The state of our planet
Natural processes interacting with air, land and water create the environment on which all living things – including humans – depend. Since their emergence some 50,000 years ago modern humans have started to change the natural environment to suit their needs. Perhaps the oldest known example of this is the use of fire by Aboriginal people to manage plant species occurring in their environment and to support some hunting practices.
The development of agriculture create an intensification of this process with humans not just managing the natural environment but using technology to completely alter parts of their environment. Over the last 250 years this process has radically altered the state of our planet under the combined influence of a growing population, the intensification of agriculture and the industrial revolution.
Concerns about these human induced changes to the natural environment have been expressed for over 100 years. They have gained in societal and political acceptance since the 1970s and are fairly widely accepted today.
The most comprehensive assessment of these changes and their implications for humans as well as the natural environment was presented by the United Nations in its Millennium Ecosystem Assessment report (2005). Among the key findings of the report are:
- About 24% of land surface on earth has been converted to cropland
- Since 1980 35% of the world’s mangroves and over 20% of the world’s coral reefs have been lost
- Humans consume 40% – 50% of readily accessible fresh water running of land
- At least a quarter of all marine fish stocks is overfished and the total volume of fish in most seas is less than one tenth of the volume it was prior to industrial fishing
- Species extinction rates are between 100 and 1,000 higher today than historical levels
- The degradation and destruction of habitat has been the dominant driver of species extinction over the past 30 years
- The conservation status of less than 10% of known species has been accessed. Of the well-studied taxa between 12% (birds) and 52% (cycads) of species are threatened
- Climate changes is becoming the dominant driver of species extinction
The list makes for very sobering reading and does not boast of a planet that is in particularly good health. The last point in particular is cause for concern. It is highly unlikely that the world will avoid less than 2° C warming. According to the IPCC this would cause extensive bleaching of all coral reefs in the world, cause the loss of up to 47% of rainforest in Queensland and result in extinction of up to 30% of all species worldwide.
The potential impacts of climate change clearly demonstrate that human impacts on the natural environment occur not just through the clearing of land for cropland. Other issues that are of increasing concern are the amount of phosphorus and nitrogen that are applied to cropland as fertiliser and make their way into waterways and other parts of the ecosystem.
In 2009 a paper was published by the Stockholm Resilience Institute in which a group of scientists described a set of nine planetary boundaries that provide a ‘save operating environment for human development’. They argue that overstepping these boundaries will result in environmental consequences that will ultimately impact on the safety and prosperity of human beings. The nine planetary boundaries are:
- Biodiversity loss
- The ozone layer
- Climate change
- Ocean acidification
- Fresh water consumption
- Land use change
- Nitrogen & Phosphorus
- Chemical pollutants
- Airborne pollutants
Scientists have not yet established a clear boundary for chemical and airborne pollutants but agree that a planetary boundary does exist given the significant impact of both pollutants on species health, reproduction and extinction as well as on physical and biological process in land, air and water that are affected by pollutants.
Three of the boundaries: Biodiversity loss, Climate change and Nitrogen have already been exceeded (with phosphorus close to its boundary).