Week 6: Planetary Boundaries Framework Pt. 1 - Post 1

Planetary Boundaries Framework Pt. 1 - Notes

Lecture 1- Introducing the Planetary Boundaries Framework

Professor Johan Rockstrom

+The first module in this cluster on Planetary Boundaries will be introducing the three large processes, the three large planetary boundaries with global scale tipping points: climate change, ocean acidification, and ozone depletion.

+In this lecture we'll be exploring the origins of the planetary boundary framework.

The first one is the insight that we've entered the Anthropocene; the exponential pressures on the Earth system that we now have become a geological force of change at the planetary scale, which collides with the insight that we can no longer exclude catastrophic, irreversible tipping points in the Earth system.

Could we as humanity push the entire Earth system outside of its current stability domain?

This graph showing that the planet can actually reside in multiple stable states separated by a threshold.

So the starting point of thinking around a planetary boundary framework is the recognition that the stable desired state of the planet is the Holocene, and therefore our endeavor is to try and define what are the Earth system processes that regulate the Earth's ability to remain in a Holocene equilibrium, in a Holocene desired state?

Can we for each one of those try and identify a control variable and put a quantitative science-based boundary beyond which we risk feedbacks, interactions, and surprise thatcould risk the entire system to move over a tipping point and push the system outside of the Holocene?

+which means that the planetary boundary concept resides on three pillars of scientific enquiry.

The first one is clearly the Earth system understanding of the planet as a self-regulating geobiochemical system where the interactions occur all the time between the biosphere, the atmosphere, the cryosphere, the hydrosphere and the climate system, and that we are safely enveloped around the stratospheric ozone layer.

The Second line of enquiry is The research advancements understanding the relationship between human needs and the capacities of our biosphere to support humanity.

The third line of enquiry is the enormous advancements we've made in understanding the nonlinear dynamics in complex ecosystems and biomes, the whole domain of resilience theory, complex systems research where we're understanding increasingly that systems can actually cross tipping points and change very rapidly.

+So planetary boundary theory and its framework originates from these three lines of enquiry and is a natural next step in our understanding.

Key Point- So the planetary boundary framework decouples itself from humanity in the diagnostic and the definition of the boundaries. This gives us a safe operating space, which is entirely biophysical. It makes no assumptions of human needs, no assumptions on human innovation capacity. And then you can put back humanity inside that safe operating space. So it liberates ourselves from the risk of making underestimates, overestimates of our ability to develop.

Lecture 2- Justification for Planetary Boundary Selection

Professor Johan Rockstrom

What makes a planetary boundary process a planetary boundary process? Well, the key criteria that have to be fulfilled is that it's an environmental process that is part of regulating the ability of the Earth system to remain in our current desired state, the Holocene equilibrium that has enabled human development of the past 10 000 years.

The planetary boundary process is an environmental process that is fundamental in regulating the ability of planet Earth to remain in the Holocene-like state.

-So it's not necessarily so that a system has to have one tipping point at the planetary scale, you can have multiple tipping points, and if they occur in enough places simultaneously they actually add up to a potential influence and impact factor at the Earth system as a whole.

-the result is nine planetary boundary processes. And I can tell you that this enquiry was extremely challenging, and we turned every stone of evidence to see what are the processes that could qualify to play this role?

-Among the nine processes that we've identified, three of them have evidence of planetary scale tipping points, as shown in this graph. That is the climate system.

-Clearly, we know that in the past history of the Earth system the climate system has been pushing the entire planet in and out of glacial and interglacial periods, for example. 

-Ocean acidification is another such process where we see paleoscientific evidence that the entire ocean can go from anoxic to oxic events, so basically oxygen-free or oxygen-rich states, that the ocean can actually flip between different stable states. 

-And clearly the stratospheric ozone layer, which is the protective layer in the upper atmosphere, which protects the entire biosphere from harmful radiation from the Sun.

-we've identified four, which are biosphere processes forming part of planetary boundaries. One is the interference, or the way we manage the large biogeochemical flows of nitrogen and phosphorus, which together with carbon are the big cycles in the world. 

-Atmospheric aerosol loading, which is the amount of soot and pollutants in the air, which in turn regulates the stability of the large rainfall systems, for example in tropical regions, such as the monsoon. 

-Global fresh water use, which is one a significant greenhouse gas, as water vapor, but also the fundamental role of water as the bloodstream of the entire biosphere, regulating the amount of biomass which in turn regulates the amount of carbon in the entire Earth system. 

-Land use change, which is the fundamental fabric for all living species on Earth. 

And biodiversity, the genetic diversity from animals and vegetation and trees, forests, which overall determine the ability of the biosphere to cope with and adapt to changing conditions on Earth.

-One final ninth planetary boundary, which we originally defined as chemical pollution, and increasingly talk of as new entities. This is the recognition from increasing evidence, despite its complexity, that the cocktail of chemical accumulation in the biosphere could potentially cause major shifts in for example the genetic composition of species non Earth, which could be a tipping point in terms of life conditions on Earth.

Overall: So overall therefore nine planetary boundaries: three of which have evidence of large scale tipping points; climate, stratospheric ozone layer, and ocean acidification; four boundaries which operate a little bit more at the smaller scale but regulating the Earth system: biodiversity, land, water, nutrients, and fresh water; and two boundaries which are very heavily anthropogenically caused: both air pollution, which we call aerosol loading, and chemical pollution

Lecture 3 – Quantification of the nine Planetary Boundaries

Professor Johan Rockstrom

-(The challenge arises of defining quantitatively the boundary position for each one of these processes which distinguishes between a safe operating space and entering a danger zone where we have a higher probability of crossing tipping points which would take us away from a safe Holocene state) We look at the vast evidence in the latest science and try to identify first of all a control variable, an indicator or a parameter that regulates each process. So for climate change, for example, it falls naturally to choose the concentration of greenhouse gases, and for each boundary we do the same.

-once we've identified a control variable, we try with the best of our knowledge to identify the point at which science indicates that we approach and are at risk of crossing a tipping point.

Exp.: Pt. 1 - So what we're doing for each boundary process is one, trying to identify a control variable which is a good indicator or proxy for the stability of a system. So for example for the climate system we've identified climate forcing in - defined in the number of watts per square meter of increased heat in the atmosphere, and also carbon dioxide concentration as two good control variables for the climate system.

Pt. 2 - What we try to identify then is the point at which evidence suggests that if we push the system even further, if we cut down even more forest, the feedback into for example the climate system is such that it could push the climate system across a tipping point. And that then becomes the point where we put the boundary.

Zone of uncertainty, essentially a standard deviation in science. And that zone of uncertainty is the zone of uncertainty within science defined here as the yellow range. And somewhere in that yellow range we, with a very high probability, have the threshold, the point where the system crosses a tipping point.

Key Point: So we have one set of boundaries defined on the point along a control variable beyond which the feedbacks can damage other systems, and for those systems which have thresholds we put the boundary at the point beyond which we actually can have a threshold. So that is the fundamental thinking around planetary boundary theory.

+if we can use science to define the boundary levels beyond which we can push the system outside of a stability domain we can actually monitor and keep track of where we are with regards to all the boundaries

+because we are beyond a safe operating space for, for example, climate does not mean that have crossed the tipping point, it just means that we're in a zone where we can potentially see tipping points occurring