Following a trail of fossils found in all the wrong places — beech trees in Antarctica, redwoods and hippo-like mammals in the Arctic — uncover the bizarre history of the poles, from miles-thick ice sheets to warm polar forests teeming with life.
More than 12 million Americans have sent their DNA to be analyzed by companies like 23andMe and AncestryDNA, but what actually happens once the sample is in the hands of testing companies? What are they looking at and how accurate are they?
As global temperatures rise, scientists are exploring geoengineering solutions, from planting trees to sucking carbon out of the air to physically blocking out sunlight. But would it work? And what are the risks of engineering Earth's climate?