Researchers analyzed centuries of tree-ring data and found that human-generated greenhouse gases were driving drought conditions around the world as early as 1900, according to a study published Wednesday in the journal Nature. The study, described by National Geographic as the “first of its kind,” substantially confirms what climate models have shown.
“These tree-ring reconstructions let us go back in time and get a picture of global drought conditions for hundreds of years before the Industrial Revolution,” said Kate Marvel, an associate research scientist at the Earth Institute and NASA’s Goddard Institute for Space Studies and the lead author of the study. “There were increased greenhouse gases in the early 1900s, and the models say, ‘Hey, you should see a signal.’ But the fact that the signal is really clear in the models and apparent in the tree rings is pretty amazing. We can argue for a detectable human influence.”
“The tree-ring data analyzed in the study highlight three periods over the past 120 years in which a human fingerprint on drought and moisture is, to varying degrees, evident,” writes Lisa Foderaro. “The first, from 1900 to 1949, reveals the strongest signal, mirroring climate models showing that parts of the world from Australia to the Mediterranean were drying as other regions, including swaths of central Asia, were moving in the opposite direction.”
The study concludes that this signal is “likely to grow stronger in the next several decades,” adding that the “human consequences of this, particularly drying over large parts of North America and Eurasia, are likely to be severe.”