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1. The Role of Marine Foods in Ancient Diets across a Coastal to Inland Transect of Monterey County

   Eerkens, Jelmer W. (January 2022, Journal of California and Great Basin anthropology)

   We examine the role of marine food across a transect of sites in Monterey County, California, from the Pacific Coast to 70 km. inland. This study presents new stable carbon, nitrogen, sulfur, and strontium isotope data from human bone, and serial samples of teeth, as well as baseline data from a range of plant and animal remains. We estimate dietary contributions using two different mixing models. Results indicate that marine foods contributed between 65-75% of protein budgets on the coast, 30-40% in locations 10 km. from the coast, and just 1-6% 70 km. inland. Serial sampling of teeth, which estimates diet at 0.5-2.0 year intervals, shows that access to marine foods 10 km. from the coast was not marked by high-amplitude pulses, but was more continual and consistent, demonstrating the strong and persistent interconnections of coastal and near-coastal groups. By contrast, people living 70 km. inland were dependent almost entirely on terrestrial foods, consistent with consumption of resources such as pine and manzanita. Although they traded with coastal people for objects such as shell beads, the movement of marine foods themselves was minimal. 

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2. Potential Predictability of Net Primary Production in the Ocean

   https://doi.org/10.1029/2020GB006531  

   Krumhardt, K. M.; Lovenduski, N. S.; Long, M. C.; Luo, J. Y.; Lindsay, K.; Yeager, S.; Harrison, C. (June 2020, Global Biogeochemical Cycles)

   Interannual variations in marine net primary production (NPP) contribute to the variability of available living marine resources, as well as influence critical carbon cycle processes. Here we provide a global overview of near‐term (1 to 10 years) potential predictability of marine NPP using a novel set of initialized retrospective decadal forecasts from an Earth System Model. Interannual variations in marine NPP are potentially predictable in many areas of the ocean 1 to 3 years in advance, from temperate waters to the tropics, showing a substantial improvement over a simple persistence forecast. However, some regions, such as the subpolar Southern Ocean, show low potential predictability. We analyze how bottom‐up drivers of marine NPP (nutrients, light, and temperature) contribute to its predictability. Regions where NPP is primarily driven by the physical supply of nutrients (e.g., subtropics) retain higher potential predictability than high‐latitude regions where NPP is controlled by light and/or temperature (e.g., the Southern Ocean). We further examine NPP predictability in the world's Large Marine Ecosystems. With a few exceptions, we show that initialized forecasts improve potential predictability of NPP in Large Marine Ecosystems over a persistence forecast and may aid to manage living marine resources. 

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3. New constraints on the last deglaciation of the Cordilleran Ice Sheet in coastal Southeast Alaska

   https://doi.org/10.1017/qua.2020.32  

   Lesnek, Alia J.; Briner, Jason P.; Baichtal, James F.; Lyles, Alex S. (July 2020, Quaternary Research)

   null (Ed.)

   Abstract Understanding marine-terminating ice sheet response to past climate transitions provides valuable long-term context for observations of modern ice sheet change. Here, we reconstruct the last deglaciation of marine-terminating Cordilleran Ice Sheet (CIS) margins in Southeast Alaska and explore potential forcings of western CIS retreat. We combine 27 new cosmogenic 10 Be exposure ages, 13 recently published 10 Be ages, and 25 new 14 C ages from raised marine sediments to constrain CIS recession. Retreat from the outer coast was underway by 17 ka, and the inner fjords and sounds were ice-free by 15 ka. After 15 ka, the western margin of the CIS became primarily land-terminating and alpine glaciers disappeared from the outer coast. Isolated alpine glaciers may have persisted in high inland peaks until the early Holocene. Our results suggest that the most rapid phase of CIS retreat along the Pacific coast occurred between ~17 and 15 ka. This retreat was likely driven by processes operating at the ice-ocean interface, including sea level rise and ocean warming. CIS recession after ~15 ka occurred during a time of climatic amelioration in this region, when both ocean and air temperatures increased. These data highlight the sensitivity of marine-terminating CIS regions to deglacial climate change. 

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4. Transient exposure to novel high temperatures reshapes coastal phytoplankton communities

   https://doi.org/10.1038/s41396-019-0525-6  

   Kling, Joshua D.; Lee, Michael D.; Fu, Feixue; Phan, Megan D.; Wang, Xinwei; Qu, Pingping; Hutchins, David A. (October 2019, The ISME Journal)

   Abstract Average sea surface temperatures are expected to rise 4° this century, and marine phytoplankton and bacterial community composition, biogeochemical rates, and trophic interactions are all expected to change in a future warmer ocean. Thermal experiments typically use constant temperatures; however, weather and hydrography cause marine temperatures to fluctuate on diel cycles and over multiple days. We incubated natural communities of phytoplankton collected from California coastal waters during spring, summer, and fall under present-day and future mean temperatures, using thermal treatments that were either constant or fluctuated on a 48 h cycle. As assayed by marker-gene sequencing, the emergent microbial communities were consistent within each season, except when culture temperatures exceeded the highest temperature recorded in a 10-year local thermal dataset. When temperature treatments exceeded the 10-year maximum the phytoplankton community shifted, becoming dominated by diatom amplicon sequence variants (ASVs) not seen at lower temperatures. When mean temperatures were above the 10-year maximum, constant and fluctuating regimes each selected for different ASVs. These findings suggest coastal microbial communities are largely adapted to the current range of temperatures they experience. They also suggest a general hypothesis whereby multiyear upper temperature limits may represent thresholds, beyond which large community restructurings may occur. Now inevitable future temperature increases that exceed these environmental thresholds, even temporarily, may fundamentally reshape marine microbial communities and therefore the biogeochemical cycles that they mediate. 

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5. Temperature, humidity, and ionisation effect of iodine oxoacid nucleation

   https://doi.org/10.1039/d4ea00013g  

   Rörup, Birte; He, Xu-Cheng; Shen, Jiali; Baalbaki, Rima; Dada, Lubna; Sipilä, Mikko; Kirkby, Jasper; Kulmala, Markku; Amorim, Antonio; Baccarini, Andrea; et al (May 2024, Environmental Science: Atmospheres)

   Iodine oxoacids are recognised for their significant contribution to the formation of new particles in marine and polar atmospheres. Nevertheless, to incorporate the iodine oxoacid nucleation mechanism into global simulations, it is essential to comprehend how this mechanism varies under various atmospheric conditions. In this study, we combined measurements from the CLOUD (Cosmic Leaving OUtdoor Droplets) chamber at CERN and simulations with a kinetic model to investigate the impact of temperature, ionisation, and humidity on iodine oxoacid nucleation. Our findings reveal that ion-induced particle formation rates remain largely unaffected by changes in temperature. However, neutral particle formation rates experience a significant increase when the temperature drops from +10 ^oC to −10 ^oC. Running the kinetic model with varying ionisation rates demonstrates that the particle formation rate only increases with a higher ionisation rate when the iodic acid concentration exceeds 1.5 × 10⁷ cm^sup>−3, a concentration rarely reached in pristine marine atmospheres. Consequently, our simulations suggest that, despite higher ionisation rates, the charged cluster nucleation pathway of iodic acid is unlikely to be enhanced in the upper troposphere by higher ionisation rates. Instead, the neutral nucleation channel is likely to be the dominant channel in that region. Notably, the iodine oxoacid nucleation mechanism remains unaffected by changes in relative humidity from 2% to 80%. However, under unrealistically dry conditions (below 0.008% RH at +10 ^oC), iodine oxides (I₂O₄ and I₂O₅) significantly enhance formation rates. Therefore, we conclude that iodine oxoacid nucleation is the dominant nucleation mechanism for iodine nucleation in the marine and polar boundary layer atmosphere. 

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