Two thirds of reef sharks and rays risk extinction: Study

Nearly two thirds of the sharks and rays that live among the world's corals are threatened with extinction, according to new research published Tuesday, with a warning this could further imperil precious reefs.

New tech to monitor climate change

Weather extremes have become more frequent and intensive since the 1950s, and international hydrology experts are using new technology to map land areas subject to hotter, dryer conditions under climate change.