The Paris Agreement signing ceremony at the United Nations in New York last week exceeded all expectations. A record-breaking 175 Parties (174 countries plus the European Union) signed on, and a further 15 countries also deposited their “instruments of ratification, acceptance or approval,” making them the first 15 Parties to officially join the Paris Agreement.

Pacific and Caribbean Islands led the charge, with Barbados, Belize, Fiji, Grenada, the Maldives, the Marshall Islands, Mauritius, Nauru, Palau, St Kitts and Nevis, St Lucia, Samoa and Tuvalu all formally joining.  Somalia became the first African country to join, as well as the first Least Developed Country (LDC). Palestine, which only just joined the UN Framework Convention on Climate Change (UNFCCC) on December 18, 2015, also joined on Friday.

The momentum didn’t stop there. At least 27 countries indicated their intent to join the Paris Agreement either this year or as soon as their domestic approval process allows—among them the United States and China. Combined, these countries would bring the total to 42 countries representing 49.3 percent of emissions. That’s pretty close to the threshold necessary for the Paris Agreement to become legally binding—when 55 Parties representing at least 55 percent of global greenhouse gas emissions join.

Filling the 6 Percent Emissions Gap

So assuming all of these countries do join the Paris Agreement early, which countries will it take to cross the 55 percent emissions threshold?

Below are four possible scenarios on how the world can get to 55 percent of global emissions. Keep in mind that these are just one side of the coin—at least 55 countries will need to join the Agreement as well.

One and Done: Russia

If Russia were to join the Paris Agreement along with the countries referred to above, the total emissions threshold would be met. If this were to occur, it wouldn’t be a first for Russia – the country also triggered entry into force of the Kyoto Protocol, the previous international climate agreement under the UNFCCC.

Russia’s Parliament, the Federal Assembly, must approve by majority vote the country’s joining. Given that Russia has yet to provide any indication of when it intends to join the Paris Agreement, it is unlikely the country is prioritizing this politically.

Pick Two: Brazil, India and Japan

Brazil, India and Japan are all relatively large emitters. If any two of these three countries were to join, the 55 percent of global emissions threshold would be met.

Brazil must get the approval of both houses of its National Congress to join. On Monday Brazil’s government indicated it would ask its National Congress to do just that, but it’s unclear whether this will happen anytime soon given the current political turmoil.

Neither India nor Japan have made firm statements about when they will join the Paris Agreement, but India’s environment and energy ministers have emphasized the country’s commitment to being part of the solution and fulfilling the targets set in its national climate commitment. At the signing ceremony, Japan indicated it would start the necessary preparations in order to ratify, but provided no timetable.

For India, the decision to join the Agreement rests with the executive government. For Japan, two houses of its legislative body, the Diet, must approve entry, with one-third of the members of either house present for the majority vote. The Agreement must then go to the Cabinet for advice and approval before being attested to by the Emperor.  

Triple Play: Japan, South Africa and South Korea

The emissions threshold would also be met if Japan, South Africa and South Korea all joined. Both South Africa and South Korea have expressed support for early entry into force and for taking the necessary measures to make this happen, but neither country has committed to completing the process in 2016.

For both South Africa and South Korea, the nature of the domestic approval process depends on the nature of the agreement.

If South Africa considers an agreement to be technical, administrative or executive in nature, the executive government has authority to join. Any other international agreement must go to both houses of South Africa’s Parliament for approval by a majority vote in each house.

South Korea’s National Assembly must consent to join any international agreements that relate to mutual assistance or mutual security; important international organizations; friendship, trade and navigation; peace; legislative matters, or any agreement that restricts the sovereignty of or places important financial obligations on the nation.  Given its global significance, the Paris Agreement is likely to fall into one of these categories.

The Variety Pack

The above scenarios all focus on small numbers of relatively large emitters getting us over the 55 percent emissions threshold.  However, there are numerous other possible country combinations. Least Developed Countries—which account for more than 3 percent of global emissions—as a group have already committed to join the Paris Agreement early. Combined with the 42 countries above, that brings us well over the 55 countries threshold, but still shy of the emissions threshold.

Countries that could play an important role in filling the emissions gap include small-to-medium size emitters:  Indonesia, Vietnam, Thailand, Iran, Turkey, Cote d'Ivoire, Algeria, Nigeria, the United Arab Emirates, Colombia and Peru.

Regardless of which countries are the ones that get us to the double threshold of 55 countries and 55 percent emissions, the significant political will demonstrated last Friday at the signing ceremony increases the likelihood that the Paris Agreement will enter into force early—perhaps even this year. The focus now shifts to turning countries’ national climate plans into steel-in-the-ground projects, ensuring the world meets the ambitious goals of the Paris Agreement.