Leading scientists, writing for Carbon Brief, explain how COP26 gave far greater recognition to science than any of the previous COPs. The scientific evidence from the latest IPCC reports was explicitly acknowledged in the Glasgow Climate Pact. That is a significant advance, say the authors. Decision-making guided by science can focus quantitively on carbon budgets, temperatures, climate change, the causes, and therefore the emissions-reductions needed from governments. Now, when targets and policies do not align with the evidence, they can more easily be exposed. Then, when commitments are finally made, all the other challenges of the transition will become much clearer and be dealt with accordingly – like people’s livelihoods, climate justice, vulnerable communities, financial, governance and societal changes. It’s when the hard numbers from science are overlooked or ignored that it becomes too easy to delay what must be done.
As climate scientists involved in the first part of the Intergovernmental Panel on Climate Change’s (IPCC) sixth assessment report (AR6), and with several of us present at COP26 in Glasgow, we were worried that the latest scientific evidence might not be recognised in the final COP26 agreement.
There was a precedent for this concern: in 2018 at COP24 in Katowice in Poland, the IPCC special report on 1.5C warming – published before the summit – was only “noted” in the final document and no conclusions from the report were acknowledged.
This was deeply troubling since the parties of the UN Framework Convention on Climate Change (UNFCCC) explicitly requested this report within the Paris Agreement.
Furthermore, IPCC reports present the most authoritative and comprehensive assessment of the risks and solutions to climate change, and the UNFCCC process aims to take into account the best available scientific evidence. After all, IPCC reports are commissioned and approved by delegations from the same countries involved in the UNFCCC process.
Despite our concerns, the scientific evidence from the latest IPCC reports was explicitly acknowledged in the Glasgow Climate Pact.
However, acknowledging the scientific evidence on climate urgency is only the very first step on a path that requires rapid acceleration of action and measurable reductions of emissions, if we want to keep a chance of limiting global warming close to 1.5C.
The IPCC AR6 WG1 report
To highlight the critical importance of science from the latest IPCC reports being included into the COP26 document, we coordinated a letter during the summit that was signed by more than 200 scientists. This summarised the main evidence from the IPCC AR6 report that was particularly relevant for decision-making.
The letter was signed by prominent scientists in the field, including former IPCC Working Group I (WG1) co-chairs Prof Susan Solomon from the Massachusetts Institute of Technology and Prof Thomas Stocker from the University of Bern, as well as present IPCC WG1 co-chair Dr Valérie Masson-Delmotte from the Laboratoire des Science du Climat et de l’Environnement. These signatures were gathered in just two days, following the presentation of the IPCC AR6 report at COP26.
At COP26, the IPCC report was also presented to the Subsidiary Body for Scientific and Technological Advice (SBSTA) of the COP. Several parties and NGOs actively represented the state of science in many of their arguments and there was also strong support for science from the UK presidency team.
Glasgow Climate Pact: acknowledging the science
Ultimately, science was markedly better acknowledged in the final Glasgow Climate Pact compared to outcomes from previous COPs. In particular, The IPCC AR6 WG1 report is “welcomed” and key elements of the report are stated in writing in the document. Most importantly, the COP26 final text:
- “Expresses alarm and utmost concern that human activities have caused around 1.1C of global warming to date and that impacts are already being felt in every region, and that carbon budgets consistent with achieving the Paris Agreement temperature goal are now small and being rapidly depleted.”
- “Stresses the urgency of enhancing ambition and action in relation to mitigation adaptation and finance in this critical decade to address gaps between current efforts and pathways in pursuit of the ultimate objective of the Convention and its long-term global goal.”
- “Notes with serious concern the findings from the contribution of Working Group I to the Intergovernmental Panel on Climate Change sixth assessment report, including that climate and weather extremes and their adverse impacts on people and nature will continue to increase with every additional increment of rising temperatures.”
- “Recognises that the impacts of climate change will be much lower at the temperature increase of 1.5C compared with 2C, and resolves to pursue efforts to limit the temperature increase to 1.5C.”
- “Also recognises that limiting global warming to 1.5C requires rapid, deep and sustained reductions in global greenhouse gas emissions, including reducing global carbon dioxide emissions by 45% by 2030 relative to the 2010 level and to net-zero around mid-century, as well as deep reductions in other greenhouse gases.”
Rapidly depleting carbon budgets
As recognised in the text of the Glasgow Climate Pact, carbon budgets are being rapidly depleted.
Carbon budgets are a simplified way to measure the maximum emissions that can still enter the atmosphere if the world wishes to limit global warming to a specific level such as 1.5C. They are based on the fact that the amount of warming that will occur can be approximated by total – that is, cumulative – CO2 emissions.
As we highlighted in our letter, the WG1 IPCC AR6 report shows that “[t]he remaining CO2 budgets compatible with a stabilisation of global warming at 1.5C are rapidly shrinking…and highlight the urgent need for a rapid and sustained decline of global emissions, under consideration of climate justice and equity”.
As of the beginning of 2021, the remaining carbon budget for a 50% probability of keeping global warming below 1.5C is 460bn tonnes of carbon dioxide (GtCO2). For a 66% or 83% likelihood, this is reduced to 360GtCO2 and 260GtCO2, respectively.
This leads to a stark conclusion in our letter:
“Given the current global annual emissions of around 40GtCO2/yr, these remaining budgets would be exhausted sometime during the period of 2027 to 2033 in the absence of marked decreases in emissions.”
These numbers clearly show a substantial gap between stated ambitions to pursue efforts to 1.5C and the current state of emissions.
Words and commitments
Greta Thunberg famously dismissed COP26 as more “blah blah blah”. As climate scientists, we recognise that the Glasgow Climate Pact indeed includes many words, but few commitments.
Nonetheless, the words do matter and by reflecting some key IPCC conclusions, the text is clear that there is no safe limit on climate change and urgent emission reductions are needed.
Because the Glasgow Climate Pact includes limited commitments actually affecting emissions in coming years, one could conclude that COP26 was largely unsuccessful.
However, both the commitments made by several countries in preparation to COP26 and the commitments for accelerated action agreed at the COP constitute some significant advances over where we were just one year ago.
While there is no question that the currently planned collective actions are not enough to limit global warming to 1.5C, the COP26 document sends a clear signal on the long-term direction and speed of travel that governments need to commit to.
This provides an initial framework to investors, corporations and the diverse group of actors involved in forging the path to net-zero emissions.
Year-on-year global emission reductions
Decisive action is needed over the next year to scale up ambition for the rest of this decade. This includes revised pledges from individual governments – known as nationally determined contributions (NDCs) – that ratchet up emissions cuts, as well as delivering the financial, governance and societal changes necessary for transformative change.
These changes need to bring about the phase out of unabated fossil fuel use to deliver year-on-year emission reductions globally. For example, we already need 5-7% decreases in CO2 emissions in 2022 and 2023 to put us on track towards a halving of emissions by 2030.
Changes are also urgently needed to help communities reduce their vulnerability to recurrent and unprecedented climate extremes, and to help them adapt to ever increasing climate risks.
2022 and COP27
In this context, the decision at COP26 to ask UNFCCC parties to submit more ambitious NDCs at the COP27 – essentially shifting the decision-making by one year – provides some chance for acceleration of action within the next 12 months.
In this timeframe, through bilateral and multilateral exchanges, the parties at the COP should develop concrete mitigation plans, including the consideration of climate justice and equity through proposals for solutions to loss and damage.
One thing is clear: There will be no more excuses at COP27 if binding commitments for concrete phasing out from coal, oil and gas – including end dates – are not on the table.
Prof Sonia Seneviratne is professor of land-climate dynamics at ETH Zurich
Dr Maisa Rojas is associate professor at the University of Chile and director of the Center of Climate and Resilience Research (CR2)
Dr Pep Canadell is chief research scientist at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and executive director of the Global Carbon Project
Dr Christophe Cassou is director of research at the French National Centre for Scientific Research (CNRS)
Prof Piers Forster is professor of climate physics at the University of Leeds and director of the Priestley International Centre for Climate
Dr Nana A B Klutse is senior lecturer in the Department of Geophysics at the University of Ghana
Dr June-Yi Lee is associate professor at the Research Center for Climate Sciences at Pusan National University
Dr Joeri Rogelj is director of research at the Grantham Institute and reader in climate science & policy at the Centre for Environmental Policy at Imperial College London
This article is published under a CC license.