Aspirations not commitments

In a 2015 article (updated this year),ⁱ the BBC lists what it describes as a series of ‘commitments’ contained in the Paris Agreement.ⁱⁱ The first is: ‘to “pursue efforts” to limit global temperature rises to 1.5C, and to keep them “well below” 2.0C above those recorded in pre-industrial times…’ But the Paris Agreement contains no such commitment. The temperature targets are found in the Agreement’s Article 2.1 (a) which is introduced by this: ‘This Agreement … aims to strengthen the global response to the threat of climate change … by’ . An ‘aim’ is not a commitment.

In other words, although widely described as commitments, the 1.5ºC and ‘well below’ 2.0ºC targets are, in the Agreement itself, no more than aspirations.ⁱⁱⁱ

But they’re important

Nonetheless the temperature goals have assumed considerable importance in climate policy and legal reasoning. Examples of how this has happened can be found in the Dutch Supreme Court’s 2019 judgment in Urgenda v Netherlands^ivand in the German Constitutional Court’s 2021 ruling.^v As a result of these and similar judicial decisions, the temperature targets have effectively been treated as benchmarks for legal obligations, at least in parts of Western Europe. Yet these obligations are not based on the Paris Agreement’s text.

Even so, the targets and their perceived consequences continue to have considerable impact on climate change discourse and commentary. For example, in 2023 the World Economic Forum stated that ‘The 1.5-degree Celsius threshold is considered a critical threshold, as it is the point at which the impacts of climate change are expected to become increasingly severe.’ ^vi Therefore it’s important to consider whether, although the Paris Agreement does not provide legal authority, they are nonetheless based on rigorous scientific research.

Where did they originate?

The 2.0ºC target first appeared in academic discussions in the 1970s and later gained political traction when the German Advisory Council on Global Change (WBGU) promoted 2.0°C as a ‘guardrail’ ^vii and when the EU adopted it in 1996 as a policy objective.^viii But these were value judgements rather than scientifically based findings.

The origin of the 1.5ºC target was very different. It emerged largely as a result of advocacy by in particular small island states (AOSIS) which claimed that exceeding 2.0ºC would for them mean existential damage. In other words, its origin was moral and political rather than scientific. ^ix

Therefore, rather than being based on rigorous science, both targets are essentially policy guardrails – arguably at least not much more than mission statements or political slogans.

Are they achievable?

However, whatever their origins, the targets have since become central to climate policy and modelling — particularly following the IPCC’s 2018 Special Report on 1.5°C.^x And it’s therefore useful to refer back to that report today as, although some doubts are developing about the prospects for the Paris Agreement’s 1.5ºC target ^xi, it’s now increasingly clear, although often overlooked, that in reality there’s no realistic prospect of humanity keeping global temperatures below that level – or even below the seemingly rather easier target of ‘well below’ 2ºC. Here’s why:

The 1.5ºC target

In paragraph C1 of its special report the IPCC recommended that, to achieve the Paris Agreement’s 1.5ºC target, global CO₂ emissions should ‘decline by about 45% from 2010 levels by 2030’. As global emissions in 2010 were 34.0 gigatonnes (Gt)^xii they would therefore have to come down to about 18.7 Gt by 2030 to meet the target. But, just three countries (China, the US and India) already exceed that (by 2.2 Gt) and, taken together, are likely to increase (or at best stabilise) their emissions over the next four years. Moreover another 194 countries, together with shipping and aviation, are the source of about 20 Gt of CO₂ and, unless established trends are reversed, it’s very likely that figure will either be unchanged or will have increased by 2030.

Therefore global emissions will probably be far above 18.7 Gt and, if the IPCC got it right, warming of much more than 1.5ºC target is overwhelmingly likely.

The ‘well below’ 2ºC target

The Paris Agreement’s ‘well below’ 2ºC target faces the same problem. In paragraph C1 of its special report the IPCC recommended that, to limit ‘global warming to below 2°C’, global CO₂ emissions should ‘decline by about 25% from 2010 levels by 2030’. Therefore, as 2010 global emissions were 34.0 Gigatonnes (Gt), they’d have to come down to about 25.5 Gt by 2030 for emissions to get ‘below’ 2ºC – say 24.5 Gt for ‘well below’ 2ºC as specified by the Paris Agreement’s Article 2.1(a). But just 7 countries (China, the USA, India, Russia, Iran, Indonesia and Saudi Arabia) already account for over 24.5 Gt and these are countries that, taken together, are likely to increase (or at best stabilise) their emissions over the next four years. Moreover another 190 countries, together with shipping and aviation, are the source of about 17 Gt of CO₂ and, unless established trends are reversed, it’s very likely that figure will either be unchanged or will have increased by 2030.

Therefore global emissions will probably be far above 24.5 Gt and, if the IPCC got it right, warming of much more than 2ºC is overwhelmingly likely.

Conclusion

The Paris Agreement’s temperature aspirations, although based on neither legal obligation nor rigorous science, have assumed significant importance and as such have a major impact on climate discourse. Yet it’s now clear that, despite their political importance, there’s no realistic prospect of humanity complying with the Agreement’s principal aim of ‘holding the increase in the global average temperature to well below 2 °C above pre-industrial levels’.

Endnotes

i BBC News, ‘What is the Paris Agreement’, updated 2025: https://www.bbc.co.uk/news/articles/c93d59d4zy1o

ii https://unfccc.int/sites/default/files/english_paris_agreement.pdf

iii Even these aspirations are hedged about with uncertainties and qualifications. For example, the terms ‘’pre-industrial’ and ‘well below’ are not defined and Article 2.1‘s ‘aim’ is qualified by ‘sustainable development and efforts to eradicate poverty’ and by the provisions of items 2.1(b) and (c) and 2.2. Moreover, Article 4.4 in effect exempts developing countries (about 150 of the 197 parties to the Agreement) from any obligation to reduce their emissions.

iv https://www.climatecasechart.com/document/urgenda-foundation-v-state-of-the-netherlands_3297

v https://www.climatecasechart.com/documents/neubauer-et-al-v-germany-order_7977 and see https://gpil.jura.uni-bonn.de/2021/05/the-federal-constitutional-courts-climate-change-order-and-the-interplay-between-international-and-domestic-climate-protection-law/?utm_source=chatgpt.com

vi https://www.weforum.org/stories/2023/09/prevent-1-5-degrees-celsius-climate-threshold/

vii German Advisory Council on Global Change (WBGU), 1995: https://www.wbgu.de/en/publications/publication/szenario-zur-ableitung-globaler-co2-reduktionsziele-und-umsetzungsstrategien

viii See https://archive.unfccc.int/european-council-conclusions-community-strategy-on-climate-change-european-union-19960701

ix Their clever slogan ‘1.5 to stay alive’ has had considerable impact: https://www.sprep.org/news/15-to-stay-alive-for-pacific-countries-is-non-negotiable

x https://www.ipcc.ch/sr15/chapter/spm/

xi See for example https://sustainabilityonline.net/explainer/uncertainty-around-the-1-5c-climate-target-makes-it-more-important-than-ever/

xii https://edgar.jrc.ec.europa.eu/report_2025?vis=co2tot#emissions_table