The presidents of Colombia and Venezuela, Gustavo Petro and Nicolas Maduro, launched a call Tuesday at the COP27 climate summit for a wide-ranging alliance to protect the Amazon, the planet's biggest tropical forest."We are determined to revitalise the Amazon rainforest... (in order) to offer humanity a significant victory in the battle against climate change," Petro said at the UN summit in the Egyptian resort of Sharm el-Sheikh.