The natural resilience of Greenland’s smaller ice caps ‘broke down’ around 1997, causing a rapid increase in their rate of decline. Until that year, the ice caps were able to contain and refreeze enough meltwater to remain stable, despite temperature fluctuations. However, it appears that around 1997 the ice caps’ deep snow cover became saturated with refrozen meltwater, breaking down that mechanism and causing mass loss acceleration – an effect that is irreversible. That is the conclusion of a study led by researchers from Utrecht University and published in Nature Communications on Friday 31st March.
Measuring almost 100,000 km2 (about twice the size of the Netherlands), the ice caps around Greenland’s edges represent the largest glacierised area on earth, outside of the large ice sheets of Greenland and Antarctica. On a healthy ice cap, tens of metres of tightly packed snow are able to absorb meltwater in summer. In winter, that water refreezes, causing the total mass to remain more or less stable from year to year. However, increasing temperatures have knocked that yearly cycle out of balance. The amount of meltwater is so great that the tightly packed snow is now completely saturated with refrozen meltwater. That means that new meltwater cannot be absorbed by the snow anymore, causing it to run off into the sea.