Nairobi national park

Global biodiversity is being lost at an alarming rate. It is well-evidenced that this is the result of human activities, primarily agriculture and other forms of land conversion, as well as overexploitation of species. The World Wildlife Fund for Nature’s most recent Living Planet Report, published in November 2018, shows that surveyed animal populations have declined by more than 50 per cent on average in the last two generations. The recently-released global assessment from the United Nations´ leading research body on nature, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, found that up to one million out of the roughly 8 million estimated existing species are threatened with extinction. Some biologists argue the situation is so severe that a sixth mass extinction event may be underway given the number of species that are known to have been lost over the past few centuries. This will radically alter the natural environment as we currently know it, but also have significant consequences for the wellbeing of current and future human generations.

In response, conservationists are calling for more land to be set aside for nature. Current international targets, agreed in 2010, call for 17% of land and 10% of oceans to be under some form of conservation protection by 2020. Currently, about 15% of land and 7% of oceans are demarcated as protected areas. However, even if these spatial conservation targets were met, widespread biodiversity declines would probably continue. A recent study found that the existing terrestrial protected area network would need to be virtually doubled in size to achieve coverage targets for all countries, ecoregions, sites of particular significance, and species (Butchart et al., 2015). Poorer countries, which are often the most biodiverse, were found to have the largest relative shortfalls. Scientific estimates of the amount of space needed to safeguard biodiversity range from 25 to 75% of major ecosystems. The large variation in these estimates is in part driven by limited knowledge of the total number of species that exist, a poor understanding of how ecosystems function and the benefits they provide, and uncertainty over the effects of new threats to biodiversity, such as climate change.

The prominent biologist E. O. Wilson has made the radical proposition that half the Earth should be set aside for nature, a claim that is gaining increasing support via the Nature Needs Half movement. Wilson argues that by preserving half of the planet, we would theoretically protect 80% of the world’s species from extinction. If protection efforts focused on the most biodiverse areas this figure could increase. Opponents of this approach argue that it fails to take into account the main drivers of biodiversity loss, namely ever-increasing levels of anthropogenic resource extraction and consumption inherent in a growth-based economy. Furthermore, human activities have global consequences that cannot be confined to a ‘human half’ (Büscher et al., 2017). The half Earth proposition also raises serious moral and political questions. For example, who decides where these areas will be located? Who creates them and decides what activities may be permitted there? Due to historical patterns of extraction and uneven global development, biological diversity tends to be concentrated disproportionately in developing countries. There are also pragmatic considerations to be taken into account. A lack of human interaction with the natural environment has been demonstrated to have negative consequences for human health and wellbeing (White et al., 2019) and could actually undermine the conservation cause, since people are generally less inclined to protect something that they don’t care about.

There does seem to be growing public support for greater ambition in biodiversity conservation. In 2014, the Zoological Society for London, in collaboration with the International Union for the Conservation of Nature, conducted the first ever systematic global public opinion survey on how much land should be set aside for nature. The online survey polled more than 7,000 people from Australia, Brazil, China, India, South America, the UK and the USA, and found that people think that 50% of the planet’s land and oceans should be protected.

In 2020, a new global biodiversity framework will be agreed at an international conference bringing together all parties to the Convention on Biological Diversity (CBD). The CBD is the major international treaty that sets the agenda for global sustainable development. The conference will offer the chance to review progress, set new targets and formulate action plans, and as part of this it is likely that new spatial targets will be agreed. For the first time these are likely to include conserved as well as protected areas. The inclusion of conserved areas (currently defined in policy documents as ‘other effective area-based conservation measures’) reflects a greater awareness of the need to mainstream conservation objectives into the management of the wider landscape. It also indicates changing attitudes, with human presence and use of natural resources increasingly seen to be compatible with conservation outcomes.

In the end, the conservation goals and ambitions that we set are a reflection of our societal values and view of our relationship with the natural environment. Science can play an important role in providing information on the causes and consequences of environmental decline, which can be incorporated into environmental decision-making and policy. However, whether targets are achieved is a matter of public and ultimately political will. Decision-making processes relating to the natural environment should aim to include all stakeholders in order to ensure equitable and lasting outcomes.


Büscher, B., Fletcher, R., Brockington, D., Sandbrook, C., Adams, W. M., Campbell, L., … Shanker, K. (2017). Half-Earth or Whole Earth? Radical ideas for conservation, and their implications. Oryx, 51(3), 407–410.

Butchart, S. H. M., Clarke, M., Smith, R. J., Sykes, R. E., Scharlemann, J. P. W., Harfoot, M., … Burgess, N. D. (2015). Shortfalls and Solutions for Meeting National and Global Conservation Area Targets. Conservation Letters, Vol. 8, pp. 329–337.

White, M. P., Alcock, I., Grellier, J., Wheeler, B. W., Hartig, T., Warber, S. L., … Fleming, L. E. (2019). Spending at least 120 minutes a week in nature is associated with good health and wellbeing. Scientific Reports, 9(1), 7730.