The escalating climate crisis demands immediate action, and education is crucial for fostering public awareness and behavioral change. Despite growing public awareness of climate change as a global emergency, understanding of the underlying science remains patchy, hindering effective action. This study uses the Climate Change Competence (C3) framework, which encompasses knowledge, skills, and attitudes, to assess the effectiveness of a MOOC in improving climate change literacy. The C3 framework aligns with the European Union's key competence framework and aims to equip citizens with the knowledge and skills needed to address climate change challenges. Accurate assessment of C3 evolution is crucial for optimizing educational interventions and ensuring efficient resource allocation given the urgency of the climate crisis. MOOCs, offering flexible and widely accessible learning opportunities, are explored as a potential tool for disseminating climate change education.

Previous research highlights the incomplete and often inaccurate understanding of climate change among the public. A better grasp of climate science is linked to increased environmental awareness and responsibility. MOOCs have emerged as a promising tool for delivering climate change education, offering large-scale access to high-quality resources and fostering interaction among learners. However, concerns remain about low completion rates and limited reach beyond higher education settings. Socio-demographic factors, such as gender, age, and income level, significantly influence climate change awareness and action. Tailoring educational interventions to specific groups is therefore essential for effective climate communication. The role of knowledge in influencing environmental behavior is complex and debated, but knowledge is considered a prerequisite for developing pro-environmental competencies and behaviors.

This study employed a pre-experimental design with pre- and post-test measurements using the validated Climate Change Competence Questionnaire (C3Q). The C3Q comprises 36 Likert-scale items assessing knowledge, ability, and attitude dimensions. The McDonald's omega coefficient was used to assess reliability. The sample consisted of 530 participants in the second edition of a Spanish-language MOOC on the basic science of climate change, with 255 completing the post-test. Participants came from various backgrounds including teachers, students, and other professionals from Spain and Latin America. The Mann-Whitney U test was used to compare pre- and post-test scores for each C3 subdimension, and the Kruskal-Wallis test was used for comparisons across age groups. Effect sizes were calculated using Glass's Rank Biserial Correlation and eta squared.

The MOOC significantly improved all three dimensions of C3 (knowledge, ability, and attitude). The knowledge dimension showed significant improvement across all subdimensions (biophysical processes, causes, consequences, and adaptation/mitigation), with biophysical processes demonstrating the highest improvement and causes the least. The ability dimension saw improvements in purchases, transport, and energy saving, with purchases and transport exhibiting the most significant gains. In the attitude dimension, trust and educational support improved, but responsibility showed no significant change. Significant differences in C3 improvement were observed based on participant characteristics. Teachers demonstrated a greater improvement across all C3 dimensions compared to non-teachers, despite having lower initial scores. Latin American participants, although having higher initial scores in ability and attitude, showed significant improvements in all dimensions similar to Spanish participants. Post-test ability scores were significantly higher for Latin American participants compared to Spanish participants. Regarding age, participants aged 20–34 and 65+ showed higher ability scores compared to those aged 35–49 and 50–64.

The findings demonstrate the MOOC's effectiveness in enhancing not only climate change knowledge but also related skills and attitudes. The strong correlation between knowledge, ability, and attitude suggests that improved understanding of climate science can positively influence behavior and environmental concern. This supports the notion that knowledge is a key element in driving pro-environmental actions. The significant improvement observed among teachers highlights the MOOC's potential for professional development and capacity building in the field of climate change education. The difference in pre- and post-test results between teachers and non-teachers might reflect differing levels of prior knowledge and engagement with the subject matter. The higher initial and improved scores of Latin American participants might be influenced by greater regional exposure to the effects of climate change, reflecting increased personal relevance and concern. The observed age-related differences are intriguing and warrant further investigation to fully understand the underlying mechanisms.

This study demonstrates the effectiveness of a MOOC in improving climate change competence (C3) across knowledge, abilities, and attitudes. The findings underscore the importance of integrating C3 into formal educational systems to effectively combat the climate crisis. Further research with larger, more diverse samples and longitudinal studies are needed to strengthen the generalizability of these results and to fully assess the long-term impact of this type of intervention on climate action. Exploring other knowledge-based interventions beyond MOOCs would also broaden our understanding of effective CCE strategies.

The study's limitations include the pre-experimental design without a control group and the self-selected nature of the MOOC participants, potentially biasing the sample towards individuals already interested in climate change. The relatively low completion rate of the MOOC and the differences in sample sizes between pre- and post-tests also introduce limitations. The findings might not generalize to the wider population due to the specific context of the MOOC and the sample's geographic and professional composition. Future studies should address these limitations by employing more robust research designs with larger, more representative samples and longer-term follow-up assessments.