Glacial Landscapes - How Cold Environments are Distributed across the Earth

Cold environments are characterised by low temperatures but are varied in their nature. They cover approximately 25% of the world’s land surface. Defining a cold environment is not always precise as some cold environments are permanently cold whereas others are seasonally cold, warming up in the summer months.

The main cause of cold environments is latitude. In the far northern and southern latitudes, where temperatures are extremely cold, permanent ice sheets exist and in Antarctica for example, they cover much of the continent and are as thick as 2000m in many areas. In the far northern hemisphere, the absence of a landmass at the North Pole means that the ice forms as sea ice. The ice here is not as consistent as in Antarctica and the thickness and distribution of the ice can vary throughout the year. These are polar cold environments.

Altitude also affects the distribution of cold environments. Alpine environments are found at high altitude in the main mountain ranges of the world beyond the European Alps, in regions such as the Himalayas, the Rockies and the Andes. They often formed as a result of tectonic uplift at destructive margins (Rockies and Andes) or – in the case of the Himalayas, in a continental interior as a result of continental collision between the Indian subcontinent and the Asian landmass. In Africa, volcanic activity – which has resulted in Mount Kilimanjaro in Tanzania – has generated the continent’s highest mountain with an Alpine environment towards its summit, where glaciers exist.

Glacial environments are found within polar and alpine areas and glaciers are present in every continent. They have a more specific location than their host cold regions in which they are found. The capacity of glaciers to move relatively fast forwards (advance) and become shorter in length (retreat) means this cold environment is more dynamic over a shorter timescale than the others.

Periglacial environments are located at the margins (peri – as in ‘periphery’) of glacial and polar environments. They are characterised by long periods each year of very cold conditions, with short periods of warmer temperatures in which the permanently frozen ground (permafrost) is overlaid by a layer that seasonally melts then re-freezes. The largest areas of periglacial landscape occur in the northern hemisphere in central to northern Canada and Alaska, northern Scandinavia and northern Siberia, along with the Tibetan plateau (lower latitude but higher altitude), although there are less extensive periglacial regions in the southern hemisphere along the flanks of the Andes, in parts of Patagonia of southern South America and the unglaciated margins of Antarctica.