UN and G20 summits reaffirm that limiting global warming to 1.5°C requires global CO₂ emissions to be reduced by 45% by 2030 relative to the 2010 level and to net zero by 2050.

During the COP 27 UN climate convention conference in Egypt in November 2022, negotiations over the second periodic review (PR2) of the long-term global goal under the convention and of overall progress towards achieving it were finalised. The PR2 process is one of the tools used by the climate convention to transfer and integrate the latest climate science facts into the political negotiations. One example of these facts are the ten conclusions of the synthesis report from three climate science hearings held as part of PR2 during 2020–2022 and which are now presented in the COP 27 decision. During the PR2 hearings the latest climate science reports from the IPCC 6 assessment cycle were assessed, along with those from other UN bodies such as UNEP and WHO. The 10 key messages of the PR2 synthesis report1 are:

1. At 1.1°C warming, the world is already experiencing extreme climate change
2. Knowledge has improved significantly since the first periodic review but important gaps remain
3. Climate impacts and risks, including the risk of irreversible impacts, increase with every increment of warming
4. It is still possible to achieve the long-term global goal with immediate and sustained emission reductions
5.  The window of opportunity to achieve climate-resilient development is rapidly closing
6. The world is not on track to achieve the long-term global goal
7. Despite some progress on mitigation and adaptation, more efforts are needed
8. Equity is key to achieving the long-term global goal
9. Key enablers of climate action are not aligned with the urgency of a rapid and equitable low-carbon transition
10. Knowledge, technology and resources are needed to transform global systems in line with low-emission pathways and climate-resilient development

The COP decision states that the impacts of climate change will be much lower at a temperature increase of 1.5°C than they would be at 2°C, and acknowledges that limiting the global average temperature increase to 1.5°C above pre-industrial levels with no or limited overshoot would avoid increasingly severe climate change impacts, stressing that the severity of impacts will be reduced with every increment of global warming avoided. The UN decision expresses alarm and utmost concern that human activities have caused a global average temperature increase of around 1.1°C above pre-industrial levels to date and that impacts are already being felt in every region and will escalate with every increment of global warming. It reaffirms that limiting global warming to 1.5°C requires rapid, deep and sustained reductions in global greenhouse gas emissions, including reducing global carbon dioxide emissions by 45 per cent by 2030 relative to the 2010 level and to net zero around mid-century, as well as deep reductions in other greenhouse gas emissions.
Climate Action Network International said at the start of COP 27 that2:

• even limiting warming to 1.5°C is NOT safe and that there is no escaping the hard science on 1.5°C;
• at 1.1°C warming, the world is already experiencing extreme climate change;
• achieving the long-term global goal without overshooting the 1.5°C limit is imperative in order to avoid the most catastrophic impacts;
• it would reduce the risk of crossing tipping points and triggering potentially irreversible changes in the climate system;
• climate impacts and risks, including the risk of irreversible impacts, increase with every increment of warming;
• it is still possible to achieve the long-term global goal of 1.5°C with immediate and sustained emission reductions;
• rapidly falling costs of renewable energy present new opportunities for pre-2030 emission reductions;
•  the window of opportunity to achieve climate-resilient development is rapidly closing;
• the world is not on track to achieve the long-term global goal;
• equity is key to achieving the long-term global goal;
• during the hearings the IPCC emphasised that immediate rapid reduction in fossil-fuel-based emissions is a prerequisite to climate-resilient development pathways;
• CAN therefore wants to draw attention to the need for a rapid phase-out of fossil fuels and is reminding governments of the call by UN Secretary-General António Guterres for an “end to our global addiction to fossil fuels”.

In the G20 summit of the 20 largest economies in the world, covering 80% of people on the Earth, just before COP 27, the following decision was taken concerning the long-term climate goal³:
“Noting the IPCC assessment that the impact of climate change will be much lower at a temperature increase of 1.5°C compared with 2°C, we resolve to pursue efforts to limit the temperature increase to 1.5°C. This will require meaningful and effective actions and commitment by all countries, taking into account different approaches, through the development of clear national pathways that align long-term ambition with short and medium-term goals, and with international cooperation and support, including finance and technology, and sustainable and responsible consumption and production as critical enablers, in the context of sustainable development.”
In summary: the global long term goal is 1.5.

Reinhold Pape

¹ https://unfccc.int/sites/default/files/resource/sb2022_03E.pdf
² https://eco.climatenetwork.org/cop27-eco1-4/
³ https://www.g20.org/content/dam/gtwenty/gtwenty_new/about_g20/previous-s...