Information & Computational Sciences

The missing pathway: Degrowth

By on 23/08/2021 in ICS

By Alessandro Gimona, Senior Scientist, ICS.

All over the world ecosystems are changing in response to climate change as well as to other pressures caused by human activities. The average global temperature has increased by about 1.1 °C since the industrial revolution, with most of the change recorded since the mid-1970s.

Already in October 2018, the Intergovernmental Panel on Climate Change (IPCC) warned that going beyond 1.5 °C of warming is likely to have serious, long-lasting and sometimes irreversible consequences for ecosystems. The recent Sixth Assessment Report (AR6) has strengthened the message.

Global temperature, the report points out, has increased since 1850 much more than would have been expected without human emissions, GHG concentrations have not been as high as today for millions of years. As a consequence, global sea level has increased at a rate not seen in historical times, arctic sea ice has shrunk to record levels, weather extremes such as floods and agricultural droughts have been worsening, forest fires have been more intense, larger, and widespread.

Some changes will be virtually irreversible for centuries, such as the melting of mountain glaciers and of permafrost, and, even in the best-case scenario, we will see at least 0.5 m of sea level rise by end the of the century.

Thanks to a better understanding of climate sensitivity, climate scientists warn that exceeding 2 °C and, a fortiori, 3 °C would have devastating consequences for humanity. They also point out that even very stringent mitigation will result in exceeding 1.5 °C by 2035 and 2 °C by ca. 2050, and that the global temperature could only decrease thanks to a very rapid fall of GHG emissions coupled with large scale deployment of negative emission technology.

The IPCC recommendations don’t compare favourably with present policy nor technological feasibility. The current emission reduction commitments, associated with the Paris Agreement, are far from the 1.5°C goal as they would lead to at least  2.4 °C of warming, and possibly more, by the end the of century. COP 26 in Glasgow (Nov. 2021) will certainly have to address this problem.

Yet again, climate scientist have advocated a correction of course. The trajectory of future change and the impacts, however, is uncertain and will depend on many factors. Among these, the atmospheric concentration of greenhouse gases, driven by human emissions, the sensitivity of the climate to such concentrations, and the ability to adapt, which is likely to be uneven among countries. Different scenarios can be hypothesised.

To explore different scenarios, “Representative Concentration Pathways” (RCPs) were created. These are time-dependent projections of atmospheric greenhouse gas (GHG) concentrations that translate into corresponding projections of climate change. ­Scientists also constructed narratives or societal “pathways” that try to project how global society, demographics and economics might change over the next century, independently of climate policy. They are collectively known as the “Shared Socioeconomic Pathways” (SSPs). It is worth noting that the SSPs generally do not include feedback on society of actual climate change, hence the narratives assume development is unrestricted by impacts. Policy makers can use the SSPs to reason about the level of mitigation needed and achievable for a given coupling of RCP trajectory and socio-economic narrative.

There is however a very significant caveat. Modelled scenarios that achieve global temperature stabilisation below 1.5 °C -and even stabilisation below 2 °C seem very challenging because, while advocating very substantial emission reductions, they also rely on technologies that do not yet exist at the necessary scale.

An important question is ‘what happens if such technology does not become available?’

At the moment, therefore, there is a high risk that relying on negative emission technology is equivalent to transferring the burden of mitigation to future generations and hope for the best. This can be seen as effectively putting all our eggs in one fragile basket.

We should assume that negative emissions technologies “do not work” – Prof Kevin Anderson

Scientific evidence shows that without the appearance of such technologies at an adequate scale, even the present effort of ‘progressive’ countries such as the UK would be far from being ‘Paris compliant’ and that the effort required is much higher than the present commitments.

Here is an interactive chart to explore the size of the task, without negative emissions.

https://ourworldindata.org/grapher/co2-mitigation-15c

In this context, nature-based solutions (NBS), which can produce negative emissions, have an important role to play, but should be put in perspective. While it is crucial that existing ecosystems be protected and kept in good condition, developed countries should have realistic expectation as to mitigation by newly created or restored areas.

This is also the case of the UK. Take for example the afforestation scenarios proposed by the UK Committee on Climate Change. The carbon sequestration achievable by new woodlands over 30 years, depending on assumptions, varies between less than 1% to less than 3% of the total UK Greenhouse Gas (GHG) emissions footprint over the same period, assuming Business as Usual emissions. Many degraded peatlands could become a carbon sink if properly restored, but this needs to happen before warmer and drier climatic conditions promote further degradation, with the risk, even for intact areas, of emissions increasing later in the century. At the moment many peatlands in the UK are still a significant source, emitting tens of Mtons of CO2-eq per year.

Other land-based solutions such as storing carbon in soil and bioenergy crops are also potentially vulnerable to the changes they try to avert, such as increased rainfall erosion, and risk of fire, and some compete with food production. This shows that, while NBS do have mitigation potential (and incidentally many additional benefits) relying heavily on NBS to decrease the country’s global emission footprint would be neither realistic nor prudent.

Because the consequences of failing to mitigate sufficiently are extremely serious, we need to consider a scenario that IPCC have not examined, namely “Degrowth”, defined as “‘equitable downscaling of … energy and resource flows through the economy, with a concomitant securing of wellbeing’. It has been shown that such a scenario, would be far less risky than pathways relying only on large-scale carbon dioxide removal and large-scale and very rapid renewable energy transformation. It might also be the only feasible way to achieve the needed emission reductions in the needed time scale.

And it is not just about not exceeding a safe carbon budget of emissions. Degrowth, if properly governed, might be the best option to stay within planetary boundaries, and also to address multiple aspects of the environmental crisis, thus decreasing pollution, protecting biodiversity, and making society more equitable. Indeed, because of the global physical boundaries, it could be argued that the choice is between a sustainable and a non sustainable economy. Between orderly degrowth vs chaotic collapse in the next few decades.

But degrowth has problems too: because it implies a GDP reduction, the acceptability and political feasibility of degrowth is far from granted and might initially be a genuine barrier.

However, nothing but transformative change will keep society within planetary boundaries, including safe climatic limits. Ideas about keeping prosperity but not growth have been put forward by scholars.  The academic debate is not settled, but it is urgent to have a serious debate in wider society regarding risks and benefits of different strategies that try to avert the worst consequences of climate disruption and unsustainable resource use. Degrowth is clearly a candidate worthy of consideration.

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