The BBC reports that European donors have unveiled a US$6 billion aid package for West Africa to "help halt the emigration of young people from the region," by creating "a Francophone West African bloc so prosperous no one will want to leave."
The idea that US$6 billion over three years will somehow make West Africa prosperous in short order is almost beneath comment. West Africa has received more than US$225 billion in aid (today's dollars) since 1960, and it is clearly not so prosperous that no one wants to leave. Serious analysts debate aid effectiveness, and I believe aid can modestly raise living standards in limited settings, but even the most sanguine researchers do not live in cloud-cuckooland, a universe in which West Africa can be "fixed" in a few years with a bag of euros.
Even if the aid could somehow cause a quick and easy jump in West African living standards, however, there is little evidence that higher incomes cause substantially lower emigration rates in the poorest countries. Indeed, when very poor countries become somewhat richer there is some evidence (pdf) from the World Bank that emigration can rise, as it becomes easier for potential emigrants to fund the costs of education, transportation, smuggling, and so on, that facilitate labor movement. Even those who dispute the evidence that emigration rates rise with incomes in the poorest countries, such as Boston University's Robert E. B. Lucas, do not find that emigration falls much with rising income.
All of this remains controversial among researchers, and economists Timothy Hatton and Jeffrey Williamson do find (pdf) that high growth in African countries of origin can slightly attenuate migration—controlling for the vast wage gaps between Africa and Europe, which have a dramatically larger positive effect on emigration. But that's the point: West Africa is very poor, and no matter what realistic degree of economic growth it experiences in the short or medium term, it will remain dramatically poorer than Europe for generations. That gap will continue to cause Africans to migrate for a very long time to come.
If you lived in a place where you had just $15 to buy your family what it needed for a whole week, would you leave? Would it change your mind if someone told you that a couple years from now you might have $16 a week instead?
Sadly, there is no quick-fix way to keep Africans from attempting the deadly journey to the Canary Islands and Lampedusa in unseaworthy craft, as there is no quick-fix way to keep Mexicans and Central Americans from attempting the risky crossing of America's southwest desert. But among the highly imperfect solutions, Harvard's Lant Pritchett has the best: give many of them a humane and dignified path to a substantial degree of economic opportunity through expanded guest worker arrangements.