Other rivers, especially those in mountain catchments, are supplied only by snow and ice melt. Some rivers, that are fed by water from multiple sources (such as rainfall) do not rely on glacial meltwater and will not be greatly impacted by the disappearance of glaciers in their headwaters. However, this situation is likely to last only temporarily, because…Įventually (usually over several decades or longer), if a glacier melts fully, there will be no meltwater feeding into rivers downstream. Increased glacier melt produces more meltwater, which means that rivers will have a higher flow and more water will be transported downstream. Here we consider some of the impacts of glacier retreat on river flow, but there are also many other impacts, including: changes to river water chemistry, and impacts on ecosystems – the plants and animals living in and around the rivers How will glacier melt affect river systems? How will glacier melt affect water flow downstream? How will glaciers respond to climate change? – Will they disappear? These include major rivers such as the Ganges and Brahmaputra, where meltwater from Himalayan glaciers and snow makes its way downstream and, together with river water from other sources such as monsoon rains, eventually supplies over 1 billion people.Īs climate change continues, and global air temperature rise leads to enhanced glacier melt, there are a number of key considerations: Many of the world’s rivers are fed by meltwater from glaciers and mountain snowpacks.
Glaciers contain around 75% of the world’s freshwater. Red and yellow colours indicate higher temperatures than normal. Glaciers here will therefore be especially sensitive to climate change.įigure 2 – Global average (mean) surface temperature January-June 2016 relative to long-term conditions. The Arctic is warming especially quickly, and is several degrees (☌) warmer than normal. Red and yellow colours mean that temperatures are hotter than usual, and it is clear that most of the world is warming. Figure 2 shows the temperature for different parts of the globe in 20167 relative to average (‘normal’) values.
Under current IPCC predictions of future global warming and climatic changes, many glaciers will have disappeared by 2100. Currently, around 90% of the world’s glaciers are retreating. Glaciers play an important role in moderating global and local climate, but they are very sensitive to changes in climatic conditions. Figure 1 shows the current distribution of glaciers around the world.įigure 1 – The global distribution of glaciers around the world from the GLIMS glacier database. in Greenland and Antarctica) as well as smaller ice caps and valley glaciers (e.g. Glaciers cover around 10% of the global land surface.
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