Search Climate Insights Directory

This report presents findings from the Schools’ Air quality Monitoring for Health and Education (SAMHE) initiative for the 2023/2024 academic year. Based on data from hundreds of UK schools, the report examines the relationship between outdoor temperatures and indoor air quality, specifically focusing on carbon dioxide (CO2), relative humidity, and particulate matter (PM2.5).

During the second half of December 2022, monarch butterfly colonies in Mexico occupied 2.21 hectares of forest, representing a 22% decrease from the 2.84 hectares recorded in 2021. Of the 11 colonies identified, six (1.52 ha) were located within the Monarch Butterfly Biosphere Reserve (MBBR) and five (0.69 ha) were outside the reserve. The largest colony (0.797 ha) was found in Ejido El Rosario, while the smallest (0.004 ha) was in Ejido El Potrero. The report identifies climate change, forest degradation in Mexico, and the decline of milkweed in the United States as primary threats to the species.

During the second half of December 2021, 10 monarch butterfly colonies were recorded in Mexico, occupying a total of 2.835 hectares of forest. This represents a 35% increase from the 2.10 hectares recorded in 2020. The colonies were distributed equally between Michoacan and the State of Mexico, with 2.174 hectares located inside the Monarch Butterfly Biosphere Reserve (MBBR) and 0.661 hectares outside of it. The largest colony was found in the Sierra Campanario Sanctuary at 1.187 hectares, while the smallest was in the Lomas de Aparicio Sanctuary at 0.003 hectares.

During the 2024-2025 overwintering season, monarch butterfly colonies in Mexico occupied 4.42 acres of forest, marking a 99% increase from the 2.22 acres recorded in 2023-2024. Eight colonies were identified: three within the Monarch Butterfly Biosphere Reserve (MBBR) covering 3.01 acres and five outside the MBBR covering 1.42 acres. The largest colony was found in ejido El Rosario, Michoacán (2.46 acres), while the smallest was in San Andrés (0.005 acres).