WASHINGTON • Up and down the US coastline, rising seas and climate change are transforming a fixture of American home ownership that dates back generations: the classic 30-year mortgage.

Home buyers are increasingly using mortgages that make it easier for them to stop making their monthly payments and walk away from the loan if the home floods or becomes unsellable or unlivable. More banks are getting buyers in coastal areas to make bigger down payments - often as much as 40 per cent of the purchase price, up from the traditional 20 per cent - a sign that lenders have awakened to climate dangers and want to put less of their own money at risk.