The Paris Agreement continued to amaze this week, with another 31 countries formally joining the treaty, including 8 AOSIS members—Tonga, Kiribati, Solomon Islands, Dominica, Papua New Guinea, Antigua and Barbuda, and Singapore. That brings the total AOSIS count to 24—nearly half of the number required to bring the agreement into force and more than one-third of the 60 parties to have formally joined it so far.

Typically, the ratification period takes years, but buoyed by AOSIS’s push for early entry into force and unprecedented political momentum for climate action around the world, the first international treaty committing nearly all nations to reducing the emissions responsible for climate change has exceeded all expectations.

Now only one final hurdle remains for the agreement to take effect: its parties must represent 55% of global emissions. Right now, they account for about 48%. Many veteran observers are wagering that there is little doubt that both thresholds will be reached this year

Still, questions remain over how the 7 percent will be breached. The European Union, which accounts for 14% of the global total, has been discussing the possibility of ratifying as a bloc to avoid the long and drawn out process of having all it’s members do so independently. That would cover the spread, so to speak, in one fell swoop.

Other pathways would require relatively large emitters to formally join. Russia, at 7.53%, could do it on its own or perhaps combination of Japan, 3.7%, and India, at 4.1%. Additional formulations could have Korea, 1.85%, South Africa, 1.46%, and a good chunk of countries with small emissions to bring the numbers over the line. How or when this will happen, at least based on public statements, remains uncertain.

Adding another nuance is language in the agreement that says it shall take effect 30 days after these thresholds are met. If that happens before Oct. 7, COP 22 in Marrakesh would become the first meeting of the Parties to the Paris Agreement. Such an occurrence could potentially create some procedural complications, but Morocco has said it is prepared to manage any possibility.

Clearly the excitement around the Paris Agreement is a good sign, but the world has been on the verge of concerted climate action before only to see the opportunity slip away. And let’s not forget, unless it is followed up with action, the numbers required to cross the ratification thresholds will mean little compared to the more exacting numbers that are rapidly bring us toward a 2 degree or more world.

Put that way, its seems the world is racing against the clock and a thermometer.