(CNN) After months of record temperatures, scientists say Greenland's ice sheet experienced its biggest melt of the summer on Thursday, losing 11 billion tons of surface ice to the ocean -- equivalent to 4.4 million Olympic swimming pools.

Greenland's ice sheet usually melts during the summer, but the melt season typically begins around the end of May; this year it began at the start. It has been melting "persistently" over the past four months, which have recorded all time temperature highs, according to Ruth Mottram, a climate scientist with Danish Meteorological Institute.

This July alone, Greenland's ice sheet lost 197 billion tons of ice -- the equivalent of around 80 million Olympic swimming pools -- according to Mottram. She told CNN the expected average would be between 60-70 billion tons at this time of year.

The weather conditions that brought a heat wave to Europe last week have reached the Arctic, where scientists say they could trigger one of Greenland's biggest ice melts since 1950, when reliable records began.

Scientists recorded unconfirmed temperatures of 2.7C at 3,000 meters above sea level on Thursday, which would be close to a new record if confirmed.

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