Answer: Conduction
Explanation: As ice melts,more sunlight is absorbed,as more sunlight is absorbed,the atmosphere heats up,as the atmosphere heats up,more ice melts. This whole process is known as CONDUCTION.
Conduction occurs when there is different temperature between two materials, when there exist a transfer energy(i.e transfer from higher-energy atoms in the hot region to the lower-energy atoms in the cold region). When the atmosphere is heated up due to sunlight,there is a rise in temperature which makes the ice to melt due to transfer of warmth it absorbed from sunlight.