How to deal with the 1.5°C Climate Target

In a position paper, the German Climate Consortium, of which the Max Planck Institute for Meteorology is a member, has made recommendations on how to deal with the widely discussed 1.5°C target in climate policy. According to the paper, the target is no longer achievable, but it cannot be abandoned either.

Under the impression of devastating recent extreme weather events – such as the heavy rainfall in Central Europe and Spain or the tropical storms in the US and the Philippines – the 29th Conference of the Parties (COP) is taking place in Baku (Azerbaijan) from November 11 to 22, 2024. At this international meeting, the European Union plans on promoting ambitious climate protection plans in order to meet the so-called 1.5°C climate target: limiting global warming to a maximum of 1.5°C compared to pre-industrial times.

Whether or not this goal is still realistic has been questioned several times: After all, the EU climate service Copernicus recently predicted that 2024 will be the first year with an annual temperature more than 1.5°C above the average of the period 1850-1900. Even though the 1.5°C target is not about a single year, but about an average value over 20 years, this, too, is likely to exceed the 1.5°C mark in the early 2030s. Against this backdrop, the German Climate Consortium (Deutsches Klima-Konsortium, DKK), of which the Max Planck Institute for Meteorology (MPI-M) is a member, has made recommendations on how to deal with the 1.5°C target. The position paper was co-authored by MPI-M Director Jochem Marotzke and published on the DKK website. The DKK is an association of 27 German climate and climate impact research institutions.

In six key messages, the authors of the position paper state clearly that the foreseeable failure to achieve the 1.5°C target should be openly communicated. They also explain its physical and political significance, name obstacles to the achievement of the target, and remind readers of the precise wording of the Paris Agreement: to hold global warming well below two degrees and to make efforts to limit the temperature increase to 1.5°C. The Paris Agreement also entails the realization of greenhouse gas neutrality in the second half of the 21st century. It is binding under international law and cannot be abandoned.

The key messages in the original wording

1. The foreseeable exceeding of the benchmark of 1.5°C should be openly communicated and taken into account in political action. The Sixth IPCC Assessment Report states that the 20-year average of the global temperature increase is expected to exceed the 1.5°C limit by the early 2030s. Climate adaptation strategies should be based on and prepare for currently plausible temperature scenarios. Irrespective of this, every effort must continue to be made to limit the temperature increase in accordance with the Paris Agreement.

2. 1.5°C is not a physical threshold for climate change. There is no clear-cut transition from a safe climate to dangerous climate change. Climate change is already causing considerable and, in some cases, irreversible damage in many parts of the world. In many places, the change in the local average temperature deviates significantly upwards and downwards from the global average.

3. With every further increase in global warming, changes in extremes will continue to increase. In its special report on 1.5°C of global warming, the Intergovernmental Panel on Climate Change (IPCC) highlighted the differences in the expected climate impacts between 1.5°C and 2°C. It states that there will be considerably more damage due to climate change at 2°C than at 1.5°C. The IPCC's Sixth Assessment Report shows that for every half degree Celsius increase in temperature, there will be clearly more heatwaves, heavy rainfall and flooding.

4. The Paris Agreement is binding under international law and therefore cannot be abandoned. It states the goal of limiting global warming to well below 2°C and specifies this with reference to 1.5°C. Article 2 states that the "threat of climate change" should be reduced by "holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change". In Article 4, the Paris Agreement specifies the goal of greenhouse gas neutrality and sets a time horizon for this. The article states that global greenhouse gas emissions should peak “as soon as possible [...] so as to achieve a balance between anthropogenic emissions by sources and removals by sinks […] in the second half of this century”. The Paris Agreement adopted by 195 countries and the EU thus politically defines what is considered dangerous climate change and what is to be avoided through appropriate political measures.

5. The Paris Agreement does not set a specific time horizon for the temperature target. However, the exact wording "holding the increase […] to well below 2°C" (Paris Agreement, Art. 2, emphasis added) can be interpreted as an indication that the climatically averaged temperature increase should be kept well below 2°C permanently and at all times. Nevertheless, the concept of "overshoot", that is, temporarily exceeding the temperature threshold of 1.5°C, has emerged in the climate change discourse. If the temperature target of 1.5°C were to be exceeded even temporarily, this would still increase the risk of irreversible damage, such as coral death, glacier melting, loss of biodiversity, dying of the Amazon rainforest.

6. It is in particular the social drivers such as consumer behavior and corporate strategies that counteract compliance with the 1.5°C target. The social sciences provide relevant information on this, as well as on political options for taking action to change course. So far, the political decisions taken are insufficient to achieve the climate policy goals, especially the goal of deep decarbonization. Above all, the great social inequality in many societies around the world stands in the way of decarbonization by 2050. Nevertheless, there are developments that promote the achievement of the 1.5°C climate target and should therefore be highlighted more clearly. These include the fact that almost twice as much is currently being invested globally in renewable energies as in fossil energy production and that the cost of solar energy has fallen by around 90 percent in the last 20 years.

Wissenschaftlicher Ansprechpartner:
Prof. Jochem Marotzke, Max Planck Institute for Meteorology, jochem.marotzke@mpimet.mpg.de

Originalpublikation:
Deutsches Klima-Konsortium: Umgang mit dem 1,5°C-Ziel. DKK-Positionspapier 2024, 11.11.2024. (in German)

Weitere Informationen:
https://www.deutsches-klima-konsortium.de/fileadmin/user_upload/pdfs/Umgang_mit_dem_1_5_Grad_Ziel_-_DKK_Positionspapier_2024_FINAL.pdf – DKK position paper (in German)