Quaternary Science Reviews, Journal Year: 2024, Volume and Issue: 344, P. 108979 - 108979
Published: Sept. 26, 2024
Language: Английский
Climate of the past, Journal Year: 2025, Volume and Issue: 21(2), P. 343 - 355
Published: Feb. 3, 2025
Abstract. Variations in the oxygen isotope composition (δ18O) of cave speleothems and numerous proxy records from loess–paleosol sequences have revealed past variations East Asian monsoon (EAM) intensity. However, challenges persist reconstructing precipitation changes quantitatively. Here, we use positive relationship between degree cyclization (DC) branched glycerol dialkyl tetraethers (brGDGTs) modern surface soils Chinese Loess Plateau (CLP) mean annual (MAP) to quantify on CLP. We present a new ∼ 130 000-year-long DC-based MAP record for Yuanbao section western edge CLP, which closely tracks orbital- millennial-scale available both speleothem δ18O hydrogen plant waxes (δ2Hwax) same section. Combing our data with existing brGDGT other CLP sites reveals spatial gradient that is most pronounced during glacials, when experiences more arid conditions receives up 250 mm less than southeast, whereas 850 across Holocene optimum. Furthermore, DC show amount varies at precession scale obliquity scale, as opposed primarily precession-scale δ2Hwax 100 kyr cycle loess proxies, such magnetic susceptibility, rather indicates relative intensity EAM. At phase record, supports hypothesis driven by Northern Hemisphere summer insolation.
Language: Английский
Citations
1
Science Bulletin, Journal Year: 2024, Volume and Issue: 69(18), P. 2930 - 2937
Published: May 18, 2024
Language: Английский
Citations
3
Communications Earth & Environment, Journal Year: 2024, Volume and Issue: 5(1)
Published: Dec. 5, 2024
Abstract Bacterial lipid branched glycerol dialkyl tetraethers (brGDGTs) are a valuable tool for reconstructing past temperatures. However, gap remains regarding the influence of bacterial communities on brGDGT profiles. Here, we identified two distinct patterns brGDGTs from surface sediments 38 Tibetan Plateau lakes using an unsupervised clustering technique. Further investigation revealed that salinity and pH significantly change community composition, affecting profiles causing brGDGT-based temperatures to be overestimated by up 2.7 ± 0.7 °C in haloalkaline environments. We subsequently used trained model examine assemblages global lacustrine dataset, confirming applicability our approach. finally applied approach Holocene records Plateau, showing shifts clusters amplified temperature variations over timescales. Our findings demonstrate microbial ecology can robustly diagnose constrain site-specific discrepancies reconstruction.
Language: Английский
Citations
1
Geochemistry Geophysics Geosystems, Journal Year: 2024, Volume and Issue: 25(9)
Published: Sept. 1, 2024
Abstract Knowledge of Late Miocene‐Early Pliocene environmental change is critical for understanding the interactions among global cooling, regional tectonic activity and Asian climatic evolution. However, their relationships remain unclear, partly due to scarcity quantitative reconstructions temperature hydroclimatic conditions, which limits our effect topography on montane Here, we quantitatively reconstructed temperature, hydroclimate, pH Xiaoshuizi peneplain, northeastern Tibetan Plateau (NETP), based glycerol dialkyl tetraethers. Our results indicate that was relatively high with large fluctuations during 6.2–4.6 Ma. The then gradually decreased until 4.0 Ma, when this trend interrupted by an intensive warming event. Additionally, combined R i/b proxies revealed region experienced a transition from wet dry conditions after integrated show climate became warm 4.0–3.6 in contrast cooling occurrence humid eastern Chinese Loess North China Plain. We ascribe anomalous Ma topographic Foehn triggered surface uplift Maxian Mountains associated extensive NETP Middle Pliocene.
Language: Английский
Citations
0
Hydrology and earth system sciences, Journal Year: 2024, Volume and Issue: 28(18), P. 4275 - 4293
Published: Sept. 18, 2024
Abstract. As global warming progresses, changes in high-latitude precipitation are expected to impart long-lasting impacts on Earth systems, including glacier mass balance and ecosystem structures. Reconstructing past hydroclimate from networks of continuous lake records offers one way improve forecasts precipitation–evaporation balances, but these reconstructions currently hindered by the incomplete understanding controls soil water isotopes. Here, we study distribution modern isotopes Icelandic lakes, streams, surface soils collected 2002, 2003, 2004, 2014, 2019, 2020 understand geographic, geomorphic, environmental their regional interannual variability. We find that open-basin (through-flowing) lakes reflect local precipitation, with biases toward cold season, particularly sub-annual residence times. Closed-basin have isotope deuterium excess values consistent evaporative enrichment. Interannual seasonal variabilities at repeatedly sampled sites instrumental winter snowfall; summer relative humidity; atmospheric circulation patterns, such as North Atlantic Oscillation. Summer span entire range Iceland appear be consistently overprinted enrichment, which can occur throughout year, although sampling depths were shallower than rooting for many plant types. This dataset provides new insight into functionality environments renewed possibilities optimized site selection proxy interpretation future paleohydrological studies this outpost.
Language: Английский
Citations
0
Quaternary Science Reviews, Journal Year: 2024, Volume and Issue: 344, P. 108979 - 108979
Published: Sept. 26, 2024
Language: Английский
Citations
0