LOS ANGELES, Jan. 4 (Xinhua) -- New research at the University of Arizona (UA) on tree rings has found that climate change caused expansion of deserts.
UA researchers studied tree rings going back 800 years and found climate change expanded the planet's most extreme deserts, including the Sonoran, which extends from the Baja Peninsula into Southern California and much of southern Arizona.
The team combined tree-ring data from five mid-latitude regions in the Northern Hemisphere.
"Wide tree rings represent wet years and narrower rings indicate dry years. The research shows from 1203 to 2003, the northern part of the tropics shifted up to 4 degrees," said Valerie Trouet, a dendrochronologist and associate professor at the Laboratory of Tree-Ring Research at the University of Arizona.
"We can determine how the edge of the tropics has moved over the last 800 years," Trouet said in a recent UA news article about the study.
Trouet's team found that the expansion of the tropics northward from 1568 to 1634 coincided with severe droughts, the collapse of Turkey's Ottoman empire and the end of China's Ming Dynasty.
"Our results suggest that climate change was one of the contributing factors to those societal disruptions," said Trouet in a recent UA news article about the study.
By looking at data, Trouet and her team analyzed changes in the tropics before human-caused climate change.
By studying the past, she hopes to provide answers for how climate change could impact global natural disaster events, such as the intensity of wildfires.
