. The Q5 calcite blocks were crushed at a temperature of ~120 °C. The liberated water was then transported to a wavelength-scanned cavity ring-down spectroscopy system (Picarro L2140-i analyzer). The analytical method is described in ref. ¹⁰⁷, the maximum error on the reproducibility of crushed speleothem samples for this system is 2‰ for δD_fi (1 SD). δD_fi values are reported on the Vienna Standard Mean Ocean Water to SLAP2 (VSMOW2 – SLAP2) scale.

Model simulations

The simulations based on the fully coupled Earth system model EC-Earth are used in this study. A consortium of European research institutions develops EC-Earth to build a fully coupled Atmosphere-Ocean-Land-Biosphere Earth system model for seasonal to decadal climate prediction and future climate projections¹⁰⁸. The atmospheric model of EC-Earth is based on the IFS, including a land model H-TESSEL, developed at the European Centre for Medium-Range Weather Forecasts (ECMWF)⁹⁸. In addition, the dynamic vegetation model LPJ-GUESS¹⁰⁹ is coupled to the land component. The ocean component is the Nucleus for European Modelling of the Ocean (NEMO)¹¹⁰ and includes a sea-ice model LIM3¹¹¹. We use the CMIP6 configuration of EC-Earth3-veg-LR, in which the atmosphere and land model has a T159 horizontal spectral resolution (roughly 1.125°–125 km) with 62 vertical levels. The NEMO and LIM have a nominal horizontal resolution of 1°, and NEMO has 75 vertical levels. The coupling between the atmosphere and ocean/sea ice is through the Ocean Atmosphere Sea Ice Soil coupler (OASIS, version 3.0)¹¹².

We simulate the 8 ka BP (8 K) and a pre-industrial control simulation (PI) using EC-Earth3-veg-LR. The simulations follow the CMIP6-PMIP4 protocol for each experiment setup¹¹³. The PI and 8 K simulations have the same boundary conditions except for the orbital forcing and greenhouse gas concentration differences (Supplementary Table 1). The orbital forcing is computed in the IFS component according to ref. ¹¹⁴, as described in ref. ¹¹⁵. The greenhouse gas concentration for PI follows CMIP6 and for 8 K using the reconstruction from ref. ¹¹⁶.

The initial condition for PI simulation with EC-Earth-veg-LR is taken from a previous PI run with EC-Earth3-LR¹¹⁵. The simulation reaches the quasi-equilibrium after 300 years (meets the criteria global mean surface temperature trend <±0.05 K per century¹¹³, and the simulation continues running for another 700 years. The initial condition for the 8 K simulation is taken from the equilibrium state of PI simulation, with changed orbital forcing and Green House Gas concentration. For the 8 K condition it takes around 300 years to reach equilibrium, and we run for another 700 years. The last 200 years’ outputs are used to analyze both simulations.

Data availability

Source data for Fig. 2 and Fig. 4 are referenced in the Source data provided with this paper. The absolute ²³⁰Th dates and multi-proxy data time series are available online on the NOAA paleoclimate database (https://www.ncei.noaa.gov/access/paleo-search/study/38279). FLEXPART model and documentation can be found at https://www.flexpart.eu/ (last accessed: 2023-03-09). Climate model simulation data is published on Zenodo (https://zenodo.org/record/8121547). Source data are provided with this paper.

References

Cheng, H. et al. Milankovitch theory and monsoon. Innovation 3, 100338 (2022).
PubMed PubMed Central Google Scholar
Cheng, H. et al. Orbital-scale Asian summer monsoon variations: Paradox and exploration. Sci. China-Earth Sci. 64, 529–544 (2021).
Article ADS Google Scholar
Zhang, H. et al. A data-model comparison pinpoints Holocene spatiotemporal pattern of East Asian summer monsoon. Quat. Sci. Rev. 261, 106911 (2021).
Article Google Scholar
Mohtadi, M., Prange, M. & Steinke, S. Palaeoclimatic insights into forcing and response of monsoon rainfall. Nature 533, 191–199 (2016).
Article ADS CAS PubMed Google Scholar
Seth, A. et al. Monsoon responses to climate changes-connecting past, present and future. Curr. Clim. Change Rep. 5, 63–79 (2019).
Article Google Scholar
Cheng, H. et al. Climate variations of Central Asia on orbital to millennial timescales. Sci. Rep. 5, 36975 (2016).
Article ADS PubMed PubMed Central Google Scholar
Kathayat, G. et al. Indian monsoon variability on millennial-orbital timescales. Sci. Rep. 6, 24374 (2016).
Article ADS CAS PubMed PubMed Central Google Scholar
Cai, Y. J. et al. Variability of stalagmite-inferred Indian monsoon precipitation over the past 252,000 years. Proc. Natl Acad. Sci. USA 112, 2954–2959 (2015).
Article ADS CAS PubMed PubMed Central Google Scholar
Wang, Y. J. et al. Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years. Nature 451, 1090–1093 (2008).
Article ADS CAS PubMed Google Scholar
Cheng, H. et al. The Asian monsoon over the past 640,000 years and ice age terminations. Nature 534, 640–646 (2016).
Article ADS CAS PubMed Google Scholar
Kutzbach, J. E. Monsoon climate of the early holocene - climate experiment with the earths orbital parameters for 9000 years Ago. Science 214, 59–61 (1981).
Article ADS CAS PubMed Google Scholar
Ruddiman, W. F. Orbital insolation, ice volume, and greenhouse gases. Quat. Sci. Rev. 22, 1597–1629 (2003).
Article ADS Google Scholar
LeGrande, A. N. & Schmidt, G. A. Sources of Holocene variability of oxygen isotopes in paleoclimate archives. Clim 5, 441–455 (2009).
ADS Google Scholar
Kutzbach, J. E., Liu, X. D., Liu, Z. Y. & Chen, G. S. Simulation of the evolutionary response of global summer monsoons to orbital forcing over the past 280,000 years. Clim. Dyn. 30, 567–579 (2008).
Article Google Scholar
Liu, Z. et al. Chinese cave records and the East Asia Summer Monsoon. Quat. Sci. Rev. 83, 115–128 (2014).
Article ADS Google Scholar
Battisti, D. S., Ding, Q. & Roe, G. H. Coherent pan-Asian climatic and isotopic response to orbital forcing of tropical insolation. J. Geophys. Res. -Atmos. 119, 11997–12020 (2014).
Article ADS Google Scholar
Bosmans, J. H. C. et al. Response of the Asian summer monsoons to idealized precession and obliquity forcing in a set of GCMs. Quat. Sci. Rev. 188, 121–135 (2018).
Article ADS Google Scholar
Hu, J., Emile‐Geay, J., Tabor, C., Nusbaumer, J. & Partin, J. Deciphering oxygen isotope records from chinese speleothems with an isotope‐enabled climate model. Paleoceanogr. Paleoclimatol. 34, 2098–2112 (2019).
Article ADS Google Scholar
Kutzbach, J. E. et al. African climate response to orbital and glacial forcing in 140,000-y simulation with implications for early modern human environments. Proc. Natl Acad. Sci. USA 117, 2255–2264 (2020).
Article ADS CAS PubMed PubMed Central Google Scholar
Breitenbach, S. F. M. et al. Strong influence of water vapor source dynamics on stable isotopes in precipitation observed in Southern Meghalaya, NE India. Earth Planet. Sci. Lett. 292, 212–220 (2010).
Article ADS CAS Google Scholar
Dayem, K. E., Molnar, P., Battisti, D. S. & Roe, G. H. Lessons learned from oxygen isotopes in modern precipitation applied to interpretation of speleothem records of paleoclimate from eastern Asia. Earth Planet. Sci. Lett. 295, 219–230 (2010).
Article ADS CAS Google Scholar
Pausata, F. S. R., Battisti, D. S., Nisancioglu, K. H. & Bitz, C. M. Chinese stalagmite delta O-18 controlled by changes in the Indian monsoon during a simulated Heinrich event. Nat. Geosci. 4, 474–480 (2011).
Article ADS CAS Google Scholar
Yuan, D. X. et al. Timing, duration, and transitions of the Last Interglacial Asian Monsoon. Science 304, 575–578 (2004).
Article ADS CAS PubMed Google Scholar
Sinha, A. et al. Variability of Southwest Indian summer monsoon precipitation during the Boiling-Allerod. Geology 33, 813–816 (2005).
Article ADS CAS Google Scholar
Krklec, K. & Dominguez-Villar, D. Quantification of the impact of moisture source regions on the oxygen isotope composition of precipitation over Eagle Cave, central Spain. Geochim. Cosmochim. Acta 134, 39–54 (2014).
Article ADS CAS Google Scholar
Kathayat, G. et al. Interannual oxygen isotope variability in Indian summer monsoon precipitation reflects changes in moisture sources. Commun. Earth Environ. 2, 1–10 (2021).
Article Google Scholar
Cai, Y. et al. The variation of summer monsoon precipitation in central China since the last deglaciation. Earth Planet. Sci. Lett. 291, 21–31 (2010).
Article ADS CAS Google Scholar
Yang, X. L. et al. Early-Holocene monsoon instability and climatic optimum recorded by Chinese stalagmites. Holocene 29, 1059–1067 (2019).
Article ADS Google Scholar
Fleitmann, D. et al. Holocene forcing of the indian monsoon recorded in a stalagmite from Southern Oman. Science 300, 1737–1739 (2003).
Article ADS CAS PubMed Google Scholar
Burns, S. J., Fleitmann, D., Matter, A., Neff, U. & Mangini, A. Speleothem evidence from Oman for continental pluvial events during interglacial periods. Geology 29, 623–626 (2001).
Article ADS CAS Google Scholar
Neff, U. et al. Strong coherence between solar variability and the monsoon in Oman between 9 and 6 kyr ago. Nature 411, 290–293 (2001).
Article ADS CAS PubMed Google Scholar
Fleitmann, D. et al. Holocene ITCZ and Indian monsoon dynamics recorded in stalagmites from Oman and Yemen (Socotra). Quat. Sci. Rev. 26, 170–188 (2007).
Article ADS Google Scholar
Gadgil, S. The monsoon system: Land-sea breeze or the ITCZ? J. Earth Syst. Sci. 127, 1–29 (2018).
Biasutti, M. et al. Global energetics and local physics as drivers of past, present and future monsoons. Nat. Geosci. 11, 392–400 (2018).
Article ADS CAS Google Scholar
Hill, S. A. Theories for past and future monsoon rainfall changes. Curr. Clim. Change Rep. 5, 160–171 (2019).
Article Google Scholar
Clemens, S., Prell, W., Murray, D., Shimmield, G. & Weedon, G. Forcing mechanisms of the Indian Ocean monsoon. Nature 353, 720–725 (1991).
Article ADS Google Scholar
Reichart, G. J., Lourens, L. J. & Zachariasse, W. J. Temporal variability in the northern Arabian Sea Oxygen Minimum Zone (OMZ) during the last 225,000 years. Paleoceanography 13, 607–621 (1998).
Article ADS Google Scholar
Ziegler, M. et al. Precession phasing offset between Indian summer monsoon and Arabian Sea productivity linked to changes in Atlantic overturning circulation. Paleoceanography 25, PA3213 (2010).
Gupta, A. K., Anderson, D. M. & Overpeck, J. T. Abrupt changes in the Asian southwest monsoon during the Holocene and their links to the North Atlantic Ocean. Nature 421, 354–357 (2003).
Article ADS CAS PubMed Google Scholar
Clemens, S. C. & Prell, W. L. A 350,000 year summer-monsoon multi-proxy stack from the Owen Ridge, Northern Arabian Sea. Mar. Geol. 201, 35–51 (2003).
Article ADS Google Scholar
Caley, T. et al. Orbital timing of the Indian, East Asian and African boreal monsoons and the concept of a ‘global monsoon’. Quat. Sci. Rev. 30, 3705–3715 (2011).
Article ADS Google Scholar
Caley, T. et al. New Arabian Sea records help decipher orbital timing of Indo-Asian monsoon. Earth Planet. Sci. Lett. 308, 433–444 (2011).
Article ADS CAS Google Scholar
Gebregiorgis, D. et al. Southern Hemisphere forcing of South Asian monsoon precipitation over the past similar to 1 million years. Nat. Commun. 9, 1–8 (2018).
Article CAS Google Scholar
Hsu, Y. H., Chou, C. & Wei, K. Y. Land-ocean asymmetry of tropical precipitation changes in the mid-holocene. J. Clim. 23, 4133–4151 (2010).
Article ADS Google Scholar
Jalihal, C., Srinivasan, J. & Chakraborty, A. Modulation of Indian monsoon by water vapor and cloud feedback over the past 22,000 years. Nat. Commun. 10, 5701 (2019).
Article ADS CAS PubMed PubMed Central Google Scholar
Jalihal, C., Srinivasan, J. & Chakraborty, A. Different precipitation response over land and ocean to orbital and greenhouse gas forcing. Sci. Rep. 10, 11891 (2020).
Article ADS CAS PubMed PubMed Central Google Scholar
Jalihal, C., Srinivasan, J. & Chakraborty, A. Response of the Low‐Level Jet to Precession and Its Implications for Proxies of the Indian Monsoon. Geophys. Res. Lett. 49, e2021GL094760 (2022).
Article ADS Google Scholar
Ruddiman, W. F. What is the timing of orbital-scale monsoon changes? Quat. Sci. Rev. 25, 657–658 (2006).
Article ADS Google Scholar
Fleitmann, D., Burns, S., Matter, A., Cheng, H. & Affolter, S. Moisture and seasonality shifts recorded in Holocene and Pleistocene speleothems from south‐eastern Arabia. Geophys. Res. Lett. 49, e2021GL097255 (2022).
Article ADS Google Scholar
Nicholson, S. L. et al. Pluvial periods in Southern Arabia over the last 1.1 million-years. Quat. Sci. Rev. 229, 106112 (2020).
Article Google Scholar
Burns, S. J., Fleitmann, D., Matter, A., Kramers, J. & Al-Subbary, A. A. Indian Ocean climate and an absolute chronology over Dansgaard/Oeschger events 9 to 13. Science 301, 1365–1367 (2003).
Article ADS CAS PubMed Google Scholar
Barkan, E. & Luz, B. Diffusivity fractionations of H₂¹⁶O/H₂¹⁷O and H₂¹⁶O/H₂¹⁸O in air and their implications for isotope hydrology. Rapid Commun. Mass Spectrom. 21, 2999–3005 (2007).
Article ADS CAS PubMed Google Scholar
Passey, B. H. et al. Triple oxygen isotopes in biogenic and sedimentary carbonates. Geochim. Cosmochim. Acta 141, 1–25 (2014).
Article ADS CAS Google Scholar
Tian, C., Wang, L. X., Kaseke, K. F. & Bird, B. W. Stable isotope compositions (δ²H, δ¹⁸O and δ¹⁷O) of rainfall and snowfall in the central United States. Sci. Rep. 8, 1–15 (2018).
Article Google Scholar
Uechi, Y. & Uemura, R. Dominant influence of the humidity in the moisture source region on the ¹⁷O-excess in precipitation on a subtropical island. Earth Planet. Sci. Lett. 513, 20–28 (2019).
Article ADS CAS Google Scholar
Luz, B. & Barkan, E. Variations of ¹⁷O/¹⁶O and ¹⁸O/¹⁶O in meteoric waters. Geochim. Cosmochim. Acta 74, 6276–6286 (2010).
Article ADS CAS Google Scholar
Aron, P. G. et al. Triple oxygen isotopes in the water cycle. Chem. Geol. 565, 120026 (2021).
Article CAS Google Scholar
Angert, A., Cappa, C. D. & DePaolo, D. J. Kinetic ¹⁷O effects in the hydrologic cycle: Indirect evidence and implications. Geochem. Cosmochim. Acta 68, 3487–3495 (2004).
Article ADS CAS Google Scholar
Uemura, R., Barkan, E., Abe, O. & Luz, B. Triple isotope composition of oxygen in atmospheric water vapor. Geophys. Res. Lett. 37, L04402 (2010).
Article ADS Google Scholar
Sha, L. J. et al. A novel application of triple oxygen isotope ratios of speleothems. Geochem. Cosmochim. Acta 270, 360–378 (2020).
Article ADS CAS Google Scholar
Landais, A. et al. Combined measurements of ¹⁷Oexcess and d-excess in African monsoon precipitation: Implications for evaluating convective parameterizations. Earth Planet. Sci. Lett. 298, 104–112 (2010).
Article ADS CAS Google Scholar
Li, S., Levin, N. E. & Chesson, L. A. Continental scale variation in ¹⁷O-excess of meteoric waters in the United States. Geochem. Cosmochim. Acta 164, 110–126 (2015).
Article ADS CAS Google Scholar
Wen, Q. et al. Local insolation drives Afro‐Asian monsoon at orbital‐scale in holocene. Geophys. Res. Lett. 49, e2021GL097661 (2022).
Article ADS Google Scholar
Cheng, H. et al. European-Asian-African continent: an early form of supercontinent and supermonsoon. Quat. Sci. 40, 1381–1396 (2020).
Google Scholar
Ziegler, M., Tuenter, E. & Lourens, L. J. The precession phase of the boreal summer monsoon as viewed from the eastern Mediterranean (ODP Site 968). Quat. Sci. Rev. 29, 1481–1490 (2010).
Article ADS Google Scholar
Rohling, E. J. Review and new aspects concerning the formation of eastern mediterranean sapropels. Mar. Geol. 122, 1–28 (1994).
Article ADS Google Scholar
Rohling, E. J., Marino, G. & Grant, K. M. Mediterranean climate and oceanography, and the periodic development of anoxic events (sapropels). Earth Sci. Rev. 143, 62–97 (2015).
Article ADS CAS Google Scholar
Rossignol-Strick, M. African monsoons, an immediate climate response to orbital insolation. Nature 304, 46–49 (1983).
Article ADS Google Scholar
Bar-Matthews, M., Ayalon, A., Gilmour, M., Matthews, A. & Hawkesworth, C. J. Sea–land oxygen isotopic relationships from planktonic foraminifera and speleothems in the Eastern Mediterranean region and their implication for paleorainfall during interglacial intervals. Geochem. Cosmochim. Acta 67, 3181–3199 (2003).
Article ADS CAS Google Scholar
Cheng, H. et al. The climate variability in northern Levant over the past 20,000 years. Geophys. Res. Lett. 42, 8641–8650 (2015).
Article ADS Google Scholar
Tierney, J. E. & deMenocal, P. B. Abrupt shifts in Horn of Africa hydroclimate since the Last Glacial Maximum. Science 342, 843–846 (2013).
Article ADS CAS PubMed Google Scholar
Kathayat, G. et al. The Indian monsoon variability and civilization changes in the Indian subcontinent. Sci. Adv. 3, e1701296 (2017).
Article ADS PubMed PubMed Central Google Scholar
Weldeab, S., Menke, V. & Schmiedl, G. The pace of East African monsoon evolution during the Holocene. Geophys. Res. Lett. 41, 1724–1731 (2014).
Article ADS Google Scholar
Weldeab, S., Lea, D. W., Schneider, R. R. & Andersen, N. 155,000 Years of West African monsoon and ocean thermal evolution. Science 316, 1303–1307 (2007).
Article ADS CAS PubMed Google Scholar
Ayalon, A., Bar-Matthews, M. & Kaufman, A. Petrography, strontium, barium and uranium concentrations, and strontium and uranium isotope ratios in speleothems as palaeoclimatic proxies: Soreq Cave, Israel. Holocene 9, 715–722 (1999).
Article ADS Google Scholar
Henderson, G. M., Slowey, N. C. & Haddad, G. A. Fluid flow through carbonate platforms: constraints from ²³⁴U/²³⁸U and Cl⁻ in Bahamas pore-waters. Earth Planet. Sci. Lett. 169, 99–111 (1999).
Article ADS CAS Google Scholar
Hellstrom, J. C. & McCulloch, M. T. Multi-proxy constraints on the climatic significance of trace element records from a New Zealand speleothem. Earth Planet. Sci. Lett. 179, 287–297 (2000).
Article ADS CAS Google Scholar
Bar-Matthews, M., Ayalon, A., Matthews, A., Sass, E. & Halicz, L. Carbon and oxygen isotope study of the active water-carbonate system in a karstic Mediterranean cave: implications for paleoclimate research in semiarid regions. Geochim. Cosmochim. Acta 60, 235–241 (1996).
Article Google Scholar
Baker, A., Ito, E., Smart, P. L. & Mcewan, R. F. Elevated and variable values of ¹³C in speleothems in a British cave system. Chem. Geol. 136, 263–270 (1997).
Article ADS CAS Google Scholar
Genty, D. et al. Timing and dynamics of the last deglaciation from European and North African delta δ¹³C stalagmite profiles—comparison with Chinese and South Hemisphere stalagmites. Quat. Sci. Rev. 25, 2118–2142 (2006).
Article ADS Google Scholar
Fairchild, I. J. & Treble, P. C. Trace elements in speleothems as recorders of environmental change. Quat. Sci. Rev. 28, 449–468 (2009).
Article ADS Google Scholar
Fairchild, I. J. et al. Controls on trace element (Sr–Mg) compositions of carbonate cave waters: implications for speleothem climatic records. Chem. Geol. 166, 255–269 (2000).
Article ADS CAS Google Scholar
Tremaine, D. M. & Froelich, P. N. Speleothem trace element signatures: a hydrologic geochemical study of modern cave dripwaters and farmed calcite. Geochim. Cosmochim. Acta 121, 522–545 (2013).
Article ADS CAS Google Scholar
Emanuel, K. A., Neelin, J. D. & Bretherton, C. S. On large‐scale circulations in convecting atmospheres. Q. J. R. Meteorol. Soc. 120, 1111–1143 (1994).
ADS Google Scholar
Nie, J., Boos, W. R. & Kuang, Z. Observational evaluation of a convective quasi-equilibrium view of monsoons. J. Clim. 23, 4416–4428 (2010).
Article ADS Google Scholar
Neelin, J. D. & Held, I. M. Modeling tropical convergence based on the moist static energy budget. Mon. Weather Rev. 115, 3–12 (1987).
Article ADS Google Scholar
Chou, C., Neelin, J. D. & Su, H. Ocean‐atmosphere‐land feedbacks in an idealized monsoon. Q. J. R. Meteorol. Soc. 127, 1869–1891 (2001).
ADS Google Scholar
D’Agostino, R., Bader, J., Sordoni, S., Ferreira, D. & Jungclaus, J. Northern hemisphere monsoon response to mid-holocene orbital forcing and greenhouse gas-induced global warming. Geophys. Res. Lett. 46, 1591–1601 (2019).
Article ADS Google Scholar
D’Agostino, R. et al. Contrasting Southern hemisphere monsoon response: midholocene orbital forcing versus future greenhouse gas-induced global warming. J. Clim. 33, 9595–9613 (2020).
Article ADS Google Scholar
Zhao, J. et al. Orchestrated decline of Asian summer monsoon and Atlantic meridional overturning circulation in global warming period. The Innovation Geoscience, 100011 (2023).
Reichart, G.-J. Late Quaternary Variability of the Arabian Sea Monsoon and Oxygen Minimum Zone, Utrecht University, (1997).
Berkelhammer, M. et al. An abrupt shift in the Indian Monsoon 4000 years ago. Geophys. Monogr. Ser. 198, 75–87 (2012).
Google Scholar
Cai, Y. et al. The Holocene Indian monsoon variability over the southern Tibetan Plateau and its teleconnections. Earth Planet. Sci. Lett. 335, 336, 135–144 (2012).
Article Google Scholar
Clemens, S. C. et al. Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: a test for future predictions. Sci. Adv. 7, eabg3848 (2021).
Article ADS PubMed PubMed Central Google Scholar
Clemens, S. C., Prell, W. L., Sun, Y., Liu, Z. & Chen, G. Southern Hemisphere forcing of pliocene δ¹⁸O and the evolution of Indo-Asian monsoons. Paleoceanography 23, PA4210 (2008).
Clemens, S. C., Prell, W. L. & Sun, Y. Orbital-scale timing and mechanisms driving Late Pleistocene Indo-Asian summer monsoons: reinterpreting cave speleothem δ¹⁸O. Paleoceanography 25, PA4210 (2010).
Jalihal, C., Bosmans, J. H. C., Srinivasan, J. & Chakraborty, A. The response of tropical precipitation to Earth’s precession: the role of energy fluxes and vertical stability. Clim. 15, 449–462 (2019).
ADS Google Scholar
European Centre for Medium-Range Weather Forecast (ECMWF). The ERA‐Interim reanalysis dataset, Copernicus Climate Change Service (C3S). https://www.ecmwf.int/en/forecasts/datasets/archive-datasets/reanalysis-datasets/era-interim (2011).
Stohl, A. & James, P. A Lagrangian analysis of the atmospheric branch of the global water cycle. part I: method description, validation, and demonstration for the August 2002 flooding in central Europe. J. Hydrometeorol. 5, 656–678 (2004).
Article ADS Google Scholar
Pisso, I. et al. The Lagrangian particle dispersion model FLEXPART version 10.4. Geosci. Model Dev. 12, 4955–4997 (2019).
Article ADS Google Scholar
Salih, A. A. M., Zhang, Q. & Tjernström, M. Lagrangian tracing of Sahelian Sudan moisture sources. J. Geophys. Res. Atmos. 120, 6793–6808 (2015).
Article ADS Google Scholar
Edwards, L. R., Chen, J. H. & Wasserburg, G. J. ²³⁸U-²³⁴U-^230Th-²³²Th systematics and the precise measurement of time over the past 500,000 years. Earth Planet. Sci. Lett. 81, 175–192 (1987).
Article ADS CAS Google Scholar
Cheng, H. et al. The half-lives of uranium-234 and thorium-230. Chem. Geol. 169, 17–33 (2000).
Article ADS CAS Google Scholar
Cheng, H. et al. Improvements in ²³⁰Th dating, ²³⁰Th and ²³⁴U half-life values, and U–Th isotopic measurements by multi-collector inductively coupled plasma mass spectrometry. Earth Planet. Sci. Lett. 371, 372, 82–91 (2013).
Article Google Scholar
Breitenbach, S. F. M. et al. COnstructing Proxy Records from Age models (COPRA). Climate 8, 1765–1779 (2012).
Google Scholar
de Villiers, S., Greaves, M. & Elderfield, H. An intensity ratio calibration method for the accurate determination of Mg/Ca and Sr/Ca of marine carbonates by ICP‐AES. Geochem. Geophys. Geosyst. 3, 2001GC000169 (2002).
Article Google Scholar
Tian, Y. et al. Measurement of oxygen and hydrogen isotopic ratios of speleothem fluid inclusion water using Picarro. Chin. Sci. Bull. 65, 3626–3634 (2020).
Article Google Scholar
Hazeleger, W. et al. EC-earth a seamless earth-system prediction approach in action. Bull. Am. Meteorol. Soc. 91, 1357–1363 (2010).
Article ADS Google Scholar
Smith, B. et al. Implications of incorporating N cycling and N limitations on primary production in an individual-based dynamic vegetation model. Biogeosciences 11, 2027–2054 (2014).
Article ADS Google Scholar
Madec, G. NEMO OCEAN ENGINE (Note du Pole de modélisation, Institut Pierre-Simon Laplace, France, 2008).
Rousset, C. et al. The Louvain-La-Neuve sea ice model LIM3.6: global and regional capabilities. Geosci. Model Dev. 8, 2991–3005 (2015).
Article ADS Google Scholar
Valcke, S. Morel, T. OASIS and PALM, the CERFACS couplers. Technical Report, TR/CMGC/06/38, CERFACS, Toulouse, France (2006).
Kageyama, M. et al. The PMIP4 contribution to CMIP6–Part 1: overview and over-arching analysis plan. Geosci. Model Dev. 11, 1033–1057 (2018).
Article ADS Google Scholar
Berger, A. L. Long-term variations of caloric insolation resulting from earths orbital elements. Quat. Res. 9, 139–167 (1978).
Article Google Scholar
Zhang, Q. et al. Simulating the mid-Holocene, last interglacial and mid-Pliocene climate with EC-Earth3-LR. Geosci. Model Dev. 14, 1147–1169 (2021).
Article ADS Google Scholar
Köhler, P., Nehrbass-Ahles, C., Schmitt, J., Stocker, T. F. & Fischer, H. A 156 kyr smoothed history of the atmospheric greenhouse gases CO₂, CH₄, and N₂O and their radiative forcing. Earth Syst. Sci. Data 9, 363–387 (2017).
Article ADS Google Scholar
Dykoski, C. A. et al. A high-resolution, absolute-dated Holocene and deglacial Asian monsoon record from Dongge Cave, China. Earth Planet. Sci. Lett. 233, 71–86 (2005).
Article ADS CAS Google Scholar

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (NSFC grants 41888101, 42150710534 to H.C.; grant 4197020225 to H.Z.), Q.Z. acknowledges support from the Vetenskapsrådet (grant nos. 2013-06476, 2017-04232), J.A.W. acknowledges support from the Institute for Basic Science (IBS), Republic of Korea, under IBS-R028-Y2. The EC-Earth simulations were performed using ECMWF’s computing and archive facilities and the Swedish National Infrastructure for Computing (SNIC) at the National Supercomputer Centre (NSC). Y.T. thanks Zhongli Liu for his support when he was at Xi’an Jiaotong University and now at Peking University.

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Authors and Affiliations

Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an, 710049, China
Ye Tian, Lijuan Sha, Haiwei Zhang, Hanying Li, Yanjun Cai, Youfeng Ning & Hai Cheng
Department of Environmental Sciences, University of Basel, Basel, 4054, Switzerland
Dominik Fleitmann
Department of Physical Geography and the Bolin Centre for Climate Change, Stockholm University, Stockholm, SE-106 91, Sweden
Qiong Zhang & Josefine Axelsson
Center for Climate Physics, Institute for Basic Science, Busan, 46241, Republic of Korea
Jasper. A. Wassenburg
Pusan National University, Busan, 46241, Republic of Korea
Jasper. A. Wassenburg
State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, 710061, China
Xianglei Li & Hai Cheng
College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361102, China
Jun Hu
School of Geography, Nanjing Normal University, Nanjing, 210023, China
Liang Zhao

Authors

Ye Tian
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Dominik Fleitmann
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Qiong Zhang
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Lijuan Sha
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Jasper. A. Wassenburg
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Josefine Axelsson
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Haiwei Zhang
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Xianglei Li
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Jun Hu
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Hanying Li
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Liang Zhao
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Yanjun Cai
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Youfeng Ning
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Hai Cheng
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Contributions

Y.T. wrote the draft manuscript. Y.T. and H.C. designed the research and experiments. Y.T. performed the fluid inclusion measurements. D.F. collected the speleothem sample and provide the stable oxygen and carbon isotope records. Q.Z. conducted EC-Earth simulations. L.S. performed triple oxygen measurements. J.A.W. contributed to the fluid inclusion and the local hydroclimate analysis. J.A. ran the FLEXPART analysis. Y.T., X.L., and Y.N. contributed to ²³⁰Th dating. Y.T., X.L., and H.L. did the trace element measurements. J.H. and L.Z. contributed to the simulation analysis. Y.T., D.F., Q.Z., L.S., J.A.W., J.A., H.Z., X.L., J.H., H.L., Y.C., L.Z., Y.N., and H.C. reviewed and provided revisions for the manuscript.

Corresponding author

Correspondence to Hai Cheng.

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Tian, Y., Fleitmann, D., Zhang, Q. et al. Holocene climate change in southern Oman deciphered by speleothem records and climate model simulations. Nat Commun 14, 4718 (2023). https://doi.org/10.1038/s41467-023-40454-z

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Received: 04 December 2022
Accepted: 28 July 2023
Published: 05 August 2023
DOI: https://doi.org/10.1038/s41467-023-40454-z

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