High mountains and glaciers are very inaccessible and unstable areas, where it is best not to venture unless highly prepared and equipped. That is why nowadays much of the surveying for glacier monitoring is done remotely, thanks to satellite constellations constantly orbiting the earth.
For example, Claudia Notarnicola, director of the Institute for Earth Observation at Eurac Research, recently published a paper  showing that globally, snow remains on average two weeks less than in 1982. NASA MODIS data , which offer daily snow cover maps from February 2000, were used for this study.
Using other satellites, we could go back even further: NASA’s Landsat program has been active since the 1970s and the first satellite was launched in 1972 .
Moreover, thanks to new tools such as STAC (SpatioTemporal Asset Catalog) based data catalogs  and operators such as Microsoft offering this data for free , we can access satellite images from around the world quickly and efficiently.
This process of democratizing satellite data allows many new scientists to analyze and understand the environment around us, reducing the barriers to entry caused by the huge amount of imagery to manage.