What an Arizona tree reveals about Earth's hottest year and future warming
Deep in the Sonoran Desert, high on a mountain’s wind-swept peak, there lives a tree known as Bigelow 224.
With its stout orange trunk and long, graceful needles, the tree looks like any other ponderosa pine growing on Mount Bigelow. But a sliver of its wood, taken amid Earth’s warmest year on record, shows that this tree has a story to tell — and a warning to offer.
Related Knowledge Center: Climate science
What began as a theory in the 1890s — that industrial emissions of carbon dioxide could increase global temperatures — had progressed to a scientific fact a century later. Scientists across a range of disciplines are studying the impact of the still-growing concentration of carbon dioxide and other so-called “greenhouse gases” in the atmosphere as they call for industrial and governmental policies to slow, then halt, the warming of the planet.