ISSN 2330-717X

1.5°C Degrowth Scenarios Suggest Need For New Mitigation Pathways


The first comprehensive comparison of ‘degrowth’ scenarios with established pathways to limit climate change highlights the risk of over-reliance on carbon dioxide removal, renewable energy and energy efficiency to support continued global growth – which is assumed in established global climate modelling.

Degrowth focuses on the global North and is defined as an equitable, democratic reduction in energy and material use while maintaining wellbeing. A decline in GDP is accepted as a likely outcome of this transition.

The new modelling by the University of Sydney and ETH Zürich includes high growth/technological change and scenarios summarised by the Intergovernmental Panel on Climate Change (IPCC) as a comparison to degrowth pathways. It shows that by combining far-reaching social change focused on sufficiency as well as technological improvements, net-zero carbon emissions can be more easily achieved technologically.

The findings published in Nature Communications.

Currently the IPCC and the established modelling community, integrated assessment model (IAM), does not consider degrowth scenarios where reduced production and consumption in the global North is combined with maintaining wellbeing and achieving climate goals. In contrast, established scenarios rely on combinations of unprecedented carbon dioxide removal from the atmosphere and other far-reaching technological changes.

The results show the international targets of capping global warming to 1.5C-2C above pre-Industrial levels can be achieved more easily in key dimensions, for example:

Lead author, Mr Lorenz Keyßer, from ETH Zürich whose Master’s thesis is on degrowth, carried out the research in Australia under supervision of global leader in carbon footprinting Professor Manfred Lenzen, from the University of Sydney’s centre for Integrated Sustainability Analysis (ISA) in the School of Physics.

Mr Keyßer said he was surprised by the clarity of the results: “Our simple model shows degrowth pathways have clear advantages in many of the central categories; it appears to be a significant oversight that degrowth is not even considered in the conventional climate modelling community.

“The over-reliance on unprecedented carbon dioxide removal and energy efficiency gains means we risk catastrophic climate change if one of the assumptions does not materialise; additionally, carbon dioxide removal shows high potential for severe side-effects, for instance for biodiversity and food security, if done using biomass. It thus remains a risky bet.

“Our study also analysed the other key assumption upon which the modelling of the IPCC and others is based: continued growth of global production and consumption.”

The senior author Professor Lenzen said the technological transformation is particularly extraordinary given the scale of carbon dioxide removal assumed in the IPCC Special Report, Global warming of 1.5C, of between 100-1000 billion tonnes (mostly over 600 GtCO2) by 2100; in large part through bioenergy to carbon capture and storage (BECCS) as well as through afforestation and reforestation (AR).

“Deployment of controversial ‘negative emissions’ future technologies to try to remove several hundred gigatonnes [hundreds of billion tonnes] of carbon dioxide assumed in the IPCC scenarios to meet the 1.5C target faces substantial uncertainty,” Professor Lenzen says.

“Carbon dioxide removal (including carbon capture and storage or CCS) is in its infancy and has never been deployed at scale.”


The new modelling was undertaken pre-COVID-19 but the degrowth pathways are based on a fraction of global GDP shrinkage of some 4.2% experienced in the first six months of the pandemic. Degrowth also focuses on structural social change to make wellbeing independent from economic growth.

“We can still satisfy peoples’ needs, maintain employment and reduce inequality with degrowth, which is what distinguishes this pathway from recession,” Mr Keyßer says.

“However, a just, democratic and orderly degrowth transition would involve reducing the gap between the haves and have-nots, with more equitable distribution from affluent nations to nations where human needs are still unmet – something that is yet to be fully explored.”

A ‘degrowth’ society could include:

Among the 1.5C degrowth pathways explored in the new research, the Decent Living Energy (DLE) scenario is closest to historical trends for renewable energy and negligible ‘negative emissions’. Mr Keyßer says the International Energy Agency projections for renewables growth to 2050 based on past trends are roughly equivalent to the DLE pathway modelled.

“That non-fossil energy sources could meet ‘decent living energy’ requirements while achieving 1.5C – under conditions close to business-as-usual – is highly significant.

“However it is clear that the DLE pathway remains extremely challenging due to the substantial reduction in energy use as well as the connected deep social changes required,” Mr Keyßer says.


For the study, a simplified quantitative representation of the fuel-energy-emissions nexus was used as a first step to overcome what the authors believe is an absence of comprehensive modelling of degrowth scenarios in mainstream circles like the IAM community and IPCC. The model is accessible in open access via the paper online.

A total of 18 scenarios were modelled under three main categories to reach 1.5C-2C:

Mr Keyßer says: “This study demonstrates the viability of degrowth in minimising several key feasibility risks associated with technology-driven pathways, so it represents an important first step in exploring degrowth climate scenarios.”

Professor Lenzen concludes: “A precautionary approach would suggest degrowth should be considered, and debated, at least as seriously as risky technology-driven pathways upon which the conventional climate policies have relied.”

One thought on “1.5°C Degrowth Scenarios Suggest Need For New Mitigation Pathways

  • May 13, 2021 at 2:24 pm

    The integrative assessment model (IAM) has been a flawed conceptional construct since its inception. Not only does it rely on a highly dubious pro-growth strategy; but in order to do so, the model has been filled with various geo-engineering schemes that have proven to be wildly unrealistic, Hence, no progress has been made in carbon mitigation since the first earth summit in Brazil, 1992. On the contrary, emissions continue to soar. No real progress in thirty years, how long can humanity allow this to continue? When will the realization strike that net-zero is an impossibility within a pro-growth model with highly unrealistic geo-engineering components? No one has an answer. Because climate science and carbon mitigation’s social and technological processes have been integrated for purposes of maintaining the domestic and geopolitical status-quo. This is not correct science or even a balanced use of modeling. The truth is, that in the history of the various IAMs, politics has won out. But politics does not solve the existential nature of climate change. Politics can either enhance or detract from the goal of ecological balance; but without an honest core to political thought and process, nothing can be, or will be solved. Take, for instance, carbon-capture technology. It is neither a proven technology, nor an inexpensive one. Yet, it remains an inexplicable component of nearly all the (IAM) models. Why? Because without it being included in the model, there is simply no way to achieve a net-zero result within a pro-growth scenario. And it is this very same growth scenario which most concerns today’s politicians. In our world today, economic growth means political and military power. That (in a nutshell) is contemporary politics. But within ecological truth, the harmony of all creation is essential. Nutshells and trees are probably more important than modern human politics. And until humanity can transform from its all-encompassing paradigm of war — euphemistically referred to as “peace through strength” or “balance of power” — climate science mitigation will remain trapped. Humanity’s dilemma can be correctly perceived as almost biblical. This dilemma is existential in nature, even many of the politicians themselves use the very same word, albeit casually. Because, if the dilemma were truly perceived by the politicians as existential, how is it that climate change can be so readily compartmentalized? Biden and Kerry say: “We can cooperate with China on climate change”. Yet, they also plan an intensive economic, geopolitical and military competition across the global strategic chess-board. In such a scenario, of course, their models toward net-zero must imply growth and dubious, unproven carbon-capture technology. The simple fact is (and it is indeed very simple) that global politics must change in order to prevent the inevitable consequences of unmitigated climate change. War and all its supporting systems have become anachronisms. In all the history of humanity, paradigm changes are few and far between. But a massive paradigm change will be necessary if our global civilization wants to live within a social and economic structure of ecological balance. All of us face a truly biblical choice: Either we end our historical institution of war and build a structure of durable international peace, with social equality, or we will certainly succumb to the ravages of a super-hot future. The choice is all of ours to make. We do, I believe, have free will. And it is, indeed, a biblical choice. Climate science cannot be compartmentalized for the sake of the politicians. And climate science models cannot be fudged for the sake of continual growth within a system of financial profit through perpetual debt. Ecology is a far more powerful reality than human history. Now we must alter our history in order to mold our human institutions to that reality. We have no choice, but the choice is our alone to make. A paradox of biblical proportion, I know. But, we are being judged. International peace, within an equitable economic structure of ecological limitation is our only way forward.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.