The report evaluates a range of emissions pathways to limit warming to 1.5°C and 2°C, all of which require a rapid shift away from fossil fuels, and some amount of reliance on carbon dioxide removal. While possible on paper, how politically expedient will such options ultimately be?
Earlier this month, the Intergovernmental Panel on Climate Change (IPCC) released the third part of its Sixth Assessment Report (IPCC AR6 WG3). This final installment of the current scientific assessment cycle evaluates options to mitigate climate change, which at present is set to lead to warming of about 3°C over this century.
Although the report highlights that there is still time to avert the worst impacts of climate change, it also states the sobering reality that current policies aimed at controlling climate change are woefully inadequate in terms of temperature reductions they will deliver. Pursuing the 1.5°C or 2°C warming limits conscribed in the Paris Agreement would entail a massive scale up of ambitions and actions, leading to a net-zero emissions scenario latest by the early 2070s to achieve the latter target.
The IPCC’s latest offering evaluates a range of emissions pathways to limit warming to 1.5°C and 2°C, all of which require a rapid shift of the world’s energy systems away from fossil fuels, and almost all of which entail some degree of negative emissions and carbon dioxide removal (CDR).
What options does the world have?
IPCC assessment reports are essentially exhaustive reviews of existing scientific literature in order to draw degrees of scientific consensus on various aspects of climate change and its impacts. For the report on mitigation, the IPCC consolidated over 1,200 emissions pathways (whittled down from a database of more than 3,000 scenarios) in order to generate eight warming scenarios through the current century. The report also presents separate illustrative pathways to reflect warming projections from current policies, including with moderate increases in climate action, and five ‘deep mitigation strategies’ that could limit warming to the 1.5°C and 2°C targets. Together, these scenarios paint a comprehensive picture of how rates of transition to low carbon energy systems affect future global emissions, including those where temperatures are stabilised following “overshoots” relative to the warming targets. These illustrative pathways, while consisting of a range of possibilities, are subject to broad uncertainties in actual emissions in the pathways as well as around the sensitivity of climate and the earth system in response to changes in CO2 and GHG emissions.
Scenarios where warming is limited to 1.5°C (listed under C1) include three illustrative pathways, namely “shifting development pathways” (SP), low demand (LD), and high renewables (Ren). While these describe scenarios with “no or limited overshoot”, the C2 pathway details how the world can bring warming down to 1.5°C by 2100 following a “high overshoot” through a heavy dependence on negative-emissions technologies and carbon removal. Realising these pathways, however, hinges on urgent and rapid emissions reductions. According to the IPCC, meeting the 1.5°C warming target would mean peaking CO2 and GHG emissions within the next three years—an unbelievably tall order given the current rates of emissions increases, particularly in the developing world, which houses the majority of the global population. Pathways to limit warming to 1.5°C with little or no overshoot would entail GHG emissions to be cut by 43% by 2030 and 84% by 2050 compared to 2019 levels, while CO2 emissions would have to be reduced by nearly half by the end of the decade.
The C3 pathway describes the warming scenarios under current policies, which are gradually strengthened to hold at least a 66% chance of limiting warming to 2°C by 2100. If countries meet their 2030 NDCs and follow it up with little additional climate action, the world is likely to see warming between 2.5°C-3°C by the end of the century (scenario C6). Emissions scenarios describing effects of current policies show an end-of-century warming estimate of about 3°C, which are reflected in scenarios C6 and C7.
While not as severe as the 1.5°C pathways, limiting warming to 2°C would also require urgent GHG emissions cuts of about 14% by 2030 compared to 2020 levels. The report states that CO2 emissions would have to be cut in half in the 2040s and achieve net-zero by the early 2070s. These pathways describe a gradual phaseout of fossil fuels as future energy demand is met dominantly by renewables, and includes the need to remove massive volumes of carbon dioxide from the atmosphere by the end of the century.
Interestingly, the WG3 report has incorporated current policies and possibilities of increased action compared to warming scenarios included in earlier reports. This has made the extreme warming scenarios described under the C7 and C8 pathways much less probable relative to similar assessments conducted in the past, underscoring the positive impacts of current policies in ameliorating future warming possibilities.
The great energy lock-ins
Throughout the exhaustive exploration of pathways included in the IPCC’s mitigation report, one clear message dominates the takeaways—an urgent and rapid shift away from fossil fuels is the only option that would realistically stabilise warming to under 2°C. The scale of the required shift, though, remains gargantuan no matter how you cut it. As stated in the IPCC, historic cumulative net emissions from 1850 to 2019 amounts to around 2,400 GtCO2. About 17% of this (around 410 GtCO2) has accumulated just over the past decade between 2010 and 2019. The situation is further exacerbated by non-CO2 GHG emissions, which have also registered growth in recent decades. While the rate of growth of emissions from fossil fuels has declined, emissions have continued to grow. Fossil fuel CO2 emissions grew by 4.6% between 2015 and 2019 (1.1% per year) and reached 38 GtCO2 per year. This number accounts for approximately two-thirds of annual global anthropogenic GHG emissions.
This rate of CO2 accumulation, particularly from burning fossil fuels, reflects the untenability of the current trends of emissions relative to the Paris Agreement targets. According to the chapter on energy systems of the WG3, “Based on central estimates only, cumulative net CO2 emissions between 2010-2019 compare to about four-fifths of the size of the remaining carbon budget from 2020 onwards for a 50% probability of limiting global warming to 1.5°C, and about one-third of the remaining carbon budget for a 67% probability to limit global warming to 2°C.” The report continues with high confidence that if current emissions trends from the energy sector continue, the world will breach the 2°C warming threshold.
Between 2015 and 2019, coal, oil and gas contributed 44%, 34% and 22% of all energy sector CO2 emissions respectively. Additionally, fugitive emissions, primarily of methane, add considerably to the carbon footprint attributable to fossil fuels. Dependence on fossil fuels, which account for almost 80% of the world’s primary energy demand, will have to be cut by about half by 2050 to limit warming to 2°C. Further, the longer it takes to wind down fossil fuel demand, the steeper the required energy decarbonisation curve gets. The urgency is by far most pronounced in coal demand. According to the WG3 report, unabated coal consumption would have to be practically eliminated by mid-century, a far cry from current energy plans around the world, which include several hundred GWs of new thermal power. Even without new thermal power infrastructure limiting warming to 2°C, existing coal power plants would have to be retired 10-25 years earlier than their historic average operating lifetime. Building new thermal power capacity will contract viable lifespans by a further 5-10 years.
The report, however, also concedes that the rapid shift away from coal “will present economic, social, and security challenges. These will vary across regions based on the characteristics of existing coal infrastructure, the availability of alternatives, economic development, and technological and institutional lock-in.” The most quantifiable of these challenges presently are reflected in the economics of such a transformational shift away from fossil fuels. Notwithstanding the finance required to move to renewables and other low carbon non-fossil energy, the low-carbon energy transition is likely to create massive stranded assets. Limiting warming to 2°C implies that about 30% of oil, 50% of gas, and 80% of coal reserves will remain unburnable. Combined with premature closures, the economic impact up to 2050 from these stranded assets are estimated to be between $1-4 trillion, 60% of which is expected to come from the abandonment of unviable fossil fuel infrastructure.
Prominent among the options to prolong the use of fossil fuels is the deployment of carbon capture and sequestration and CO2 removal (CDR) technologies. Despite the text being peppered generously with these options, the viability of such technologies remain largely unproven and expensive, with current literature suggesting low emission reduction potential and high costs (see figure below). Further, while rolling back fossil fuel demand is imperative in the battle to avert the worst consequences of climate change, urgent scaling up of renewables and other non-fossil energy requires a carefully planned navigation of possible conflicts arising from pressures on environment, food security, land and economy.
More political division on the cards
The IPCC report on mitigation identifies GDP and population as the two major factors that influence carbon emissions from energy systems. While population growth tends to drive energy demand, the report admits that these implications from population are dwarfed by those attributed to economic growth. The correlation between economic growth, energy demand and associated carbon emissions are evidenced by the close correlation between energy system emissions with per capita GDP and emissions in practically every region of the world, complete with a pause in emissions growth during periods of global economic downturns, most notably in 2009 and 2020.
The report, through a new chapter on Demand, Services and Social Aspects of Mitigation, advocates for transformative changes (particularly in urban settings) in infrastructure planning and deployment to generate the deepest emission reductions. Such a shift to more emission-efficient modes of planning and infrastructure deployment in construction, food systems, transport and industry, according to the report, holds potential to drive down emissions by an incredible 40%-70% by mid-century and practically ensure a fighting chance to limit warming to under 2°C.
Such measures, however, will not be painless. Lockdowns imposed around the world to contain the COVID pandemic, which resulted in a temporary collapse of energy demand and a pause in emissions growth in 2020, have been used in the report to highlight the potential rapid behavioral and societal change. Somewhat contradictorily, the report also concedes that the top-down imposition that made such a change possible was accompanied by widespread economic distress, which drove hundreds of millions of people below poverty thresholds and reversed decades of poverty alleviation accomplishments in practically every corner of the world.
While authors have leaned on the concept of Decent Living Standards to guard against the rapid deterioration of standards of living and the economic limitations, there is also recognition that such economic risks would make large-scale demand-side changes hugely unpopular. Authors of the report admit that the acceptability of collective social change over a longer term towards less resource-intensive lifestyles will heavily depend on social mandate building through public participation, discussion and debate—a process that could take several decades, far longer than needed to address urgent mitigation needs. The new chapter, which effectively calls for a much more distributed approach to mitigation, is in line with larger trends in climate action, which seek to blur the lines of responsibility towards climate action, and so are bound to be politically onerous.
Flashes of the growing chasm in the politics of climate action were once again evident during the plenary review of the report that immediately preceded the release of the report. Flashpoints included the long-divisive subject of finance for the required transformative changes, which the developed world has increasingly sought to redefine through and obfuscation of what “finance” entails. Among the most controversial aspects at the plenary dealt with mitigation investment flows due to absence of consensus around terms segregating developing and developed countries. While developed countries argued that including such classifications in the report would effectively politicise the scientific process and make the report prescriptive when the IPCC was supposed to be policy neutral, developing countries countered that such classifications are not just policy relevant, but also a significant finding of the underlying report.
Interestingly, the plenary session also provided a window into the growing discontent among emerging economies and developing countries with regards to the emissions modelling included in the report, which segregates the world in accordance with geographic boundaries rather than on socio-economic lines.
While authors have claimed that the models reflect regional emissions projections and pathways, government-appointed reviewers of the report from the Global South have pointed out that such categorisations blur the lines on historic responsibility and equity as encoded in the UNFCCC charter and the Paris Agreement. These concerns were reflected most strongly in India’s closing statement at the plenary which included the lines- “The classification between developed and developing countries that signals the responsibility for emissions is sought to be removed using models as the basis for a different classification than has been signalled in various earlier IPCC reports.”
The politics of climate change and climate action is heating up, and divisions are likely to get further entrenched given ongoing geopolitical and economic realignments arising from the Russian invasion of Ukraine, fears of further deterioration of security around the world and persistent supply chain disruptions, which have driven up prices of several commodities essential for decarbonisation. Notwithstanding the options for mitigation, consensus on climate action will ultimately depend on the maintenance of a political climate that is conducive for global collaboration as we move towards November’s COP 27—a prerequisite that seems more improbable with each passing day.