Subscriptions to satellite alerts can help tackle deforestation, one of the main drivers of greenhouse gas emissions and biodiversity loss, a new study showed. A group of African countries where organizations received warnings from a service using satellites saw an 18% plunge in forest loss over a two-year period.

Land-use changes like deforestation account for 6% to 17% of global carbon emissions. And avoiding deforestation is much more effective at reducing emissions than regrowing forests. Needless to say, forests also provide essential support not just for countless ecosystems, but also for human populations.

A group of US researchers wanted to understand whether automated deforestation alerts could help to reduce forest loss. They focused on the Global Land Analysis and Discovery (GLAD) system, which provides frequent, high-resolution alerts when it detects a drop in forest cover. Governments and organizations can freely access the service and receive weekly emails with geographic coordinates of the alerts within the monitored areas.

“The first question was to look at whether there was any impact from having access to this free alert system. Then we were looking at the effect of users subscribing to this data to receive alerts for a specific area,” Fanny Moffette, lead author of the paper and researcher at the University of Wisconsin–Madiso, said in a statement.

Moffette and her team looked at the impact of GLAD in 22 tropical countries across South America, Africa, and Asia from 2011 to 2018. Subscriptions to alerts decreased the probability of deforestation in Africa by 18% relative to the average 2011–2016 levels, the study showed, with no effect seen in other continents.

Africa’s tropical forests include the Guinean Forests and the Congo Basin, an expansive rainforest often referred to as the “world’s second set of lungs”. The continent’s forests store 171 gigatons of carbon, are home to many plants and animals that exist nowhere else in the world, and support an estimated 100 million people.

Calculated using the social cost of carbon for avoided deforestation in Africa, the researchers estimated the alert system’s value to be between $149 million and $696 million. In other words, that’s how much money was saved by preventing deforestation. Protected areas and concessions were the most benefited areas, suggesting alerts can increase the capacity to enforce deforestation policies.

However, being covered by GLAD doesn’t automatically mean less deforestation, the researchers said. Only those African countries in which organizations had actually subscribed to receive alerts saw a decrease in deforestation. Having access to information is good but it’s more important to have people committed to using it.

But the situation is more complex when looking at the entire planet.

While the results were positive in Africa, the researchers found no decline in deforestation in South American or Asian countries, even where organizations subscribed to receive warnings. There are multiple possible reasons for this discrepancy, such as political unrest that limited the use of GLAD in other countries, or a lack of interest in tackling deforestation.

“We see an effect mainly in Africa due to two main reasons,” said Moffette. “GLAD added more to efforts in Africa than on other continents, in the sense that there was already some evidence of countries using monitoring systems in countries like Indonesia and Peru. And Colombia and Venezuela, which are a large part of our sample, had significant political unrest during this period.”

Looking forward, the researchers believe the influence of the GLAD program might grow, as a larger number of governments and organizations register to receive deforestation warnings. Moffette and her team wish to keep looking at GLAD and the effects of the new features recently added to the platform.

The study was published in the journal Nature Communications.