World population will reach 9.8 billion in 2050, says UN. Half of the world population will be in 10 countries. Roughly 83 million people are added to the world's population every year. Expected contribution to the total growth of the following countries. India, Nigeria, Congo, Pakistan, Ethiopia, Tanzania, USA, Uganda and Indonesia. Within the seven years India's population (now 1.3 million ) to surpass China in about seven years.