Measure the cost of destructive climate change-related impacts in the trillions of dollars, says a United Nations report published Thursday.

The report, which focuses on the world's 52 Small Island Developing States (or SIDS) found predominantly in the Caribbean and the South Pacific, highlights how the nations and people least responsible for the climate crisis face the most severe damage. However, the report notes, the costs associated with the destruction of low-lying nations, coral reefs, and vulnerable coasts will be felt globally.

According to the UN's Environment Program (UNEP), the coral reefs in all SIDS regions are already severely impacted by rising ocean surface temperatures. And the report says that the global net loss of the coral reef cover - around 34 million hectares over the coming two decades - will cost the international economy nearly $12 trillion, with the economies and very existence of those small nations especially impacted.

"For example," said UN Under-Secretary-General and UNEP Executive Director Achim Steiner, "these 52 nations, home to over 62 million people, emit less than one per cent of global greenhouse gases, yet they suffer disproportionately from the climate change that global emissions cause."

The threats to low-lowing nations and those highly-dependent on their proximity to ocean resources, according to the report, are increased flooding, shoreline erosion, ocean acidification, warmer sea and land temperature, and damage to infrastructure from extreme weather events.

The UNEP reports says that though the challenges are enormous, there do existence mitigation efforts that could lessen or forestall the worst impacts, but only if governments quickly create new policies and change course.

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