You are right.

But it’s less certain.

There’s a decent amount of carbon emissions associated with management of land, however, and if you want the land to continue to be optimised for carbon sequestration you’ll need to manage it and, besides, in most areas you can’t just buy land, plant some trees on and leave it - it’ll need active management to stay a forest and to comply with local regulation.

But let’s say you’re doing that and planting for carbon sequestration, then you’d probably choose something like pine (fast growing, absorbs a lot of carbon, stays green through the year so tends to prevent competition on the floor). A tree that like will absorb roughly a tonne (1000-1100 kg of carbon) in its life. Then it dies and you’ll need to remove it to ensure a new tree can grow (otherwise it’ll be taken over by other species slowly).

A hectare of dense pine trees can probably hold 3000 trees (if we are being generous) so a hectare (100x100 metres of land) can hold 3000 tonnes of carbon. On average in Europe we emit about 9 tonnes of carbon per year and live for 80 years so a hectare can hold about 4 people’s worth of life time emissions.

In the U.K. you’ll end up spending about £25,000 for a hectare of woodland (give or take), but then you’ll need public liability insurance and management fees (let’s just say £20/year for for a hectare of insurance and £750/year for management of a hectare) … so let’s assume £800/year for a hectare or £200/year to manage the size of woodland required to absorb a person’s life time emissions (remember, 4 people per hectare). Now you need a trust manager who runs it, permanently forevermore, to manage it all. Let’s say £40,000/year and assume that they manage 1000 people’s life time emissions (this obviously could scale down to almost zero as the scheme grew) or £40/year per person.

But don’t forget additionally: This has to be NEW woodland, so you need to buy non-woodland and then plant the woodland. Otherwise you’re not absorbing more carbon. Typical quotes for a hectare of pine planting will be about £4000.

And this cost needs paying forevermore: £6000 to buy the space for a person’s emission £4000 to plant it £250/year to manage it (insurance, management)

To deliver £250/year you’ll need an investment of 250/0.04=£6250. Let’s just say £7000 to leave some buffer for bad years and to pay for the additional carbon that’s emitted from the management. So:

£6000 to buy the space for a person’s emissions. £4000 to plant it.
£7000 to manage it forevermore.

So all in you’ll need to spend £17000 to absorb your lifetime’s worth of emissions.

Now let’s compare that to geological sequestration. Climeworks, the only publically available scheme to suck carbon out of the air and sequester it into rock, permanently, quotes £1100/ton of carbon. So to extract the 720 tones you’ll emit in your lifetime it would be £792,000.

So yeah, trees do it a LOT cheaper (2% of the cost), but it requires active management and it’s not guaranteed to be on geological scale.

And I’m not aware of a scheme that enables this to happen. Are you?