On August 9, the United Nations’ Intergovernmental Panel on Climate Change (IPCC) has published the first part of its sixth assessment report (AR6), which presents the results of the Working Group I (WG1) work and summarizes the “physical science basis” for climate change.
Two more parts of the IPCC AR6 will be published in 2022: the Working Group II (WG2) report on Impacts, adaptation and vulnerability and the Working Group III (WG3) report on Mitigation of climate change.
What did we learn from the IPCC AR6? The report concludes that it is “unequivocal” that humans have warmed the planet, noting that concentrations of CO2 in the atmosphere are higher than they have been for at least the past two million years. It states that many of the human-activity-caused planetary changes are “irreversible”.
Compared to the previous assessment report (AR5), IPCC AR6 provides more robust evidence of the links between human-caused warming and increasingly severe extreme weather events. The document states that there is no way of securing a stable climate on the planet unless net-zero levels of CO2 and other greenhouse gas (GHG) emissions are achieved in the coming decades. The updated scientific evidence suggests even higher degrees of warming associated with different levels of emissions than the ones indicated previously, which is a conclusion that leaves societies with even less time for implementing fundamental system changes.
More alarming, the report’s new estimate of the remaining carbon budget warns that under the 2020 level of CO2 emissions, only 11.5 years are left to achieve the goal of 1.5 °C degrees, a target to reach by 2050 in line with the Paris Agreement. The remaining time is even less if the emissions rebound in 2021, as expected with the easing of the Covid-19-related restrictions.
In the IPCC AR6 WG1, the emissions and climate warming scenarios are juxtaposed with the so-called shared socio-economic pathways (SSPs).
The SSPs are essential inputs for the climate models. By describing broad socio-economic trends that might shape human society up to 2100, SSPs help to outline potential social realities with their corresponding emission levels and temperature increases scenarios. The development of the SSPs has been happening outside of the IPCC AR6 working groups, but was intended to provide inputs for the IPCC AR6 climate scenarios.
Presenting somewhat simplified storylines of how human society might develop by the end of this century, the SSPs include several main components such as population and economic growth, education, urbanization, the rate of technological development, lifestyle changes. Five SSPs describe a variety of social development trajectories and emission levels associated with them:
SSP1 – a world of sustainability-focused growth and equality
SSP2 – a “middle of the road” world where trends broadly follow their historical patterns
SSP3 – a fragmented world of “resurgent nationalism”
SSP4 – a world of ever-increasing inequality
SSP5 – a world of rapid and unconstrained growth in economic output and energy use
According to the findings of the IPCC AR6 WG1, only SSP1 – “a world of sustainability-focused growth and equality “ - is in line with the Paris Agreement goal of reaching a maximum 1.5 °C temperature increase by the mid of this century. All of the other SSPs do not qualify for achieving this target.
What is the storyline behind SSP1? This pathway is based on the assumptions of fast technological development, relative global equality of income, and strong focus on environmental sustainability. The world population peaks at 8.5 billion around mid-century and then declines to 7 billion by 2100. SSP1 features a relatively equitable development globally, assuming that the least developed countries will catch up over the coming century.
Regarding energy system development assumptions, SSP1 features the highest share of renewables compared to other SSPs. However, even in this most ambitious scenario, around 60% of energy demand in 2100 comes from fossil fuel sources. Coal use in this scenario is close to today’s levels even in 2100. The increase in the electrification of transportation or heating is assumed at a modest level. Overall, climate goals in the SSP1 are possible to achieve primarily due to heavy reliance on negative carbon emissions and very optimistic decoupling assumptions. Based on the current scientific evidence, this scenario does not look viable.
While IPCC AR6 WG1 gives a robust and the most up-to-date analysis of the possible futures for the planet, the action-oriented conclusion re-confirmed by the report is the following: it is highly urgent to construct a socio-economic reality desirable for humanity and compatible with a maximum of 1.5 °C temperature increase.
The example of SSPs shows that even the most sustainable scenarios lack many essential details and contain unrealistic assumptions. When it comes to the features of specific sectors, especially the energy sector, the first step could be to connect some of the most recent and ambitious energy scenarios with the most recent IPCC AR6 findings. As per the assumptions on overall economic development, the existing SSPs remain very conservative and business-as-usual-oriented. For instance, only a few examples of post-growth economic thinking are available.
One thing is certain – the IPCC AR6 WG1 has made it even clearer that we must act now. From EERA’s perspective, and in the light of its soon to be published White Paper on the Clean Energy Transition, developing a detailed and inclusive narrative of the clean energy transition would be a valuable contribution to making possible a climate-neutral society.