The first comprehensive comparison of “ degrowth ” scenarios with established pathways to limit climate change highlights the risk of over-reliance on carbon dioxide removal, renewables and energy efficiency for support continued global growth – which is assumed in established global climate modeling.
Degrowth focuses on the Global North and is defined as a fair and democratic reduction in the use of energy and materials while maintaining well-being. A decline in GDP is accepted as a likely consequence of this transition.
The new modeling from the University of Sydney and ETH Zurich includes high growth / technological change and scenarios summarized by the Intergovernmental Panel on Climate Change (IPCC) in comparison to the decay trajectories. It shows that by combining large-scale social changes focused on sufficiency and technological improvements, net zero carbon emissions can be more easily achieved technologically.
The results published today in Nature communications.
Currently, the IPCC and the established modeling community, the Integrated Assessment Model (IAM), do not take into account decay scenarios where the reduction in production and consumption in the Global North is combined with the maintenance of the property. -being and the achievement of climate objectives. In contrast, the scenarios established are based on combinations of unprecedented removal of carbon dioxide from the atmosphere and other far-reaching technological changes.
The results show that international targets of capping global warming to 1.5C-2C above pre-industrial levels can be more easily achieved in key dimensions, for example:
- 1. The decline in northern countries / high income countries results in an annual decline of 0.5% of global GDP. However, a significantly increased use of renewable energies associated with negative emissions remains necessary, although significantly less than in established pathways.
2. The warming cap at the upper limit of 2C can be achieved with 0 percent growth, while still being consistent with low levels of carbon dioxide removal (i.e. planting of carbon dioxide). ‘trees) and increases in renewable energy and energy efficiency.
Lead author Mr. Lorenz Keyßer, from ETH Zürich, whose master’s thesis is on degrowth, conducted the research in Australia under the supervision of the global leader in carbon footprinting, Prof. Manfred Lenzen, of the Center Integrated Sustainability Analysis (ISA) from the University of Sydney in the School of Physics.
Mr Keyßer said he was surprised by the clarity of the results: “Our simple model shows that decay paths have clear advantages in many central categories; it seems a big oversight that decay is not even taken into account. in the conventional climate modeling community.
“Over-reliance on unprecedented carbon dioxide removal and energy efficiency gains means we risk catastrophic climate change if either of the assumptions does not materialize; furthermore, the removal of carbon dioxide has a high potential for serious side effects, for example for biodiversity and food security. , if it is made with biomass, it therefore remains a risky bet.
“Our study also analyzed the other key assumption upon which the IPCC and other modeling is based: the continued growth of global production and consumption.”
Lead 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 1.5 ° C, between 100 and 1000 billion tonnes (mainly over 600 GtCO2) by 2100; largely through bioenergy for carbon capture and storage (BECCS) as well as afforestation and reforestation (AR).
“Deployment of future controversial ‘negative emissions’ technologies to attempt to remove several hundred gigatons [hundreds of billion tonnes] of carbon dioxide assumed in the IPCC scenarios to reach the 1.5 ° C target faces substantial uncertainty, ”says Professor Lenzen.
“The elimination of carbon dioxide (including carbon capture and storage or CCS) is in its infancy and has never been deployed on a large scale.”
WHAT WOULD DEGROWTH BE
The new modeling was undertaken before COVID-19, but the decline trajectories are based on a fraction of the reduction in global GDP of around 4.2% in the first six months of the pandemic. Degrowth also focuses on structural social change to make welfare independent of economic growth.
“We can still meet people’s needs, maintain jobs and reduce inequalities with degrowth, which sets this path apart from recession,” says Keyßer.
“However, a just, democratic and orderly transition to degrowth would involve narrowing the gap between the haves and have-nots, with a more equitable distribution from rich countries to countries where human needs are still unmet – which is still left. to explore. “
A “ degrowth ” society might include:
- · A shorter working week, resulting in reduced unemployment, increased productivity and stable economic output.
· Basic universal services independent of income, for necessities such as food, health care, transport.
· Limitation of maximum income and wealth, making it possible to increase the universal basic income and reduce inequalities, rather than increasing inequalities as is the current global trend.
Of the 1.5 ° C decay pathways explored in the new research, the Decent Living Energy (DLE) scenario is closest to historical trends for renewables and negligible “negative emissions”. Mr Keyßer says that the International Energy Agency’s projections for renewable energy growth to 2050 based on past trends are roughly equivalent to the modeled DLE trajectory.
“The fact that non-fossil energy sources can meet ‘decent living energy’ needs while reaching 1.5 ° C – under conditions close to the status quo – is very significant.
“However, it is clear that the DLE path remains extremely difficult due to the substantial reduction in energy consumption as well as the profound social changes required,” says Mr Keyßer.
MODELING CLIMATE PATHS
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 to be a lack of full modeling of decay scenarios in traditional circles like the IAM community and the IPCC. . The model is freely accessible via the online paper.
In total, 18 scenarios were modeled under three main categories to achieve 1.5C-2C:
- 1. Degrowth and “decent living energy”, looking at the low energy-GDP decoupling.
2. Average energy-GDP decoupling, including approximate IPCC scenarios.
3. High energy-GDP decoupling (strong to extreme technological pathways / energy efficiency leading to separation between economic growth and emissions).
Mr Keyßer says: “This study demonstrates the viability of degrowth by minimizing several key feasibility risks associated with technology-driven pathways, so it represents an important first step in exploring climate scenarios for degrowth.”
Prof Lenzen concludes: “A precautionary approach would suggest that degrowth should be considered and debated, at least as seriously as the risky technological pathways on which conventional climate policies have relied.”