Earth Day this year heralds the opening of the Paris Agreement for signing at the United Nations Headquarters in New York.

The Paris Agreement was created at the end of last year to combat climate change by focusing on reducing CO2 emissions in order to keep the global temperature increase under 2 C. Two degrees Celsius marks the threshold where climate change becomes permanent. As such, the limit has been set at 1.5 C, which would be met by ensuring no net emissions during the second half of this century.

Under the Paris Agreement, each nation would set its own target for emissions with no formal enforcement system, but with reports given every five years for transparency.

Included is the Green Climate fund, a nonbinding plan to provide $100 billion to developing countries per year as aid towards reducing their emissions.

168 countries are expected to sign at the signature ceremony this afternoon.  While this number is a UN record, it is only the first step towards the agreement taking effect– 55 countries representing 55% of global greenhouse gases contributions have to sign and ratify before the treaty goes into effect.

So far, only 14 countries representing 0.17% of global emissions are expected to ratify immediately. However, countries do have a year to sign the Paris Agreement, starting today.

So far, China and America announced a joint pledge to ratify this year– together, these two countries contribute 38% of global greenhouse gases. In total, about 90 countries are expected to ratify this year.

The total emissions, however, falls short of the 55% required for the agreement. One of the larger emitters, such as Russia- sitting at 7.53%, or two like India (4.1%) and Japan (3.79%) would be required to ratify the agreement before it goes into effect.

Climate Analytics has a ratification tracker if you want to get a  visual representation of who has ratified so far.

IFLScience has an infographic detailing this information and more.