Agree, if your plan was to stay in the US after graduation, this will not work. Immigration rules are extremely strict. You are expected to return to your home country after graduation. The universities will provide an education for you but once you graduate, that Visa is completed.
The fields of environmental studies and economics have plenty of candidates for available jobs such that it is not a field where the US is lacking in applicants. US employers are required, by law, to seek out US citizens first and foremost, in filling their labor needs, before considering non-citizens for sponsorship/employment.