May 15, 2022

IPCC Sixth Assessment Report: On Mitigation


RESPONSE of the media and the public to the series of reports together forming the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC/AR6) has been surprising, yet telling, in important ways.

IPCC’s Assessment Reports are written and released roughly at intervals of six years and, as reports based on extensive peer-reviewed information and data, written up by leading scientists and experts from other disciplines with many rounds of consultations, are widely regarded as the broadest updated consensus of the scientific community on the issue of climate change. Each AR is released by separate Working Groups (WG) in three volumes, the first dealing with the latest scientific data on the status and causes of climate change, the second on the currently observed and projected likely impacts of climate change, and the third on mitigation i.e., on how and by how much human-induced carbon dioxide (CO2) and other greenhouse gases (GHGs) may be reduced in order to limit climate change and its impacts to within tolerable limits. Needless to say, the IPCC/ARs have been hugely influential in the bi-annual climate summits and other international conferences that together seek to agree on international goals and targets, as well as targets for individual countries within that framework, to control GHG emissions as well as arrange technological and financial assistance to developing countries to enable them to make the difficult transition to a decarbonised future.


In the present cycle, IPCC/AR6/WG1 was released just prior to the important Glasgow Summit, or COP 26, the 26th Conference of Parties to the UN Framework Convention on Climate Change. AR6/WG1 had been preceded by three IPCC Special Reports. The first was on the implications of the recently firmed-up goal of limiting global temperature rise to 1.5C, superseding the earlier goal of 2C with the promise to try for lower warming up to 1.5C. The second was on the status and impacts on the cryosphere and the oceans, and the third on the land and desertification.   In many ways, these three Special Reports had stolen the thunder of IPCC/AR6/WG1 in having disclosed many of its most important findings, as was only to be expected since these had been widely anticipated in the scientific community.

Nevertheless, AR6/WG1 grabbed headlines with its dire projections, reinforcing public perceptions and fears due to dramatic forest fires in Southern Europe and North America, extreme rainfall and widespread flooding in northern Europe, apart from similar extreme weather events elsewhere in the world, especially in Asia. Yet, the modest outcomes from COP26 did not reflect the urgency felt by the public to tackle climate change with strong measures. Many countries had already upgraded their NDCs or Nationally Determined Contributions or national emissions reduction targets, and the emission cut targets announced by developed countries at or before Glasgow were far below expectations and requirements. Altogether, while all NDCs put together had somewhat reduced the gap between projected emissions in 2030 and the requirement to meet the goal of 1.5C, the gap remaining was still too wide, leaving the world staring at a temperature rise well above 2C, perhaps even approaching 3C.

It, therefore, looked as if, for all the scientific data and projections, the directly observed realities of polar and glacial melts, extreme rainfall, heatwaves and forest fires, national governments around the world, especially in developed countries, “economies in transition” as in Eastern Europe and large emerging economies, were not really prepared to commit themselves collectively to more urgent and severe emissions reductions, and to the decarbonized development pathways those would entail.

It is then no small wonder that AR6/WG2 received lesser media coverage and public attention than WG1 since the impacts had been directly experienced, widely covered and had yet not resulted in the commensurate enhanced international response.

Now AR6 is before us, pointing the way to how the required emissions reductions may be achieved, albeit with many qualifications and hesitant policy recommendations about which more later, and the media silence is deafening. Public perception has barely registered the release of AR6/WG3 and national governments, including India, have maintained a studied silence.

These are not good signs. They reflect a growing sense of resignation among the wider public in the face of weak response by national governments. Sadly, they may also reflect fatigue among civil society organisations and activists, staring at diminishing policy returns on their advocacy efforts. These depressing signs must be reversed, and activists must rally once again to more vocal demands for urgent and concerted action to combat climate change.


Before doing so, it would be useful to lay out the framework of the Report, particularly its Synthesis for Policy Makers (SPM). It must be emphasised that increasingly since the Fifth Assessment Report, the SPMs of each Report are not purely scientific Reports, but Reports of scientists along with governments who have literally gone through and approved each Report line by line. Therefore, all SPMs of IPCC Reports are “policy-relevant” but not “policy prescriptive,” that is, they provide information useful for policy-makers and to shape policy, but do not propose specific policies, but rather describe different options and related socio-economic and technological considerations.

It may also be pointed out that the studied “policy neutrality” of the IPCC Reports has, over the years, led to implicit biases and rather specific policy orientations. For instance, ever since the Copenhagen Summit in 2009, when a new architecture for international emissions control was first formally articulated, after being introduced at several earlier US-led meetings of the “Major Economies Forum” and G7+, historical emissions and their role in determining future burden-sharing responsibilities have been underplayed. Instead, the “forward-looking perspective” pushed by the US has been adopted, with the distinction between developed and developing countries not forming part of the calculus of a global emissions control regime. In AR6/WG3 too, there is little if any discussion of this distinction. Instead, the Report gives pictographs of historical emissions by geographic region, leaving it to the reader to draw conclusions but thereby also ensuring that developed and developing countries are not used as analytical categories.

Similarly, as all those who follow the climate negotiations well know, the issue of financial assistance from developed countries to developing nations has been going through a series of changes in terminology with significant operational implications. From a figure of US$100 billion a year of budgetary assistance for adaptation and mitigation, with compensation of loss and damage supposed to have been added to it, the actual quantum transferred has been a mere fraction while the number itself has been redefined several times to include loans, assistance from multilateral institutions etc. AR6/WG3 continues this trend by often referring to “climate investment” rather than “climate finance,” completely changing the nature of financial transfers and the uses to which they are likely to be put.


Now to the specifics. Rather than getting caught up in the various model projections (it is emphasized repeatedly that these are not predictions) which are better discussed in technical publications, it may be better to look at major pointers in AR6/WG3 at sectors where emissions reduction action may be taken.

At the outset, AR6/WG3 notes that we are further away from realising the 1.5C target than we were at the time of the Special Report on 1.5C, mainly because global emissions have risen since 2017. Further, while global emissions are projected to peak between 2020 and 2025 if existing emissions reduction commitments made on the eve of the Glasgow Summit are not further strengthened, the global temperature rise may reach 3.2C (2.2 – 3.5C) by 2100, a far cry from the 2C target leave alone the 1.5C goal.

In terms of carbon budgets, i.e., the cumulative CO2 and other GHGs that the atmosphere can hold for a given rise in global temperature above that in the industrial era, taken to be 1850, the remaining carbon budget from 2020 onwards to ensure the 1.5C target is about 500 Gt CO2 (1 Giga tonne = 1000 Mega tonnes or 1 billion tonnes) or 1150 Gt CO2 for 2C. To put this in perspective, cumulative CO2 emissions between 2010-19 were roughly 80 per cent of the budget i.e., for all future CO2 emissions of 1.5C! This is an extremely limited future budget, and cannot be met at current or projected emissions at present NDCs.

AR6/WG3 also draws attention to the need, and potential, for reducing non-CO2 emissions, notably methane (CH4) and, to a lesser extent, nitrous oxide mostly coming from agriculture, power plants and automobiles. The possible role of these non-CO2 GHGs has been much debated lately, and AR6/WG3 throws useful light on this. It points out that reduction of Methane released mostly from municipal solid wastes, from cattle and other ruminant animals, and from coal mining, could reduce the warming at peak emissions, thus buying some time for tackling the main driver CO2.

Another subject of intense debate has been the subject of so-called Black Carbon, that is, for example, unburnt coal dust from power plants, brick kilns, cooking devices etc. Black Carbon belongs to a larger family of aerosols, or suspended solid particles or liquids in air. Many of these aerosols have an overall cooling effect in the atmosphere, whereas carbon particles absorb and retain heat for a long, thus causing an increase in warming. Wood-burning cookstoves release many unburnt particles besides soot, such as organics, arguably having an overall cooling effect. AR6/WG3 puts these disputations to rest by stating that “reduction of cooling and warming aerosol emissions over time leads to net warming in the near- to mid-term,” i.e., aerosols put together to have a cooling effect. On a cautionary note, Black Carbon may still have other bad effects such as accelerating glacial melting etc.

AR6/WG3 discusses various mitigation options other than energy supply, consumption and efficiencies which are the clearly largest source of CO2 and often other GHGs too.

Major options discussed include reduction of the clearly growing emissions from urban areas, including from poor planning leading to increased transport and higher emissions, besides emissions due to energy used for cooling or heating, and emissions locked into buildings due to the type of materials used and processes of construction. The Report cautions that urban areas at different stages of development and growth would call for different strategies, and also points out that yet-to-be-constructed infrastructure, commercial and residential buildings would either lock in emissions for several decades or could be utilised to achieve significant emissions reductions through both one-time choices of materials and techniques, or longer-term recurring energy savings through building materials and processes, as well as urban re-design. About 60 per cent of emissions from buildings could be mitigated.

Obviously, huge emissions reductions are possible in the transport sector by improving efficiencies in the short-term, shifting away from motorised and personal transport, and making a complete shift to clean electric or hydrogen in the medium to longer term. All these measures would also have considerable co-benefits in reduced air pollution and human health. AR6/WG3 projects that transport-related emissions could be reduced by 30-67 per cent but, due to the technologies, complexities and regional variations, it is however unlikely that the transport sector could reach net-zero emissions by 2100.

The broad takeaway from AR6/WG3 is that there are many options to reduce emissions. It also argues that taking up only some options and leaving out others leads to considerably fewer emissions reduction, and to missed opportunities in equity, such as through clean public transportation. In overall terms, an approach that seeks to build and promote transformative development pathways would not only optimise emissions reduction across sectors but also bring substantial co-benefits in different sectors and to deprived sections of the population

India would do well to re-look at its NDCs in a more holistic manner.