During the summer heatwaves of 2019, glacier melt rates reached record levels. This led to another year of major losses of ice volume, as reported by the Cryospheric Commission of the Swiss Academy of Sciences.
The strong glacier melt which has been underway for some years is continuing. In 2019, once again, glacier ablation (through melting) outpaced accumulation (through snowfall), as indicated by measurements of the mass balance of 20 Swiss glaciers. The situation was, however, less dramatic than in the previous two years. In April and May, snow cover on the glaciers was 20–40 per cent higher than usual. In some places, depths of 6 metres were measured as late as the beginning of June. As the onset of snowmelt was relatively late, it had been hoped – until the arrival of the first summer heatwave – that the loss of glacier volume might be relatively limited this year.
But, during the two week-long periods of intense heat at the end of June and the end of July, the volume of snow and ice melting on Swiss glaciers within just 15 days was equivalent to the country’s total annual consumption of drinking water. As a result, the thick snow layer rapidly disappeared, and the strong melt persisted until the beginning of September. This means that, over the past 12 months, around 2 per cent of Switzerland’s total glacier volume has been lost. Altogether, over the past five years, the loss exceeds 10 per cent – a rate of decline never previously observed in the time series extending back for more than a century.
The glacier mass balance data for 2019 show marked regional variations. Particularly in eastern Switzerland and on the northern side of the Alps, losses were higher than the average for the last ten years. A reduction of 1–2 metres in mean ice thickness was measured in many cases (e.g. Silvrettagletscher, Glacier de Tsanfleuron). Conditions were, however, more favourable in the southern Gotthard region, thanks to heavy snowfall at the beginning and end of the winter; several glaciers (e.g. Sankt Annafirn, Ghiacciaio del Basòdino) experienced relatively low mass losses. The retreat of small glaciers continues unabated: more than 500 (generally unnamed) glaciers have already disappeared since around 1900. 2019 saw the removal of the Pizol glacier – one of the first with a long time series – from the monitoring network.
Continue reading at Swiss Academy of Sciences
Image via Swiss Academy of Sciences
