Since 1958, atmospheric CO₂ has been measured continuously near the summit of Mauna Loa in Hawaii. The resulting curve climbs year after year, but it also wiggles: CO₂ dips during the Northern Hemisphere summer, as plants across its vast continents take up carbon, then rises again in winter as leaves fall and decay. The planet breathes in and out with the seasons.
On 27 August 1883, the eruption of the Indonesian volcano Krakatoa was heard as far away as Rodrigues Island, nearly 4,800 km away. Its pressure wave was picked up by barometers worldwide and circled the globe several times. The tsunamis that followed killed more than 36,000 people.
The deepest known point in the ocean, Challenger Deep, lies roughly 10,900 m below the Pacific surface. Drop Everest in and its summit would still sit about 2 km underwater. Down there, the pressure is more than 1,000 times what you feel at sea level, roughly a tonne pressing on every square centimetre.