Somebody needs to explain this to me: If half of our CO2 emissions get absorbed in year one, how can it have a half life of "centuries", and how can 20% persist for 20,000 years?

Say it's 2011, and half of 2010's human CO2 emissions have already been absorbed. When the ocean or a flower is about to absorb another CO2 molecule emitted by humans back in 2010, does Gaia blow a whistle and ensure that a 2011 molecule is absorbed instead?   Does each CO2 molecule have a unique serial number issued by Gaia?

If half of the human CO2 emissions are absorbed in year one, why isn't half of the remainder absorbed in year 2?

Lukewarmers, Denialists, and Other Climate Change Skeptics - Reason Magazine

Romm characterized the ICCC6 as part of “a dwindling number of increasingly vocal people who spread disinformation on climate science and who attack and harass climate scientists.”
...
Denning reprised the arguments for man-made global warming caused by greenhouse gas emissions. He noted that the atmosphere contains around 800 million tons of carbon dioxide and that humans are emitting 8 billion tons per year. Of that amount, two tons are being absorbed by the oceans and two tons are being absorbed by plants, leaving four tons per year in the atmosphere. The carbon dioxide emitted now will stay in the atmosphere for centuries as the oceans slowly absorb it

How China accidentally geoengineered the climate | Grist

the carbon dioxide from all that coal we burned has a half life of centuries.

Al Gore: Climate of Denial | Rolling Stone Politics

Twenty percent of the global-warming pollution we spew into the sky each day will still be there 20,000 years from now!

YouTube - ‪CO2 Experiment Video‬‏

This video shows that a candle floating on water, burning in the air inside a glass, converts the oxygen in the air to CO2. The water rises in the glass because the CO2, which replaced the oxygen, is quickly dissolved in the water. The water contains calcium ions Ca++, because we initially dissolved calcium hydroxide Ca(OH)2 in the water. The CO2 produced during oxygen burning reacts with the calcium ions to produce solid calcium carbonate CaCO3, which is easily visible as a whitening of the water when we switch on a flashlight. This little kitchen experiment demonstrates the inorganic carbon cycle in nature. The oceans take out our anthropogenic CO2 gas by quickly dissolving it as bicarbonate HCO3-, which in turn forms solid calcium carbonate either organically in calcareous organisms or precipitates inorganically. The CaCO3 is precipitating and not dissolving during this process, because buffering in the ocean maintains a stable pH around 8. We also see that CO2 reacts very fast with the water, contrary to the claim by the IPCC that it takes 50 - 200 years for this to happen. Try this for yourself in your kitchen!