The eternal ice and the sea level
In 2007, the Intergovernmental Panel on Climate Change warned about the ice sheets melting away in Greenland and West Antarctica. A rise in sea level from four to six meters would be imminent. This could happen within the next centuries, perhaps even millennia. Now researchers from the NGO Climate Central predict in their newest November statement a rise of up to two meters in the year 2100 already. Estimated impacts of global warming have suddenly shifted into the near future and threaten to hit mankind in the form of a rise in sea level as soon as in the next decades. In the meantime, looking into the past shows how fragile the interaction between ice and ocean can be.
Martin Zahno and Luisa, translated by Romuald Bolliger | 01.01.2020
Ellsworth Mountain Range in Antarctica (Image by skeeze from Pixabay)
A rise of one or even two meters does not seems much at first. And yet, if the sea level continues to rise so rapidly, the consequences will be drastic and felt in the near future. Horst Machguth, Professor for glaciology at the University of Freiburg: “Paired with storm tides, such a new sea level will lead to flood disasters.” According to the latest calculations, such extreme events not only occur more frequently due to the increased volume of water, but above all much more regularly. “Areas that are barely above sea level far inland run the risk of being hit by such floods,” Machguth continued. Countries like Vietnam, Bangladesh or the Netherlands, but also cities like Jakarta, Mumbai or Venice would thus already face storm tides in the coming decades. Such scenarios have already been predicted by researchers worldwide in recent decades. However, the period in which such devastating extreme events could occur has now moved much closer to the present. It is no longer a matter of millennia. For example, in its latest report of September 2019, the Intergovernmental Panel on Climate Change assumes that the six meters rise in sea level could be reached as early as 2300. Such a scenario would pose considerable problems for each of the world’s almost 700 million coastal inhabitants. Large areas could thus become permanently inhabitable. The consequences of sea-level rise can thus be regarded as quite threatening for the foreseeable future. The situation is equally alarming when one considers the causes of this phenomenon.
Ice sheet in Antarctica (Image by David Mark from Pixabay)
Where does this rise in sea level come from?
In order to understand the reasons for these new scenarios, one must first distinguish between glaciers and ice sheets. Ice sheets refer to the huge ice masses that are tied up on Greenland and in the Antarctic. Although melding glaciers have little effect on rising sea levels, it is clear that around half of the ice that melts in the world is currently coming from glaciers. “This is mainly due to the large surface area of the world’s glaciers,” says Machguth. Ablation, or melting of the ice, takes place primarily on the surface of the ice mass. “However, this is not sustainable,” the glaciologist continues. “At the time when most of the glaciers have melted away, there will still be a lot of ice left in the Arctic, which will continue to cause sea levels to rise for a long time to come. The ablation Greenland’s glaciers has also increased in recent years, by much more than the 2007 reports estimated.
“Although melting glaciers have little effect on rising sea levels, it is clear that around half of the ice that melts in the world is currently coming from glaciers.”
Greenland’s ice sheet is already contributing significantly to the rise in sea level. Significantly more than the ice that is currently tied up in Antarctica. “The reasons are different”, explains Machguth, “on one hand large parts of Greenland lie far to the south and, on the other hand, it is important to understand that it is much warmer in the Arctic than at the South Pole”. According to the glaciologist, this is partly due to the fact that Greenland is surrounded by large land masses. Antarctica, for its part, has its own climate system due to its location surrounded by oceans where temperatures below freezing point prevail even during summer months.
WIBLO infographic by Luisa Morell
Risk factor Antarctica
However, the fact that Antarctica is anything but a stable system can be inferred by looking into the past. Between the last two ice ages, the global sea level rose by up to nine meters within a relatively short period of about 1000 years, and reaching five meters above today’s sea level at times. Machguth argues that this abrupt rise is not due to the rapid melting alone: “This event was most likely related to enormous calving events in West Antarctica”. During the so-called calving process, entire ice masses break away from the ice sheet and then float to the open sea until they finally melt.
Infobox Antarctica
The estimated maximum ice thickness in the Adélie Land region is 4’776 meters. With a surface area of around 13’924 km2, Antarctica is larger than the EU and around 337 times larger than Switzerland! In addition, Antarctica is subject to above-average winds. Year-round wind speeds of up to 300 km/h are not uncommon.
Ominous is the fact that large parts of the West Antarctic ice sheet, unlike in Greenland, reside on land masses below sea level. If West Antarctica were to destabilize, subglacial melting could follow. The consequence of such a subglacial melt as well as mechanical destabilization would be the rapid calving of enormous masses of ice. With a potential rise in sea level of seven meters in West Antarctica, this remains a threatening idea. “Nevertheless such scenarios are to be taken with a pinch of salt, because this kind of sudden event could in turn affect global phenomena such as ocean currents, which in turn have an impact on climate,” explains Machguth.
Even if the consequences of such a scenario are difficult to fathom, the short-term effects of sea level rise are already evident today. Its impact on the whole of mankind is now slowly becoming apparent and tangible. Consequences of such a process can hardly be stopped, but at best only contained.
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Ellsworth Mountain Range in Antarctica (Image by skeeze from Pixabay)
A rise of one or even two meters does not seems much at first. And yet, if the sea level continues to rise so rapidly, the consequences will be drastic and felt in the near future. Horst Machguth, Professor for glaciology at the University of Freiburg: “Paired with storm tides, such a new sea level will lead to flood disasters.” According to the latest calculations, such extreme events not only occur more frequently due to the increased volume of water, but above all much more regularly. “Areas that are barely above sea level far inland run the risk of being hit by such floods,” Machguth continued. Countries like Vietnam, Bangladesh or the Netherlands, but also cities like Jakarta, Mumbai or Venice would thus already face storm tides in the coming decades. Such scenarios have already been predicted by researchers worldwide in recent decades. However, the period in which such devastating extreme events could occur has now moved much closer to the present. It is no longer a matter of millennia. For example, in its latest report of September 2019, the Intergovernmental Panel on Climate Change assumes that the six meters rise in sea level could be reached as early as 2300. Such a scenario would pose considerable problems for each of the world’s almost 700 million coastal inhabitants. Large areas could thus become permanently inhabitable. The consequences of sea-level rise can thus be regarded as quite threatening for the foreseeable future. The situation is equally alarming when one considers the causes of this phenomenon.
Ice sheet in Antarctica (Image by David Mark from Pixabay)
Where does this rise in sea level come from?
In order to understand the reasons for these new scenarios, one must first distinguish between glaciers and ice sheets. Ice sheets refer to the huge ice masses that are tied up on Greenland and in the Antarctic. Although melding glaciers have little effect on rising sea levels, it is clear that around half of the ice that melts in the world is currently coming from glaciers. “This is mainly due to the large surface area of the world’s glaciers,” says Machguth. Ablation, or melting of the ice, takes place primarily on the surface of the ice mass. “However, this is not sustainable,” the glaciologist continues. “At the time when most of the glaciers have melted away, there will still be a lot of ice left in the Arctic, which will continue to cause sea levels to rise for a long time to come. The ablation Greenland’s glaciers has also increased in recent years, by much more than the 2007 reports estimated.
“Although melting glaciers have little effect on rising sea levels, it is clear that around half of the ice that melts in the world is currently coming from glaciers.”
Greenland’s ice sheet is already contributing significantly to the rise in sea level. Significantly more than the ice that is currently tied up in Antarctica. “The reasons are different”, explains Machguth, “on one hand large parts of Greenland lie far to the south and, on the other hand, it is important to understand that it is much warmer in the Arctic than at the South Pole”. According to the glaciologist, this is partly due to the fact that Greenland is surrounded by large land masses. Antarctica, for its part, has its own climate system due to its location surrounded by oceans where temperatures below freezing point prevail even during summer months.
WIBLO infographic by Luisa Morell
Risk factor Antarctica
However, the fact that Antarctica is anything but a stable system can be inferred by looking into the past. Between the last two ice ages, the global sea level rose by up to nine meters within a relatively short period of about 1000 years, and reaching five meters above today’s sea level at times. Machguth argues that this abrupt rise is not due to the rapid melting alone: “This event was most likely related to enormous calving events in West Antarctica”. During the so-called calving process, entire ice masses break away from the ice sheet and then float to the open sea until they finally melt.
Infobox Antarctica
The estimated maximum ice thickness in the Adélie Land region is 4’776 meters. With a surface area of around 13’924 km2, Antarctica is larger than the EU and around 337 times larger than Switzerland! In addition, Antarctica is subject to above-average winds. Year-round wind speeds of up to 300 km/h are not uncommon.
Ominous is the fact that large parts of the West Antarctic ice sheet, unlike in Greenland, reside on land masses below sea level. If West Antarctica were to destabilize, subglacial melting could follow. The consequence of such a subglacial melt as well as mechanical destabilization would be the rapid calving of enormous masses of ice. With a potential rise in sea level of seven meters in West Antarctica, this remains a threatening idea. “Nevertheless such scenarios are to be taken with a pinch of salt, because this kind of sudden event could in turn affect global phenomena such as ocean currents, which in turn have an impact on climate,” explains Machguth.
Even if the consequences of such a scenario are difficult to fathom, the short-term effects of sea level rise are already evident today. Its impact on the whole of mankind is now slowly becoming apparent and tangible. Consequences of such a process can hardly be stopped, but at best only contained.
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If you enjoyed reading this article, maybe you would like to support our work? Thanks a lot!
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Expert University of Bern
