The Stockholm Resilience Center in Sweden has measured and quantified nine of the major environmental threats to our planet. The purpose is to define the boundaries within which humans can safely continue to thrive and develop for generations to come without irreversible impacts on the environment causing negative feedbacks to human survival (Figure 24).
Throughout Healing Earth, we will explore all nine of these environmental threats. For now, we concentrate on biodiversity, the most severely threatened feature of the environment. What are the main causes of Earth’s declining biodiversity and what can be done about it?
The 2005 MEA reported that changes in biodiversity due to human activities were more rapid in the past 50 years than at any time in human history, increasing the risks of abrupt and irreversible changes to ecosystems.
Anthropogenic (human-induced) modification and destruction of habitat via land use is the most severe driver to loss of biodiversity. Land use transforms the physical environment, rendering it unsuitable to support high biodiversity (Figure 25). Different types of land use and its consequences include conversion of land to agriculture, urbanization, deforestation, desertification from over-grazing by livestock, infrastructure development (i.e., pipelines, construction of roads and railways) and introduction of toxins and other pollutants.
Habitat loss is the primary cause of decline for species and populations because it removes the flora and fauna that each species requires for life. When more and more land use occurs within areas of high species richness, loss of biodiversity is greatly exacerbated and species extinctions increase.
Habitat fragmentation occurs when land use activities divide and separate previously continuous habitats within a landscape. The effects of habitat fragmentation tend to be most severe for species that have large area requirements, poor dispersal ability, naturally unstable populations, or low population growth rates.
You will learn in the upcoming Biodiversity and Spirituality section that many biodiversity hotspots contain lands preserved by Indigenous People as sacred lands.
The major cause of habitat loss on the planet is agriculture and its expansion. The demand for food security – and recently, for biofuel – has led to agricultural expansion that accounts for >30% of conversion of land from diverse ecosystems to primarily large scale growth of monoculture crops.
One could argue that humans are the most destructive invasive species, in that our influence is expansive and affects life in all biomes on Earth. As a result of human activities, extinction rates are now 1,000 – 100,000 times higher than the natural rate of extinctions, referred to earlier as the Anthropocene Mass Extinction. In contrast to other extinctions, which occurred over long periods of geologic time, this sixth extinction event is occurring much more rapidly.
It is believed that around 10,000 species have gone extinct within the last 100 years. According to Conservation International, one third of all amphibian species are threatened with extinction, as well as nearly half of turtles and tortoises, one in eight bird species, and one in four species of mammal. The World Conservation Union reports that 52% of known insect species, and 73% of known flowering plants are in danger of extinction. In addition, overfishing and climate change are putting countless marine species at risk.
Questions to Consider
- What type of terrestrial biome do you live in?
- What aquatic ecosystem is closest to where you live?
- Imagine that you had a chance to change a parcel of land near where you live in order to benefit your community. How would you change it? Would this change improve biodiversity where you live, or threaten it? Explain.
To slow the rate of biodiversity loss on Earth, broad cooperation is needed from industry, agriculture, governments, non-governmental organizations, communities, and individuals around the world. However, without sincere recognition of the moral value of biodiversity, cooperation will be difficult to sustain when economic and political pressures push against the good intentions of people and institutions. An ethical perspective is necessary to direct and strengthen our scientific knowledge of biodiversity toward a healed Earth. This is the subject of our next section.