The Planetary Ecosystem

The information here is provided by courtesy of the Network's short online course -

"An Introduction to Global Health". 



The human body is made up of millions and millions of cells that function together to form “us”. Each cell depends on another and together they form a complex interdependent system that forms a whole. They are constantly working to keep in balance. 


The cells that make up humans are not alone in the world. We depend on the other things around us – animal, vegetable and mineral - to survive. In the same way, the animals and plants also depend on the other parts of the system in order to survive.


We form part of an inter-dependent group of living things that need each other for survival. If one part of that survival group disappears, then all are threatened.


This interdependence is an ecosystem.


Across the world there are many, many small ecosystems. Figure 1 is an example of one 


Figure 1





The ecosystems interact with each other and they all add up to a planetary ecosystem. Although the loss of a few small individual ecosystems may not have a significant effect on the planet as a whole, the loss of many ecosystems, does. These can lead to extinctions of species and mass extinction events 


Mass extinction events 


There have been 5 major extinction events that we know of in the history of the earth. 


The first, 450 – 440 million years ago, was thought to be from global warming and 60% - 70% of species were killed.


The last, around 66 million years ago, was from the effect of the earth being struck by a large meteorite. 75% of all species became extinct and it was responsible for the end of the 165 million years reign of dinosaurs.


Present day threats of extinctions


Now, the main threat now comes from humans.  Three-quarters of the land-based environment and about 66% of the marine environment having been significantly altered by human actions. Their effects have been, for example, 


  • Land degradation has reduced the productivity of 23% of the global land surface, 
  • At least 680 vertebrate species have been driven to extinction since the 16th century
  • More than 9% of all domesticated breeds of mammals used for food and agriculture had become extinct by 2016, and at least 1,000 more breeds are still threatened.
  • In 2015, 33% of marine fish stocks were being harvested at unsustainable levels; 


As it says in the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Report in 2019 (see below in further reading)


“Nature is declining globally at rates unprecedented in human history – and the rate of species extinctions is accelerating, with grave impacts on people around the world now likely.” 


The health of ecosystems on which we and all other species depend is deteriorating more rapidly than ever. We are eroding the very foundations of our economies, livelihoods, food security, health and quality of life worldwide.”


The main threats to our ecosystem 


The main threats come from  


  • Changes in our use of the land and sea
  • Direct exploitation of the land, animals, fish etc. 
  • Climate change
  • Pollution
  • Invasive alien species 


These have been set out in the report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), 2020, which has a 30 second clip summarising the situation. 


The report finds that


a) Around 1 million animal and plant species are now threatened with extinction,


b) The average abundance of native species in most major land-based habitats has fallen by at least 20%, mostly since 1900.


c) Threatened are


  • More than 40% of amphibian species,
  • almost 33% of reef-forming corals
  • more than a third of all marine mammals
  • around 10% of insect species


Contributing to this


  • Plastic pollution has increased tenfold since 1980,
  • 300-400 million tons of heavy metals, solvents, toxic sludge and other wastes from industrial facilities are dumped annually into the world’s waters,
  • fertilizers entering coastal ecosystems have produced more than 400 ocean ‘dead zones’, totalling more than 245,000 km2 (591-595) – a combined area greater than that of the United Kingdom.


Why this matters 


Our ecosystem is being altered in a way that has never been seen before in human history and the pace of this is increasing. We depend on a biodiverse ecosystem for our health survival. 


What do we need to do about it?


The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (2020) outlines in detail both the issues that we are facing and what we need to do. 


Importantly recommendations include the need for decision makers to base what they are doing on evidence and in a planned rather than ad hoc way. This is encapsulated in the short clip below. 




Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services recommendations



Further Reading 


Overview of the report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), 2020


Summary for Policymakers of the IPBES Assessment


The Intergovernmental  Science-Policy Platform on Biodiversity and Ecosystem Services Organisation 


Human Ecology

Wikipedia :



Wikipedia :


Extinction Event


The Living Planet Report, 2018  


Natural History Museum

The museum has produced a series of YouTube presentations entitle "Our Broken Planet" that examine a variety of topics related to sustainability and pollution.


You Tube videos from the IPBES overviews on : 


a) Assessment of Land degradation and restoration 





b) IPBES Assessment of Pollinators, Pollination and Food Production 







The Planetary Ecosystem image