Land in Svalbard is rising both due to recovery from
the last glaciation and melting glacier mass at present. Norwegian Mapping
Authority measurements confirm that the land rising rate varies depending on
amount of melting ice from the glaciers from one year to another.
Land is still going through an isostatic rise after last glacial period but
there is additional rise on top it of caused by shrinking mass of present
time glaciers in Svalbard. The latter is en elastic response of land. Land
rise that started after the glacial period is stable and does not show any
annual variations. In Ny-Ålesund this stable rise is 2 mm per year.
On the other hand there is a difference in land rise
observed so this effect must be caused by other factors. The researchers
observe an agreement between the land rise variations and the amount of mass
lost by the glaciers in Svalbard. The variation can be 10 mm or more in
consecutive years.
The land rise rate is measured by combination of three
different remote sensing systems: VLBI (Very Long Baseline Interferometry),
GPS and DORIS (the Doppler Orbitography and Radio-positioning Integrated by
Satellite instrument). The average rise in Ny-Ålesund is 8.2 mm/year in
1997-2008 but it shows large annual variations.
This kind of data is valuable to assess the sea level
rise near Svalbard accurately. The Norwegian Mapping Authority (Statens
Kartverk) has prepared a scenario where they took into account measured land
rise, post-glacial land rise, and expected glacier melting of 50 cm per year
over the period of 100 years. If the global sea rise is 50 cm higher than
today in 100 years, the sea level in Svalbard will be in fact 0-50 cm lower
than today.
Geodetic references for Earth monitoring and climate
research are based on precise positioning. Ny-Ålesund is one of the most
important geodetic observatories in the Arctic and plays a central role in
making decisions about the global reference frames. The existing references
do not take into account a dynamic response of land to present-day glacier
mass changes. Therefore the research from Ny-Ålesund has to continue to
provide long-term time series
Source: Forskning.no:
Smelting gir mer landheving (in Norwegian only)
Contact: Halfdan Kierulf
(Halfdan.Kierulf@statkart.no) and/or Terje Dahlen, Statens Kartverk (terje.dahlen@statkart.no)
<< Return
|
|
Yearly land rise in millimeters in Ny-Ålesund. Measured rate in red and
estimated from the loss of glacier mass in blue.
Predicted sea level in Svalbard in 100 years (in cm, compared to the
present-day level). Both illustrations by Statens Kartverk.
|
