The average person in the UK has a carbon footprint of about 13 tonnes per year. This is a ‘carbon dioxide equivalent’ value (CO2e), as it also includes emissions of other greenhouse gases such as methane and nitrous oxide, adjusted so that the warming from these gases can be compared to the warming from carbon dioxide.
Multiplying that figure by 47 years, and taking into account the fact that average carbon footprints have generally increased since you were born, gives a rough value of 500 tonnes CO2e (assuming also that your carbon footprint as a child was equal to that of an adult).
This value of 500 tonnes is about the same amount of CO2 that would be taken out of the atmosphere if you planted a hectare (100 x 100m) of mixed broadleaved woodland in the UK and let it grow for 50 years. This would be about 2,250 trees, and it’d cost you between about £10,000 and £25,000 to do this through a government grant-aided scheme.
However, there are only so many trees we can ever plant in the UK, or even in the world. And it takes years for trees to capture useful amounts of carbon. So tree-planting projects have their limits. Much better is to reduce our carbon footprint in the first place by addressing some of the segments in the pie chart above.