Humid tropical forests impact the world’s weather patterns and temperatures, and are home to enormous biological biodiversity. These forests are also crucial in the global cycling of carbon dioxide and water.
At the same time, tropical forests are extremely vulnerable to changes in land use and climate. They are being cleared at an alarming rate, often to make space for farmlands, palm oil plantations and ranches.
“Frequent droughts, higher temperature, and longer dry seasons, along with increasing pressures from deforestation and degradation in the last two decades, have pushed the tropical rainforests to the verge of a tipping point,” said Sassan Saatchi of NASA’s Jet Propulsion Laboratory.
To address this problem, almost 60 scientists, backed by the National Geographic Society and Rolex watch manufacturers, have worked together to devise an early warning system to monitor forest vulnerability. The team combined satellite data on weather patterns with other indicators of forest ecological health to develop the Tropical Forest Vulnerability Index (TFVI).
The TFVI index helps monitor changes in climate and land usage in forest areas. It can be used by researchers to identify forests that are becoming increasingly vulnerable before they reach a “tipping point” beyond which the forest no longer functions as a stable ecosystem.
According to Saatchi, the results of the study suggest that rainforests are losing their capacity to cycle carbon and water as before. “This is occurring gradually at the continental scale and more rapidly at the regional scale, with significant implications for the global carbon sink and climate.”
However, not all tropical forests are responding to changes in climate in the same way. Forests in Africa appear to be more resilient to such changes, while those in the Americas respond more rapidly to stress and show greater vulnerability.
Some of these forests show almost no resilience to climate warming and droughts, particularly if they have been significantly disturbed by human activities or fragmented into small patches.
It is hoped that scientists and policy makers will make use of the TFVI to monitor changes in forest vulnerability and step in with appropriate solutions before forests become degraded beyond repair.
“Now is the time to do something and not later,” said Saatchi. “This work takes advantage of a suite of satellite observations made for the past few decades to show how and where the tipping points may be reached and to help policy makers plan for conservation and restoration of these forests.”