The Global Learning and Observations to Benefit the Environment (GLOBE) Program is calling on volunteers of all ages to help students and citizen scientists document seasonal change through leaf color and land cover. The data collection event will support students across North America, Latin America, Central America, and Europe, who are working together to document the seasonal changes taking place from September through December – see Figure. The observations will also provide vital data for GLOBE students creating student research projects for the GLOBE 2025 International Virtual Science Symposium (IVSS). The project is part of GLOBE’s Intensive Observation Period (IOP), which collects data during a focused period to assess how climate change is unfolding in different regions of the world.

Green down is the seasonal change when leaves change from green to brown and then fall to the ground. During green-down data collection, volunteers take regular, daily photos of trees to document the transition in color. Regular observations of land cover and tree height capture the broader changes happening around the tree.

By gathering this data, you can provide important information about when a single tree changes ahead of or behind the others in your region. When this data is paired with satellite observations, researchers gain a much stronger picture of how seasonal and climate variations impact the life cycles of plants and animals.

The GLOBE European Phenology Campaign has created materials to assist educators in these efforts. This includes a series of YouTube videos that volunteers can use to select a tree for the phenology project, estimate tree height, and assess land cover. In addition, volunteers can refer to the green-down protocol for guidance at the beginning of the survey. Educators can learn more about the importance of the green-down study by registering as a GLOBE Educator at the GLOBE “Create an Account” website.

GLOBE students have been collecting seasonal variability in plant and animal data for decades. This work will augment global databases to help students, educators, and scientists around the world study climate change.

These observations are taking place around the world. This IOP is being conducted in conjunction with the GLOBE North America Phenology Campaign and the European Phenology Campaign, which focus on monitoring and reporting of cycles in plants and animals to help validate the timing of changes in growing season and habitat. The work is also being conducted in conjunction with the Trees Within LAC Campaign, which is collecting information about tree species and their dynamics over time.