BRUSSELS/LONDON (Reuters) - Wealthy nations could provide 100 of the world's most vulnerable countries a combined $25 billion in annual protection against climate disasters for as little as $10 million per nation, research published on Tuesday showed. With rich nations under pressure to fill the pot, researchers from the University of Cambridge's Institute for Sustainability Leadership said they had reached a "breakthrough" in understanding how to use this money to protect countries from the spiralling cost of storms, drought and rising sea levels. Donor funds of $10 million per recipient country, when used as premium support, could yield $200 million...