The anthropause — the period of global decline in human mobility caused by Covid19 restrictions — will be recorded as an unusual episode within the centuries of continuous intensification of human activity. Even though the anthropause may not reverse the impacts of long-term human development, it is helping scientists understand how humans affect species distribution as well as habitat quality and availability worldwide.
Since the 18th century, the human population has increased by 6 billion. The area of developed land has increased seven times. And the application of faster and more aggressive technologies for resource extraction (agriculture, mining, forestry, etc) and land modification has challenged ecological succession and traditional methods of ecosystem restoration. Reverting these trends can begin by quantifying and understanding the distribution of the global human footprint.
Measuring human activity.
Humans have transformed more than half of the natural environment since the 1800s. This has been the general conclusion of 30 years of scientific initiatives to measure the global human footprint, despite their differences on their inputs and methods.
Among these initiatives, the relatively recent Global Human Modification Index (2019) was developed as a quantitative methodology based on the scaling and aggregation of different datasets and human stressors to quantify anthropic land modification in a manner that is useful for conservation planning. On the other hand, the anthromes (anthropogenic biomes) were defined to categorise the world land into six major classes (and a total of 18 subclasses) based on global population, land use, and land cover. While the classification of the world into anthromes is qualitative, the calculations behind them quantify numerous metrics, and are comparable to the Global Human Modification Index. In fact, recent research has identified correlations between both methods, where areas classified as (densely) populated anthromes and croplands score greater human modification index than wilderness and semi-natural lands.
Wilderness: Wilderness or wildlands (usually in the plural), are natural environments on Earth that have not been significantly modified by human activity or any non urbanized land not under extensive agricultural cultivation. (Wikipedia, accessed 19 October 2020)
Wildlands: Lands without human populations or substantial land use (Ellis et al. 2010)
Semi natural lands: Inhabited lands with minor use for permanent agriculture and settlements (Ellis et al. 2010)
From wildlands, semi-natural lands, and rangelands, to croplands, villages, and dense settlements, Ellis et al.’s research has produced an overview on the extent and distribution of world’s anthromes since the 18th century. This allows us to look into how humans modified the world during the past 400 years, and the results are staggering.
Results from long-term anthrome changes show that wilderness (wildlands and semi-natural lands) has decreased 42% globally. This decrease comes at the expense of a 25% increase in rangelands and a 17% increase in populated lands and croplands since the 1700s. During these four centuries, land changes have been more widespread in Australia, Europe, North America, and South Africa. On the other hand, areas with harsher conditions for humans are the ones that remained less impacted: Sahara, the North-American north west, and north-eastern Asia.
Hope for all!
While these results show great habitat loss at the expense of human development, we remain hopeful. There is space to work on and improve the current situation. These models do not only show a grim depiction of the effects of human development on Earth. They also show potential for restoration, and vast knowledge on how to advise land management worldwide. Based on the findings by the previously mentioned research, rangelands (grasslands, shrublands, woodlands, wetlands, and deserts that are grazed by domestic livestock or wild animals) could constitute restorable lands with the potential to reach near-natural state.
Restoration and conservation efforts, however, cannot put at risk the identity, culture, and livelihood of the human populations that inhabit them. “Restoration interventions are as much about people as they are about environments” (Koech et al., 2020), although this has not always been considered. Even more important is the consideration that traditional and Indigenous knowledge on land management has been proven successful at conserving ecosystems. Despite constituting less than 5% of the global population, Indigenous peoples manage most of the planet intact landscapes.
Considering its social implications, the restoration of these lands could partially revert four centuries of increasing degradation trends and contribute to the protection of biodiversity worldwide. Scientific research supports the idea of short-term effective action to tackle human-activity-derived issues on biodiversity and climate change. Furthermore, science-backed public calls for change have been successful in the past. For example, Rachel Carson’s Silent Spring started a movement that ended with the banning of DDT pesticides worldwide.
Reinforcing positive —and realistic— science-backed messages can prompt public and non-profit calls for change, political action, and encourage the private economic sector to revise supply chain management. Only with collective action can we make the temporary effects that the planet experienced during the 2020 anthropause long-lasting and improve ecosystem quality worldwide.