More people, less nature?

Does a large global population constrain our ability to limit climate change and biodiversity loss? Is a growing population an inevitability that policymakers feel unable or unwilling to tackle? At 8 billion people, studies say that we have already exceeded Earth’s carrying capacity - the maximum population size an environment can sustain indefinitely, but the most-cited UN population projections forecast growth to around 11 billion by 2100. Can this many people live in harmony with nature on our unique planet?

In our work at Earthwatch we are frequently asked whether there are simply too many people on Earth, and whether reducing our numbers will make it easier to tackle the climate and nature crises. The answer is not simple, but let’s start with some facts:

• Much of the world has undergone the ‘demographic transition’ – moving from high fertility rates and high death rates to low fertility rates and low death rates. Infant mortality rates are decreasing and life expectancy is improving almost everywhere.
• Global population growth rate peaked in the sixties, and many developed countries’ populations have now fallen below the replacement rate, as well as experiencing declining numbers. One in four people is expected to live in a country with a decreasing population by 2050.
• Many countries with falling populations are located in Eastern Europe, mostly caused by emigration, but the population decline in countries such as Italy, Japan and Greece is due to low fertility rates.
• Sub-Saharan population trends go against the grain: the region accounted for just 13% of the global population in 2017, but will increase to 35% by 2100. It will be the only region in the world to experience strong population growth before 2100.
• The 10% of the world's population in the G7 countries consume 40% of the Earth's biological productivity, and the richest 10% of people are responsible for half of Earth’s fossil-fuel emissions, while the poorest half contribute a mere 10%.

Many academics believe that the biggest cause of biodiversity loss lies in the last point in the above list: biodiversity loss is not about too many people consuming too much, but ‘some people consuming too much’. Whilst it is true to say that G7 countries are heavy per-capita consumers and carbon emitters, this group does not include the likes of China, Turkey, Iran and Russia, which are also consuming more than their fair share. Once these four countries, with a combined population over 1.7 billion, are added to the list of countries consuming above global equity, can it still be said that just ‘some’ people are consuming too much? Richer nations must drastically reduce their per-capita ecological footprint and carbon emissions, partly to mitigate the climate and nature crises and partly to allow poorer nations space to increase theirs to a reasonable and sustainable level as they develop and improve their lives.

Policymakers often portray shrinking, ageing populations as a negative phenomenon, since it would theoretically mean higher public expenditure on the health, care and pensions of older people - and fewer economically productive people to provide taxes to fund this care. Older people fare worse in a warming world, being more vulnerable to extreme heat and climate disasters, and the economic and societal challenges faced by greater proportions of older people are not insignificant. But should we not celebrate the fact that fewer babies are dying; that our healthcare systems now enable people to live longer; and that women across the world (though by no means everywhere, as highlighted by the theme of 2023 World Population Day this month) now control their own fertility? A glance at the Sustainable Development Goals (SDGs) shows that these achievements are consistent with the desired direction of travel: good health and wellbeing, gender equality, no poverty, and quality education – since we know that educating girls, access to affordable contraception and family planning are the keys to lower fertility rates. African women with no education have 3.2 more children than those who go on to attend college after secondary school.

Some experts are frustrated that conservation biologists are reluctant to acknowledge the importance of the link between population size and biodiversity loss; perhaps they feel it is not the primary problem or are worried that policy solutions to slow the growth or reduce the size of global population would be perceived as coercive or violating human rights, even with imperialist undertones. As for the developed world, there are claims that it is ‘dangerous’ for couples to have more than one child and that incentives or penalties should be used to discourage it. Profligate consumption of Earth’s resources by western families diminishes and degrades those available to future generations; we have a responsibility to leave a rich and fertile planet to people who do not yet exist.

Supporters of policies to reduce population - which they feel will alleviate the pressure on natural systems - berate conservationists for relying on the ‘demographic transition’ taking its natural course in sub-Saharan Africa. This transition will eventually take place, but not before the region’s population has expanded hugely. The fear is that the projected tripling of the population in sub-Saharan Africa over the next 80 years and the resources and infrastructure that will be needed to sustain this growth are a major threat to ecosystems in the region. These concerns appear legitimate if one examines the ecological significance of and risk of climate catastrophe to the countries in which population will expand so dramatically: the Democratic Republic of Congo, the most forested country in Africa, has projected population growth of 121% by 2050, and was already the fifth leading country in annual tree cover loss worldwide in 2022, alongside high vulnerability to food insecurity and water stress. Uganda, already very vulnerable to food insecurity, water stress and natural disasters, is projected to have the third highest population growth in Africa by 2050, at 124%. Without rapid transformation in food systems, water efficiency, climate mitigation and adaptation, huge numbers of people will be born into a life of frightening food and water scarcity and near-inevitable nature and climate collapse.

Sustainable technological innovations will doubtless increase agricultural yields on existing land, but it is difficult to see that this will be sufficient to feed nearly 3 billion additional people by 2100. A change to a more plant-based diet would, however, release an enormous amount of land to nature: replacing all animal-based items in the American diet would release enough land to feed an extra 350 million people – a greater benefit even than eliminating all food waste, currently at one third of total food production.

Land conversion from wild habitats to agriculture is the most substantial cause of biodiversity decline and greater human numbers, at whatever rate of consumption, mean more pressure on natural resources. With fewer humans on the planet, more progress can be made on ecological restoration. This is already happening in the Danube Delta, Europe’s largest wetland area, now undergoing an extensive programme of rewilding comprising wetland, steppe and forest restoration, alongside natural grazing and the introduction of nature-based tourism. As rural populations thin out due to humans’ continued migration to urban centres, increasing amounts of abandoned farmland are being reclaimed by nature.

So, if you ever wonder whether there are simply too many people on the planet for us to solve the climate and biodiversity crises, remember that the answer is, well, complicated.

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Author: Lene Bryant, Learning Manager

Lene designs and delivers online and in-person experiential learning programmes for our corporate partners. She has a background in learning and development management and delivery, teaching, and organisational culture and change, and has a Masters in Climate Change & Development. She enjoys taking a systems perspective in her learning work on the climate and biodiversity crises, and believes in the power of experiences in nature for everybody on Earthwatch programmes.