Global warming: Tropical forests at 'tipping point'; scientists call for 'immediate steps'

Tropical forests such as the Amazon is often referred to as "lungs of the planet" because of its ability to release a large amount of oxygen and store carbon dioxide. However, a new study by 225 researchers about 600 forest sites reveals that things might change for the worse if global warming is not curbed immediately.

A new report published in Science calls for "immediate steps" to save forests and stabilise the global climate as the forests reach their temperature tipping point. The team led by Martin Sullivan from the University of Leeds and Manchester Metropolitan University found out that the maximum daily temperature above 32.2 degrees Celsius could lead to the trees dying and release their stored carbon content in the environment.

Explaining the phenomenon, the scientists reveal that when the temperature rises, trees get dry and hot leading to closed pores in their leaves and loose moisture. This stops them from absorbing the harmful carbon gas and die. When trees die, they release the stored carbon back in the atmosphere. In their study of about 600 forest sites, the researchers measured the capacity of tropical forests in different regions to store carbon dioxide and it was discovered that the tropical forests across the world hold about 40 percent of all the carbon stored plants.

"Tropical forests grow across a wide range of climate conditions," said Stuart Davies, director of Smithsonian ForestGEO, a worldwide network of 70 forest study sites in 27 countries, in a news release on STRI's website. "By examining forests across the tropics, we can assess their resilience and responses to changes in global temperatures," he added.

According to Davies, this study explores the implications of thermal conditions currently experienced by all tropical forests by using a novel approach. The international team of researchers discovered that there is a vast difference in the ability of the amount of carbon stored by tropical forests in South America, Africa, Asia, and Australia.

Some of the findings suggest that forests of South America store less carbon than the forests in Asian, African, and European regions. As per the study, the other two important factors in measuring the amount of stored carbon being released in the atmosphere are "maximum daily temperature and the amount of precipitation during the driest times of the year."

It is found that when the maximum daily temperature reaches 32.2 degrees Celsius, carbon is released at a much higher rate. Through their study, the scientists predict that global warming impact South American forests more than other regions due to increasing temperatures. It is said that forests can adapt to changes, but it may take a few generations before they change is observed.

"This study highlights the importance of protecting tropical forests and stabilising the Earth's climate," said Jefferson Hall, co-author, and director of the Smithsonian's Agua Salud Project in Panama. "One important tool will be to find novel ways to restore degraded land, like planting tree species that help make tropical forests more resilient to the realities of the 21st century," he added.