Countries around the world are reporting a decline in student interest in geoscience careers, even as the need for trained geoscientists who can help solve global challenges in sustainability is becoming more urgent. This “geoscience crisis” is attributed to learners’ insufficient exposure to geosciences in the school curriculum, resulting from both lack of content and low teacher confidence in geoscience topics. Our team developed and studied an extracurricular programme of field excursions and mentored research to increase geoscience career interest among students who were in their first or second year of university but had not yet chosen their degree programme. Using the conceptual framework of social influence, the research team employed longitudinal surveys and interviews to examine geoscience identity and sense of belonging in the geosciences. The results showed that the programme had positive outcomes, with student geoscience identity emerging or increasing as students progressed. Field excursions led by an interdisciplinary faculty team were the pivotal component for increasing students’ belief that they could become a geoscientist and for enhancing student awareness of the importance of geosciences to society. The project affirms the critical need to increase teacher knowledge and skills to teach earth system science in field settings at primary and secondary level, well in advance of students choosing their university major. Field trip design should include activities that ask students to apply geoscience understandings to future Earth scenarios. This teaching approach reinforces for students that the geoscience profession has a role in our sustainable future.