Online encyclopaedias are great for concise and correct overviews.
Suggested articles include:
The GLOBAL MIGRATION FLOWS interactive app tracks migrants around the world. This application is now being hosted by IOM.int. It is endlessly fascinating to explore where we're from. The underlying data for the map was published by the UN DESA in 2015.
Using the app:
Choose whether you want to access information about migrants leaving a country (Outward) or migrants entering a country (Inward). Then click on a country and watch the pattern of migration to or from the chosen country. Countries that neither send nor receive migrants will fade out. Hover over a country or over a migrant cluster to access the data. Each circle represents up to 20,000 migrants.
Comparing satellite data from 2012 and 2016 reveals where the planet has dimmed and brightened. Looking at Earth at night from space turns the planet’s extremely varied and complex surface into a much simpler view of light and dark. The ghostly outlines of continents, laced with webs of light, are beautiful and eerily peaceful. But these images can also reveal clues about what the humans on Earth are up to, and how that is changing.
American Museum of Natural History, 2016, Human Population Through Time, 4 November, accessed 18 May 2017, <https://www.youtube.com/watch?v=PUwmA3Q0_OE>.
Dalton, D 2005, Environmental migrants, Heinemann Library, Oxford.
Migration of people 2017. Britannica School. Retrieved 18 May 2017, from http://school.eb.com.au/levels/middle/article/migration-of-people/275837