34
these include the rate of biodiversity loss, climate change, and the human interference with the nitrogen cycle (Rockström et al., 2009). The ‘planetary boundaries’ model tries to identify an earth-system
process and associated thresholds that, if exceeded and crossed, could generate unparalleled environmental impacts and change (Fig. 3.4). Rockström et al. (2009) have identified nine processes that they
believe are necessary to define the planetary boundaries of sustaining the earth’s systems, and these
include:
• Climate change;
• Rate of biodiversity loss (terrestrial and marine);
• Interference with the nitrogen and phosphorus cycles;
• Stratospheric ozone depletion;
• Ocean acidification;
• Global fresh water use;
• Change in land use;
• Chemical pollution; and
• Atmospheric aerosol loading.
In the context of climate change, the proposed boundary for atmospheric CO 2 concentrations
should not exceed 350 ppm (parts per million by volume), and radiative forcing should not exceed 1 watt
per square meter above pre-industrial levels (Hansen et al., 2013). In December 2019 the average
monthly level of CO 2 concentration in the Earth’s atmosphere exceeded 413 ppm,
2
and the annual average in 2018 was 407.4 ppm (Lindsey, 2019). The question that I raise is: Will we be able to reduce or
stop the increase in CO 2 concentration levels?
The on-going growth of the built environment and global urbanisation will continue to have significant impacts on the global climate system, biodiversity and the different levels of organisation of
ecosystems. On the other hand, the provision of ecosystem services to communities and society in
general will be negatively affected (Campbell et al., 2009; McCarthy, 2001). There is also solid evi2 CO 2 records provided by CO2.earth, compiled from two independent records and databases, NOAA-ESRL and
SCRIPPS UCSD. Retrieved on 6 January 2020, from https://www.co2.earth
Fig. 3.4 The Planetary Boundaries of Sustaining the Earth’s Systems (Drawing by Jesse Delmo, synthesised by
Roös, from the model by Rockström et al., 2009)
3 The Challenge of a Changing Environment
these include the rate of biodiversity loss, climate change, and the human interference with the nitrogen cycle (Rockström et al., 2009). The ‘planetary boundaries’ model tries to identify an earth-system
process and associated thresholds that, if exceeded and crossed, could generate unparalleled environmental impacts and change (Fig. 3.4). Rockström et al. (2009) have identified nine processes that they
believe are necessary to define the planetary boundaries of sustaining the earth’s systems, and these
include:
• Climate change;
• Rate of biodiversity loss (terrestrial and marine);
• Interference with the nitrogen and phosphorus cycles;
• Stratospheric ozone depletion;
• Ocean acidification;
• Global fresh water use;
• Change in land use;
• Chemical pollution; and
• Atmospheric aerosol loading.
In the context of climate change, the proposed boundary for atmospheric CO 2 concentrations
should not exceed 350 ppm (parts per million by volume), and radiative forcing should not exceed 1 watt
per square meter above pre-industrial levels (Hansen et al., 2013). In December 2019 the average
monthly level of CO 2 concentration in the Earth’s atmosphere exceeded 413 ppm,
2
and the annual average in 2018 was 407.4 ppm (Lindsey, 2019). The question that I raise is: Will we be able to reduce or
stop the increase in CO 2 concentration levels?
The on-going growth of the built environment and global urbanisation will continue to have significant impacts on the global climate system, biodiversity and the different levels of organisation of
ecosystems. On the other hand, the provision of ecosystem services to communities and society in
general will be negatively affected (Campbell et al., 2009; McCarthy, 2001). There is also solid evi2 CO 2 records provided by CO2.earth, compiled from two independent records and databases, NOAA-ESRL and
SCRIPPS UCSD. Retrieved on 6 January 2020, from https://www.co2.earth
Fig. 3.4 The Planetary Boundaries of Sustaining the Earth’s Systems (Drawing by Jesse Delmo, synthesised by
Roös, from the model by Rockström et al., 2009)
3 The Challenge of a Changing Environment