After reports on climate evolution and impacts, the Intergovernmental Panel on Climate Change (IPCC) released its last report on mitigation in March of 2022 (AR6 by Working Group III). It addresses the needs and potential for societies to reduce Greenhouse Gas (GhG) emissions and hold the increase in global average temperature to well below 2°C above pre-industrial levels and as close as possible to 1,5°C. This target range is made explicit in the Paris Agreement signed in 2015 – to avoid temperature increases that would transform our planet’s biosphere with dire consequences for modern human civilization.
The IPCC mitigation report is critical as it explains what options are available to policy makers and implementers, based on available scientific evidence, and informs negotiations, for example on burden sharing between nations (under the principle of common but differentiated responsibilities and respective capabilities). While both optimistic and pessimistic arguments can be made about the attainability of the global goal, we interpret the report as a demonstration that solutions do remain within technical and economic reach. However, solutions need to be applied at unprecedented spatial scales and time frames, and multiple prominent socio-political hurdles that have emerged over three decades of climate change debate and negotiation.
One primary piece of information synthesized is that global mitigation efforts have been somewhat successful and that emissions have reduced a great deal compared to business-as-usual scenarios as envisaged in earlier reports. Importantly, the carbon intensity of GDP has improved – we thus emit less carbon than in the recent past for similar levels of economic output, which is a necessary intermediate step for maintaining (for developed countries) or achieving (for developing countries) a decent level of prosperity while reducing global warming. By contrast, however, economic activity (partly due to population dynamics) has increased overall, and so these gains are far from enough to achieve the global goal.
Inequality of wealth and related emissions remains a challenge – disproportionate contributions to the problem originate in the developed countries in general, and further in the wealthiest segments of the world population. Indeed, the 10% of households with the highest per capita emissions contribute 34-45% of global consumption-based household GHG emissions, while the bottom 50% contribute only 13-15%. When looking at geographic distribution, Africa contributes only 9% of global anthropogenic emissions in 2019 (almost unchanged since 1990) and has relatively very low emissions per capita. These figures mean that the wealthy not only would need to contribute much more than the rest of the population, but their choices also very concretely influence the outcomes in terms of climate change mitigation.
Overall, commitments undertaken since the adoption of the Paris Agreement are in the form of Nationally-Determined Contributions (NDC – which include countries’ plans for mitigation action), but despite increasing levels of ambition through regular updates, their implementation by 2030 would result in warming of well above 1,5°C during the 21st century. Moreover, even these commitments have not been met in general so that global warming is on track to reach even higher levels.
With these data in mind, the report surmises that emissions would need to peak by 2025, 2 years from now at the latest, to avoid an “overshoot” of the lower 1,5°C end of the global goal. Emissions reductions after this would need to be around 43% by 2030 relative to 2019, and net zero emissions (i.e., carbon sequestered on earth through all possible means would compensate remaining emissions) would need to occur around 2050. Meeting this lower end global goal thus requires considerable and immediate action in all sectors; in other words, action must be optimized by implementation on all fronts at the same time. Given current trends, and especially the tragic military developments in Europe, this trajectory seems unlikely, at best (the IPCC euphemism used is “challenging”).
While the absolute necessity of urgent action has been obviously interpretable from IPCC reports since 2000, at least, experience shows that policies and societies’ responses are lagging badly – for example, estimates of future CO2 emissions from existing and planned fossil fuel infrastructures are close to the cumulative net emissions in pathways that would limit global warming to 2°C compared to preindustrial levels. The relative lack of visibility in the media of these latest IPCC reports, and the relative absence of discussion around their findings and messages, does not augur well for a decisive shift towards safer emissions levels soon. The war in Ukraine and its impacts on the energy markets, which are at the core of climate change mitigation, have triggered immediate strong reactions and debates in Europe that are unprecedented and show that climate change concerns do not yet stimulate matching levels of ambition. Nonetheless, disrupted fossil fuel supply chains and associated price shocks that affect Africa with abrupt fuel shortages across the continent, may provide the external shock to stimulate the kind of energy policy creativity that would be required for tackling climate change.
The global economic benefit of limiting warming to 2°C is often reported to exceed the cost of mitigation, meaning that the world would gain from investing immediately and massively in mitigation – a point repeatedly made for years. The cost of mitigation to remain under 2°C would hardly exceed 0,1% of global GDP loss per year from now until 2050; a figure that can be disputed, also considering the great uncertainties conveyed by economic models and the very imperfect nature of GDP to reflect well-being). When factoring in the benefits of mitigation with avoided adverse impacts from climate change and the needs for investments in adaptation, these costs turn to significant benefits. The global benefit is more complex when devolved to regional and sub-regional scales, costs would vary significantly across regions and across society segments within countries, so that some would make more sacrifices and both national and international solidarity (the latter promoted by the Common But Differentiated Responsibilities principle) would be required to achieve the breakthroughs needed.
While the current IPCC assessment is compelling and can only support the “do it now” mantra, some major uncertainties remain, particularly at the level of carbon dioxide removals (CDR). These refer to the anthropogenic activities that remove CO2 from the atmosphere and store it durably in geological, terrestrial, or in ocean reservoirs (or alternatively in products). They are essential to reach net zero emissions in the future, which is one milestone on the way to limited global warming. However, their measurement is more challenging than other anthropogenic emissions, and may often involve living organisms and ecosystems (grasslands and forests, for example), and may be spatially diffuse, and subject to changing climate conditions and unexpected events. On a higher level, they also entail a risk of conveying a false sense of comfort due to their capacity to compensate other emissions, whereas they can only be complementary to emissions reductions in the required portfolio of mitigation strategies.
Fundamentally, the latest IPCC report says that there is no room for hesitation and half-measures, and that even in the best-case scenario, substantial changes to life on earth as experienced for generations are projected. Solutions that are theoretically within reach appear frustratingly difficult to achieve politically. A lack of decisiveness is diffuse in and across all societies, which in turn have proved incapable to act collectively in their own interests. We are literally members of a global society at increasingly high risk not because of a lack of knowledge, expertise or technical solutions, but because of a lack of leadership, courage and selflessness in governance, and market failures. It is imperative that this information is leveraged and pressure is placed upon those in the right leadership spaces. Change must be brought about globally, and so the action taken towards mitigating climate change impacts by scientists, activists, economists, and other stakeholders, must continue strongly.