A botanical castaway
On Campbell Island, 700 kilometers south of New Zealand's mainland, the weather is relentlessly harsh. Rain falls on an average of 325 days a year, and hurricane-force winds blast the landscape for at least 100 days annually. The native vegetation is a low-lying mix of shrubs and immense "megaherbs," plants that have adapted to the climate by growing unusually large leaves. Trees do not naturally grow here. Yet, one tree stands alone: a Sitka spruce (Picea sitchensis).
This solitary tree is a transplant from another hemisphere. Its species is native to the west coast of North America, from Alaska to northern California. The most likely origin story is that Lord Ranfurly, the governor of New Zealand from 1897 to 1904, planted it during an expedition around the turn of the 20th century. Now over 100 years old, it is the Guinness World Record holder as the most remote tree on Earth. Its nearest arboreal neighbor is more than 222 kilometers away on the Auckland Islands.
Despite the inhospitable conditions, the tree has grown to over 9 meters tall, though its shape is unusual. Meteorological staff who once lived on the island periodically chopped off its top to use as a Christmas tree, causing it to grow in a bushy, cauliflower-like form rather than a typical cone shape.
An atomic archive
The tree's extreme isolation makes it invaluable for climate science. In the 1950s and 1960s, above-ground nuclear weapons testing released vast amounts of radioactive carbon-14 into the atmosphere. This "bomb pulse" of radiocarbon was absorbed by plants worldwide through photosynthesis, creating a permanent marker in their growth rings.
Scientists drilled a core sample from the Campbell Island spruce to analyze its radiocarbon record. The tree's rings show a sharp spike in carbon-14 that peaked in the Southern Hemisphere between October and December 1965. Because Campbell Island is so remote from industrial pollution, the tree provides a clean, baseline measurement of atmospheric changes. This data helps scientists understand how carbon moves through the atmosphere and is absorbed by the Southern Ocean, one of the planet's most important carbon sinks.
This distinct and globally synchronized radiocarbon signal is so clear that the tree has been proposed as a "golden spike" to officially mark the beginning of a new geological epoch: the Anthropocene, the age of significant human impact on Earth. The tree's wood records a chemical signature of the moment humanity's actions became a dominant force on the planet.