sydney (reuters) ：australian scientists have found that deforestation along the amazon river in south america was reducing rainfall and causing climate change in the region. a study in the amazon found that a loss of forests meant less water evaporated back into the atmosphere, resulting in less rainfall, said ann henderson-sellers, director of environment at the australian nuclear science and technology organization. 

key to the study was plotting the cycle of a heavy molecular¹ version of water common in the amazon that evaporates more readily through plants than from lakes and rivers. water from household taps consists of two "regular" hydrogen atoms and one "regular" oxygen atom, explained henderson-sellers, but some water molecules² see the second hydrogen atom replaced by a heavier version called deuterium. "plants transpire³ the water molecules and pumps them back into the air, without discriminating⁴ between heavy or regular molecules," henderson-sellers told reuters. 

as the study tracked the water cycle as it flowed from the amazon river into the atlantic ocean, evaporated, fell as rain and returned back to the sea, scientists discovered there had been a reduction in heavy-molecule water since the 1970s. henderson-sellers said the only possible explanation for the decline was that heavy-molecule water was no longer being returned to the atmosphere to fall as rain due to less vegetation, signaling a relationship between deforestation and rainfall.

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