Let’s first recall the magnitude of the issue such a measure would try to address: a mass species extinction, which has been emphasized in an increasing number of scientific studies. The biosphere is currently incurring an extensive erosion of its basis: species extinction rates are estimated to be hundreds to thousands times higher than the extinction rates normally observed in a stable ecosystem. From a population perspective, it has been recently demonstrated that more than 40% of vertebrate species have experienced severe population declines over the past decades. The causes are multiple but all anthropogenic: habitat destruction and fragmentation, chemical and genetic pollution. Climate change is another threat to add to the list, which could lead to a loss of one sixth to one fifth of species by the end of the century. Such a collapse would create important ecological risk for human societies, as biological diversity determines what is called the natural capital, which is providing essential ecosystem services to economies (in developing countries in particular).
According to E. O. Wilson, protecting half of Earth is the only option if we want to protect ourselves from biological insecurity. The eminent professor estimates that, doing so, about 85% of the species could be saved from extinction.
Presently, a large number of countries have already selected parts of their territory as protected zones. At the global scale, it accounts for 15% of the total land area, and for 12% of aggregated territorial waters (2014, World Bank). This represents about 20 million sq.km, i.e. the surface area of North America. The figures hereunder display the countries that present the largest protected zones:
As it can be directly observed, just a few countries (Australia, Brazil, Russia, China, USA, EU, Canada) already account for 10 million sq.km of protected areas.
If the aggregation of present protected areas is already a significant number, the objective of 50% is still far away: there are still about 50 million sq.km to find, and the effort is all the more important as we may consider that the zones already designated for preservation are (to some extent) the zones which were the most obvious (or easy) to protect, and that difficulty will rise for every additional acre. Moreover, a question remains about the nature of the zone that would be protected: obviously, one acre of desert does not contain the same biological diversity and does not provide the same ecosystem services than one acre of rainforest.
Would the protection of 50% of the Earth preserve the biosphere from a biological annihilation? There are at least three pending conditions: (i) areas designated for protection must shelter a sufficient part of the richest ecosystems, which provide the most important ecosystem services; (ii) these areas have to be adequately designed in order to avoid fragmentation, which is known to be an important biodiversity erosion driver; (iii) the preserved half Earth must be sufficiently safeguarded from pollution flows coming from the other half. The increasing emission of GHG to the atmosphere, for instance, would sooner or later also affect the conserved land.
An additional condition remains, and not the least significant: future governments would have to resist the temptation to breach the security of protected land; they would have to resist the temptation, possibly in the middle of a resource crisis, to clear protected land below which some valuable minerals would be laying; or to move into these free territories, pushed up by a tense demographic situation. This would be unprecedented in human history. In fine, it would all depend on the recognition by the majority of countries of the vital importance of the biosphere. We cannot do this without a new paradigm, without a new global ecological awareness, because some formal laws, if they are not recognized by the majority, will never resist the scarcity of coming times.
Hadrien Lantremange, Natural Capital Analyst