A small group of researchers from Italy, France, and the United States discovered that most forests around the world are becoming less resilient to environmental changes caused by global warming. The group describes their study of satellite images of forested areas of the planet over time in a paper published in the journal Nature.
As the planet warms as a result of humanity’s inability to reduce greenhouse gas emissions, scientists around the world continue to investigate potential consequences. A slew of studies in recent years has shown that cutting down trees in rainforests and other forests to make way for crops is bad for the climate—forests produce oxygen and absorb and sequester carbon dioxide from the atmosphere. Less research has been done to learn more about the impact of global warming on forests, though it has been noted that rising temperatures and decreased moisture may make it difficult for some forests to survive.The researchers wondered if such changes were also making forests less resilient, reducing their ability to withstand temporary challenges like floods, pests, droughts, or pollution. They used years of satellite imagery to figure it out.
The researchers used a learning algorithm to sift through massive amounts of satellite data showing vegetation covering regions of the planet from 2000 to 2020 to learn more about the resilience of the world’s forests. In their effort, they defined resilience as a forest’s ability to recover after a disruptive event. When such efforts fail, the vegetation changes from forest to something else, such as savannah, they observe.
They discovered that over half of the world’s forests show declining resilience. They also discovered that global warming appears to be improving tree resilience in some areas, such as boreal forests in northern latitudes. The researchers discovered that increases in moderate heat and decreases in available water were the most important factors in reducing forest resilience.