Polar bear declared "threatened," but Secretary limits decision's impact.

A kilometers-long ice core from Antarctica has been recording climate information for the past 800,000 years and has revealed a three millennia–long period when carbon dioxide levels in the air were lower than any previously measured.

Monster data crunch strengthens case that climate is disrupted.

To help raise awareness about the plight of frogs and toads, which are disappearing globally, Amphibian Ark is selling formal naming rights to an unusual frog.

Inhaling tiny pollution particles, even at concentrations allowed in urban air, appears to increase the risk that an individual’s veins will develop potentially lethal blood clots.

When it comes to Arctic air, various regions of the Northern Hemisphere are equal opportunity polluters. Even some subtropical countries in southern Asia get into the act.

Climate change affects the timing of flowering, migration and other natural cycles, meaning spring is coming earlier in many parts of the world.