For comparison, at 400 ppm, Earth’s atmosphere contains 40 tons of carbon dioxide per hectare of land area. The study area shown is about 2000×6000 km = 1.2 B hectares.

A precise record of the last major reversal of the Earth's magnetic poles can be found in ancient trees. Researchers say this event 42,000 years ago had a huge impact on the planet and ancient humans.

These are some of the highlights from a very-high-resolution (1-meter) map of canopy heights that can detect single trees at a global scale, in a development with massive implications for tracking ...

An ancient, well-preserved tree that was alive the last time the Earth's magnetic poles flipped has helped scientists pin down more precise timing of that event, which occurred about 42,000 years ago.