2024-08-23 22:05:44
Studying trees allows us to answer questions about how the climate of a territory has varied in the past, as their growth rings indicate whether a year was very dry or very rainy, for example.
*Read the article in El Desconcierto.
In the case of the tropical Andes, a new study published in the journal Nature Communications Earth & Environment reconstructed the rainfall that has occurred in this area from 1700 to the present day. The study was conducted by specialists from Chile, Argentina, Spain, France, and the United States.
Duncan Christie, an academic at the Institute of Conservation, Biodiversity and Territory at the Universidad Austral de Chile, and one of the authors of the study, stated that the research focused on the South American tropics, a region where such studies are scarce, which allowed filling a gap in information regarding its past climate.
“The tropical climate is like a motor of the global climate. What happens there influences global climate circulation, making it a key area. On the other hand, the Andes act as true water towers for South America, with its regional hydroclimate being crucial not only for local water availability but also for all the surrounding lowlands,” explained Christie, who is also a researcher at the Center for Climate Science and Resilience CR2.
Natural Archives
To carry out this research, the growth rings of queñoas (Polylepis tarapacana) from the Bolivian altiplano were analyzed. Additionally, the oxygen atom content within the studied species individuals was determined.
“This technique of determining the atomic oxygen content in tree rings allowed us to discover that these natural archives represented by trees can converse with other natural archives such as corals from the Pacific Ocean and ice cores from the tropical Andes, for which there were already records of oxygen atom content in their structure,” explained Christie.
On the other hand, Milagros Rodríguez, a researcher at the National Council for Scientific and Technical Research of Argentina (CONICET) and one of the study authors, highlighted the importance this type of research can have in facing the current climate crisis.
“Climate reconstructions based on natural archives are extremely useful for obtaining information in time periods or geographic locations without instrumental records. Thanks to natural records from different parts of the earth, we know that current climatic conditions are unprecedented in the last millennia. Thus, natural records, along with other sources of information, have allowed us to determine that the current climate crisis is closely related to human activities,” explained Rodríguez.
The researchers discovered a close relationship between the oxygen isotope series of tree rings, corals, and ice cores. This similarity is mediated by the behavior of tropical climate on a large scale and by the evolution of the El Niño phenomenon.
“We have a natural rain gauge, and the message that such different indicators as a Pacific coral and trees and ice cores from the Andes deliver is surprisingly similar, indicating a coupled connection between what happens at sea and the Andes in the tropical region,” detailed Duncan Christie.
Additionally, the academic explained the differences that affect the studied elements. “In trees, it matters whether they have water to grow annually, for corals the sea temperature is key, and for the ice cores, the amount of snow the glacier receives and its annual melt is predominant. All of this is modulated by how the tropical climate functions and the El Niño phenomenon.”
Using these different “natural sensors” allows for evaluating current climatic changes within a context of several centuries, “It’s like having a network of satellite antennas monitoring the climate of the past from the Andes and the sea,” affirmed the lecturer from UACh.
Currently, researchers are continuing to develop records from different natural archives in South America to combine them and achieve more reliable results regarding the magnitude of climate changes over the last decades, in the context of the last millennium.