Planetary Boundaries

Back in 2009, two scientists, Johan Rockström and Will Steffen introduced the concept of planetary boundaries. They presented this information to all the relevant people who work in government, science, public sector, private sector... basically all the people that should/need to be concerned with sustainable development. This year, they updated their research and produced a recent paper on this concept (they gathered more data essentially, that allowed them to be more specific with their theory).

The idea is that the Earth is treated like a framework, which is very sensitive to change. What drives these changes? Human activity, and what it does to the global environment. Rockstrom and Steffen (along with 26 other academics) broke down this framework into nine different 'planetary boundaries':

• Climate Change
• Biosphere Integrity
• Biogeochemical flows (sulphur and nitrogen cycles)
• Ocean Acidification
• Land-System Change
• Freshwater Use
• Stratospheric Ozone Depletion
• Atmospheric Aerosol Loading
• Novel Entities a.k.a Chemical Pollution

Each boundary has three thresholds, where most of them can be defined by controlled variables such as temperature, sea level, amount of chemicals found in the atmosphere, etc., and each threshold has a range of values, because the Earth is just too complex to pin-point exact figures.

The 'below boundary' (the safe zone) is where any change to these variables is seen to not have a negative affect on a continental or global scale to the environment;

The 'zone of uncertainty' is where we have evidence that the variables have reached a point where change in the environment is being noticed, but isn't necessarily detrimental;

And then there's 'Beyond the zone of uncertainty', which is deemed 'unsafe' as it is definitely causing a change that is (most likely) not reversible.

Rockstorm and Steffan, have come to the conclusion that two of these boundaries have entered the danger zone (beyond the zone of uncertainty). Biosphere Integrity - Genetic Diversity (we have seen the extinction rate of species increase significantly from 0.1-1 extinctions per million species-years, to >100 E/MSY); Biogeochemical Flows (the use of fertilisers and burning of fossil fuels has increased the level of Nitrogen which is polluting water systems).

Interesting to note that in their original 2009 report, they concluded a crossing of zones within three boundaries! The third being (shocker) Climate Change, but since then it's no longer in the danger zone... very interesting! Why not?!

All but three of the boundaries have definite quantified limits: Biosphere integrity - functional diversity, novel entities and atmospheric aerosols. Why? Because there just isn't enough data (yet!) regarding the usage and impact, however, they do have proposed boundary zones.

I'm going to be focusing on these novel entities, and what evidence there is that they are affecting the environment. Maybe in my research, I'll help find what the quantified limits should be!

"Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it's the only thing that ever has." - Margaret Mead