The Language of Climate: Kyoto to Paris

by Hannah Melville-Rea

The Paris Agreement was adopted in 2015 and became the first global agreement to invite all nations to decarbonise in an attempt to ensure global temperature rise stays well below 2 degrees. The Kyoto Protocol, its predecessor, was adopted in 1997, and extended in 2012 under a Second Commitment Period. The goal of the Protocol was to reduce developed countries’ emissions by 5% relative to 1990 levels – with national targets ranging from 87.5% of the baseline in the UK to 125% for Greece [1]. 

New insights can be derived from the two treaties when the words in the documents are analysed as a data form. In this article, I summarise my observations from statistically analysing the text that makes up the Paris Agreement and Kyoto Protocol (methodology here) and provide a reflection on how climate agreements have changed over time.

From Coordinated Targets to Holistic Pledges

Certain words are used at least 20 times in both of the agreements, Figure 1. Some of the lexicon has remained consistent from 1997 to 2015. Most notably, ‘Parties’ is the most used term, and refers to the subjects (in this case, countries) that will carry out what is specified in the agreements. This indicates that the agreements are subject driven, giving signatories the agency to carry out the agreement.

Figure 1. Words that appear at least 20 times in the agreements

A word that only appears in the Kyoto Protocol is ‘annex’. The annex country system used in the Kyoto Protocol (referenced over 70 times) separated developed and developing countries into Annex I and Annex II groupings [2]. In contrast, the Paris Agreement moved towards a system of ‘common but differentiated responsibilities’ where all countries became responsible for decarbonising [3]. 

Under Paris, countries submit national climate pledges called Nationally Determined Contributions – hence the high frequency of ‘nationally’ and ‘determined’. As a result of moving away from the annex system, in the Paris Agreement we see that ‘developing’ countries are singled out and terms such as ‘support’, ‘serving’ and ‘development’ are often used to highlight that while the developing world is expected to contribute, this relies on a flow of support from developed nations. 

A Broadening Scope for Climate Action

The Kyoto Protocol has a narrower scope than the Paris Agreement. The repetition of the terms ’emissions’ and ‘commitments’ reflects the Kyoto Protocol’s focus on building national emissions targets. To achieve this, the Kyoto Protocol established an international emissions trading scheme. Further, the Joint Implementation scheme and Clean Development Mechanism were created to reward countries for investing in decarbonising activities outside of their borders.

In contrast, the Paris Agreement has a broader, more flexible approach. Notably, ‘adaptation‘ is a core focus of the text and appears in the text twice as many times as the term ‘mitigation‘. Thus the agreement goes beyond urgent emissions reduction and stresses the need to shift economies and societies to build resilience in the face of climate impacts. This signals a greater acceptance that climate change is happening. 

A Positive Tone on a Serious Challenge

When it comes to the sentiment of these agreements, both texts are made up of mostly positive words. Despite dealing with a serious topic, the tone is action oriented – less time is taken on outlining the risks and impacts of environmental damage and climate change and the focus is solely on the actions that will be taken. In Figure 2, I highlight words with positive and negative connotations throughout the Kyoto Protocol and Paris Agreement.

Kyoto ProtocolParis Agreement
Positive Words
Negative Words

Figure 2. Words with positive and negative connotations in the climate agreements

Our discourse for describing sustainability has changed over time. For example, the word ‘clean’ despite having been a frequently used term in the Kyoto Protocol has been eradicated from the Paris Agreement. Meanwhile, rigid words such as ‘commitments’ and ‘approvals’ have shifted to ‘contributing’, ‘enhancing’ and ‘supporting’. This indicates that in order to create a globally applicable text, we adopted more flexible terms in the Paris Agreement. 

Finally, the risk-related words used in climate agreements have become more human oriented. For example, the Kyoto Protocol focuses on the depletion of resources and its adverse impacts. In contrast, ‘vulnerable’, ‘loss’, ‘poverty’ in the Paris Agreement all reflect how climate change is now viewed as a human problem that will directly impact people. 

Examining the words that make up the Paris Agreement and Kyoto Protocol reveals how our discourse of climate change has changed over time. The Kyoto Protocol was seen as a huge step forward in climate policy and elements of it are no doubt reflected in the Paris Agreement. The agreement has aided food security and ‘established a flexible, broad-based, international mechanism that provides a valuable starting point for shaping efficient climate policies in the future’ [4, 5]. However, it was limited in scope by focusing only on developed nations’ contribution, thereby giving no targets to the largest emitter, China. With the Paris Agreement, we have moved towards a more collaborative and human-centric approach to climate cooperation.


[1] UNFCCC, URL:, (accessed May 2021)
[2] UNFCCC (1997) Kyoto Protocol, URL:, (accessed May 2021)
[3] UNFCCC (2015) Paris Agreement, URL:, (accessed May 2021)
[4] FAO (2005) Kyoto Protocol – important tool for sustainable development. URL:, (accessed May 2021)
[5] Christoph Böhringer (2003). ‘The Kyoto Protocol: A Review and Perspectives’ Oxford Review of Economic Policy, Volume 19, Issue 3, September 2003, Pages 451–466, DOI:, (accessed May 2021)
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