The 1.5°C goal of the Paris Agreement

With the adoption of the Paris Agreement in 2015, the global community set itself the overarching goal to hold “the increase in the global average temperature to well below 2°C above pre-industrial levels” and pursue efforts “to limit the temperature increase to 1.5°C above pre-industrial levels. [...]”. Over time, the 1.5°C goal became the benchmark in global climate policy and action. The importance of this upper temperature limit for the protection of people and the environment was underlined by the 2018 special report on global warming of 1.5°C by the Intergonvernmental Panel on Climate Change (IPCC).

Read the UBA position on the 1.5°C goal here.

The 1.5°C goal of the Paris Agreement refers to the increase in global average temperature compared to pre-industrial levels (1850-1900). While a global warming of 1.5°C would still have a significant impact, it would be significantly less catastrophic than a warming of 2°C or more.

The Paris Agreement does not explicitly define the baseline, i.e. the exact reference period for pre-industrial temperature data. However, the IPCC uses a baseline from 1850 to 1900, which is the earliest period with reliable, near-global measurements.

The 1.5°C goal was agreed on in 2015 as part of the Paris Agreement, but its roots go back further:

• In 1992, the United Nations Framework Convention on Climate Change (UNFCCC) was adopted at the UN Conference on Environment and Development in Rio de Janeiro to coordinate a global response to climate change.
• In 1997, the Kyoto Protocol set legally binding emissions targets for industrialised countries for the first time, but without specific temperature targets.
• In 2010, the Cancun Agreement at the climate conference in Cancun confirmed the long-term goal of limiting global warming to below 2°C. The 1.5°C goal was demanded by particularly vulnerable countries.
• In 2015, as a result of scientific research and intensive diplomatic negotiations at COP21 in Paris, Parties agreed to the goal of limiting global warming to well below 2°C and making efforts to limit it to 1.5°C, as part of the Paris Agreement

Scientific findings and studies, largely compiled in the IPCC reports, have shown that warming beyond 1.5°C can have serious and possibly irreversible impacts on the climate. Even at 1.5°C global warming, sea level rise, the loss of large areas of ice, heat waves and the threat to island states are significant. Towards a global warming of 2°C and beyond, irreversible tipping points are very likely to be triggered, which would destabilize the climate system and cause irreversible changes.

The drastic impacts of ongoing climate change include:

• Extreme weather events: Warming above 1.5°C would further increase the frequency and intensity of extreme weather events such as heatwaves, heavy rainfall and hurricanes. These events can cause considerable damage to infrastructure and agriculture and threaten the livelihoods of many people.
• Sea level rise: Limiting warming to 1.5°C would slow down sea level rise, which is particularly important for island states and coastal regions. The impacts of sea level rise include flooding and loss of land.
• Ecosystems and biodiversity: Many ecosystems, including coral reefs and arctic habitats, are severely threatened by a global warming of more than 1.5°C. The preservation of these ecosystems is crucial for biodiversity and the well-being of many animal and plant species.
• Health effects: Less global warming would also reduce the negative health impacts that can result from heat waves, air pollution and the spread of disease.
• Economic stability: Climate change-related damage can cause considerable economic costs. Limiting warming would help minimize economic losses and create new jobs in green technologies.

In 2024, the latest temperature data from the European climate data agency Copernicus confirmed that for the first time the Earth has reached a global warming level of more than 1.5°C above pre-industrial levels for a full year.

However, this does not mean that the long-term goal of the Paris Agreement has been exceeded. Global warming is measured as a long-term average temperature (usually 20- to 30-year averages), not on the basis of individual hot years or months, as shorter periods can be heavily dominated by natural fluctuations. Based on the current warming trend, the world is expected to exceed the 1.5°C goal in the long-term between 2030 and 2040.

The debate about the feasibility and interpretation of the 1.5°C goal illustrates how urgently we need global and effective climate action, and how complex the political, economic and technological challenges involved are. While some experts are sceptical as to whether the goal of the Paris Agreement is still achievable at all, there is still hope that climate change can be limited to a tolerable level through swift action. To keep the goal of 1.5°C within reach, global greenhouse gas emissions would have to be reduced by 43 percent by 2030 compared to 2019, then by 60 percent by 2035, and global CO₂ neutrality needs to be realised by the early 2050s at the latest, i.e. the emission and removal of CO₂ from the atmosphere has to be balanced through sinks. 

This requires drastic measures such as reducing dependence on fossil fuels and a more ambitious promotion of renewable energies. Emissions must be drastically reduced worldwide and limited to unavoidable residual emissions. International cooperation on climate action, particularly between major emitters such as the USA, China and the EU, is seen as crucial.

An overview of the most important measures in climate action:

• Renewable energies: Investing in solar and wind power to replace fossil fuels.
• Energy efficiency: Improving energy efficiency in all sectors.
• Reforestation: Protecting and restoring forests to capture CO₂ from the atmosphere.
• Technological innovation: Developing and deploying new technologies to reduce emissions.
• Circular economy: Transition to a sustainable, regenerative and greenhouse gas-neutral circular economy.
• Behavioural change: Promotion of sustainable lifestyles and consumption patterns, e.g. mobility sufficiency.
• International cooperation: Global support and cooperation, especially for developing countries

An overshoot of the 1.5°C benchmark would have serious consequences. For example, the melting of the ice sheets on Greenland and in the Antarctic would be virtually unstoppable, which would cause sea levels to rise in the long-term. The risk of extreme weather events such as droughts and heatwaves would also increase.

It would theoretically be possible to achieve a lowering back to below 1.5°C even after an overshoot. This would require enormous efforts and, in addition to the already necessary strengthening of natural CO₂ sinks such as forests, the large-scale use of carbon capture and storage technologies. These technologies, which remove CO₂ from the atmosphere and store it in e.g. geological formations are currently only available on a small scale. They are extremely expensive, resource-intensive and their potential impact on the environment is not (yet) foreseeable.

It is therefore important to keep the global temperature increase as low as possible: Every temperature increase that is avoided, however small, counts. A temporary overshoot of the 1.5°C benchmark must be minimised in extent and duration. Any overshoot can result in serious and potentially irreversible changes in the climate system, with unforeseeable effects on people and the environment. The premise therefore remains to act early and consistently in order to avoid such scenarios.

The 1.5°C goal applies to all countries that have signed the Paris Agreement. A total of 195 countries have committed to drawing up Nationally Determined Contributions (NDCs) to reduce their greenhouse gas emissions and develop adaptation strategies. These differences between countries are important:

• Developed countries: They have a special responsibility as they have historically emitted most of the greenhouse gases and have more resources to act against climate change. These countries must drastically reduce their emissions and support developing countries financially and technologically.
• Developing countries: These countries are often hit the hardest by the effects of climate change and have the least resources to adapt. International support and cooperation are therefore particularly important.
• Particularly vulnerable states: Small island states and low-lying coastal countries are particularly vulnerable to sea level rise and extreme weather events. These countries have campaigned particularly strongly for the 1.5°C goal in the climate negotiations.

Conclusion: The 1.5°C goal is still of central importance for international climate policy. The goal is to keep the 1.5°C global warming limit within reach. Furthermore, the Paris Agreement is binding under international law. In order to prevent or minimize the dangerous effects of ongoing global warming, the global community must continue to implement ambitious climate action. Limiting global warming means a more liveable future for all of us and is essential for the survival of vulnerable societies and groups as well as many endangered species and biodiversity.

Read more here: UBA position on the 1.5°C goal of the Paris Agreement.