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1. Greenland-wide accelerated retreat of peripheral glaciers in the twenty-first century

   https://doi.org/10.1038/s41558-023-01855-6  

   Larocca, L. J. ; Twining–Ward, M. ; Axford, Y. ; Schweinsberg, A. D. ; Larsen, S. H. ; Westergaard–Nielsen, A. ; Luetzenburg, G. ; Briner, J. P. ; Kjeldsen, K. K. ; Bjørk, A. A. ( November 2023 , Nature Climate Change)

   The long-term response of Greenland’s peripheral glaciers to climate change is widely undocumented. Here we use historical aerial photographs and satellite imagery to document length fluctuations of >1,000 land-terminating peripheral glaciers in Greenland over more than a century. We find that their rate of retreat over the last two decades is double that of the twentieth century, indicating a ubiquitous transition into a new, accelerated state of downwasting.

    

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2. Georectified Mosaic of Aerial Images of Baltimore City in 1953

   https://doi.org/10.6073/pasta/6b583e08366f53fd8665e835f1bad44c  

   Lagrosa IV, John J ; Sonti, Nancy ; Grove, J Morgan ( January 2022 , Environmental Data Initiative)

   Landscape analyses are typically done using spatially explicit color aerial imagery. However, working with non-spatial black and white historical aerial photographs presents several challenges that require a combination of techniques and approaches. We analyzed 113 aerial images covering approx. 700 km2 (270 mi2) including all of Baltimore City, and a portion of Baltimore County surrounding the City. The images were taken between August 23rd 1952 and February 14th 1953. High-resolution scans were georeferenced and georectified against modern satellite imagery of the area and then combined to create a single raster mosaic. This process converted the images from a disparate set of photographs into a spatially explicit GIS data set that can be used to observe changes in land patches over time—and ultimately integrated with other long-term social, economic, and ecological data. 

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3. Extracting Impervious Surface from Aerial Imagery Using Semi-Automatic Sampling and Spectral Stability

   https://doi.org/10.3390/rs12030506  

   Zhang, Hua ; Gorelick, Steven M. ; Zimba, Paul V. ( February 2020 , Remote Sensing)

   The quantification of impervious surface through remote sensing provides critical information for urban planning and environmental management. The acquisition of quality reference data and the selection of effective predictor variables are two factors that contribute to the low accuracies of impervious surface in urban remote sensing. A hybrid method was developed to improve the extraction of impervious surface from high-resolution aerial imagery. This method integrates ancillary datasets from OpenStreetMap, National Wetland Inventory, and National Cropland Data to generate training and validation samples in a semi-automatic manner, significantly reducing the effort of visual interpretation and manual labeling. Satellite-derived surface reflectance stability is incorporated to improve the separation of impervious surface from other land cover classes. This method was applied to 1-m National Agriculture Imagery Program (NAIP) imagery of three sites with different levels of land development and data availability. Results indicate improved extractions of impervious surface with user’s accuracies ranging from 69% to 90% and producer’s accuracies from 88% to 95%. The results were compared to the 30-m percent impervious surface data of the National Land Cover Database, demonstrating the potential of this method to validate and complement satellite-derived medium-resolution datasets of urban land cover and land use. 

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4. Spatiotemporal remote sensing of ecosystem change and causation across Alaska

   https://doi.org/10.1111/gcb.14279  

   Pastick, Neal J. ; Jorgenson, M. Torre ; Goetz, Scott J. ; Jones, Benjamin M. ; Wylie, Bruce K. ; Minsley, Burke J. ; Genet, Hélène ; Knight, Joseph F. ; Swanson, David K. ; Jorgenson, Janet C. ( May 2018 , Global Change Biology)

   Contemporary climate change in Alaska has resulted in amplified rates of press and pulse disturbances that drive ecosystem change with significant consequences for socio‐environmental systems. Despite the vulnerability of Arctic and boreal landscapes to change, little has been done to characterize landscape change and associated drivers across northern high‐latitude ecosystems. Here we characterize the historical sensitivity of Alaska's ecosystems to environmental change and anthropogenic disturbances using expert knowledge, remote sensing data, and spatiotemporal analyses and modeling. Time‐series analysis of moderate—and high‐resolution imagery was used to characterize land‐ and water‐surface dynamics across Alaska. Some 430,000 interpretations of ecological and geomorphological change were made using historical air photos and satellite imagery, and corroborate land‐surface greening, browning, and wetness/moisture trend parameters derived from peak‐growing season Landsat imagery acquired from 1984 to 2015. The time series of change metrics, together with climatic data and maps of landscape characteristics, were incorporated into a modeling framework for mapping and understanding of drivers of change throughout Alaska. According to our analysis, approximately 13% (~174,000 ± 8700 km2) of Alaska has experienced directional change in the last 32 years (±95% confidence intervals). At the ecoregions level, substantial increases in remotely sensed vegetation productivity were most pronounced in western and northern foothills of Alaska, which is explained by vegetation growth associated with increasing air temperatures. Significant browning trends were largely the result of recent wildfires in interior Alaska, but browning trends are also driven by increases in evaporative demand and surface‐water gains that have predominately occurred over warming permafrost landscapes. Increased rates of photosynthetic activity are associated with stabilization and recovery processes following wildfire, timber harvesting, insect damage, thermokarst, glacial retreat, and lake infilling and drainage events. Our results fill a critical gap in the understanding of historical and potential future trajectories of change in northern high‐latitude regions. 

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5. Georectified Mosaic of Aerial Images of Baltimore City in 1927

   https://doi.org/10.6073/pasta/045e3001129aca3b34fd0e91b1a6f596  

   Lagrosa IV, John J ; Sonti, Nancy ; Grove, J Morgan ( January 2021 , Environmental Data Initiative)

   Landscape analyses are typically done using spatially explicit color aerial imagery. However, working with non-spatial black and white historical aerial photographs presents several challenges that require a combination of techniques and approaches. We analyzed 93 aerial images covering 544 km2 (210 mi2) including all of Baltimore City, and an area immediately adjacent to the city known at the time as the Metropolitan District of Baltimore County. The images were taken from a biplane between October 1926 and February 1927. High-resolution scans were georeferenced and georectified against modern satellite imagery of the area and then combined to create a single raster mosaic. This process converted the images from a disparate set of photographs into a spatially explicit GIS data set that can be used to observe changes in land patches over time—and ultimately integrated with other long-term social, economic, and ecological data. 

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