Vulnerabilities - Present risk of landslides

Analyses indicate that the number of recorded landslide events has increased exponentially since 1960 (1). It is impossible to conclude whether this increase is partly due to an increase in the natural release frequency of slide events because of climate change (1). More likely, any natural changes in release frequency are masked by a combination of

• an increase in the number of infrastructural units, and
• more consistent registration of events.

Still, it is likely that some hazards, such as debris flows and floods, which are closely related to intense and prolonged rainfall, have become more frequent as positive trends are observed in rainfall variables in most places (2). Although the connection between meteorological variables and rockfall is not as strong (3), it is reasonable to suggest that a wetter climate will decrease rock stability and favor the initiation of a rockfall or rock slide (2).

Precipitation events during more than 3, 10, or 30 days have been the most important parameters for triggering mudslides and landslides in southern and southwestern Norway in the past (1). Thus, with the detected positive trends in precipitation variables in this region, such hazards are possibly more frequent than previously (2).

Vulnerabilities - Present risk of snow avalanches

Near-zero (freeze-thaw) events have become more frequent in most non-coastal parts of the country,especially in cold areas. Positive trends in snowfall variables and near-zero events can potentially produce increased frequency of snow avalanches in cold areas. More frequent near-zero events along with more heavy rainfall might also trigger a larger number of rockfalls and rock slides due to decreased rock stability.

Vulnerabilities - Future risk of landslides

Near-zero (freeze-thaw) events have become more frequent in most non-coastal parts of the country,especially in cold areas. More frequent near-zero events along with more heavy rainfall might trigger a larger number of rockfalls and rock slides due to decreased rock stability (2).

Vulnerabilities - Future risk of snow avalanches

Positive trends in snowfall variables and near-zero events can potentially produce increased frequency of snow avalanches in cold areas. Near-zero events have an effect on snowpack stability, and as they have increased in snow-rich areas, the initiation of snow avalanches might have been facilitated here (2).

Based on the obtained trends in snow-related variables, it can be argued that most lower-elevation areas, which is where the majority of the population lives, experience fewer snow avalanches, as there is less available snow. On the other hand, many of these areas are not even prone to snow avalanches due to the lack of steep slopes. Infrastructure at higher elevations, such as mountain roads, ski resorts, and cabin communities, might experience more snow avalanches than a few decades ago due to more frequent and intense snowfall in these areas, and possibly also due to more available snow. Another facilitating condition for snow avalanches might be more events of rain on snow, since more winter precipitation comes as rain, and rainfall events seem to be more intense (2).

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Norway.

1. Førland et al. (2007), in: Dyrrdal et al. (2012)
2. Dyrrdal et al. (2012)
3. Jaedicke et al. (2008), in: Dyrrdal et al. (2012)