Vetle Supphellebreen Glacier is resisting the melting trend by advancing in 2017, while Haugabreen Glacier is retreating.
For glacier-interested people there are always good news when a glacier is advancing. Vetle Supphellebreen Glacier advanced for the third year in a row, this year 2 metres. The glacier retreated the first couple of years we did front position measurements, but in total the glacier has advanced 4 metres since 2011. This means the glacier is more or less stable. A surplus of snow in the measurement period may explain the glacier development. If we take a look at local weather stations we see that precipitation is above average for the period 2011-2017. There is a complex symphony which governs glacier development, but in simple terms it is the relationship between winter snow and summer temperature that determines the glacier balance between years.
The bad news is that Haugabreen Glacier is retreating. The glacier hit a negative personal record by retreating 18 metres this year. Since we started the measurement program, the glacier has a total retreat of 53 metres. We do see an increase in precipitation by looking at data from nearby weather stations, but this is probably not sufficient to resist the melting.
The changes in glacial extension tells us something about changes in climate. Since the presence of glaciers is mainly controlled by winter snow and summer temperatures, a glacier will reflect changes in these climatic parameters. Large amounts of snow and low temperatures during the winter favour glacier growth, while low amounts of snow and/or high summer temperatures causes glacier retreat.
Growth or retreat is a reaction to a positive or negative mass balance. But, due to different reaction time, there may be a delay of several years between a measured positive mass balance and glacier growth. Short and steep outlet glaciers, like Briksdalsbreen or Bøyabreen, reacts relatively fast. Long, large and gentle sloping glaciers, like Tunsbergdalsbreen and Nigardsbreen, has slower reactions to changes in climatic conditions.