• Energy Research

Greenland's fjords and coastal waters are highly productive and sustain important fisheries. However, retreating glaciers and increasing meltwater are changing fjord circulation and biogeochemistry, which may threaten future productivity. The freshening of Greenland fjords caused by unprecedented melting of the Greenland Ice Sheet may alter carbonate chemistry in coastal waters, influencing CO2 uptake and causing biological consequences from acidification. However, few studies to date explore the current acidification state in Greenland coastal waters. Here we present the first-ever large-scale measurements of carbonate system parameters in 16 Greenlandic fjords and seek to identify the drivers of acidification state in these freshening ecosystems. Aragonite saturation state (Ω), a proxy for ocean acidification, was calculated from dissolved inorganic carbon (DIC) and total alkalinity from fjords along the east and west coast of Greenland spanning 68-75°N. Aragonite saturation was primarily >1 in the surface mixed layer. However, undersaturated-or corrosive--conditions (Ω < 1) were observed on both coasts (west: Ω = 0.28-3.11, east: Ω = 0.70-3.07), albeit at different depths. West Greenland fjords were largely corrosive at depth while undersaturation in East Greenland fjords was only observed in surface waters. This reflects a difference in the coastal boundary conditions and mechanisms driving acidification state. We suggest that advection of Sub Polar Mode Water and accumulation of DIC from organic matter decomposition drive corrosive conditions in the West, while freshwater alkalinity dilution drives acidification in the East. The presence of marine terminating glaciers also impacted local acidification states by influencing fjord circulation: upwelling driven by subglacial discharge brought corrosive bottom waters to shallower depths. Meanwhile, discharge from land terminating glaciers strengthened stratification and diluted alkalinity. Regardless of the drivers in each system, increasing freshwater discharge will likely lower carbonate saturation states and impact biotic and abiotic carbon uptake in the future.

Ecologically relevant measures of contemporary global climate change can predict species distributions and vulnerabilities.

AbstractAimTo assess confidence in conclusions about climate‐driven biological change through time, and identify approaches for strengthening confidence scientific conclusions about ecological impacts of climate change.LocationGlobal.MethodsWe outlined a framework for strengthening confidence in inferences drawn from biological climate impact studies through the systematic integration of prior expectations, long‐term data and quantitative statistical procedures. We then developed a numerical confidence index (Cindex) and used it to evaluate current practices in 208 studies of marine climate impacts comprising 1735 biological time series.ResultsConfidence scores for inferred climate impacts varied widely from 1 to 16 (very low to high confidence). Approximately 35% of analyses were not associated with clearly stated prior expectations and 65% of analyses did not test putative non‐climate drivers of biological change. Among the highest‐scoring studies, 91% tested prior expectations, 86% formulated expectations for alternative drivers but only 63% statistically tested them. Higher confidence scores observed in studies that did not detect a change or tracked multiple species suggest publication bias favouring impact studies that are consistent with climate change. The number of time series showing climate impacts was a poor predictor of average confidence scores for a given group, reinforcing that vote‐counting methodology is not appropriate for determining overall confidence in inferences.Main conclusionsClimate impacts research is expected to attribute biological change to climate change with measurable confidence. Studies with long‐term, high‐resolution data, appropriate statistics and tests of alternative drivers earn higher Cindex scores, suggesting these should be given greater weight in impact assessments. Together with our proposed framework, the results of our Cindex analysis indicate how the science of detecting and attributing biological impacts to climate change can be strengthened through the use of evidence‐based prior expectations and thorough statistical analyses, even when data are limited, maximizing the impact of the diverse and growing climate change ecology literature.

Larval stages are among those most vulnerable to ocean acidification (OA). Projected atmospheric CO2 levels for the end of this century may lead to negative impacts on communities dominated by calcifying taxa with planktonic life stages. We exposed Mediterranean mussel (Mytilus galloprovincialis) sperm and early life stages to pHT levels of 8.0 (current pH) and 7.6 (2100 level) by manipulating pCO2 level (380 and 1000 ppm). Sperm activity was examined at ambient temperatures (16–17 °C) using individual males as replicates. We also assessed the effects of temperature (ambient and ≈20 °C) and pH on larval size, survival, respiration and calcification of late trochophore/early D-veliger stages using a cross-factorial design. Increased pCO2 had a negative effect on the percentage of motile sperm (mean response ratio R= 71%) and sperm swimming speed (R= 74%), possibly indicating reduced fertilization capacity of sperm in low concentrations. Increased temperature had a more prominent effect on larval stages than pCO2, reducing performance (RSize = 90% and RSurvival = 70%) and increasing energy demand (RRespiration = 429%). We observed no significant interactions between pCO2 and temperature. Our results suggest that increasing temperature might have a larger impact on very early larval stages of M. galloprovincialis than OA at levels predicted for the end of the century.

Greenland’s fjords and coastal waters are highly productive and sustain important fisheries, but retreating glaciers and increasing meltwater supply are changing fjord circulation and biogeochemistry, which may threaten the future productivity of these unique ecosystems. The freshening of Greenland fjords caused by unprecedented melting of the Greenland Ice Sheet has the potential to alter carbonate chemistry in coastal waters, which would influence CO2 uptake as well as have biological consequences from acidification. However, few studies to date explore the current acidification state in Greenland coastal waters. Here we present the first-ever large-scale measurements of carbonate system parameters and δ18O measurements in 16 Greenlandic fjords and by combining datasets from two August cruises. HDMS Lauge Koch and RV Sanna cruises sampled on the East and West coast of Greenland in August 2018 and 2016 respectively. This dataset consists of 52 carbonate chemistry sample sites where dissolved inorganic carbon (DIC), total alkalinity (TA), and δ18O-H2O were measured throughout the water column. Water samples were collected in Niskin bottles and were transferred directly into triplicate 12 ml exetainers with a gas tight Tygon tubes, allowing overflow of at least 3 times the volume of the exetainer. Triplicate exetainers were collected for both DIC and TA at each depth. Samples were preserved with HgCl2 (saturated solution) to a final concentration of 0.02%. TA was measured on an Apollo SciTech AS-ALK2 total alkalinity titrator based on the Gran titration procedure for samples in West Greenland. While samples for East Greenland were measured on automatic titrator (Metrohm 888 Titrando), and a combined Metrohm glass electrode (Unitrode). DIC samples were analyzed on Apollo SciTech's AS-C3 analyzer for both cruises, using a sample volume of 0.5 ml. Routine analysis of Certified Reference Materials (provided by A. G. Dickson, Scripps Institution of Oceanography) verified that the accuracy of DIC and TA measurements. Coalescing this dataset therefore provides the first-ever analysis of wide-scale Greenland Fjord carbonate chemistry. Environmental variables recorded by CTD instruments are available for cruises from the West and East coasts respectively at the following DOIs: https://doi.org/10.5281/zenodo.4062024 and https://doi.org/10.5281/zenodo.5572329. We would like to thank the crew on board the HDMS Lauge Koch and RV Sanna for their collaboration. The Cruises were funded by Danish Centre for Marine Science (Grants: 2016-05 and 2017-06) and by the EU Horizon2020 funded project INTAROS (grant no. 727890) and the Danish Cooperation for Environment in the Arctic. This dataset is a contribution the project FACE-IT (The Future of Arctic Coastal Ecosystems – Identifying Transitions in Fjord Systems and Adjacent Coastal Areas). FACE-IT has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 869154. Version 2 presents corrections in one file reporting DIC and TA data from Western Greenland. A systematic error was discovered in the labratory where the DIC samples were analyzed when converting from µmol L-1 to µmol kg-1. This error was corrected and the accurate values are now displayed in the file: SANNA_DIC_TA_corrected_2024.csv. Only the DIC values have changed. 

Arctic Ocean primary productivity is limited by light and inorganic nutrients. With sea ice cover declining in recent decades, nitrate limitation has been speculated to become more prominent. Although much has been learned about nitrate supply from general patterns of ocean circulation and water column stability, a quantitative analysis requires dedicated turbulence measurements that have only started to accumulate in the last dozen years. Here we present new observations of the turbulent vertical nitrate flux in the Laptev Sea, Baffin Bay, and Young Sound (North-East Greenland), supplementing a compilation of 13 published estimates throughout the Arctic Ocean. Combining all flux estimates with a Pan-Arctic database of in situ measurements of nitrate concentration and density, we found the annual nitrate inventory to be largely determined by the strength of stratification and by bathymetry. Nitrate fluxes explained the observed regional patterns and magnitudes of both new primary production and particle export on annual scales. We argue that with few regional exceptions, vertical turbulent nitrate fluxes can be a reliable proxy of Arctic primary production accessible through autonomous and large-scale measurements. They may also provide a framework to assess nutrient limitation scenarios based on clear energetic and mass budget constraints resulting from turbulent mixing and freshwater flows.