Representatives of African economic consultative bodies meeting in the DR Congo capital's Kinshasa heard the warning from Ahmed Reda Chami in his address to the assembly.
There could be "internal migration of about 86 million people by 2050 if no action is taken to reduce the impacts of climate change," he said on Tuesday.
The UCESA study, funded by the World Bank, will try to anticipate the scale of future problems.
FILE - Migrants sit outside the Lampedusa's migrant reception center, Sicily, Thursday, Sept.14, 2023.
Reda Chami is head of the Union of Economic and Social Councils and Similar Institutions of Africa (UCESA), which has delegates from 19 mainly French-speaking countries.
Its general assembly started in Kinshasa on Tuesday, with envoys from similar European and Chinese institutions also attending.
"The destiny of humanity is at play," said Jean-Pierre Kiwakana, the president of the Democratic Republic of Congo's economic and social council.
Experts argue that Africa faces acute risks linked to global warming, with increases in extreme temperatures and decreased rainfall set to wreak havoc in impoverished countries.
For example, a flash flood in conflict-torn Libya this month killed over 3,800 people, according to official figures. Tens of thousands more have been displaced.