PLANETARY BOUNDARIES Part 2
LOSS OF BIOSPHERE INTEGRITY (BIODIVERSITY LOSS & EXTINCTIONS)
CHANGE OF BIOSPHERE INTEGRITY
This planetary boundary is one of two core boundaries. This means that if this threshold has been crossed, it affects other processes on earth. The other core boundary is climate change.
By looking at the planetary boundary picture above, you can see that the green to yellow to red piece of the pie, indicates that we have crossed this threshold.
We are now experiencing the sixth mass extinction of planet earth. This beautiful blue and green planet of ours has experienced 5 mass extinctions before. These have been said to be caused by volcano eruptions, asetroid strikes, climate shifts and other natural causes. During these natural phenomenons, species extinction occurs at 1 to 5 species a year. This is called a background rate.
The sixth mass extinction known as the Holocene or Anthropocene extinction is caused by humans. The extinction rate of species is 1,000 to 10,000 times larger than the background rate of previous extinctions.
We are facing a future of losing 30 – 50% of all species by 2050 if we don’t act dramatically now.
This is caused by a number of factors:
- Habitat loss and degration due to farming especially animal agriculture
- Climate change through heat stress and drought stress
- Excessive nutrient load and other forms of pollution
- Over-exploitation and unsustainable use (e.g. unsustainable fishing methods) we are currently using 25% more natural resources than the planet
- Armed conflict, which disrupts human livelihoods and institutions, contributes to habitat loss, and intensifies over-exploitation of economically valuable species, leading to population declines and local extinctions.
- Invasive alien species that effectively compete for a niche, replacing indigenous species
The threat of extinction is at large and includes:
- 1 out of 8 birds
- 1 out of 4 mammals
- 1 out of 4 conifers
- 1 out 3 amphibians
- 6 out of 7 marine turtles
- 75% of genetic diversity of animal crops have been lost
- 75% of the world’s fisheries are fully or over exploited
- Up to 70% of the world’s known species risk extinction if the global temperatures rise by more than 3.5°C
- 1/3rd of reef-building corals around the world are threatened with extinction
- Over 350 million people suffer from severe water scarcity