Unseasonably high temperatures are being recorded across Reunion Island, with coastal areas experiencing 26 to 27 degrees Celsius, and temperatures in the Cirques region reaching the same levels. Higher elevations, above 1500 meters, are seeing temperatures around 20 degrees Celsius, according to local reports.
These warmer conditions are occurring as glacial formations in mountainous regions worldwide are subject to increased scrutiny. Glacial cirques, amphitheater-like depressions carved into mountains by glacial erosion, are key indicators of glacial activity and landscape evolution, particularly in regions like the Transantarctic Mountains, according to recent studies published in ScienceDirect.
Cirques, also known as corries or cwms depending on the region, are formed through a combination of frost action and glacial scouring. As detailed by the U.S. National Park Service, these bowl-shaped depressions develop at high elevations where glaciers originate. The process begins with the formation of a bergschrund – a large crevasse separating stationary and moving ice – which exposes the rock base to temperature fluctuations, leading to disintegration, and avalanche. The resulting debris is then embedded within the glacier, contributing to the erosion of the cirque floor.
The floor of a cirque often contains a tarn, a small lake formed by glacial overdeepening and dammed by moraine or bedrock. According to Britannica, this overdeepening occurs because the converging ice flows and rock burdens experience greater erosive forces. The concave shape of the cirque, with its steep headwall and gently sloping floor, is a defining characteristic of these glacial landforms.
While traditionally associated with glacial erosion, cirque-like formations can also arise from fluvial erosion, as seen in karst landscapes where rivers cut through layers of limestone and chalk, creating sheer cliffs. These fluvial cirques, or makhtesh, share the amphitheater-like shape but are formed by different erosional processes, as outlined in Wikipedia.
The AntarcticGlaciers.org website notes that cirques are common in many mountainous regions, and their expansion can lead to the formation of sharp arêtes, cols, and horns – further evidence of glacial sculpting of the landscape. The current warming trend raises concerns about the future stability of these glacial features and the potential impact on water resources and ecosystems.
As of today, no official statements have been released by the Reunion Island government regarding the potential impact of the warmer temperatures on local glacial formations, if any exist, or on water supplies. Further monitoring of glacial activity in the region is planned for the coming months.
