Dataset: Accelerated Retreat of Coastal Glaciers in the Western Prince William Sound, Alaska

Analyzing historical maps and Landsat imagery indicates that coastal glaciers in the western Prince William Sound (PWS) have retreated since the end of the Little Ice Age, exhibiting accelerated retreat after the mid-2000s. A multi-temporal inventory of 43 glaciers was developed using historical field observations, topographic maps, and Landsat imagery. Area and length measurements are derived from digitized outlines, and center lines are derived from a semi-automatic, GIS-based algorithm. Land-based glaciers retreated at a peak rate of 48 m a-1 from the mid-2000s to 2018, more than doubling the average rate of retreat (22 m a-1) for the preceding 50-year period. From ~1950 to 2018, the total area of land-based glaciers decreased by 228 km2, with 36% of the glacier loss occurring after the mid-2000s. Simple upscaling of area and volume changes to unmeasured glaciers across the entire PWS resulted in an estimated aggregate glacier mass loss of 379 Gt, equivalent to a 1.047 mm rise in sea level from the 1950s to 2018. Tidewater glaciers respond asynchronously with differing periods of peak area and length loss and lower average rate of retreat compared to land-based glaciers. Glacier retreat correlates with increased summer and winter temperatures and decreased winter precipitation.

I manually digitize outlines from historical maps, topographic maps, and Landsat images for glaciers 10 km2 or larger. Each study glacier is identified by a project identification number; Global Land Ice Measurements (GLIMS) and Randolph Glacier Inventory (RGI) identification numbers; and glacier name, if available. I manually digitize and adjust glacier boundaries based on the interpretation of 1950/57 topographic maps and Landsat images acquired in 1973/75, 1986, 1994, 2004/06, and 2018. Glacier length changes are measured from the intersection of the centerline with each glacier terminus. I repeat measurements for 1950/57 topographic maps and the Landsat images acquired in 1973/75, 1986, 1994, 2004/06, and 2018, resulting in a glacier length change chronology for each glacier.

Glacier outlines are available from the GLIMS database (www.glims.org).

See disclaimer in the "Data" section.

通过对历史地图和Landsat影像的分析，表明自小冰期结束以来，威廉王子海峡西部（PWS）的沿海冰川已发生退缩，并在2005年中期之后呈现加速退缩的趋势。采用历史现场观测、地形图和Landsat影像，构建了一个包含43个冰川的多时相清单。面积和长度测量值来源于数字化轮廓，中心线则由基于GIS的半自动算法得出。陆基冰川在2005年至2018年间的退缩速度达到峰值，为48米/年，比之前50年的平均退缩速度（22米/年）翻了一番以上。从1950年至2018年，陆基冰川的总面积减少了228平方公里，其中36%的冰川损失发生在2005年中期之后。简单地将面积和体积变化向上扩展至未测量的冰川，整个PWS的估计冰川质量损失为379吉吨，相当于从1950年代至2018年海平面上升了1.047毫米。潮汐冰川的退缩响应与陆基冰川不同，具有不同的峰值面积和长度损失周期，以及较低的平均退缩速度。冰川退缩与夏季和冬季温度升高以及冬季降水的减少相关。手动从历史地图、地形图和Landsat影像中数字化冰川轮廓，针对10平方公里或更大的冰川。每个研究冰川均以项目识别号码、全球陆地冰测量（GLIMS）和兰道夫冰川清单（RGI）识别号码，以及如有的冰川名称进行标识。根据对1950/57年地形图和1973/75年、1986年、1994年、2004/06年以及2018年获取的Landsat影像的解释，手动数字化并调整冰川边界。从中心线与每个冰川终点的交汇处测量冰川长度变化。对于1950/57年地形图和1973/75年、1986年、1994年、2004/06年以及2018年获取的Landsat影像，进行重复测量，从而为每个冰川得出长度变化的时间序列。冰川轮廓数据可从GLIMS数据库（www.glims.org）获取。请参阅“数据”部分的免责声明。