Tag Archives: the nitrogen cycle

Don’t Buy “Planetary Boundaries” Hype

From Science Matters

By Ron Clutz

Latest diagram from Stockholm Resilience Centre

The usual suspects are beating on their “planetary boundaries” drum to scare up submission to Zero Carbon restrictions.  Remember these are the same climate justice warriors pushing the notion of a new geological era named “Anthropocene”.  For example, cue the following:

Six of nine planetary boundaries now exceeded–Phys.org

Humans Have Crossed 6 of 9 ‘Planetary Boundaries’–Scientific American

Earth is now outside most of the “planetary boundaries” under which human civilization emerged–TechSpot

Six out of 9 planetary boundaries breached, Earth increasingly becoming uninhabitable for humans–MSN.com

Humanity deep in the danger zone of planetary boundaries: study–YAHOO!News

Etc., Etc. Etc.


In 2009, a group of 29 scholars published an article in Nature, advancing an approach to define a “safe operating space for humanity” (1). The group argued that we can identify a set of nine “planetary boundaries” that humanity must not cross at the cost of its own peril. Since this 2009 publication, the concept of planetary boundaries has been highly influential in generating academic debate and in shaping research projects and policy recommendations worldwide. At the same time, the concept has come under heavy scrutiny as well, and many critics have taken the floor contesting the broader framework as well as its implementation and interpretation. Partially because of this critique, the original proposition of nine planetary boundaries has undergone various reformulations and updates by their proponents and an emerging network of scholars specializing in planetary boundary research.

The original 2009 paper in Nature suggested nine boundary conditions in the earth system that could, if crossed, result in a major disruption in (parts of) the system and a transition to a different state, which is likely to be hostile to human prosperity. The proposed planetary boundaries included:

♦  climate change,
♦  biodiversity loss,
♦  the nitrogen cycle,
♦  the phosphorus cycle,
♦  stratospheric ozone depletion,
♦  ocean acidification,
♦  global freshwater use,
♦  land use change,
♦  atmospheric aerosol loading, and
♦  chemical pollution.

For each of these planetary boundaries, one or more control variables were identified (e.g., atmospheric carbon dioxide concentration), which in turn were assigned with numerical boundary values at a “safe” distance from dangerous levels, or where applicable, “tipping points” in earth system processes (1).

Eventually, the framework should allow for quantification of threshold parameters, as a guide also for political responses. For some planetary boundaries, the group in 2009 suggested that the current state of knowledge was too uncertain to allow for quantification. Yet, for other earth system processes, the group felt confident enough to suggest a specific boundary value. In this endeavor, they erred on the side of caution and a strict interpretation of the precautionary principle: Where they saw remaining uncertainties, the group suggested the lower values for the boundary that they identified.

They concluded that three planetary boundaries had been crossed already.

On climate change, for instance, the boundary value proposed was 350 ppm, which had been passed long ago in the second half of the twentieth century. Regarding biodiversity, the current extinction rate is more than 100 extinct species per million species per year, whereas the suggested boundary was 10 extinctions. As for the nitrogen cycle, humans remove today approximately 121 million tons of nitrogen per year from the atmosphere, whereas a safe rate would be a maximum of 35 million tons. In these three areas, therefore, this analysis suggested that humankind had pushed the earth system past planetary boundaries and possibly dangerous levels, into a new—and unknown—world.  Source: The Boundaries of the Planetary Boundary Framework: A Critical Appraisal of Approaches to Define a “Safe Operating Space” for Humanity.  Annual Review of Environment and Resources October 2020

We don’t know how long we can keep transgressing these key boundaries before combined pressures lead to irreversible change and harm.–Johan Rockström, co-author and Centre researcher

Critics of the Planetary Boundaries Framework

Leaving aside those who want the boundaries to be tighter and harder than presented, let’s hear from critics challenging the whole enterprise. Shortly after the invention of “planetary boundaries,” Breakthrough Institute published a thorough critique of the notion and the framework.  Planetary Boundaries: A Review of the Evidence.  Linus Blomqvist (2012)

The planetary boundaries hypothesis – embraced by United Nations bodies and leading nongovernmental organizations like Oxfam and WWF – has serious scientific flaws and is a misleading guide to global environmental management, according to a new report by the Breakthrough Institute. The hypothesis, which will be debated this month at the UN Earth Summit in Brazil, posits that there are nine global biophysical limits to human development. But after an extensive literature review and informal peer review by leading experts, the Breakthrough Institute has found the concept of “planetary boundaries” to be a poor basis for policy and for understanding local and global environmental challenges.


♦   Six of the “planetary boundaries” — land-use change, biodiversity loss, nitrogen levels, freshwater use, aerosol loading, and chemical pollution — do not have planetary biophysical boundaries in themselves.

♦   Aside from their impacts on the global climate, these non-threshold “boundaries” operate on local and regional, not global, levels.

♦   There is little evidence to support the claim that transgressing any of the six non-threshold boundaries would have a net negative effect on human material welfare.  The full report is linked below:

A new report from the Breakthrough Institute highlights scientific flaws
of the “planetary boundaries” hypothesis

Planetary Boundaries as Power Grab–Giving Political Decisions a Scientific Sheen–Roger Pielke Jr. (2013)

When the cover of the Economist famously announced Welcome to the anthropocene’ a couple of years ago, was it welcoming us to a new geological epoch, or a dangerous new world of undisputed scientific authority and anti-democratic politics?

The basis for the power grab by the experts – really old wine in new bottles – is the fashionable idea of planetary boundaries which holds that there are hard and fast ecological limits within which human activity must be constrained. The concept is much contested scientifically — such as in this excellent review by my colleagues at The Breakthrough Institute.

A real-world example of the implications of the planetary boundaries political philosophy is vividly seen through the issue of global energy access. Future global development, at least in the short term, necessarily will involve trade offs between expanded use of carbon-emitting fossil fuels and the expansion of energy access to the world’s poorest. The planetary boundaries advocates, consist with their hierarchical values framework, call for “universal clean energy” and recommend development targets focused not on measuring expanded energy access, but rather carbon dioxide emissions (here in PDF).

In other words, expanded energy access to the world’s poorest is deemed acceptable
only if it first satisfies the demands of planetary boundaries – in other words,
the political demands of the scientists couched in the inviolable authority of science.

An major recent critique was: Planetary Boundaries for Biodiversity:  Implausible Science, Pernicious Policies  by Montoya, Donohue and Pimm. Trends in Ecology and Evolution (2018)

The notion of a ‘safe operating space for biodiversity’ is vague and encourages harmful policies. Attempts to fix it strip it of all meaningful content. Ecology is rapidly gaining insights into the connections between biodiversity and ecosystem stability. We have no option but to understand ecological complexity and act accordingly.

How best should environmental science articulate its concerns, set research agendas, and advise policies?One solution embraces the notion of planetary boundaries [1] arguing that global environmental processes very generally have ‘tipping points’. These are catastrophes involving thresholds beyond which there will be rapid transitions to new states that are very much less favorable to human existence than current states. The associated notion is that humanity’s ‘business as usual’ can only continue so long as it remains within some ‘safe operating space’.

We show that notions of planetary boundaries add no insight into our understanding
of the threats to biodiversity and ecosystem functioning, have no evidence to support them,
are too vague for use by those who manage biodiversity, and promote pernicious policies.

Fatally, the boundaries framework lacks clear definitions, or it has too many conflicting definitions, does not specify units, and fails to define terms operationally, thus prohibiting application by those who set policy or manage natural resources. Moreover, recent reviews indicate that tipping points occur only rarely in
natural systems [6], while policies related to boundaries are unlikely to be evidence based. A need for operational definitions to aid managers is self-evident [7].

At the heart of the problem are terms such as ‘planetary boundaries’, but also ‘sustainability’, ‘health’, ‘harmony’, and others, that are emotionally appealing but rarely, if ever, defined. They all speak to the urgent need to understand how human impacts change ecosystems, when at best we aspire to protect only
half of it. We must set policies and establish management for the vast tracts of land and sea that we do not protect. Fatally, those who do so often use language that does not borrow from the existing knowledge about ecosystem processes, nor readily translates its aspirations to those who study them [7].

See Also:

Planetary Boundaries as Millenarian Prophesies  Malthusian Echoes

The identification of the planetary boundaries is dependent on the normative assumptions made, for example, concerning the value of biodiversity and the desirability of the Holocene. Rather than non-negotiables, humanity faces a system of trade-offs – not only economic, but moral and aesthetic as well. Deciding how to balance these trade-offs is a matter of political contestation (Blomqvist et al, 2012:37). What counts as “unacceptable environmental change” is not a matter of scientific fact, but involves judgments concerning the value of the things to be affected by the potential changes. The framing of planetary boundaries as being scientifically derived non-negotiable limits, obscures the inherent normativity of deciding how to react to environmental change. Presenting human values as facts of nature is an effective political strategy to shut down debate.

Beyond Planetary Boundaries by Michael Shellenberger, Ted Nordhaus, and Linus Blomqvist (2012)

There are useful implications for environmental change science that can be drawn from where planetary boundaries went wrong. First, any pragmatic framework on environmental change must look at benefits and costs. Some of the hypothesis’s authors have said that their motivation was to provide a useful framework for helping global leaders manage environmental change. We applaud and support this motivation. But for any environmental change framework to be useful, it must seek to understand not only the costs of change but also its benefits.

One of the implications of this is that simply measuring variance from Holocene baselines is a highly misleading metric of human sustainability. Since so much variance from the Holocene has been good for humans, future environmental change cannot be assumed, as planetary boundaries does, to be negative for our welfare.