Geoscience Reference
In-Depth Information
Table 6
. Planetary boundaries
Boundary
Control variable
Boundary
crossed
1. Climate change
Atmospheric carbon dioxide concentration (ppm by
volume)
yes
Alternatively: Increase in radiative forcing (W/m
2
)
since the start of the industrial revolution (~1750
CE)
yes
2. Biodiversity loss
Extinction rate (number of species per million per
year)
yes
3. Biogeochemical
(a) anthropogenic nitrogen removed from the atmo-
sphere (millions of tonnes per year)
yes
(b) anthropogenic phosphorus going into the oceans
(millions of tonnes per year)
no
Global mean saturation state of aragonite in surface
seawater (omega units)
no
4. Ocean acidification
5. Land use
Land surface converted to cropland (per cent)
no
6. Freshwater
Global human consumption of water (km
3
/yr)
no
7. Ozone depletion
Stratospheric ozone concentration (Dobson units)
no
8. Atmospheric aerosols
Overall particulate concentration in the atmosphere,
on a regional basis
Not defined
Concentration of toxic substances, plastics, endo-
crine disruptors, heavy metals, and radioactive con-
tamination into the environment
Not defined
9. Chemical pollution
The planetary boundaries concept only deals with the physical environment and there is a
strong argument that human societal boundaries should also be included. These could be
access to food, water, health services, education, and energy. At the moment, the state of
humanity is completely unacceptable: seven million children die needlessly each year;
700 million people go to bed hungry each night; 1,000 million people do not have regular
access to clean safe drinking water; 1,100 million people do not have access to electricity;
and 3,500 million people live on less than $3.25 per day. The UN Millennium Develop-
ment Goals (MDGs) have had a significant impact over the last 15 years in reducing
poverty and increasing life expectancy, though all agree there is still a very long way to
go. Concurrent with the climate change negotiations are UN negotiations on the post-2015
MDGs, which will be called the Sustainable Development Goals that will encapsulate the
need for poverty eradication while protecting the environment. Hence climate change and
environment considerations will be central to the UN view of economic development.
