Ireland's population to peak at 5.8 million next century

Researchers believe that an accelerated decline in fertility rates mean the global population will reach an eventual peak of 9.7 billion before it begins to fall. Photo: Pexels

Ireland's population will peak at 5.8 million in 2057, it has been predicted.

Researchers believe that an accelerated decline in fertility rates will mean the global population will reach an eventual peak of 9.7 billion, before it begins to fall significantly.

By the end of the century, 183 of 195 countries are expected to have fallen below the replacement threshold. 

More than 20 countries, including Spain, Italy, Thailand, Portugal, Poland, Japan South Korea will see their total population numbers decrease by at least half.

By 2100, China will no longer be the most populous country in the world - its population will drop from 1.4bn people (currently) to 730m.

Conversely, countries in Sub-Saharan Africa will see their populations triple in size to some three billion people. Nigeria's population will expand to almost 800m in 2100, which will make it the world's second-most populous country, after India.

Speaking to Newstalk, Emeritus Professor of Reproductive Health at University College London, Professor John Guillebaud said that population can be a hard issue to predict:

"In Spain and Japan and Italy, they are having less than replacement fertility.

"Now from the environmental point of view, if you’re thinking of damage to the planet, actually, one less child in a family in a rich environment, means that there will be thirty times less damage to a child in a poor family.

The whole world needs fewer, and eventually, we need to stabilise our numbers at less than we’ve got now," he added.