In many countries, we number the years based off of proximity to an event in the Christian religion - we are over 2016 years past that date. However, in this scenario, religion has become less mainstream, as, you could argue, it has been doing steadily over time in real life.
In this scenario, the world no longer wants to count based on proximity to that date - it wants to count years relative to the age of the Earth.
Clarifying how the system will work
- The length of one revolution around the sun (a "year") changes significantly after millions of revolutions, so the "years" counted in this system are all equal; conversion has taken place. The actual number of revolutions around the sun since the "birth" of Earth will be divided into a number of revolutions roughly equivalent to the time it took to orbit the sun from January 1st, 2015 to January 1st, 2016.
- Leap days and associated added dates are averaged into the length of the "year".
- This system assumes that the Earth was "born" once it became relatively spherical, and did not have sufficient debris in orbit. The moon doesn't need to be present at this time.
Technology based on scientific reasoning but out of the grasp of modern science that allows absolute dating of the age of the Earth will be accepted.
Answers should justify how close we can get to perfect accuracy when estimating the age of the Earth within the bounds of what we can physically observe (or otherwise calculate) assuming, as above, that we can "invent" whatever we need for it.
Time travel, asking aliens when they saw the Earth form, and other extremely bizarre methods are unlikely to be accepted.
How accurately can we calculate the starting date for this system, so that December 3rd, 2016 becomes December 3rd, 4,543,(?)(?)(?),(?)(?)(?)?