Satellite data alerts help stop Africa forest cover loss: Study

Tree-felling in Africa decreased when satellite data was used to send free alerts about trees being destroyed, a new study has shown.

Overall, the risk of deforestation was 18 per cent lower in 2016-2018 than in earlier years in nine African countries, the study showed. These included Cameroon, the Central African Republic and the Democratic Republic of Congo.

There were downward trends for deforestation in West Africa after a large increase in primary forest loss last year. Ghana and Ivory Coast both reduced primary forest loss by over 50 per cent in 2019 compared to the previous year.

The decrease in tree-felling across Africa was higher in protected areas. This meant that alerts either increased the capacity to enforce existing deforestation policy or acted as a catalyst for the development of more effective anti-deforestation policies.

The alerts were issued by the Global Land Analysis and Discovery alert system. Launched in 2016, the alerts are available for free through a simple interface called Global Forest Watch. 

The alerts map all forms of tree cover loss, including logging, clear-cuts and intensive fires in both natural forests and plantations. 

The alert system draws on satellite images updated every eight days and uses artificial intelligence to identify where trees are vanishing by comparing pictures. It then warns subscribers covering the area so they can investigate and take action.

The study looked at whether the alert system was affecting tree losses in 22 tropical countries in South America, Africa and Asia.

The alert system has an important limitation: The felling of trees can only be detected if there are no clouds above it when satellites pass over.

The study authors estimated the alert system’s value to be between $149 million and $696 million by using the social cost of carbon for avoided deforestation in Africa.

However, tree felling did not decrease in South American or Asian countries, even when organisations subscribed to receive warnings.

The study was published January 4, 2021 in the journal Nature Climate Change.