Getting an internship offer with UN is a dream for many. UN offers a great range of opportunities for the students with Geography, Economics, International relation and environmental management background. Refer to the following links
https://www.unhcr.org/how-to-apply.html …to have an idea about the application process and requirements.
The World Bank Group offers unique programs that provide learning and capacity-building opportunities for juniors too to experience first-hand what working at the WBG is like. They also provide serval study scholarships for the talented students. Refer: https://www.worldbank.org/en/about/careers/programs-and-internships