The Retreat of Mountain Glaciers since the Little Ice Age: A Spatially Explicit Database

Abstract

Most of the world’s mountain glaciers have been retreating for more than a century in response to climate change. Glacier retreat is evident on all continents, and the rate of retreat has accelerated during recent decades. Accurate, spatially explicit information on the position of glacier margins over time is useful for analyzing patterns of glacier retreat and measuring reductions in glacier surface area. This information is also essential for evaluating how mountain ecosystems are evolving due to climate warming and the attendant glacier retreat. Here, we present a non-comprehensive spatially explicit dataset showing multiple positions of glacier fronts since the Little Ice Age (LIA) maxima, including many data from the pre-satellite era. The dataset is based on multiple historical archival records including topographical maps; repeated photographs, paintings, and aerial or satellite images with a supplement of geochronology; and own field data. We provide ESRI shapefiles showing 728 past positions of 94 glacier fronts from all continents, except Antarctica, covering the period between the Little Ice Age maxima and the present. On average, the time series span the past 190 years. From 2 to 46 past positions per glacier are depicted (on average: 7.8).

The importance of species addition versus replacement varies over succession in plant communities after glacial retreat

“…For each glacier foreland, the chronosequence approach 30 was used to select 3-17 sites along deglaciated terrains for which the date of each glacier retreat is known. The number of sites depended on the number of documented positions of the glacier foreland available from the literature, and we tried to cover as much as possible the whole history of the retreat of each glacier 54 . Each site corresponded generally to the line delimiting the position of the glacier's front on a given date.…”

“…1), 1255 soil samples were collected from 2014 to 2020 to capture eDNA. In the sampled forelands, information on the dates of glacier retreat is available from the literature, remote sensing images, and eld surveys 54 . For each glacier foreland, the chronosequence approach 30 was used to select 3-17 sites along deglaciated terrains for which the date of each glacier retreat is known.…”

Ecosystems at Glacier Margins Can Serve as Climate‐Change Laboratories

“…Because glaciers respond to regional cooling and warming trends by advancing and retreating, which in turn causes cold microclimates to strengthen and weaken at their margins, regional climate trends can be amplified in glacier‐adjacent ecosystems. This is a widespread phenomenon: The magnitude of the La Perouse Glacier's ice‐margin fluctuations over the last 200 years is similar to or less than other land‐terminating glaciers in southern Alaska (Barclay et al., 2009), and numerous alpine glaciers located in other parts of the planet have undergone fluctuations of similar magnitude (Marta et al., 2021).…”

Heterogeneous changes of soil microclimate in high mountains and glacier forelands

“…To account for this cooling effect, we measured the distance between each sampling station and the glacier front, under the assumption of decreasing cooling effects with distance 59 . For each glacier, the most recent outline was retrieved from Marta et al 60 , checked against glacier position between 2015 and 2019 using USGS Landsat 8 imagery (available at https://developers.google.com/earth-engine/datasets/catalog/LANDSAT_LC08_C01_T1_TOA) and eventually updated to include other nearby glaciers or more recent outlines. Outlines were transformed to polygons, rasterized, and distance maps at 30 m resolution were calculated using the function gridDistance from the raster R package 61 .…”