Independent: Tropical insects rather than polar bears could be among the first species to become extinct as a result of global warming, a study has found. Insects in the tropics are already living at the limit of their temperature range and any further increases could quickly kill them off with huge repercussions for tropical habitats, which rely on insects for everything from pollination to waste disposal. Scientists have found that a rise in average temperatures in the tropics of just 1C or 2C …