At the start of COP21, Art. 2 had directive language such as "to enhance," "to achieve," and, "Parties [shall][agree to] take urgent action…." By the Dec. 9 draft, the purpose had become a choice between: a) enhancing the Convention’s implementation and achieving its objective, or b) simply further implementing its objective. In the ensuing 24 hours, the language on achieving the Convention’s objective was eliminated, thereby setting the stage for a weaker final purpose. The addition of a new phrase, "in the context of sustainable development and efforts to eradicate poverty," possibly indicates that developing countries secured something important to them in exchange. The final language of Art. 2.1’s chapeau presented a whole new and more action-based purpose: “aims to strengthen the global response to the threat of climate change.” Although "enhancing the implementation of the Convention, including its objective” survived, it was no longer the focus. This weakening trend is also evident in the rest of the purpose-setting chapeau. The "urgent threat of climate change" phrase became the "threat of climate change." The Parties also negotiated away from directly tasking themselves to pursue a "strengthen[ing of] the global response" to that threat, to a non-specific collective action, with no one to hold accountable. The Paris Agreement's purpose contains no phrase directly assigning any responsibility, either aspirational or mandatory, to the Parties to pursue it.

ADP2-12 began its negotiations with six options for phrasing the long-term temperature goal: "Hold the increase in the global average temperature [below 2°C][below 1.5°C][well below 2°C][below 2°C or 1.5°C][as far below 2°C as possible] above pre-industrial levels." During the first week of COP21, these options contracted to two, but then expanded again during the second week. The goal finally solidified between December 9 and 10. Throughout, the LDCs and SIDS remained insistent on including a 1.5°C target, and emerging economy states' continued to push back, concerned that such a low limit on the global temperature increase would constrain their development. An alliance that began initially between the most vulnerable countries and the most advanced economy states, but which grew to more than 100 countries in the final days of COP21, found acceptable language for the 1.5°C goal. In the end, all Parties were able to support the phrase: "pursu[ing] efforts to limit the temperature increase to 1.5°C above pre-industrial levels" as an aspirational component of the long-term goal. This acquiescence to a two-tiered temperature goal may have been part of the tradeoff that also retained "in the context of sustainable development and efforts to eradicate poverty" in the chapeau. It is unclear whether the final crafting occurred in preparing the COP decision on the 2013-2015 review of the long-term temperature goal (Dec. 1/CP21 para. 4) or in the Paris Agreement negotiations, since these are identical.

The presence of a two-tiered long-term temperature goal combined with the vagueness of the first tier creates significant uncertainty for monitoring achievement of the Paris Agreement’s purpose. While both are specific, the first is directive ("[h]olding the increase in the global average temperature to well below 2°C above pre-industrial levels."), and the second is aspirational ("to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels”). From a negotiating perspective, this goal raises at least two science-based issues. The first is one of definition. What does "well below 2°C" mean? At what tenth of a degree below 2°C will Parties agree the "well below" point has been achieved? At no place in the Agreement, or the Decision adopting it, is the phrase "well below 2°C" defined. Nor are the subsidiary bodies tasked with agreeing on a definition. This is important, because "the approximately linear relationship between cumulative total anthropogenic CO2 emissions and the global average temperature rise," and other conclusions of the Structured Expert Dialogue seem to have guided the selection of the long-term emissions goal of Art. 4.1. It specifies GHG emissions peaking, plus a subsequent reduction time frame for reaching a dynamic 'end point,' for operationalizing a long-term temperature goal. Yet, the vagueness of Art. 4.1 could result in a failure to achieve that long-term temperature goal. Future negotiations on this part of the Agreement will be important to watch. The second issue is the matter of the timeliness of the science. The Parties will likely rely predominantly on the IPCC reports to keep tabs on the trajectory of the average global temperature increase. Yet, many consider the IPCC’s reports to be dated upon their release, because of the length of time required for the working group and peer-review processes. Recommendations for IPCC "topical assessment papers" in addition to the full assessments may address this constraint and advance the capacity of Parties to achieve a closer-to-real-time understanding of the global temperature rise as it nears the limit established by Art. 2.1(a). Of note is that, in Dec. para. 21, Parties invited the IPCC "to provide a special report in 2018 on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways." This report may ultimately have implications for the long-term emissions goal.

The financial flow goal of Art. 2.1(c) applies specifically to a portion of the second goal (Art. 2.1(b)). Article 2.1(b) speaks to capacity building for both: i) adaptation to climate change impacts; and ii) development in terms of low GHG emissions and climate change resilience. Article 2.1(c) states the intention for finance flows to be "consistent with a pathway towards low greenhouse gas emissions and climate-resilient development." Thus, while the language does not explicitly restrict financial flows to building capacity for a certain kind of mitigation and adaptation-related development, its focus is there, rather than additionally on building current adaptation capacity. What does this mean for future negotiations on the implementation of the Agreement? In terms of adaptation funding, perhaps we can see this Art. 2.1(c) language of the Paris Agreement as an enhancement of the Convention, which addresses only current adaptation needs and only for the most vulnerable countries (UNFCCC Art. 4.4). This is certainly in line with the robust adaptation work of the UNFCCC over the past decade; and the link between Art. 2.1(c) and the chapeau phrase of Art. 2.1, "in the context of sustainable development and efforts to eradicate poverty," would seem to give ground for broadening the intent of climate-related financial flows to developing countries in future negotiations. Still, there are complicating influences of the language. Not only are there no UNFCCC definitions for climate resilient development and low GHG development, these are wide-ranging concepts, and multiple pathways can be envisioned for even just a single community, much less those for a region or nation. Assessing the consistency of financial flows with these pathways would seem to involve a complex matrix of benchmarks, processes, and outcomes. Given that the Agreement nowhere directly addresses these concepts, can alignment truly be determined? And, if not, how can the effectiveness of the financial aspect of the Agreement be evaluated? It will be very important to follow the scholarship on these intersections, as well as the negotiations of the CMA. The development of modalities and guidelines for activities related to financial support for developing countries to mitigate and adapt (Art.9 and Decision paras. 52-64), are directly linked to the finance flow goal of the Agreement's purpose. Of particular importance are such queries as: a) what level of financial resources will be considered adequate in what circumstances and for what pathways; and b) how will financial resources provided and developing country needs and progress be categorized, monitored and aggregated to actually assess the adequacy of the financial support. The fact that much of the financial flows will be leveraged funds makes even the most modest of characterization and assessment tasks quite complicated.

Throughout most of the drafts, Art. 2.2 comprised a number of principles (on the basis of equity, on the basis of science, and in accordance with differentiation) and a number of rules-of-conduct phrases under the umbrella of "while ensuring…." These included, among others: "the integrity and resilience of natural ecosystems," "the protection of health," and "the respect, protection, promotion and fulfillment of human rights for all." Types of human rights (e.g. ensuring gender equality and intergenerational equity) and groups (e.g., indigenous peoples) were also included. As COP21 proceeded, however, the science basis as a principle was extracted and all of the rules-of-conduct qualifiers were incrementally shifted to the Preamble. The most tenacious rule-of-conduct, which survived well into week 2, was: "on the basis of respect for human rights." Three significant players spoke out against its inclusion in the operative articles of the Agreement during the last days of COP21: Saudi Arabia, Norway, and the U.S. They gained enough silent support to win its move from Art. 2.2 to the Preamble. In this way, the Agreement omits any legally binding obligation for Parties to respect human rights. In the end, Art. 2.2 reverted to the differentiation phrasing contained in the Lima Call to Climate Action. This represented the intention of most Parties to maintain a strict focus on the Parties, rather than include sub-groups of stakeholders. At the same time, it also reflected the insistence by highly developed countries to expand beyond the Convention’s original strict bifurcation of developed and developing countries, while also protecting themselves from accountability for climate change impacts.

A single paragraph (para. 17) in the Decision version first considered by ADP2-12 at the beginning of the COP referenced the Agreement's purpose. While the paragraph retained the same general focus through to the final version of December 12, the statement regarding the inadequacy of the current INDCs "in fulfilling the purpose of the Agreement" was removed. This leaves only one place in the final Decision that the purpose is now referenced. Paragraph 52 establishes developing country accountability for the financial support they receive to enhance their mitigation and adaptation actions to "contribute to the achievement of the purpose of the Agreement as defined in its Article 2." Of note is that para. 17, when referring to the gap between the aggregate effects of the INDCs and target temperature increase limits, neither originally nor in the final Decision, uses the "well below 2°C" language of the long-term temperature goal of Art. 2.