The fields you listed tend to be interdisciplinary themselves. Public policy, which relies on insights from political science, economics and philosophy for its foundation, emphasizes practical approaches to seemingly complex issues. Environmental studies, from a policy perspective, applies science and statistics to areas such as environmental justice and climate change. Data science uses tools from statistics and computer science toward applications to a variety of fields. To start with, you may want to seek colleges offering majors in all three of these interdisciplinary fields. Specificity beyond this may counterproductively narrow your choices.