The Antarctic Peninsula is undergoing increased summer melting, according to research published in the Journal of Geophysical Research.
It reveals the ‘summer melt’ season has grown over the last 60 years – one weather station reports the season has doubled since 1948.
“We found a significant increase in the length of the melting season at most of the stations with the longest temperature records,” said Dr Nick Barrand who carried out the research while working for the British Antarctic Survey.
The additional melting has been caused by a strengthening of local westerly winds causing the warmer air above the ocean to be swept up and over the mountainous peninsula.
The meltwater makes a contribution to rising sea levels but is has secondary effects too.
Melting and refreezing water widens cracks in the ice that can accelerate its break up. In the case of floating ice shelves, their collapse can accelerate the advance of glaciers, which can surge forward when ice ahead of them breaks away.
The Peninsula, which curls north towards South America, has warmed by 3°C since 1950, three times the global average.
Funded by the European Union’s ice2sea programme, Barrand used satellite data to map the melting and matched it with the records of 30 weather stations. They found a strong correlation with a regional climate model, RACMO2.
“We found that the model was very good at reproducing the pattern and timing of the melt, and changes in melting between years. This increases confidence in the use of climate models to predict future changes to snow and ice cover in the Antarctic Peninsula,” said Dr Barrand who now works for the University of Birmingham.
North and South
Arctic sea ice has also witnessed increases in summer melting. Last September it shrank to record low levels.
The two polar regions are very different with the South Pole dominated by the Antarctic continent while the Arctic is a mix of land and sea.
Sea ice in the Arctic reflects much solar radiation back into the atmosphere. Less ice means the sea absorbs more energy, which in turn melts more ice.
Claims that gains in Antarctic sea ice balance out losses in the Arctic have been rejected by polar experts.