A report by the market research company, Ipsos, says the global population will start to decline in about three decades. A spokesperson, Mari Harris, says recent calculations show that the current global population of 7.8-billion people will grow to about 8.5-billion before starting to decline, and at the end of this century the total population will be similar to today’s figures. She pointed out that Africa’s population will continue to grow at a faster rate than most populations.