Scientists have filled a gaping hole in the world's climate records by reconstructing 600 years of soil-moisture swings across southern and central South America.
Scientists have filled a gaping hole in the world's climate records by reconstructing 600 years of soil-moisture swings across southern and central South America. Along with documenting the mechanisms behind natural changes, the new South American Drought Atlas reveals that unprecedented widespread, intense droughts and unusually wet periods have been on the rise since the mid-20th century. It suggests that the increased volatility could be due in part to global warming, along with earlier pollution of the atmosphere by ozone-depleting chemicals. The atlas was published this week in the journal Proceedings of the National Academy of Sciences.
Recent droughts have battered agriculture in wide areas of the continent, trends the study calls "alarming." Lead author Mariano Morales of the Argentine Institute of Snow, Glacier and Environmental Sciences at the National Research Council for Science and Technology, said, "Increasingly extreme hydroclimate events are consistent with the effects of human activities, but the atlas alone does not provide evidence of how much of the observed changes are due to natural climate variability versus human-induced warming." The new long-term record "highlights the acute vulnerability of South America to extreme climate events," he said.
Coauthor Edward Cook, head of the Tree Ring Lab at Columbia University's Lamont-Doherty Earth Observatory, said, "We don't want to jump off the cliff and say this is all climate change. There is a lot of natural variability that could mimic human-induced climate change." However, he said, armed with the new 600-year record, scientists are better equipped to sort things out.
Read more at Earth Institute at Columbia University
Image: Araucaria araucana trees in northern Patagonia, Argentina, some of which were used in the study. Some trees can live 1,000 years. (Credit: Ricardo Villalba, Argentine Institute of Snow, Glacier and Environmental Sciences, at the National Research Council for Science and Technology)