Scientists have unveiled a powerful new method for predicting Arctic sea ice months in advance, just as climate change drives rapid ice loss.

From Hudson Bay to the Chukchi Sea, meet 19 polar bear groups and the people racing to protect them as ice disappears.

As the Arctic Ocean loses its sea ice due to climate change, sunlight penetrates deeper into the water and encourages the growth of tiny plant-like organisms (phytoplankton). But to thrive, they need ...