We all know that climate change threatens to devastate coastal cities, disrupt food production, and trigger a refugee crisis of untold proportions. It’s also bad for a nation’s credit rating, according to a report released Thursday by Standard & Poor’s.

That would be seem to be the least of the worries of, say, Vietnam, which S&P ranked dead last of 116 countries’ vulnerability to climate change-related credit risk. (Investors, on the other hand, might want to bet on Luxembourg, which was deemed least vulnerable to climate catastrophe.)

Yet those countries most at risk from global warming­—primarily those in low-lying Southeast Asia and Africa—are precisely those that will need to tap global credit markets to both prepare for ever-stronger hurricanes and super-typhoons like the one that struck the Philippines last November, as well as deal with the aftermath. And if the world’s governments ever get their act together on a plan to reduce greenhouse gas emissions—don’t hold your breath—those countries will need investment to switch to carbon-free renewable sources of energy.

“Extreme weather events, especially floods, can be expected to increasingly take a toll on a country's infrastructure and thus productivity, exacerbating weakening endowment of productive infrastructure observable in a number of countries,” wrote the report’s authors. “National budgets would invariably come under additional strains, potentially putting downward pressure on sovereign ratings as debts and deficits mount.”