“Climate Change 2021: The Physical Science Basis”, the report of Working Group I of the Intergovernmental Panel on Climate Change (IPCC), was launched on 9 August 2021, two days after its publication and “subject to final copy-editing, corrigenda, and trickle-backs”. The report was the first of its kind to be approved virtually, by all 195 member-governments of the IPCC, over a two-week period from 26 July onwards. It was the first instalment of the IPCC’s Sixth Assessment Report (AR6), representing the work of 284 authors from 66 countries, and supplemented with contributions from an additional 517 authors.
The full report runs to thirteen chapters, and includes a 41-page Summary for Policy Makers. According to the authors, the report is based upon the latest advances in the physical science of climate change, supplemented by evidence from paleoclimate archives; observed changes in the atmosphere, oceans, cryosphere, and biosphere; a better understanding of physical, chemical, and biological climate processes; and higher-resolution climate model simulations. This collated information has enabled the attribution of extreme weather events to human activities. The densely worded report includes a series of probabilistic statements, outlining various possible outcomes of global warming along with the likelihoods of these resulting from greenhouse gas (GHG) emissions.
The report paints the picture of an unprecedented and rapid progression of human-induced global warming that overshadows natural climatic fluctuations and directly threatens lives and livelihoods. Urgent action to combat global warming is thus recommended. GHG emissions from human activities have contributed to 1.070C (range of 0.8 to 1.30C) of global surface temperature warming from 1850-1900 to 2010-2019. Carbon dioxide (CO2) is the primary GHG driver of this climate change, with other greenhouse gases, especially methane, and air pollutants playing a subsidiary role. If allowed to proceed unchecked, a level of 1.50C global warming can result over the next two decades. This can prove catastrophic, increasing the frequency and severity of already noticeable patterns of heavy rainfall, increased flooding, rising sea levels, and extreme weather events such as heat waves, snowfalls, and wildfires.
The Working Group recommends a target of global net zero emissions to stabilise global surface temperature change. This can be achieved by ensuring a balance between anthropogenic (human-generated) emissions of CO2 and the anthropogenic removal of CO2. The term “remaining carbon budget”, amounting to 440 gigatonnes at the beginning of 2020, refers to the perilously low amount of emissions permitted so that subsequent warming is kept below a specific temperature level.
The report provides the rationale for climate change interventions, leading to immediate, rapid, and large-scale reductions in CO2 and other GHG emissions, sustained over at least the next twenty to thirty years. The difficult part, as usual, lies in the implementation of change. This is when action on climate change and a desire for unfettered economic growth come into conflict, especially as the process of transition threatens vested financial interests, particularly in fossil fuel (coal, gas, and oil) industries. Despite the climate change denial fostered by sections of the fossil fuel industry and by libertarians opposed to regulatory measures to offset climate change, there appears to be an international consensus about the reality of a climate energy resulting from global warming. But for the world’s three major CO2 emitters-China, the US, and India, the short-term economic priorities may override the longer-term objectives of acting on climate change. Even closer to home, investment in fossil fuels continues nonetheless, for example in proposals for the new Woodhouse Colliery, off the coast of west Cumbria, and for the Cambo oil field project, west of Shetland.
There are many short-term costs of transition to a low-carbon or green economy, which it is expected will be offset by the longer-term gains of environmental protection, efficient waste management, and better air and water quality, in addition to the desired stabilisation of global warming. The new instruments of green finance will fund green projects, enabling sustainable infrastructure, energy production, transportation, and housing. CO2 emission reduction will require the generation and storage of “green” energy from renewable sources (solar, wind, geothermal, tidal, hydroelectric, and biomass power), thereby reducing reliance on hydrocarbon energy. CO2 emissions can be further reduced by new carbon capture and storage technologies, as well as by natural carbon sinks, created by reforestation or establishing new forests. New technological solutions will inevitably emerge as industry faces up to the challenges of the green economy and starts to cash in on its projected benefits.
A lot needs to happen over the next few decades to allow net zero emission targets to be attained by 2050, a date already felt to be too late by some. The challenges are not insurmountable, but will require considerable political will, financial investment, and private sector support to become a reality. The deliberations of the forthcoming 26th UN Climate Change Conference of the Parties (COP26) in Glasgow, to be held between 31 October and 12 November 2021, will undoubtedly provide us new insights into the ways the world’s leaders propose to act in dealing with climate change.
Ashis Banerjee