Nepal, March 11 -- Emerging-market and developing economies (EMDEs) will need an estimated $2.4 trillion in climate investment annually to meet climate goals, according to the Independent High-Level Expert Group on Climate Finance, with $1 trillion coming from external sources. Achieving the United Nations Sustainable Development Goals (SDGs) will require even more financing: An increase of $3.5 trillion in new investments annually by 2030. These are daunting figures. But they are also non-negotiable.

Raising trillions of dollars in new external finance would be difficult at the best of times. It is even trickier when the world is facing an escalating debt crisis. After examining newly available data on 108 EMDEs, the Boston University G...