This analysis has been done in terms of the 1.5°C temperature limit. This objective is extremely demanding, but we have no choice. As the IPCC made clear in Global Warming of 1.5°C, more than 1.5°C degrees of warming would yield immeasurable suffering and destruction (and impacts will be severe even at 1.5). It is crucial to recognize the basic truth of our predicament: 1.5°C can only be reached within an emergency global mobilization, which can only come together if it prioritizes justice just as much as ambition.
While 2°C remains enshrined as a goal in international law, the scientific community no longer sees 2°C as a “guardrail” of any kind[1] (and indeed the Paris Agreement acknowledges that we should aim to stay as close to 1.5°C as possible). In fact, it is now understood that such a degree of warming would yield immeasurable levels of suffering and destruction, and could be both socially and ecologically unmanageable. The 1.5°C target is and must be our proper goal, but achieving it will be almost impossible, and will require sustained international effort of an unprecedented scale. Such effort will demand deep and robust cooperation, and will only be possible if the overall effort is widely seen as fair.
[1] Global Warming of 1.5°C, Intergovernmental Panel on Climate Change, Summary for Policymakers, Section C.2.1, page 21. https://www.ipcc.ch/sr15/