The investigation of submerged speleothems for sea level studies has made significant contributions to the understanding of the global and regional sea level variations during the Middle and Late Quateranry. This has been especially the case for the Mediterranean Sea, where more than 300 submerged speleothems sampled in 32 caves have been analysed so far. Here, we present a comprehensive review of the results obtained from the study of submerged speleothems since 1978. The studied speleothems cover the last 1.4 Ma and are focused mainly on Marine Isotope Stages (MIS) 1, 2, 3, 5.1, 5.3, 5.5, 7.1, 7.2, 7.3 and 7.5. Results reveal that submerged speleothems represent extraordinary archives providing accurate information on former sea level changes, also considering that the Mediterranean Sea is devoid of any tropical corals since the Miocene. New results from a stalagmite collected at Palinuro (Campania, Italy) characterized by marine overgrowth are also reported. The measured elevations of speleothems are contaminated by the local response to glacial- and hydro-isostatic adjustment (GIA), and thus might significantly deviate from the global eustatic signal. Age and altitude comparation between Mediterranean speleothems, flowstone from Bahamas with local GIA provide a new scenario for MIS 5 and 7 sea level reconstrutions.

This study presents a world review as well as new additional data in form of submerged speleothems that are used for paleo sea level reconstructions. Speleothems significantly contributed to the understanding of the global and regional sea level variations during the Middle and Late Quaternary. The studied speleothems cover the last 1.4 Myr and are focused mainly on Marine Isotope Stages (MIS) 1, 2, 3, 5.1, 5.3, 5.5, 7.1, 7.2, 7.3 and 7.5. Results reveal that submerged speleothems represent extraordinary archives providing detailed information on former sea level changes. We present also new results from stalactites collected in central Mediterranean sea, at Favignana and Ustica islands (Sicily, Italy), both characterized by continental, phreatic or marine layers. The study and analysis of the latter speleothems provide results of great interest for relative sea level changes over the last 1000 years.

Africa spans the hemispheres from temperate region to temperate region, has a long history of hominin evolution and yet has a relatively poorly understood Quaternary climate history. Speleothems, as archives of terrestrial hydroclimate variability, can help reveal this history, and here we review the progress made to date, with a focus on the first version of the Speleothem Isotopes Synthesis & Analysis (SISAL) database. The geology of Africa has limited development of large karst regions to four areas - the northern and eastern coasts bordering the Mediterranean and the Indian Ocean, west Africa and southern Africa. Exploitation of the speleothem palaeoclimate archives in these regions is uneven, with long histories of research in South Africa and Morocco but no investigations elsewhere e.g. West Africa. Consequently, the evidence of past climate change reviewed here is irregularly sampled in both time and space. Nevertheless, we show evidence of migration of the monsoon belt, with enhanced rainfall during interglacials observed in northeast Africa, southern Arabia and the northern part of southern Africa. Evidence from East Africa also indicates significant centennial scale rainfall variability. In northwestern and southern Africa precession and eccentricity influence speleothem growth, largely through changing synoptic storm activity.

The Middle East spans the transition between temperate Mediterranean climate in the Levant to hyper-arid sub-tropical deserts in the southern part of the Arabian Peninsula, with the complex alpine topography in the northeast feeding the Euphrates and Tigris rivers which support life in the southeastern Fertile Crescent (FC). Climate projections predict severe drying in major parts much of the ME in response to global warming, making it important to understand the controls of hydro-climate perturbations in the region. Here we discuss 23 ME speleothem stable oxygen isotope (δ¹⁸Occ) records from 16 sites from the SISAL_v1 database, which provide a record of past hydro-climatic variability. Sub-millennial changes in ME speleothem δ¹⁸Occ values primarily indicate changes in past precipitation amounts superimposed on variations of the main synoptic pattern in the region, specifically Mediterranean cyclones. The coherency (or lack thereof) between regional records is reviewed from Pleistocene to present, covering the Last Glacial Maximum (LGM), prominent events during deglaciation, and transition into the Holocene. The available speleothem δ¹⁸Occ time-series are investigated by binning and normalizing at 25-year and 200-year time windows over the Holocene. Important Holocene climatic oscillations are discussed, such as the 8.2 ka, 4.2 ka and 0.7 ka (the Little Ice Age) Before Present events. Common trends in the standardized anomalies are tested against different climate archives. Finally, recommendations for future speleothem-based research in the region are given along with comments on the utility and completeness of the SISAL database.

As one of the most prominent seasonally recurring atmospheric circulation patterns, the Asian Summer Monsoon (ASM) plays a vital role for the life and livelihood of about a third of the global population. Changes in the strength and seasonality of the ASM significantly affect the region, yet the drivers of change and the varied regional responses of the ASM are not well understood. In the last two decades, there have been a number of studies reconstructing the ASM using stalagmite-based proxies such as oxygen isotopes (18O). Such reconstructions allow examination of the drivers and responses, increasing monsoon predictability. In this review paper, we focus on stalagmite 18O records from India at the proximal end of the ASM region. Indian stalagmite 18O records show well dated, high amplitude changes in response to the dominant drivers of the ASM on orbital to multi-centennial timescales and indicate the magnitude of monsoon variability in response to these drivers. We examine Indian stalagmite records collated in SISAL_v1 (version 1) database (http://researchdata.reading.ac.uk/139/) and support the database with a summary of record quality and regional climatic interpretations of the 18O record during different climate states. We highlight current debates and suggest the most useful time periods (climatic events) and locations for further work using tools such as data-model comparisons, spectral analysis methods, multi-proxy investigations and monitoring work

Western Europe is the region with the highest density of published speleothem δ18O (δ18Ospel) records worldwide. Here we review these records in light of the recent publication of the Speleothem Isotopes Synthesis and Analysis (SISAL) database [1]. We investigate how representative the spatial and temporal distribution of the available records is for climate in Western Europe, and review potential sites and strategies for future studies. We show that spatial trends in precipitation δ18O are mirrored in the speleothems, providing means to better constrain the factors influencing δ18Ospel at a specific location. Coherent regional δ18Ospel trends are found over stadial-interstadial transitions of the last glacial, especially in high altitude Alpine records. Over the Holocene, regional trends are less clearly expressed, due to lower signal-to-noise ratios in δ18Ospel, but can potentially be extracted with the use of statistical methods. Overall, this first assessment highlights the potential of the European region for speleothem palaeoclimate reconstruction, while underpinning the importance of knowledge of local factors for a correct interpretation of δ18Ospel.

Speleothem oxygen isotope records from the Caribbean, Central, and North America reveal climatic controls that include orbital variation, deglacial forcing related to ocean circulation and ice sheet retreat, and the influence of local and remote sea surface temperature variations. Here, we review these records and the global climate teleconnections they suggest following the recent publication of the Speleothem Isotopes Synthesis and Analysis (SISAL) database. We find that low-latitude records generally reflect changes in precipitation, whereas higher latitude records are sensitive to temperature and moisture source variability. Tropical records suggest precipitation variability is forced by orbital precession and North Atlantic Ocean circulation driven changes in atmospheric convection on long timescales, and tropical sea surface temperature variations on short timescales. On millennial timescales, precipitation seasonality in southwestern North America is related to North Atlantic climate variability. Great Basin speleothem records are closely linked with changes in Northern Hemisphere summer insolation. Although speleothems have revealed these critical global climate teleconnections, the paucity of continuous records precludes our ability to investigate climate drivers from the whole of Central and North America for the Pleistocene through modern. This underscores the need to improve spatial and temporal coverage of speleothem records across this climatically variable region.

Speleothems have proven to be one of the most reliable terrestrial archives for palaeoclimate research. However, due to the complexity of karst systems, long-term monitoring and high-resolution analyses of the cave atmosphere and water geochemistry have become essential to better constrain the factors that control calcite growth and how geochemical palaeoclimate proxies are encoded into speleothems. While calcite precipitation incorporates the palaeoclimate signals into the speleothem fabric, certain conditions in caves can favour dissolution, which may form hiatuses or even destroy these signals. In extreme cases, in-cave dissolution by dripwater can form cup-shaped features (i.e., corrosion cups), which were the main focus of this study. The study site in Postojna Cave, Slovenia, was investigated through cave climate monitoring and drip and cup water sampling, which took place during 2017–2021. We found that the cups are fed by low calcium drips as the consequence of the thin vadose zone above the cave. Due to the specific configuration of airflow pathways, the study site accumulates high levels of CO2 (>10,000 ppm), which shifts low calcium dripwater into undersaturation. This causes dissolution on rock surfaces and speleothems on the cave floor. The results of this study have broader significance in addressing the suitability of cave environments and speleothems used in paleoclimate research.