A1.1.5 Human Interventions


Human Interventions and Ecological Systems

All ecosystems change; they are dynamic, living things. However, human activity has done a great deal to damage the planet’s natural ecosystems – through pollution, exploitation of natural resources, biodiversity loss and even the introduction of outside species.

Ecosystems are dynamic and changing within themselves and are also subject to the action of outside forces, not least of all climate change. Climate and vegetation are the prime definers of an ecosystem and changing climates can exaggerate the damage done by other damaging inputs into systems, such as pollution and destruction of habitats.

Whilst human caused greenhouse gas emissions continue to rise, the global capacity to absorb them is declining due to ecosystem degradation. Continuation of this imbalance will lead to climate instability and reduce essential ecosystem services.

Climate stabilisation can only be achieved by balancing emissions sources (human and natural) and the global ecosystems’ sink capacity. The protection and management of the world’s ecosystems offers a highly cost effective multiple “˜win’ mechanism for mitigation by enhancing sink capacity and protects the essential life supporting ecosystem services that will enable societal adaptation to climate change. Even if there were no human activities on Earth, carbon would flow through the atmosphere because of natural biological and geological activity. Our planet is a dynamic geological and biological system. It produces and absorbs carbon and other greenhouse gases through a range of natural cycles and across a wide variety of ecosystems,

Natural ecosystems could also play a role in stopping some of the harmful effects of climate change. Plants store carbon, keeping it out of the atmosphere, so ecosystems as carbon stores, are a natural defence for our future.

Human activity has intervened in these natural carbon cycles in two main ways:

  • By creating major new sources of carbon emissions from the use of fossil fuels;
  • By degrading natural sinks of carbon by polluting or transforming natural ecosystems.


The combined result of these human interventions has been to change the planetary balance between the sources, sinks and storage pools of carbon. Put crudely, Earth is now emitting more carbon to the atmosphere than it can absorb. This changing imbalance is reflected in a progressive increase in CO2 concentrations in the atmosphere which has led to climate change. Putting these things together, it can be seen that there are three main components to the global carbon cycle.

  • Those emissions due to human activity.
  • Those emissions from ecosystems.
  • There is only one assured sink: the capacity of global ecosystems to absorb carbon.


This is shown in the diagram below:

Imbalance of components for climate stabilisation

(Note proportions of size are not to scale and do not reflect actual values of fluxes)

Source: http://www.worldresourcesreport.org/