Larger part of the Amazon at risk of crossing tipping point than previously thought — ScienceDaily

A larger part of the Amazon rainforest is at risk of crossing a tipping point where it could become a savanna-type ecosystem than previously thought, according to new research. The research, based on computer models and data analysis, is published in the journal Nature Communications.

Rainforests are very sensitive to changes that affect rainfall for extended periods. If rainfall drops below a certain threshold, areas may shift into a savanna state.

“In around 40 percent of the Amazon, the rainfall is now at a level where the forest could exist in either state — rainforest or savanna, according to our findings,” says lead author Arie Staal, formerly a postdoctoral researcher at the Stockholm Resilience Centre and the Copernicus Institute of Utrecht University.

The conclusions are concerning because parts of the Amazon region are currently receiving less rain than previously and this trend is expected to worsen as the region

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Seismic sound waves crossing the deep ocean could be a new thermometer

A seismometer on the atoll of Diego Garcia (left) can calculate ocean temperature with earthquakes near Sumatra (right).
Enlarge / A seismometer on the atoll of Diego Garcia (left) can calculate ocean temperature with earthquakes near Sumatra (right).

Geophysics has shown that precise measurements and a little modeling can perform wonders, like showing us the detailed structure of the Earth’s interior despite the fact that it is inaccessibly buried beneath hundreds of kilometers of rock. This is possible because seismic waves produced by earthquakes subtly change velocity or direction as they pass through different materials. A new paper shows that something similar can actually measure small temperature changes in the deep ocean.

An idea to use acoustic waves from man-made sources was actually floated several decades ago but died out after some trials. A team led by Wenbo Wu at the University of Toronto realized that earthquakes could be taken advantage of in the same way, removing the expensive logistics of constantly setting off booms to get

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