Some of the nations most vulnerable to climate change face a sharp rise in debt service payments in the coming two years, hampering their ability to invest in climate proofing and shoring up their economies, a research report found. The Vulnerable Group of Twenty (V20) - a group of 55 economies exposed to the fallout from climate change - expect debt service payments to rise to $69 billion by 2024 - the highest level in the current decade, according to calculations from the V20 and the Boston University Global Development Policy Centre.