Even assuming a decline in fertility rates, global population will reach 8.5 billion by 2030, 9.7 billion by 2050 and 11.2 billion by 2100, compared to the average variant projections. And even if fertility decline should speed up, population growth until 2050 will be virtually inevitable.

But that has not always been the case. Actually, for very long periods of time, human population grew very little, stabilizing below 100 million up until around 2000 BCE. According by several scholars’ authoritative calculations, at the beginning of the Christian era, 225 million people lived on the planet. It was not until 1820 that the population reached the first billion. Then, in just a little over a century, in 1930, it hit 2 billion. Growth has been quite considerable since then and in thirty years, from 1930 to 1960, the population grew to 3 billion; then 4 billion in 1974, 5 billion in 1987, 6 in 1999 up to 7 billion in 2011.

Today, in Africa, there are 1 billion and 186 million people that – according to the UN report – will become 1 billion and 679 million in 2030, 2 billion and 478 million in 2050 and 4 billion and 387 million in 2100. Asia is now populated by 4 billion and 393 million individuals, expected to rise to 4 billion and 923 million in 2030, 5 billion and 267 million in 2050 and 4 billion and 889 million in 2100.

Today, population growth and our production and consumption processes have a shocking impact on natural capital and ecosystem services that people use daily and free of charge and this will make itself increasingly felt in the future.

Also, the extraordinary natural capital of the world’s forests is increasingly at risk due to our growing and ongoing impact. Nature’s cover was about the scientific work that divulged the first numbers Earth’s trees.

By reminding us how important it is to know the global extension and distribution of trees and forests to fully grasp earth’s biosphere and its precious role as a source of fundamental ecosystem services (from oxygen and carbon biogeochemical cycles, to water cycles, soil maintenance etc.), scholars estimated that there are 3.04 trillion trees on the planet, of which approximately 42.8% is in tropical or subtropical forests, 24.2% in northern areas and 21.8% in temperate ones. 

According to their estimates, 15 billion trees are cut every year: it is thought that since the dawn of human civilization the total number of trees on the planet has shrunk by 46%.

The World Resources Institute, with its Global Forest Watch, highlighted that the 2014 world’s deforestation data have soared again, as it has been the case since 2012. In essence, over 18 million hectares have been lost, an area double the size of Portugal, of which 9.9 million hectares – a surface equivalent to South Korea and equal to more than half of 2014 total deforestation – in tropical countries.

According to data provided by the 2015 Global Forest Resources Assessment carried out by FAO, since 1990, 129 million hectares have disappeared through clear-cutting, an area the size of South America.

If 25 years ago – in 1990 – there were 4.128 billion hectares of forests, in 2015 we have about 3.999 billion hectares. Moreover, today around 7% of the total is covered by forests planted by man.

It is fundamental – both for our generation as well as future ones – to keep this extraordinary natural capital and its natural wealth of biodiversity in good health. Therefore it is imperative that we strongly commit ourselves to achieving Zero Net Deforestation and Forest Degradation as soon as possible and no later than 2020-2030.

2015 Report Revision of World Population Prospects published by the United Nations, esa.un.org/unpd/wpp.

Crowther T. W. et al., 2015, “Mapping tree density at a global scale,” Nature 525; 201-205, tinyurl.com/p82t48t.

World Resources Institute, www.wri.org.

Global Forest Watch, www.globalforestwatch.org.