Dramatic future for Norwegian glaciers

[Menydh]

Dramatic future for Norwegian glaciers

New climate scenarios from the research program RegClim may, if realized, have dramatic consequences for glaciers in Norway.

CICERO
May 24, 2006
By Atle Nesje, Jostein Bakke, Øyvind Lie and Svein Olaf Dahl


Briksdalsbreen Glacier

The “long-term forecast” for Western Norway shows a 2.3 ºC increase in summer temperatures and 16 percent increase in precipitation during the glaciers’ accumulation season over the period 1961–1990 to 2070–2100. The accumulation season, that is, the time of the year when precipitation normally falls as snow on Norwegian glaciers, lasts from the beginning of October to the end of April in the following year. If this scenario unfolds, it can mean that 98 percent of all glaciers in Norway will melt away and that 30-40 percent of the glacial area will disappear by 2100.

Glaciers are often called the “canaries” of the climate system. This expression comes from the old mining custom of bringing caged canaries into the mines because they had a lower tolerance for carbon monoxide than people. If the canary died, it was a warning to the miners to evacuate. Glaciers are used in a similar way, for example in the IPCC Third Assessment Report from 2001. The significant melting that was observed throughout the world over the last few decades can be a forewarning of the effects of global warming.

With few exceptions, all glaciers in Norway have become smaller since the mid-1700s. Some increased a little at the beginning of the 1900s, but since 1930 most glaciers have retreated rapidly. The rapid melting culminated for many glaciers around 1960. Over the last 40 years, the inland glaciers have slowly retreated, while many of the coastal glaciers – those that receive a lot of precipitation in the winter – have grown, which has led to an advance of many of the glacial fronts in the 1990s. In the period 1989-1995, the winter precipitation was particularly heavy in Western Norway, which meant that glaciers in this area advanced. In the period 2001-2004, there was an overall loss of glacial mass in Norway. This was a result of both low winter precipitation (in 2001 and 2003) and significant summer melting (2002 and 2003) (Andreassen et al., 2005).

The glacier mass balance, or material budget, depends on how much snow falls on the glacier in the winter (winter balance), and how much snow and ice melts away during the following summer (summer balance). The net balance is the winter balance minus the summer balance. A positive net balance means that the glacier grows in volume and has retained some of the precipitation that fell. In contrast, a negative net balance means that the glacier shrinks in volume, and that it has lost more water to the watercourse below than it received as precipitation. Changes in the position of the glacier fronts are not visible until a few years later, depending on the reaction time the particular glacier has. Short and steep glaciers, such as Briksdalsbreen (see picture), have a reaction time of three to four years, while glaciers with a long and gentle slope can have a reaction time of 20-30 years.

Glaciers in Norway today

In total, there are 1627 glaciers in Norway, of which about 714 are in Southern-Norway, and 913 are in Northern-Norway (Østrem et al., 1988). The glaciers have a total area of 2609 km2, of which 1592 km2 are in Southern Norway, and 1017 km2 are in Northern Norway. The total glacial volume in Norway is roughly estimated to be 164 km3, of which 100 km3 are in Southern Norway and 64 km3 are in Northern Norway. The 34 largest glaciers (two percent of the total number of glaciers in Norway) cover an area of 1800 km2 (68 percent of the total area) and make up a glacial volume of 114 km3.

Climate scenarios

In 2005, RegClim presented scenarios for climate change – temperature and precipitation – for the period 1961–1990 to 2070–2100, for each season and the whole year, for various regions in Norway. The “long-term forecast” for Western Norway shows a 2.3 ºC increase in summer temperatures and an increase in precipitation during the glaciers’ accumulation season (fall–spring) of about 16 percent for the period from 1961–1990 to 2070–2100.

Glacier mass balance

The scenario of a 2.3 ºC increase in summer temperatures and a 16 percent increase in winter precipitation from 1961–1990 to 2070–2100 in Western Norway (RegClim 2005) can reduce the glacial volume in Southern Norway by an amount equivalent to a 140-meter thick layer of water evenly distributed over the entire glacier surface. Since this melting does not occur evenly over the entire glacier but mostly down by the glacial tongue, the edge zones of the glacier will melt at a greater rate, thus reducing the total glacial area even more.

Equilibrium-line altitude

The line of equilibrium on a glacier is the area or zone on the glacier where the net balance is zero at the end of the ablation season in the fall. A winter with a substantial amount of precipitation in the form of snow, followed by a cool summer, will push the line of equilibrium further down on the glacier. In the opposite case – a winter with little snow followed by a warm summer – the line of equilibrium will be located high up on the glacier, sometimes even higher than the glacier itself. It is then possible to observe blue ice or snow from the previous year also on the topmost part of the glacier. A 2.3 ºC increase in summer temperatures and a 16 percent increase in winter precipitation from 1961–1990 to 2070–2100 can push the line of equilibrium on glaciers in Southern Norway up by about 260 meters by the year 2100. The temperature increase without the precipitation increase raises the line of equilibrium by 350 meters – thus the increased winter precipitation accounts for the difference of 90 meters. We have not taken into account the increase in temperature in the fall and spring. This means that the accumulation season – when winter precipitation falls as snow and adds to the winter balance – is shortened considerably. It is thus likely that the changes will be even more dramatic than outlined here.

Number of glaciers

A rise in line of equilibrium of 260 (± 50) meters is likely to result in the disappearance of between four and eleven of the largest Norwegian glaciers (larger than 8 km2) by 2100. Since so many of the large glaciers are disappearing, it is probable that also most of the small glaciers will also disappear. The number of glaciers is thus likely to drop from 1627 (Østrem et al., 1988) to about 28 – a dramatic reduction of 98 percent by 2100.

Glacial area

The glacial area may be reduced by about 884 (~837-939) km2, or 34 percent by 2100: from 2609 km2 (Østrem et al., 1988) to about 1725 (~1670-1772) km2. A 34 percent reduction in glacial area is the equivalent of about 2.4 times the area of Mjøsa (362 km2).

Glacial volume

It is estimated that there is about 164 km3 of glacial ice in Norway – based on a figure from Østrem et al. (1988) that shows the relationship between glacial area and glacial volume. This is about the same as three times the water volume in Mjøsa (56.24 km3), and an average glacial thickness for all the glaciers in Norway of about 60 meters. If all the glaciers in Norway melted this would result in an increase in the global sea level of about 0.34 mm. It is estimated that the glacial volume in Norway can be reduced by about 56 km3 to about 108 km3 by the year 2100. A reduction in the glacial volume by about 56 km3 corresponds exactly to the volume of water in Mjøsa. The remaining approximately 108 km3 of glacial ice is equivalent to about 1.9 times the volume of water in Mjøsa.

Glacial fluctuation over the past 10 000 years

Over the past 15-20 years, several research projects have studied many of the largest glaciers in Norway and reconstructed their fluctuations over the last 10 000 years. This information makes it possible to test which climate changes the glaciers tolerate before they disappear. In the period from about 8000 to about 4000 years before the present, most (perhaps all) glaciers in Norway melted away at least once. The summer temperature was then about 1– 2 ºC warmer than it is today. The main reason for the warmer summer temperature in the first thousand years after the last ice age was that the solar radiation in the summer was about 10 percent greater than today because at that time the earth was closest to the sun in the summer. Today, however, the earth is closest to the sun in the winter.
Below follows a summary of the climate when the largest glaciers disappeared:

• Jostedalsbreen melted away about 7600 years ago. The summer temperature at that time was about 0.7 ºC warmer than today, and the winter precipitation was about the same as today.
• Hardangerjøkulen melted away about 8000 years ago. The summer temperature was about one degree higher than today and winter precipitation was about 80 percent of what it is today (1961–1990).
• Folgefonna melted away 9700 years ago during a time when the summer temperature was about the same as today and the winter precipitation was only 70 percent of what it is today (1961–1990).
• Svartisen melted away about 9800 years ago. The summer temperature was then about one degree warmer than today, and winter precipitation was only half of what it is now (1961-1990).

The reconstructions of the glacial fluctuations in Scandinavia over the last 10 000 years show that it is by no means an unrealistic scenario that the glaciers can melt away, or retreat significantly, within only 100 years. Studies of inland sediments downstream from glaciers indicate substantial changes in glacial size over a short period (Nesje et al., 2005). For example, Folgefonna went from being larger than it is today to disappearing entirely in less than 100 years about 9700 years ago. In more recent times, Briksdalsbreen retreated about 250 meters in an eight-year period 1997–2005. During this time, about six million cubic meters (equivalent to about 700 000 truckloads) of ice melted at the bottom of the glacial tongue (see picture).

Impacts on water systems

This substantial melting of glaciers will have major impacts on patterns of runoff, water temperature, and sediment transport from current glacial water systems. Some of the sectors that will be affected are power production, tourism, fresh water fishing, and agriculture. In Norway, 98 percent of the electricity comes from hydroelectric power, and 15 percent of the exploited water flow comes from water systems that have glaciers in the precipitation field. Because a large share of the runoff in the glacial water systems comes from melting, most of this runoff – up to 80 percent – takes place in the summer. In dry and warm years, glacial melting helps maintain a substantial water flow. The summer of 2002 had unusually high temperatures and significant glacial melt; the mean temperature for the entire country in the summer season May-September (the ablation season) was 2.1 ºC above normal for the period 1961-1990, and is the highest summer temperature since the mid-1700s. Thus 2002 can be used as a possible analogue for what may be considered “normal” in the future. Data from the Norwegian Water Resources and Energy Directorate (NVE) shows that in Southern Norway glacial melting was between 50 and 100 percent greater than normal. The glaciers in Jotunheimen in particular melted substantially. The warm and dry summer resulted in unusually little water flow in rivers without glaciers in their catchment area. The high temperatures, however, led to large amounts of runoff from the glaciers. Nigardsbreelva in Jostedalen, where 75 percent of the catchment area is covered by glaciers, had, for example, water flow approaching average flood levels throughout most of August. Substantial water flow in glacial rivers also usually leads to significant sediment transport. In one glacial river course, the average concentration of suspended material – floating in the water – was 254 mg/l for the entire summer season (data from NVE). In the two previous years, the concentrations were respectively 1/5 and 1/3 this amount. At its highest levels, the concentration of suspended material reached more than 2500 mg/l. In 2002, measurements taken by NVE show that about 23 000 metric tons of sediment was added to the delta at the mouth of the Nigardsbrevatnet. This is twice as much as in an average year.

When the glaciers melt dramatically in warm summers, the runoff is augmented. When the glaciers disappear from a catchment area, all or most of the winter snow will melt during the summer, such that the year’s runoff becomes almost dependent on the annual precipitation. When the glaciers rapidly retreat, local pools of water can be formed that can be quickly emptied by local deposits or bursting ice dams. This can lead to larger or smaller glacier outburst floods (also known as jökulhlaup), as the case was in Søndre Folgefonna in the fall of 2002 and at Flatbreen in Fjærland in Spring 2004.

References

• Andreassen, L. M., Elvehøy, H. and Kjøllmoen, B. 2005: Major changes in Norway’s glaciers. Cicerone 2/2005
• Nesje, A., Jansen, E., Birks, H.J.B., Bjune, A.E., Bakke, J., Andersson, C., Dahl, S.O., Klitgaard-Kristensen, D., Lauritzen, S.-E., Lie, Ø., Risebrobakken, B. and Svendsen, J.-I. 2005: Holocene climate variability in the Northern North Atlantic Region: A review of terrestrial and marine evidence. In: Drange, H., Dokken, T., Furevik, T., Gerdes, R. and Berger, W. (eds): The Nordic Seas: An Integrated Perspective. Geophysical Monograph Series 158, 289-322.
• RegClim 2005: Norges klima om 100 år. Usikkerheter og risiko.(Norway’s climate in 100 years. Uncertainties and risks.)
• Østrem, G., Dale Selvig, K. and Tandberg, K. 1988: Atlas over breer i Sør-Norge (Atlas of glaciers in South Norway). Meddelelse nr. 61 fra Hydrologisk avdeling 1988, Norwegian Water Resources and Energy Directorate (NVE), 248pp.

[source]

[Savage]

Glaciers melting at record rate

It's been a warm summer in Norway, and that's sped up the shrinking process that already had hit the country's glaciers. Experts say the glaciers
The Briksdal Glacier is one of Norway's most popular tourist attractions, and here's how it looked in 2001.


PHOTO: NVE

Here's a photo of the Briksdal Glacier last summer. New measurements set to be taken in September are expected to show that the glacier has shrunk even more.


PHOTO: NVE

The melting of the glaciers will make them more dangerous, experts warn, adding that some may even disappear entirely within the next 50 years.

The glacial runoff, meanwhile, is filling up the local rivers they feed. The river tied to the glacial Nigardsbreen, part of the Jostedals glacier in the county of Sogn og Fjordane, has been recorded as having 50 percent more water in it than normal.

"Never before has there been such a large difference in the rivers coming off glaciers and those that aren't fed by glaciers," Rune Engeset of the Norwegian Water Resources and Energy Directorate (Norges vassdrags- og energidirektorat, NVE) told newspaper Aftenposten.

"Tourists on board the cruiseships ask why there's so much water in some rivers while others are almost dry," he noted. The answer lies in the extremely warm and unusually dry summer over most of southern Norway, and especially in the mountains.

The Vosso river system, for example, has no links to glaciers and its reservoirs now hold only half the amount of water in a normal year.

This summer marks the third time in the last six years that scientists are registering a considerable reduction in the glaciers. Measurements taken in Jotunheimen, in the mountains of western Norway, at Svartisen and in West Finnmark show that the snows that fell last winter have disappeared quickly. Only at Svartisen were larges areas of the glacier still covered with the past winter's snow.

Engeset expects temperatures to keep rising, leading to more glacial melting. The uncertainty is tied to how much snow may fall this winter.

[Menydh]

The comparison of the images is frightening. The consequences of these global warming and ice meltings are going to be of a magnitude hard to imagine. Dissecation of lands further south and a raise in the water level of the seas with coastal lowland regions being reclaimed by the seas.

[Savage]

And the Greenland ice is going too.... The melting is accelerating, as darker layers are recovered and absorbs more heat. The Greenland inland ice are gone in 50 years. But as the temperature is rising generallly on this globe, Greenland may however be a cool place on hot days...

The scary is not that the claciers disappears, but what realities it reflects....
And the process cannot just be switched off. It may take hundreds of years to brake down the man-influenced contribute to the meltdown.

One could say that the coastal line has always gone in waves, the sea has retreated the latest 1000 years, in Norway...but other may need long rubber boots...

[Señor Malo]

Originally Posted by Thore Hund

The scary is not that the claciers disappears, but what realities it reflects....

One could say that the coastal line has always gone in waves, the sea has retreated the latest 1000 years, in Norway...but other may need long rubber boots...

Every summer in Paris is organiated what it's called "Paris Plage" (Paris Beach): the town council displays layers of sand of the Seine River boarding streets, put some palms trees, folding chairs and folding beds so that people, even if they can't swim on the Seine, can have
a foretaste of being at the beach...
Let glaciers keep on shrinking and "Paris plage" will become a natural resort...