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A new study published in Geophysical Research Letters shows that the so-called Little Ice Age—a period stretching from 1500 to 1850, during which mean temperatures in the northern hemisphere were considerably lower than present—exerted effects on the climate of South America.
Based on an analysis of speleothems (cave formations) in the Brazilian states of Mato Grosso do Sul and Goiás, the study revealed that in the 17th and 18th centuries, the climate of southwestern Brazil was wetter than it is now, for example, while that of the country's Northeast region was drier.
Cave - Records - Climate - Brazil - Period
The same Brazilian cave records showed that the climate was drier in Brazil between 900 and 1100 during a period known as the Medieval Climate Anomaly (MCA), when the northern hemisphere's climate was warmer than it is now.
The study's authors are physicist Valdir Felipe Novello and geologist Francisco William Cruz, researchers at the University of São Paulo's Geoscience Institute (IGC-USP), in collaboration with colleagues in Brazil, the United States and China. The study detected dry and wet periods in the Brazilian paleoclimate by analyzing the oxygen isotopes in calcium carbonate molecules found in speleothems. "In Professor Cruz's group, we traveled throughout Brazil collecting samples of cave rocks. The composition of oxygen isotopes in the calcium carbonate deposited over centuries and millennia to form speleothems [stalagmites and stalactites] shows whether the climate was drier or wetter in the past," said Novelo.
Isotopes - Variants - Chemical - Element - Isotopes
Isotopes are variants of a chemical element. While all isotopes of any element have the same number of protons in each atom, different isotopes have different numbers of neutrons. For example, oxygen 16 (16O) has eight protons and eight neutrons, while oxygen 18 (18O) has eight protons and ten neutrons.
"In nature, there is approximately one atom of oxygen 18 for every 1,000 atoms of oxygen 16," Novello explained. 18O is heavier...
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