Climate adaptation can protect sovereign repayment capacity, but legacy debt can depress the sovereign's private return to investing and thereby induce underadaptation. Revisiting classic insights about debt overhang, debt relief, and buybacks, we show that this distortion also creates gains from debt restructuring. The restructuring can be financed without outside aid over a wide range of debt: creditors pay at moderate debt levels, the sovereign at higher debt levels, and aid is needed only after sovereign liquidity is exhausted. An open-market buyback is costlier than a collective exchange because creditors free-ride on the debt appreciation created by the intervention.