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Low Carbon Pulse Edition 24

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    Welcome to Edition 24 of Low Carbon Pulse. This edition reports on the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report – Climate Change 2021, The Physical Science Basis (2021 Report).

    This Edition 24, intended as a high-level summary of the key findings in the 2021 Report, is divided under the following headings: 1. Context of the 2021 Report; 2. Conclusions from the 2021 Report; 3. What organisations need to know; 4 The key findings of the 2021 Report (including specifically under its five models); and 5. Description of the subject matter of Twelve Chapters in the 2021 Report.

    A PDF version of this article is available for download below.

    1. Context of the 2021 Report:


    The 2021 Report is the first fully fledged report from the IPCC since its 2013 Report (the Fifth Assessment Report), and the first report since the 2018-2019 Special Reports.

    The findings outlined in the 2013 Report informed the provisions included in the Paris Climate Agreement (Paris Agreement) which entered into force on November 4, 2016. The Paris Agreement now has 195 signatories; each was consulted on the 2021 Report. The 2021 Report is subject to further work from which a Synthesis Reports will emerge.

    The Paris Agreement recognises the science of the 2013 Report: the imperative of keeping the increase in "global average temperature to well below 2OC above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5OC above pre-industrial levels".

    For these purposes, it was agreed "to reach global peaking of greenhouse gas emissions as soon as possible", "to undertake rapid reductions thereafter … so as to achieve a balance between anthropogenic emissions by sources (NZE) and removals (GHG Removal) … in the second half of this century…", with each Party to set a nationally determined contribution (NDC) to the reduction in greenhouse gas emissions (GHG), with a stock-take to be undertaken periodically; the first undertaken in 2018, the second to be undertaken in 2023.


    The purpose of the 2021 Report is to provide a basis for informed progress at COP-26, and to allow countries to adjust their NDCs in the lead-up to the 2023 stocktake, or before (ideally before COP-26).

    2 . Conclusions from the 2021 Report:

    • The 2021 Report confirms what was already known. All of the findings in the 2021 Report tie back to the Paris Agreement. The key finding is that:
      It is more likely than not that the earth will be 1.5OC warmer in 2050 than it was in the 19th century
    • What makes the 2021 Report powerful is that it is one of six Assessment Reports from the IPCC, all of which have been accurate to a great extent, and all of which are based on science, and affirming that the symptoms of climate change are visible.
    • The findings in the 2021 Report represent the work of countless scientists, each an expert, with each finding peer-reviewed and verified. The conclusion: "What is past is prologue" - accelerate to NZE.

    3. What organisations need to know:

    Key points:

    • It is unequivocal that emissions of "well-mixed greenhouse gases", i.e., carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), arise from human activities, that they are the principal cause of, and continued driver of, increased climate system GHG concentrations – climate change is human-induced.
    • Every tonne of GHG emitted to the climate system contributes to an increase in average global climate system temperature - increased temperature results in climate change.
    • Reduction of GHG emissions and increased GHG Removal are the accepted and proven means to reducing climate system concentrations of GHG.
    • Concentrations of CO2, CH4 and N2O (underreported in the 2021 Report because the report is based on 2019 data) contribute to climate change, and addressing CO2 reductions and removal is key.
    • More likely than not the average global temperatures will increase by more than 1.5OC by 2050, but addressing the causes of climate change is still possible, with acceleration to NZE being key.

    The science is unequivocal, action plans are business critical:

    • The starting point for any organisation seeking to reduce the GHG emissions arising from its activities is to identify its GHG emissions profile: which activities give rise to GHG emissions, and what mass? Both direct (Scope 1) and indirect (Scopes 2 and 3) should be included in that assessment.
    • Organisations can respond to the findings of the 2021 Report by:
      1. developing a net zero strategic action plan, and to adjust that plan to respond to on-going assessment and oversight (NZE Plan);

      2. demonstrating that the NZE Plan is modelled as achievable and is fully-costed, and includes the impact on earnings, and distributions, from the implementation of the NZE Plan;

      3. establishing data capture and measurement systems that capture all relevant data to allow effective monitoring and reporting on compliance with the NZE Plan anticipating that climate-related disclosure obligations will tighten overtime;

      4. appointing executives with responsibility for the implementation of the NZE Plan, with board approval and overnight of its implementation; and

      5. engaging actively with investors and other key stakeholders on an on-going basis and expecting investors to require consultation in respect of, and, over time, approval of, the NZE Plan.

    • For all corporations, there is a need to focus primarily and consistently on reducing GHG emissions (decarbonisation) across activities in Scopes 1, 2, and 3. (Ideally the acquisition of carbon credits / permits to acquit mandatory legal obligations, or assumed voluntary targets, will be a secondary focus and reduce overtime.)

    Task Force on Climate-Related Financial Disclosures (TCFD)

    • The 2021 Report deals with the global action required, at an individual organisational level the role of the TCFD cannot be ignored and comes into (even) sharper focus. The TCFD is a global, private sector-led taskforce, that requires boards and companies to assess, and to disclose publicly, climate risks and opportunities that are material or significant. Many readers will be familiar with the work of the TCFD. In the context of the G7 decision in June 2021, the role of the TCFD is taking on more significance, and the leadership role of the TCFD (chaired by Mr Michael R. Bloomberg) may be expected to become more prominent, and more important.
    • Physical climate change risks are now widely understood by the international business community as financial risks that represent a critical business challenge as well as opportunity: the long-term connection between the health of the planet and the health of the world economy is accepted. The Swiss Re Climate Institute Report from April 2021 shows this clearly.

    • At the recent June 2021 meeting of the Group of Seven, comprising Canada, France, Germany, Italy, Japan, UK and US (G7), there was agreement on the need to require compulsory disclosure of climate-related financial risks.

    • It is clear that the TCFD understands that reporting on an activity requires an assessment of that activity, and that reporting on NZE means that NZE is an objective: the progress towards, and ultimately the achievement of, NZE across each of Scope 1, 2 and 3 emissions, is being measured.

    • All corporations require financial services, including from debt and equity markets, financial institutions providing working capital facilities, and insurers insuring the risks arising from those activities. Disclosure on progress to NZE is a key tool: even before disclosure is made compulsory, many key participants in the financial services industry want to understand how corporations are progressing to NZE, and how they plan to achieve NZE. The TCFD has made assessment, monitoring, analysis and disclosure a positive for organisations: key to risk assessment, capital allocation and strategic planning.

    • Access to debt and equity from the financial services industry has ceased in respect of certain activities in some jurisdictions, and the terms on which financial services are provided are increasingly differing depending on progress to, and achievement of, NZE. As lawyers, Ashurst people see this on a daily basis.

    4. Key findings of the 2021 Report:

    Background as to form of the 2021 Report:

    • 2021 Report is fact based: The 2021 Report expresses findings by reference to the IPCC "calibrated language": first, confidence expressed: very low, low, medium, high and very high, second, likelihood expressed: exceptionally unlikely, very unlikely, unlikely, about as likely as not, likely, very likely, and virtually certain. This Edition 24 reports in findings that are expressed to be high or very high or very likely (90 -100% probability) or virtually certain (99 -100% probability), unless stated otherwise.
    • Form of the 2021 Report: The 2021 Report has a Summary for Policymakers (SPM) and Twelve Chapters. The SPM is drawn from the findings in the Twelve Chapters. Each of the Twelve Chapters directs: "Do Not Cite, Quote or Distribute". This reflects the development of the Synthesis Report. Given this direction, necessarily, the findings reported on in this Edition 24 are derived from the SPM, and conclusions are in line with the direction. Each of the Twelve Chapters is "fact packed", and replete with references. Section 5, Description of the subject matter of Twelve Chapters in the 2021 Report, highlights on of the parts of each Chapter that the author found to be of particular interest.

    Every tonne of well mixed GHG emitted contributes to an increase in average global atmospheric temperature:

    Stated another way, the root cause of climate change is the increase in temperature caused by increased mass of GHGs in the climate system, increasing the concentration of GHGs in the climate system, principally CO2, CH4 and N2O.

    Average concentration  CO2CH4N2O
    2019 410 ppm1866 ppb322 ppb
    JUNE 2020416.60 ppm1876 ppb332.7 ppb
     JUNE 2021418.54 ppm1891 ppb334.1 ppb

    The CO2 concentrations are higher than at any time in the last two million years, and concentrations of CH4 and N2O are higher than at any time in at least 800,000 years.
    CO2-e (carbon dioxide equivalent) recognises that different GHGs have different global warming effects, with the use of CO2-e allowing a like-for-like comparison taking account of potency and time retained in the climate system. What is clear however is that CO2 is the GHG on which GHG reduction and GHG Removal initiatives need to concentrate because globally, by mass, it is, by far, the most emitted GHG. At the same time, there needs to be a near to medium term concentration on the reduction of CH4.

    Overview of science underpinning climate change:

    • All readers will be familiar with the greenhouse effect. Placing the greenhouse effect in the context of anthropogenic GHG emissions and the resulting human-caused / induced climate change: GHG emissions cause net-positive radiative forcing, resulting in an accumulation of additional energy in the climate system. This energy is absorbed, and retained, by CO2, CH4 and N2O molecules.
    • This is known, and the greenhouse gas effect has been known for centuries, indeed in newspapers in the early 20th century were reporting on the impact of burning increasing quantities of coal, and that in a few centuries this may become problematic.
    • The problem has eventuated: both the cause and the cure for global warming are known, and both have long been recognised, critically, by the IPCC: 
      • reduce GHG emissions through decarbonisation of activities that give rise to GHG emissions; and

      • increase the negative GHG emission initiatives (NGHGEIs) for the purpose of removing CO2 from the atmosphere on an absolute basis, and, long term, to limit continued emission of GHGs using carbon credits / permits to off-set those continued GHG emissions.

      The policy settings that will achieve these outcomes rest with governments. As noted in Edition22 of Low Carbon Pulse, free markets will respond to policy settings, not make them.
      Remarkable progress has been made in some countries and economic blocs, but acceleration to NZE ahead of 2050 is now required, and responsibility for this rests with all governments and economic blocs.
      One of the lesser reported findings in the 2021 Report (at least over the first few days after its release), is that of itself the concentration of CO2 in the climate system would have already resulted in an increase of greater than 1.5OC in global average temperature. This has not occurred because of certain aerosols.
      There is a paradox that sits at the centre of this, the paradox emphasises the need to reduce GHG emissions. The burning of coal gives rise to both CO2 and sulfate / sulphate aerosols, one capturing heat, the other reflecting heat. The IPCC suggests there has been a net-cooling effect of up to 0.5OC due to sulfates / sulphates. The adverse effects on health of sulfate / sulphate aerosols are well-known, and as such sulfur / sulphur is removed from hydrocarbon products or captured on their use, thereby reducing the cooling effect of emission of sulfate / sulphate aerosols.
      This is not to suggest seeding the atmosphere with sulfate / sulphate aerosols (as part of a Solar Radiation Modification (SRM) scheme) is a solution, it suggests accelerated reduction in CO2 and CH4 emissions is the solution.
    • While the reduction of CH4 emissions is not as important as a reduction in CO2 emissions, it is still important, because of global warming potential of CH4, in terms of its potency by tonne, is greater than CO2. There has been a spike in the level of CH4 emissions since the mid-2000's. A reduction of CH4 emissions will accelerate the beneficial effects of reduced warming.
    • Observed climate change: Figure SPM.2: Assessed contributions to observed warming in 2010–2019 relative to 1850–1900 taken from page SPM-8 of the SPM shows the findings in relation to increases in average global temperatures resulting from different GHGs. Things could be worse. The fact that they are not worse is the result of luck, not judgment or knowledge.

    What is climate change for the purposes of the 2021 Report?

    The 2021 Report considers the impact of increased concentrations of GHG emissions on all aspects of the climate system, focusing on the atmosphere (air and surface temperatures), biosphere (parts of earth where life exists), cryosphere (parts of the world that are frozen) and oceans. Each of the Twelve Chapters considers these impacts.

    It is necessary to emphasise that the impact of increased concentrations on GHG emissions is not the same globally, or by GHG.

    The 2021 Report makes it clear that climate change can result in increased GHG emissions, which in turn results in climate change: "climate-change-on-climate-change", as a result of additional biogeochemical feedbacks in the climate system, which may amplify or attenuate the impact of increasing temperature on the climate system.

    Key changes to climate system:

    The length of this Edition 24 does not permit consideration of each climate impact, but the following climate impact findings are key:

    • "It is virtually certain that hot extremes have become more frequent and more intense across most land regions since the 1950s, while cold extremes (including cold waves) have become less frequent and less severe, with high confidence that human-induced climate change is the main driver of these changes."
    • "The frequency and intensity of heavy precipitation events have increased since the 1950s over most land area for which observational data are sufficient to trend analysis (high confidence), and human-induced climate change is likely the main driver".

    Figure SPM.3: Synthesis of assessed observed and attributable regional changes from page SPM-12 of the SPM show the findings as to climate system change on a regional basis.

    In addition to the findings, the balance with which the findings are expressed in the 2021 Report is telling, and provides the reader with considerable confidence of the analysis of the underlying data, and the calibration of the assessment of it. This may be regarded as contrasting with some of the reporting of the findings in the 2021 Report: it is best to go to the findings itself, rather than the reporting of any findings.

    What might the future hold?

    The 2021 Report has five SSP models (each allowing for solar activity and background forcing from volcanic activity), with each SSP model making the following assumptions:

    • SSP1-1.9: assumes acceleration of NZE and NZE by 2050, followed by effective NGHGEI;
    • SSP1-2.6: assumes 2050, following by varying levels of NGHGEI;
    • SSP2-4.5: assumes that CO2 NZE emissions staying at current levels until 2050, i.e., no increase;
    • SSP3-7.0: assumes that CO2 roughly double from current levels by 2100; and
    • SSP5-8.5: assumes that CO2 roughly double from current levels by 2050.

    SSP refers to Shared Socio-Economic Pathway, i.e. how society, demographics and economics might change this century.

    Projected outcome for each SSP model

    The projected outcome for each SSP model is represented graphically in the SPM as follows:

    • Figure SPM.4: Future anthropogenic emissions of key drivers of climate change and warming contributions by groups of drivers for the five illustrative scenarios used in this report (page SPM-17)
    • Table SPM.1 (page SPM-17)
    • Figure SPM.6: Projected changes in the intensity and frequency of hot temperature extremes over land, extreme precipitation over land, and agricultural and ecological droughts in drying regions (page SPM-24)

    What does all of this mean?

    Going to the root cause of climate change, reducing GHG emissions slows the rate of increase and stabilises the GHG emissions in the climate system, there is then the need to peak and reduce and remove GHG.

    Peaking and reducing: If the world passes peak GHG emissions (and it is noted that it may not), with continued reductions after the peak to a point at which the mass of GHG emissions arising is less than the mass of GHG emissions removed, there will be a decline in GHG emissions, but there will be a lag. The length of the lag will depend on the profile of GHG emissions leading up to peaking and the rate of GHG emission reductions and GHG Removal. In the language of the 2021 Report: the accumulation of GHGs in the climate system is determined by the balance between anthropogenic emissions, anthropogenic removals and physical-biogeochemical source and sink dynamics on land and in the ocean.

    CDR: afforestation, soil carbon sequestration, bioenergy with carbon capture and storage (BECCS), wet land restoration, ocean fertilisation, ocean alkalinisation, enhanced terrestrial weathering and direct air capture and storage (DACS) are all means of CO2 removal. For these purposes, author has chosen not to include SRM.

    Every organisation undertakes activities that give rise to GHG emissions, Scopes 1, 2 and 3. Every organisation can decarbonise those activities or remove GHG emissions, or both. As noted above, the starting point for any organisation seeking to reduce GHG emissions arising from those activities is to identify its GHG emissions profile: which activities give rise to GHG emissions, and what is their mass?

    5. Description of the Chapters in the IPCC 2021 Report:

    Detailed below is a description of what each of the Twelve Chapters covers (bold and italics indicating Sections of interest to the author):

    1. Chapter 1 (Introduction to 2021 Report): Section 1.1: Report and Chapter Overview; Section 1.2: Where are we now? How We Got here; Section 1.4: Foundations and Concepts; Section 1.5: Major Developments since ARS 5; Section 1.6: Dimensions of Integration; and Section 1.7: Final Remarks;

    2. Chapter 2 (Changing State of the Climate System): Section 2.1: Introduction; Section 2.2: Changes in Climate Drivers; Section 2.3: Changes in Large Scale Climate: 2.3.1: Atmosphere and Surface, 2.3.2: Cryosphere; 2.3.3: Oceans, and 2.3.4: Biosphere and 2.3.5: Synthesis of evidence for past changes; Section 2.4: Changes in Modes of Variability; and Section 2.5: Final Remarks;

    3. Chapter 3 (Human Influence on the Climate System): Section 3.1: Scope and Overview; Section: 3.2: Methods; Section: 3.3 Atmosphere and Surfaces; Section 3.4: Cryosphere; Section 3.5: Ocean; Section 3.6: Biosphere; Section 3.7: Modes of Variability; and Section 3.8: Synthesis across Earth System Components (of Human Influences on Atmosphere and Surfaces, Cryosphere, Ocean and Biosphere);

    4. Chapter 4 (Future Global Climate: scenario-based projections and near term information): Section 4.1 and 4.2: Overview and Methodology; Section 4.3: Selected key indicators over the 21st Century; Section 4.4: Near Term; Section 4.5: Mid-to-long term; Section 4.6: Policy Implications; Section 4.7: Beyond 2100; and Section 4.8; High Warming Storylines;

    5. Chapter 5 (Global Carbon and other Biogeochemical Cycles and Feedbacks): Section 5.1: Introduction and Palaeo Context; Section 5.2: Historical Trends, Variability and Budgets of CO2 (Section 5.2.1), CH4 (Section 5.2.2) and N2O (Section 5.2.3), Relative Importance of CO2, CH4 and N2O (Section 5.2.4); Section 5.3: Ocean Acidification and Deoxygenation; Section 5.4: Biogeochemical Feedbacks on Climate Change; Section 5.5: Remaining Carbon Budgets; Section 5.6: Biogeochemical Implications of CO2 Removal and Solar Radiation Modification, and Section 5.7: Perspectives on the Limits of the Assessment;

    6. Chapter 6 (Short-lived climate forcers): Section 6.1: Importance of SLCFs for Climate and Air Quality; Section 6.2: SLCF emissions; Section 6.3: SLCF atmospheric abundance; Section 6.4: SLCF radiative forcing, climate effects and feedbacks; Section 6.5: Implications of changing climate on Air Quality; Section: 6.6: Air Quality and Climate Response to SLCF mitigation; Section 6.7: Future projections of atmospheric composition and climate response in SSP scenarios; and Section 6.8: Perspectives;

    7. Chapter 7 (The Earth's energy budge, climate feedbacks, and climate sensitivity): Section 7.1: Introduction, conceptual framework, and advances since AR5 [i.e., 2013 Report]; Section 7.2: Earth's energy budget and its changes through time; Section 7.3: Effective radiative forcing; Section 7.4: Climate feedbacks; Section 7.5: Estimates of ECS and TCR; and Section 7.6: Metrics to evaluate emissions;

    8. Chapter 8 (Water Cycle Changes): Section 8.1: Introduction; Section 8.2: Why should we anticipate water cycle changes?; Section 8.3: How is the water cycle changing and why?; Section 8.4: What are the projected water cycle changes?; Section 8.5: What are the limits for projecting water cycle changes? Section 8.6: What is the potential for abrupt change? and Section 8.7: Final remarks;

    9. Chapter 9 (Ocean, cryosphere and sea level change): Section 9.1: Introduction; Section 9.2: Oceans; Sections 9.3, 9.4 and 9.5: Cryosphere; and Section 9.6: Sea Level, and Section 9.7: Final Remarks;

    10. Chapter 10 (Linking global to regional climate change): Section 10.1: Foundations; Section 10.2: Observations; Section 10.3: Models; Section 10.4: Attribution and emergence; Section 10.5: Context and distillation; Section 10.6: Comprehensive examples; and Section 10.7: Final Remarks;

    11. Chapter 11 (Weather and climate extreme events in a changing climate): Section 11.1: Framing; Section 11.2: Data and Methods; Section 11.3: Temperature Extremes; Section 11.4: Heavy precipitation / pluvial floods; Section 11.5: River Floods; Section 11.6: Droughts; Section 11.7: Extreme Storms, including tropical cyclones; Section 11.8: Compound Events; and Section 11.9: Regional information; and

    12. Chapter 12 (Climate change information for regional impact and for risk assessment): Section 12.1: Framing; Section 12.2: Methodological Approach; Section 12.3: Climatic impact drivers and affected sectors; Section 12.4: Regional Changes to climatic impact drivers; Section 12.5: Global perspective of changes in climatic impact drivers; Section 12.6: Climatic change information in climate services; and Section 12.7: Final Remarks.

    IPCC Reports:

    Below is a list of the reports referenced in this edition of Low Carbon Pulse:

    AR6 Climate Change 2021: The Physical Science Basis (2021 Report)
    Climate Change 2013: The Physical Science Basis (2013 Report)
    Special Report: Climate Change and Land
     Special Report: Global Warming of 1.5 oC
    2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories
     Special Report on the Ocean and Cryosphere in a Changing Climate

    The author of Low Carbon Pulse is Michael Harrison.

    The information provided is not intended to be a comprehensive review of all developments in the law and practice, or to cover all aspects of those referred to.
    Readers should take legal advice before applying it to specific issues or transactions.


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