ALBERT

Description: Calcifying marine organisms provide a valuable means to access high-resolution historical records of the marine environment captured within their skeletal geochemistry. These records are essential for comprehending the effects of human-induced climate change and reducing uncertainties in future projections. Integrating investigations across various taxa, depths, and geographic locations can help identify universal environmental proxies and serve as a basis for targeted studies in the future. Here, we provide a comprehensive georeferenced database of measured values of Li/Mg, Mg/Ca, Sr/Ca, Ba/Ca, U/Ca and Sr-U in coral and coralline algae compiled from the scientific literature (1950-2021; http://www.webofknowledge.com, accessed 2022-09-30) for the purpose of interrogating and refining global, mineralogy specific and/or taxon-specific proxies for seawater temperature and barium. We include metadata relating to the source, timing and location of each study, the methodology used, and environmental and experimental information. The dataset presents an opportunity to quantify uncertainty and test the robustness of trace and minor element proxies for past environmental conditions, of which will be of value within the fields of geochemistry, ecology, climate, and palaeobiology. Full methodology and additional information provided in Williams et al. (2024).

Description: A comprehensive georeferenced database of measured values of Ba/Ca in coral and coralline algae compiled from the scientific literature (1950-2021; http://www.webofknowledge.com, accessed 2022-09-30).

Description: A comprehensive georeferenced database of measured values of Li/Mg, Mg/Ca, Sr/Ca, Ba/Ca, U/Ca and Sr-U in coral and coralline algae compiled from the scientific literature (1950-2021; http://www.webofknowledge.com, accessed 2022-09-30).

Description: Highlights: • We present a T5 record of the Pb isotope composition Labrador Sea seawater. • These data can be used to track Laurentide Ice Sheet (LIS) extent over Hudson Bay. • LIS retreat during T5 occurred over longer timescales than that for T2 and T1. • LIS deglaciation played important role in protracted nature of T5 sea-level rise. • Ice retreat during T1 may not be applicable template for older terminations in GIA modelling. Termination (T) 5, ∼424 ka, involved the biggest deglaciation of land-ice mass during the Quaternary. Warming and ice-sheet retreat during T5 led to an exceptionally long period of interglacial warmth known as Marine Isotope Stage (MIS) 11, ∼424–395 ka. A detailed understanding of the history of continental ice-sheet decay during T5 is required to disentangle regional contributions of ice-sheet retreat to sea-level rise (that range between ∼1 and 13 m above present day) and to correct it for glacio-isostatic adjustments (GIA). Yet little is known about the timing and magnitude of retreat during this time of the volumetrically most important continental ice sheet in the Northern Hemisphere, the Laurentide Ice Sheet (LIS). Here we present new authigenic Fe-Mn oxyhydroxide-derived high-resolution records of Pb isotope data and associated rare earth element profiles for samples spanning T5 from Labrador Sea IODP Site U1302/3. These records feature astronomically-paced radiogenic Pb isotope excursions that track increases in chemical weathering of North American bedrock and freshwater routing to the Labrador Sea via Hudson Straits associated with LIS retreat. Our records show that LIS retreat during T5 began 429. 2 ± 7.9 ka (2σ) and likely occurred over a longer timescale (by ∼10 to 5 kyr) than that observed for T2 and T1. They also show that Hudson Bay Ice Saddle collapse (and therefore LIS break-up) occurred ∼419 ± 4.7 ka (2σ), around the same time as best estimates of southern Greenland deglaciation, but ∼12 kyr before LIS deglaciation and the sea-level high-stand associated with the latter half of MIS 11 likely occurred. Our findings therefore highlight that ice-mass loss on North America likely played an important role in the seemingly protracted nature of T5 sea-level rise. A comparison of the deglaciation histories of the LIS and the southern Greenland Ice Sheet during T5, T2 and T1 also demonstrates that the well-constrained history of regional ice-sheet retreat during T1 is not always applicable as a template for older late Pleistocene terminations in GIA modelling.

Description: The geological record encodes the relationship between climate and atmospheric carbon dioxide (CO 2 ) over long and short timescales, as well as potential drivers of evolutionary transitions. However, reconstructing CO 2 beyond direct measurements requires the use of paleoproxies and herein lies the challenge, as proxies differ in their assumptions, degree of understanding, and even reconstructed values. In this study, we critically evaluated, categorized, and integrated available proxies to create a high-fidelity and transparently constructed atmospheric CO 2 record spanning the past 66 million years. This newly constructed record provides clearer evidence for higher Earth system sensitivity in the past and for the role of CO 2 thresholds in biological and cryosphere evolution. Editor’s summary The concentration of atmospheric carbon dioxide is a fundamental driver of climate, but its value is difficult to determine for times older than the roughly 800,000 years for which ice core records are available. The Cenozoic Carbon dioxide Proxy Integration Project (CenCO2PIP) Consortium assessed a comprehensive collection of proxy determinations to define the atmospheric carbon dioxide record for the past 66 million years. This synthesis provides the most complete record yet available and will help to better establish the role of carbon dioxide in climate, biological, and cryosphere evolution. — H. Jesse Smith