The global population projects to reach 8 billion people on Tuesday, November 15, the United Nations says, in a historic milestone for humanity as the organization gives a look into what the future could look like.

"This unprecedented growth is due to the gradual increase in human lifespan owing to improvements in public health, nutrition, personal hygiene and medicine. It is also the result of high and persistent levels of fertility in some countries,” reads a statement by the UN.

The global life expectancy is 72.8 years as of 2019, an increase of nearly nine years since 1990. Current projections believe the life expectancy could be 77.2 years by 2050.

In a statement, the UN Secretary-General António Guterres said: "This is an occasion to celebrate our diversity, recognize our common humanity, and marvel at advancements in health that have extended lifespans and dramatically reduced maternal and child mortality rates.”

"At the same time, it is a reminder of our shared responsibility to care for our planet and a moment to reflect on where we still fall short of our commitments to one another,” he continued.

The U.N. projected in its World Population Prospects 2022 report, released in July, the milestone would be reached on November 15.

While it took the global population 12 years to grow from 7 to 8 billion, it will take approximately 15 years—until 2037— for it to reach 9 billion, a sign that the overall growth rate of the global population is slowing, the UN states.

Countries with the highest fertility levels tend to be those with the lowest income per capita. Global population growth has therefore over time become increasingly concentrated among the world’s poorest countries, most of which are in sub-Saharan Africa.

According to the UN, in these countries, sustained rapid population growth can thwart the achievement of the Sustainable Development Goals (SDGs), which remain the world’s best pathway toward a happy and healthy future.