Menopausal Mother Nature

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Visualised: glaciers then and now

The world’s glaciers are melting at an ever-increasing pace, with one report suggesting the rate of ice loss roughly doubles every 10 years. Scientists are saying the rapid disappearance of mountain glaciers – separate from the Greenland and Antarctic ice shields – is one of the most dramatic signs of global heating.

Now, a Guardian visualisation makes these stark changes visible to the naked eye. The graphics show the outlines of glaciers from Alaska to the Andes shrinking over the course of just a few decades.

Losing ground

The graphic shows 90 of the largest and best surveyed glaciers in the world. All glaciers are drawn to the same scale.

The animation cycles between the oldest and the most recent snapshot of each glacier. Each pair of snapshots is at least 40 years apart. Hover over individual glaciers for more information.

The visualisations were generated from a database of glaciers called Global Land Ice Measurements from Space (Glims). Scientists around the globe are continually adding new records to Glims, building a comprehensive inventory of glaciers and how they are changing over time.

Researchers have reconstructed these glacier outlines from satellite images, aerial photography and ground surveys. Some shapes resemble withering plants; some once monumental glaciers have broken up into small fragments.

In some cases, an apparent change in a glacier’s extent can be caused by different teams of researchers measuring it differently. But the vast majority of glaciers are losing more ice than they accumulate because global temperatures are much higher today than they were in pre-industrial times.

A map from 1882 showing the Oberaletsch and Grosser Aletsch glaciers in the Swiss Alps. Photo: swisstopo / geo.admin.ch

Glacial melt drives a fifth of global sea level rise, and a 2019 report suggested that up to a quarter of the world’s population depended on glaciers functioning as “natural water towers”, storing water in winter and gradually releasing it in summer.

Data source and methodology

Glacier outlines from Glims. Glaciers were selected for visualisation based on a number of criteria, including rate of ice loss, size and temporal coverage in the database (40 years or more). The analysis aimed to include glaciers from as many world regions as possible.

In a small number of cases, an apparent change in a glacier’s shape can reflect methodological differences or errors in how these outlines were processed. However, the glaciers chosen for visualisation were carefully cross-referenced against other data sources.

With thanks to glaciologists Samuel Nussbaumer, Frank Paul and Tobias Bolch who advised on the capabilities and limitations of the database.