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1. The Northeast Pacific Ocean and Northwest Coast of North America within the global climate system, 29,000 to 11,700 years ago

   https://doi.org/10.1016/j.earscirev.2024.104782  

   Mann, Daniel H; Gaglioti, Benjamin V (July 2024, Earth-Science Reviews)

   The Northwest Coast of North America stretches 4000 km from Bering Strait to Washington State. Here we review the history of glaciation, sea level, oceanography, and climate along the Northwest Coast and in the subarctic Pacific Ocean during the Last Glacial Maximum and deglaciation. The period of interest is Marine Isotope Stage 2 between ca. 29,000 calendar years ago (29 ka) and 11,700 calendar years ago (11.7 ka). The glacial history of the Northwest Coast involved multiple glacial systems responding independently to latitudinal variations in climate caused by changes in the North American ice sheets and in the tropical ocean-atmosphere system. Glaciers reached their maximum extents 1–5 kyrs later along the Northwest Coast than did large sectors of the Laurentide and Fennoscandian Ice Sheets. Local, Last Glacial Maxima were reached in a time-transgressive, north to south sequence between southwestern Alaska and Puget Sound. The history of relative sea level along the Northwest Coast during Marine Isotope Stage 2 was complex because of rapid isostatic adjustments by a thin lithosphere to these time-transgressive glacial fluctuations. Multiple lines of evidence suggest Bering Strait was first flooded by the sea after 11 ka and that it probably did not assume its present-day oceanographic functions until after 9 ka. The coldest intervals occurred during Heinrich Event 2 (ca. 26–23.5 ka), again between ca. 23 and 21.5 ka, and during Heinrich Event 1 (ca. 18–15 ka). During these times, mean annual sea surface temperatures cooled by 5o to 8o C in the Gulf of Alaska, and glacial equilibrium-line altitudes fell below present sea level in southern Alaska and along the Aleutian Island chain. Sea ice episodically expanded across the subarctic Pacific in winter. Oceanographic changes in the Gulf of Alaska tracked variations in the vigor of the Asian Summer Monsoon. The deglaciation of the Northwest Coast may have served as the trigger for global climate changes during deglaciation. Starting ca. 21 ka, marine-based glaciers there were increasingly destabilized by rising eustatic sea level and influxes of freshwater and heat associated with the rejuvenation of the Asian Summer Monsoon. Rapid retreat of marine-based glaciers began ca. 19 ka and released large numbers of ice bergs and vast amounts of freshwater into the Northeast Pacific. Resultant cooling of the North Pacific may have been teleconnected to the North Atlantic through the atmosphere, where it slowed Atlantic Meridional Overturning Circulation and initiated the global effects of Heinrich Event 1, ca. 18–15 ka. During the Younger Dryas, ca. 12.8–11.7 ka, mean annual sea surface temperatures were 4o to 6o C cooler than today in the Gulf of Alaska, and sea ice again expanded across the subarctic Pacific in winter. Conditions of extreme seasonality characterized by cold, dry winters and warm, steadily ameliorating summers caused by the southward diversion of the Aleutian Low in winter may explain the previously enigmatic records of Younger Dryas climate along the Northwest Coast. 

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2. Arctic-Boreal Vulnerability Experiment (ABoVE): Burned Area, Depth, and Combustion for Alaska and Canada, 2001-2019

   https://doi.org/10.18739/A2542JB0Z  

   Potter, Stefano; Rogers, Brendan (January 2022, NSF Arctic Data Center)

   This dataset provides annual gridded estimates of fire locations and associated burn fraction per pixel for Alaska and Canada at approximately 500 meter (m) spatial resolution for the period 2001-2019. Gridded predictions of carbon combustion and burn depth for the same period within the Arctic-Boreal Vulnerability Experiment (ABoVE) extended domain using the burn area maps and field data are also available. Fire locations and date of burn (DOB) were detected by MODIS-derived active fire products. Burned area was primarily estimated from finer-scale Landsat imagery using a differenced Normalized Burn Ratio (dNBR) algorithm and upscaled to an approximate 500 m MODIS resolution. Aboveground combustion, belowground combustion, and burn depth were statistically modeled at the pixel level for every mapped burned pixel in the ABoVE extended domain based on field observations across Alaska and western Canada. Predictor variables included remotely sensed indicators of fire severity, topography, soils, climate, and fire weather. Quality flags for burned area and combustion are available. Fire is the dominant disturbance agent in Alaskan and Canadian boreal ecosystems and releases large amounts of carbon into the atmosphere. These data are useful for studies of disturbance, fire ecology, and carbon cycling in boreal ecosystems. 

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3. Eight Mile Lake Research Watershed, Carbon in Permafrost Experimental Heating Research (CiPEHR): Weekly thaw depth data, 2009-2024

   https://doi.org/10.6073/pasta/3b0062b5861ad057d81d539bbdfbadaa  

   Kelley, Allison K; Pegoraro, Elaine; Mauritz, Marguerite; Hutchings, Jack; Natali, Susan; Hicks-Pries, Caitlin Elizabeth; Schuur, Edward; LTER, Bonanza Creek (January 2025, Environmental Data Initiative)

   The Carbon in Permafrost Experimental Heating Research (CiPEHR) project addresses the following questions: 1) Does ecosystem warming cause a net release of C from the ecosystem to the atmosphere?, 2) Does the decomposition of old C, that comprises the bulk of the soil C pool, influence ecosystem C loss?, and 3) How do winter and summer warming alone, and in combination, affect ecosystem C exchange? We are answering these questions using a combination of field and laboratory experiments to measure ecosystem carbon balance and radiocarbon isotope ratios at a warming experiment located in an upland tundra field site near Healy, Alaska in the foothills of the Alaska Range. This data set includes weekly thaw depth measurements collected from winter warming, summer warming, and control treatment plots at CiPEHR. Additional measurements from on-plot gas flux wells, water table monitoring wells, and off-plot locations are also reported. Note that the experimental warming portion of this experiment concluded in 2022. These data are a continuation of measurements taken at previously warmed plots but plots were not actively manipulated after 2022. 

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4. The Role of an Atmospheric River in Amplifying the June 2021 Western North American Heat Wave

   https://doi.org/10.1175/MWR-D-25-0074.1  

   Lackmann, Gary M; Getker, Lauren E; Cordeira, Jason M (May 2026, Monthly Weather Review)

   Abstract In this study, we explore the role of upstream processes associated with the western North American heat wave of late June 2021. Upstream latent heat release associated with an atmospheric river (AR) contributed substantially to both upper- and lower-tropospheric features of this event, including a contribution from an unusual chinook/foehn mechanism. A subset of lower-tropospheric back trajectories from the heat wave region exhibited latent warming during ascent associated with an AR over the Gulf of Alaska and also over mountainous coastal regions of southeast Alaska. Thermodynamic analysis of air trajectories demonstrates that latent heat release in the AR and with orographic lift contributed to the extreme lower-tropospheric warmth in the Pacific Northwest and British Columbia. Numerical experiments with reduced relative humidity over the Gulf of Alaska weaken the upstream AR and demonstrate a strong connection between the upstream latent heating, upper-tropospheric ridging, and exceptionally hot boundary layer temperatures in the U.S. states of Washington and Oregon and the Canadian province of British Columbia. Objectively sorted trajectories reveal distinct warming processes, including adiabatic descent, upstream condensational heating, and radiational warming in the planetary boundary layer. Trajectories originating in the lower troposphere in an experimental simulation in which the upstream atmospheric river was weakened are associated with cooler near-surface temperatures in the heat wave region. We propose that for some warm-season heat waves, upstream condensational warming contributes substantially to lower-tropospheric heat. Significance StatementIn late June 2021, a record-setting heat wave affected parts of western North America. Where did the hot air originate, and what processes heated it? Here, we explore the processes that generated the extreme near-surface warmth using air trajectories (calculated flow pathways) and numerical model experiments. Our analysis shows that heat released by condensation over the Gulf of Alaska and mountainous coastal Alaska associated with a preceding atmospheric river contributed to the heat, though this was one of several processes driving the heat wave. 

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5. Seasonal detections of bearded seal (Erignathus barbatus) vocalizations in Baffin Bay and Davis Strait in relation to sea ice concentration

   https://doi.org/10.1007/s00300-020-02723-1  

   Boye, Tenna K.; Simon, Malene J.; Laidre, Kristin L.; Rigét, Frank; Stafford, Kathleen M. (August 2020, Polar Biology)

   There is limited information about the biology and seasonal distribution of bearded seals (Erignathus barbatus) in Greenland. The species is highly ice-associated and depends on sea ice for hauling out and giving birth, making it vulnerable to climate change. We investigated the seasonality and distribution of bearded seal vocalizations at seven different locations across southern Baffin Bay and Davis Strait, West Greenland. Aural M2 and HARUphone recorders were deployed on the sea bottom during 2006–2007 and 2011–2013. Recordings were analyzed for presence/absence of bearded seal calls relative to location (including distance to shore and depth), mean sea ice concentration and diel patterns. Calling occurred between November and late June with most intense calling during the mating season at all sites. There was a clear effect of depth and distance to shore on the number of detections, and the Greenland shelf (< 300 m) appeared to be the preferred habitat for bearded seals during the mating season. These results suggest that bearded seals may retreat with the receding sea ice to Canada during summer or possibly spend the summer along the West Greenland coast. It is also possible that, due to seasonal changes in bearded seal vocal behavior, animals may have been present in our study area in summer, but silent. The number of detections was affected by the timing of sea ice formation but not sea ice concentration. Diel patterns were consistent with patterns found in other parts of the Arctic, with a peak during early morning (0400 local) and a minimum during late afternoon (1600 local). While vocalization studies have been conducted on bearded seals in Norwegian, Canadian, northwest Greenland, and Alaskan territories, this study fills the gap between these areas. 

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