Calibrating Greenland coralline algal proxies with high-resolution in situ water temperature
Bibliographic record
Abstract
Geochemical paleoproxies from marine archives are typically calibrated with temperatures from satellite- or ship-based observations that are spatially averaged over large areas, or with temperature data measured at a distance to the sampling site. These observations do not necessarily reflect local conditions and averaging effects potentially reduce variability. However, this is often the only viable option as no other direct observations are available in most settings. In subarctic and arctic regions in situ observations are even rarer and the availability of subannual-resolution surface ocean climate archives is very limited as well, especially when compared to the tropics. Encrusting coralline algae are important shallow-marine calcifiers that provide high-resolution archives of past ocean and environmental variability, but only few calibration studies of algal proxies exist from the climatically important high-latitude regions. At the same time these regions have experienced the most drastic changes in recent decades, e.g. Arctic surface temperature warming is more than twice as large as the global average.Here, we present results from calibrating subannual-resolution coralline algal proxies with four years of continuous in situ measured temperature in Disko Bay, Greenland. Sensors were deployed in summer 2019 at sites of sample collection, recording water temperature in hourly resolution, providing data from the same water depth where the corallines grow. Coralline algal samples (Clathromorphum compactum) were retrieved together with sensors in summer of 2023. Temperature cycles are matched to coralline growth increments and geochemical data analyzed by Laser Ablation ICP-MS. The four year overlap makes our record the longest continuous calibration interval for coralline algae from high-latitudes. We align element/Ca-ratios with sclerochronological results and compare temperature measurements and proxies to high-resolution satellite observations and reanalysis data. Pairing of sub-seasonal resolution element/Ca-ratio time series measured in the uppermost years of algal growth with high-resolution in situ temperature allows us to directly connect individual short-time variability and warming/cooling recorded in the algal record to real-time observations. Water temperature plays a major role in controlling underlying processes in recently observed regional and large-scale Arctic and Greenland Ice Sheet (GIS) change. Coralline algal samples resolve ultra-high-resolution Disko Bay environmental variability in close proximity to Jakobshavn Glavier, one of the largest GIS glaciers, which delivers a significant amount of freshwater to the coastal West-Greenland surface ocean. Our study is testing proxy-temperature relationships on multiple algal samples, facilitating intra- and intersample comparisons, and thus helps to improve calibration of long-term algal proxy records used for paleo-reconstructions.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".