PARIS, France- One of the trickiest issues at the Paris climate talks involves a term called differentiation- and Singapore is playing a key role as broker on this issue.
Singapore and Brazil have been tasked with listening to myriad views on differentiation among the 195 nations trying to finalise a new climate change agreement at the end of the week.
Differentiation refers to the different roles and responsibilities of developed and developing nations in addressing climate change, particularly cutting emissions and financing.
It goes back to a key principle in the 1992 United Nations Framework Convention on Climate Change (UNFCCC) that carved up the world into developed and developing nations. Under the 1997 Kyoto Protocol, which is part of the Convention, only rich nations are obliged to take on binding emissions cuts.
The Convention also spells out that nations should act "in accordance with their common but differentiated responsibilities and respective capabilities".
Rich nations were meant to recognise their historic role that they have emitted more carbon dioxide (CO2) than developing countries and should therefore take the lead in efforts to fight climate change.
The world, though, is a very different place than either 1992 or 1997. Many developing nations are far wealthier and now comprise some of the top carbon emitters, with China pumping out about a quarter of mankind's greenhouse gas emissions.
Developing nations also now emit more than half the world's CO2 emissions.
So the distinction between roles and responsibilities of rich and poor nations has blurred somewhat, though not entirely.
The Paris agreement aims to bring all nations on board in cutting emissions, depending on what their capabilities are, and to settle on a way to review and ratchet up these national climate plans, called Intended Nationally Determined Contributions (INDCs), over time to ensure the planet doesn't overheat.
Differentiation, though, still cuts across the draft negotiating text on issues such as finance, mitigation (emissions reductions) and transparency and will likely be part of the final text.
The issue of historical responsibility is also likely to be part of the final text in which developed nations will have to take the lead on some issues.
It is the role of Minister for Foreign Affairs, Dr Vivian Balakrishnan, and Brazilian Environment Minister Ms Izabella Teixeira, to help smooth over differences. Both have been appointed by the French government as co-chairs to guide discussions on differentiation.
On finance, such as cash for developing nations to green their economies and pay for climate change impacts, poorer nations expect wealthier states to take the lead in providing annual streams of funding that will be scaled up over time from 2020.
On mitigation, developed nations are not expecting poorer states to take on the same targets but for everybody to do their fair share in cutting emissions over time and that all national actions be transparent, open to review and able to be measured and verified to ensure no backsliding.
The issue of transparency is a complex one. Some developing countries want to maintain the current system of reporting on climate actions which is less onerous for them and more detailed and binding for rich nations.
This is in part because a lot of developing nations do not have the technical expertise in reporting and measurement of climate actions and need time to build up capacity.
Developing nations are also wary of having their individual INDCs open to external scrutiny during regular reviews and prefer developed countries to still face deeper scrutiny. The draft text mentions that any review of national climate plans be non-punitive, facilitative, non-intrusive, respectful of national sovereignty. These words reflect developing countries' wish of not being put on the spot.
Transparency of support, such as financial and technological aid, is another disputed area. Wealthy states want recipients to tell them how they¡¯ve used the money, whereas developing countries want accountability for the donors and the sources of financing to ensure no double counting.
Another key issue is getting agreement on the timetable on when INDCs will be reviewed. Climate scientists and some NGOs say it is crucial the INDCs are revisited as soon as possible, and certainly before the 2020 start of the Paris agreement.
Leaving it any longer means a lot of the INDCs on the table now will be out of date and risks leaving it too late to rapidly cut growing CO2 emissions in time to prevent catastrophic climate change.