I have used this simulation in an upper level undergraduate class for science and non-science majors. Works especially well for environmental science / studies classes.

A fundamental understanding of climate change dynamics and the potential impacts of climate change will help students appreciate the desired outcome to reduce greenhouse gases.

I find it most useful at end of semester/term as a culminating project for a class on climate change, and environmental studies or environmental science.

To examine possible policy solutions to mitigate climate change.
To determine how much reduction in greenhouse gases is feasible.
To determine which policy actions will result in a large (and small) reductions in greenhouse gases.
To determine the complexity and difficulty of climate change negotiations.

Critical evaluation of policy alternatives to climate change—which ones are workable, which ones are "best", which ones are acceptable to the international community?
Critical thinking skills; synthesis of different ideas to lower greenhouse gas emissions

Collaborating with other students. Learning negotiating skills—how to most effectively accommodate interests which are different from the ones you represent? Oral presentation of arguments.

Teaching about policy solutions to climate change using an in-class simulation results in increased understanding of the process and is more interesting for the students compared to a lecture-based approach. For those teachers like myself whose expertise is in science rather than policy this approach has the added advantage that much of the student learning derives from their own initiative and resourcefulness instead of the "teacher as expert" method. It develops essential skills including collaboration, cooperation, negotiation, and requires an understanding of different perspectives.

To prepare for the simulation, I give a short lecture and assign background readings presenting an overview of international climate change negotiations. During this class, students then choose one country to represent making sure that countries from key groups are represented, e.g. G77 + China, EU, island nations, oil producing countries, and JUSCANZ (Japan, US, Canada, Aus., NZ). Before the next class, each student writes a background paper about their country and their future energy demands as well as a draft resolution on how to mitigate climate change reflecting their countries interests. Once students have determined their own positions, they introduce themselves to the other representatives in class and state their position. I circulate their background papers and position papers.

The next class is devoted to informal meetings and discussion between countries (aka caucusing). This can occur in the classroom, or at a local coffee house, which adds to the novelty and enjoyment. Based on conversations, negotiations, and reading position papers, students revise and refine their draft resolution to produce a formal position paper. They present this during the last class which is a final negotiating session

Evaluation is based on background papers, as well as the draft and final position paper on how to mitigate climate change. I grade based on how accurate the draft version is, as well as how they have changed their resolution to reflect the real world realties. Assessment is also based on their oral presentation of their formal resolution, and overall class participation. Outcomes of actual negotiations, learning during lecture, and in readings, are assessed during a written examination.

There are numerous web sites associated with model UN simulations, which is essentially what this exercise is like. Some relevant web sites include:
National Model UN: http://www.nmun.org
The Haugue International Model UN: http://www.thimun.org
Model UN Headquarters: http://www.un.org/Pubs/CyberSchoolBus/
Official site for the UN: http://www.unausa.org

Framework Convention on Climate Change: https://unfccc.int
Lots of information—take care and don't get bogged down in irrelevant bureaucracy.

Climate Change resources in the United Nations: http://www.un.org/climatechange/un-partners/

Key UN documents on Climate Change
http://www.un.org/sustainabledevelopment/climate-change-2/

Documents for the previous COP 9 meeting in Milan, Italy:
https://unfccc.int/cop9/index.html
replace the number "9" with 10, 11, 12 for following meetings

Climate & Development Knowledge Network: [link http://cdkn.org/ 'http://cdkn.org/?loclang=en_gb]