A tiny percentage of upper canopy leaves have already crossed that threshold, reaching temperatures so high — above 47 degrees Celsius — as to prevent photosynthesis, the study published in Nature reported.
Currently, some leaves exceed such critical temperatures only 0.01 percent of the time, but impacts could quickly scale up because leaves warm faster than air, the researchers said.
“You heat the air by two to three degrees and the actual upper temperature of these leaves goes up by eight degrees,” lead author Christopher Doughty of Northern Arizona University told journalists.
If tropical forest’s average surface temperature warms 4C above current levels — widely considered a worst-case scenario — “we’re predicting possible total leaf death,” he said.
The new research suggests that leaf death could become a new factor in the predicted “tipping point” whereby tropical forests transition due to climate change and deforestation into savannah-like landscapes.
American Buddhist Net 