Global warming has already reached 1°C above pre-industrial levels and the consequences of this for people and planet are immense. As the air and the oceans become warmer, glaciers are melting, their compositions changing and the resulting rising sea levels are causing increasingly severe events, both coastal and inland.
Evidence of this effect on climate change was demonstrated last year when a huge part of the Spalte Glacier, the largest remaining ice shelf in the Arctic, broke away. The glacier, located in northeast Greenland, has been slowly disintegrating over the last two decades. However, the disintegration has dramatically accelerated recently, with it losing more than 100 square miles of mass in the last two years.
The slowly melting glaciers are no longer able to balance the amount of snow accumulation on the surface with the loss of ice through warming, evaporation, glacier separation and other processes.
“Temperatures in the Arctic are rising faster than the global average. More heat is available from air and ocean to melt away the bottom and surface of ice shelves, and the thinning ice shelves are more susceptible to breaking up.” Dr Niels J. Korsgaard, a researcher at The Geological Survey of Denmark and Greenland (GEUS), said.
This change in the formation of glaciers is an important aspect of climate change. Large areas of ice, or ice shelves, act as corks that hold back glaciers flowing downstream. When these ice shelves reduce in size, the cork is removed and the ice flows more freely into the ocean causing sea levels to rise.
There are many other factors affecting sea levels so it is difficult to predict exactly how much they will rise, but one studyestimates a rise of over 2 meters within the next 100 years. This has the potential to displace hundreds of millions of people across the world.
And its not just sea levels that are affected. A recent study of Greenland’s ice shelf reveals that many glaciers were showing signs of physical changes, such as the rerouting of freshwater rivers beneath the glaciers. The potential impact on the ecology and the communities that depend on such sources of water is huge.
Although the Arctic is the area with the biggest loss, mountain glaciers are also depleting at a rapid rate. Under current high emission predictions, smaller glaciers in Europe, eastern Africa, the tropical Andes and Indonesia, for example, are projected to lose more than 80% of their current ice mass by 2100.
“Changes in water availability will not just affect people in these high mountain regions, but also communities much further downstream,” said Panmao Zhai, Co-Chair of IPCC Working Group I.
Indeed, hundreds of millions of people across the world who live in high mountain regions and low-lying coastal zones depend directly on these systems.
As these glaciers melt, it alters the water availability and the water quality downstream. The implications of this effect not only freshwater supplies for individuals but also many industries, including agriculture and hydropower. Furthermore, it increases the risk of flooding, as demonstrated last month in the Himalayas when a portion of the Nanda Devi glacier broke off, causing devastation in the state of Uttarakhand.
Another important consequence of melting glaciers is the increase in lakes. One study reports that glacial lakes have increased in size by 50% over the last 30 years. This significantly increases the temperature of the earth and one result of warmer earth is the thawing of permafrost.
When permafrost thaws, microbes digest the remains of plants and animals that have been frozen in the ground for centuries. As the remains are digested, they enter the atmosphere as methane or carbon dioxide which rapidly increases the concentration of greenhouse gases across the globe.
As explained by National Geographic: “Researchers now suspect that for every one degree Celsius rise in Earth’s average temperature, permafrost may release the equivalent of four to six years’ worth of coal, oil, and natural gas emissions—double to triple what scientists thought a few years ago. Within a few decades, if we don’t curb fossil fuel use, permafrost could be as big a source of greenhouse gases as China, the world’s largest emitter, is today.”
Projections regarding the effects of permafrost thaw are now being incorporated in the UN’s Intergovernmental Panel on Climate Change data. Although there are still a lot of unknowns, taking permafrost into account could indicate that the emissions targets set out in the Paris Agreement need to be revisited if we hope to limit global warming to two degrees.
Even if greenhouse gas emissions are reduced and global warming is successfully decelerated, glaciers will continue to melt and sea levels will continue to rise. But the process happening at a reduced speed will be far less catastrophic for the millions of people, and the ecosystems in which they live, than if it continues at the current rate.
Collective action is needed now to limit and even reverse emissions, and investment in monitoring, warning and adaptation measures is urgently required. The strength of this will determine the future of the glaciers and all that depend on them.