Assessing the carbon footprint of the 15th International Coral Reef Symposium (ICRS) in Bremen, Germany.

International scientific conferences serve as vital platforms for networking, knowledge exchange, and collaborative responses to global challenges. To exemplify sustainable practices, it is essential to organize these events in a climate-friendly manner, particularly for topics directly tied to environmental conservation, such as coral reef research. The 15th International Coral Reef Symposium (ICRS), held in Bremen, Germany, in July 2022, aimed to minimize its environmental impact through a comprehensive green strategy. This included reducing CO emissions and offsetting unavoidable emissions investments in climate protection projects. This study presents a detailed assessment of the symposium's carbon footprint over its five-day duration, accounting for both travel-related and local emissions. Total CO emissions were estimated at approximately 1,491 tons, with transportation contributing 84% and local activities 16%. Local emissions were reduced through measures such as the use of renewable energy, sustainable catering, and waste reduction. The hybrid format of the conference, which enabled online participation, significantly lowered emissions compared to full in-person attendance. The findings highlight the importance of integrating green strategies and virtual participation options to reduce the environmental impact of scientific gatherings. By offsetting all unavoidable emissions, the 15th ICRS successfully achieved carbon neutrality, setting a benchmark for future conferences to prioritize sustainability and environmental responsibility.