The driest desert on Earth, the Atacama Desert in northern Chile, has long been a subject of fascination and study. Geologists have traditionally attributed its extreme aridity to the rise of the Andes Mountains and the arrival of the cold Humboldt Current around 23 million years ago. However, a recent study challenges this timeline, suggesting that the desert's drying began much earlier, tens of millions of years before these events.
The research, led by geologist Benedikt Ritter-Prinz of the University of Cologne, focused on quartz pebbles from the desert's core, which have been exposed to cosmic rays over vast periods. These cosmic rays create a rare form of neon, neon-21, inside the quartz grains. The study found that some pebbles contained over a billion neon-21 atoms per gram, indicating that they had been exposed for an astonishingly long time, with some pebbles dating back to the Eocene epoch, around 62 million years ago.
This discovery raises intriguing questions about the desert's formation and the role of global climate change. The researchers propose that the cooling of the Earth around 50 million years ago may have initiated the desert's drying, leading to the spread of dry zones worldwide. This global cooling event, known as the Miocene Climate Transition, could have triggered the desert's transformation, with the Andes and the Humboldt Current playing a more secondary role in the desert's aridity.
The implications of this finding are significant. It suggests that the driest places on Earth may owe less to local geography than previously thought and that global climate change can have profound and lasting effects on regional environments. The Atacama Desert's extreme conditions also make it a valuable natural laboratory for studying the survival and disappearance of life under endless drought, a topic of great interest to Mars exploration.
This study, published in the journal Nature Communications, highlights the dynamic nature of our planet and the interconnectedness of global climate change. It serves as a reminder that even the driest places on Earth can have a much longer history of aridity than we might have imagined, and that understanding these processes is crucial for comprehending the past, present, and future of our planet's diverse environments.
