The heat of fusion is eventually absorbed in the atmosphere when the contrail dissipates and is net zero. But in the meantime, the contrails increase the earth

The heat of fusion is eventually absorbed in the atmosphere when the contrail dissipates and is net zero. But in the meantime, the contrails increase the earth’s albedo, resulting in a net loss of incoming solar energy. The decrease in albedo caused by the soot particles also has to be accounted for. It’s complicated.