Washington — Former President Barack Obama slammed the Trump administration's repeal of a landmark climate finding from the Democrat's presidency, saying the United States is "less safe" after President Donald Trump eliminated the legal basis for federal regulations targeting greenhouse gases.

A warming Arctic can stretch the polar vortex, a high-altitude air ribbon, one says. The “wobble” can disrupt the jet stream, causing extreme cold in the East.

The animals chosen as Olympic mascots are stoats — creatures that are at risk because of climate change. Learn more about the color-changing critters.

The EPA rescission sets a dangerous environmental precedent, critics say. But legal challenges and prevailing trends mean the industry won’t “crank the CO₂ all the way up.”

Cities everywhere are running experiments to respond to climate change and sustainability challenges, such as new mobility trials, energy pilots, green space projects, circular economy approaches, and more.

Warmer winters are shrinking reliable snow worldwide. From Milan’s Olympic slopes to North Carolina’s mountains, ski resorts are adjusting.