Abstract
Global warming and climate anomalies have attracted worldwide attention. The study of global climate change has received increasing attention from all countries and fields worldwide. Paleoclimate research is an important way to understand past global change and environmental evolution and to simulate and predict future climate development. A stalagmite ND3 collected in Naduo Cave was used to reconstruct the history of local climate and environmental changes from 0.55 to 5.07 ka BP based on the data of 13 230Th ages and 642 groups of oxygen and carbon stable isotopes. First, according to correlation analysis, δ18O and δ13C were significantly correlated (correlation coefficient r = 0.308, n = 318, P < 0.001 ) during the 5.07–2.00 ka BP period. However, during the period of 2–0.55 ka BP, there was no significant correlation P > 0.05 . The δ18O and δ13C data indicate that the climatic environment changed asynchronously during the period of 2.00–0.55 ka BP. During the period of 5.07–2.00 ka BP, the influence of human activities was weak, and δ18O and δ13C indicate similar climatic and environmental conditions, both of which changed in the same direction (positive correlation). In other words, when δ18O was positive, it indicated weak summer monsoons and lower precipitation, which led to declines in vegetation, weakened biological activity, and decreased soil CO2 and positive δ13C. The reverse patterns were also true. Since 2.0 ka BP, the intensity of human activities and the transformation and influence of surface vegetation have increased, and native vegetation has been destroyed in large quantities. Therefore, the climatic and environmental significance indicated by δ13C and δ18O has been well demonstrated. Second, the δ18O records showed that stalagmite ND3 responded to the weak monsoon drought events of 4.2 ka BP and 2.8 ka BP in the Holocene in a discontinuous deposition manner, which brings up new directions for future research.
Highlights
Paleoclimate research is an important way to understand past global change and environmental evolution and to simulate and predict future climate development
With the broadening research, many important technical and scientific problems still need to be solved. e timing, cycle, and mechanism of millennial-scale climate fluctuations during the Holocene are controversial [7,8,9]. These climate fluctuations show complex characteristics, which are closely related to solar activity and the internal variability of the Earth system due to the PDO (Pacific Decadal Oscillation) and NAO (Northern Atlantic Oscillation) [10], for example
Fluctuations may be mainly controlled by the 2- to 7-year El Nino-Southern Oscillation (ENSO) (El NiñoSouthern Oscillation) cycle [14,15,16]. erefore, it is helpful to study the timing, duration, and internal characteristics of millennium climate events, especially those from the mid-late Holocene, to better understand the climate interaction mechanism between the land, atmosphere, and ocean, and to deepen the understanding of the characteristics and mechanisms of global climate change
Summary
Paleoclimate research is an important way to understand past global change and environmental evolution and to simulate and predict future climate development. Among all kinds of high-resolution palaeoenvironmental record carriers, karst cave stalagmites have become an important carriers of late Quaternary palaeoenvironmental research because of their highly-precise age dating and reliability as palaeoenvironmental records. Climate change in the mid-late Holocene was closely related to several changes in civilization throughout human history. Current climate simulations [17, 18] and modern climate research [19] have conducted extensive studies on the interannual-decadal-multidecadal scale, but there are still many problems, such as the driving mechanism of the ENSO cycle. The climate anomalies accurately recorded, with high precision and high resolution, by Holocene stalagmites, are associated with the development of human society, and the study of the paleoclimate and palaeoenvironment in the mid-late Holocene is of great importance to the sustainable development of human society. Based on the data of 13 230 ages and 642 groups of oxygen and carbon stable isotopes of stalagmite in Naduo Cave, Guizhou, China, the history of climate and environmental changes in the study area during the period of 0.55 to 5.07 ka BP is discussed in this paper
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