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Only 3% of the World's Ecosystems Remain Intact

Jonny Rogers explores how human activity has changed life on this planet, and why scientists believe that reintroducing key species might make a significant difference.

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According to a study published in Frontiers in Forests and Global Change, no more than 2.9% of the Earth’s land surface currently remains ‘faunally intact’, with animal or plant species undisturbed by human activity.

Although ‘intactness’ is often loosely-defined, the study follows the Key Biodiversity Areas Standard established in 2016, according to which an ‘intact ecological community’ is one which has “the complete complement of species known or expected to occur in a particular site or ecosystem, relative to a regionally appropriate historical benchmark, which will often correspond to pre-industrial times”.

However, by comparing the biodiversity of areas larger than 10,000 sq. kilometres with maps showing where animals have disappeared since the year 1500 AD (as included in the IUCN Red List), the study concluded that less than 3% of the world’s terrestrial surface could satisfy this description.

Why Biodiversity Matters

An ecosystem is defined by National Geographic as an area in which “plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life”. These ecosystems are often connected to biomes, or larger sections of land, sea and atmosphere such as forests, ponds, reefs and tundra.

Every factor involved in an ecosystem depends on the presence of every other factor: even a small change in temperature, for example, might affect what species of plants grow in the area, thereby forcing local animal populations to adapt, relocate or perish. As such, biodiversity – or the healthy presence of a wide range of plants, insects and animals (even including the ones we don’t like!) – is essential for our mutual flourishing.

However, recent decades have seen a growing recognition that the impact of human activity on global ecosystems is one of the most important and understated issues facing contemporary civilisation. WWF’s Living Planet Report 2020 estimated that the population sizes of mammals, birds, fish, amphibians and reptiles have dropped by 68% since 1970. Another study published this January criticised world leaders for underestimating the present threat to biodiversity, predicting a ‘ghastly future’ for all life on Earth if we fail to change our actions and priorities.

Previous research, calculated through a combination of satellite imagery and computer algorithms, estimated that 20 to 40% of the planet’s terrestrial surface is under low human influence. However, the latest study showed that habitats which might appear intact are often missing species that play important roles in local ecosystems.

Although habitat degradation as a result of human activity is one of the most significant causes of species loss, the study points out that this is not the only cause. For example, overexploitation, hunting, invasive species and disease, though harder to calculate or identify, can also severely disturb animal populations, thereby causing calamitous repercussions for entire ecosystems. An intergovernmental report in 2019 concluded that the biggest threats to global biodiversity are, in descending order: changes in land and sea use; direct exploitation of organisms; climate change; pollution and invasive alien species.

Some scientists, such as Professor Pierre Ibisch, have criticised the latest research for failing to properly take the impact of climate change into account:

“Accelerating climate change is becoming the overarching threat to the functionality of entire ecosystems. Yesterday’s mammal intactness hardly tells us a lot about the functioning ecosystems in the [global heating] age.”

However, Dr Andrew Plumptre, the paper’s lead author, acknowledges that the 3% figure is a “ballpark estimate”, suggesting that future research could focus on smaller regions and apply more detailed data. Nevertheless, it is undeniable that human civilisation has become a dominant force in shaping life on this planet.

Species Reintroduction

The few areas that currently remain unaffected by human activity include parts of the Amazon and Congo, east Siberia and northern Canada, and the Sahara Desert. However, only 11% of the areas defined as ‘functionally intact’ – habitats in which there is no reduction in faunal densities below ecologically-functional level – are included within existing protected areas, though many of these coincide with territories managed by indigenous communities.

Although the study’s conclusions might be deeply troubling, the researchers do not intend to encourage despair or passivity. In fact, the study also suggested that up to 20% of the Earth’s land surface could be restored through the reintroduction of certain key species such as forest elephants in areas of the Congo Basin, or buffalo and giraffes in African savannas.

The reintroduction of Yellowstone grey wolves in 1995 caused a ripple of positive changes throughout the entire ecosystem: deer populations were driven away to graze elsewhere, trees grew five time larger, bare landscapes became forests, migratory birds returned, new beaver colonies provided habitats for other creatures and so forth. Even the landscape was changed in the process - regenerating forests stabilised the banks of rivers and reducing deer populations limited soil erosion in the area.

Nevertheless, such significant and lasting change can only come about if world leaders shift their priorities and introduce laws preventing restored animal populations or land conservation efforts from being later used for commercial purposes. As Paul de Zylva, senior sustainability analyst for Friends of the Earth, explains:

“There are few truly wild places left and too many are under assault from oil and gas exploration, mining and land grabs. Our political and business leaders [...] need to stand up to vested interests who seek to profit at the expense of both people and planet.”

How we act today will determine the future of life on this planet. Thankfully, some world leaders have already recognised this: at the beginning of this year, a coalition of more than 50 countries pledged to protect 30% of the Earth’s land and oceans to slow wildlife extinction. While this commitment will not restore what has been lost, it is certainly a huge step in the right direction.


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