Planting trees to sequester carbon emissions

[Bolt]

7 hours ago, the village idiot said:

This would depend entirely on what any final crop was used for (furniture/building/future fossil fuel replacement), and whether once forested the land was kept under tree cover into the future.

Indeed, Mr TVI.

 

For this approach to work, our generation would indeed 'depend'  on future generations do the 'right' things with our carbon (the carbon that we so nonchalantly released from deep, deep underground ) such as furniture making, construction or continuous cover forestry, in order to keep 'our carbon' out of their atmosphere whist it remains on the surface of the planet.

 

Maybe we can also rely on them to come up with a proper long term solution to return it back underground to where we found it (that will probably be a pleasant diversion from dealing with the legacy of Sellafield et al.).

 

 

[Squaredy]

13 hours ago, markieg31 said:

Have they ever thought that permemant pasture also sequesters carbon. Infact i think that you can do more with an extensive grazing system carbon wise.

Permanent pasture must be grazed and this is of course a problem, as the grazing animals especially if cows or sheep emit large amounts of greenhouse gas.  But apparently if done in the right way the world's vast grasslands can be well managed with grazing, and then sequester carbon on a huge scale.

[markieg31]

Grazing, in the right manor, helps sequester more carbon! Grazed Silvopasture is the pinnacle

[openspaceman]

On 03/11/2019 at 19:49, Bolt said:

Maybe we can also rely on them to come up with a proper long term solution to return it back underground to where we found it

Who are the "them " you refer to?

 

We have had a solution proposed, which I have followed and supported for the last two decades. It doesn't fit in with current economic systems, actioning and verifying it is possibly beyond the ken of governments.

 

Carbon exists in the ground as fossil fuels and rocks.  there are estimated to be 16000 billion tonnes there or under the deep ocean. It all derived from living organisms. This is all in a long term geological cycle unless we dig it up and release the carbon as a fuel or to make cement. Similarly there are rocks formed from volcanic activity and buried which will absorb CO2 if they are exposed to weathering. Geoengineering solutions want to go down the path of mining, crushing and scattering such CO2 absorbers, I consider that a dangerous route.

 

Currently terrestrial photosynthetic activity cycles about 120 billion tonnes annually by fixing carbohydrates during photosynthesis and releasing about the same as it dies and rots. The oceans similarly cycle about 90 billion tonnes annually.

 

As humans started managing their environment thousands of years ago they cleared land for agriculture, this reduced the above ground biomass carbon content but as we know the increased release of carbon really took off 200 years ago.

 

When I was at school we learned that as CO2 in the atmosphere increased it favoured plants which stored had superior ability to utilise sunlight. These should have had the ability to  keep more carbon as living biomass, and they do for over half of the carbon we are setting free.

 

However currently fossil fuels are releasing 9 billion tonnes back into the atmosphere of which plan and marine life is only managing to buffer 5 billion tonnes over and above the 210 billion tonnes of their exchanges with the atmosphere and oceans, plus as 45% of the carbon in the surface cycle at any moment is in an equilibrium between surface ocean and atmosphere marine activity that would form chalky sediments  is reduced as CO2 in solution tends to make the ocean less alkaline.

 

To my mind intercepting some of the 60 billion tonnes that would rot and decay back to CO2 and water and making it recalcitrant and burying it could be done anywhere on the planet where crops are grown or timber harvested.

 

At the turn of the millennium an even more elderly friend of mine hoped before he died he would witness the first billion tonnes of carbon returned to the soil in this way, it isn't happening or likely.

[richy_B]

Practically,  what are you proposing?  Deeply bury freshly felled trees etc?  I think conceptually it is interesting but how would it be achieved in reality? 

 

It is often quite controversial point when I say it to people (particularly as a tree contractor) but planting trees isn't going to be the 'silver bullet' that many people portray it as. As you stated - its a cycle so isn't actually de-carbonising above the above ground environment, merely lengthening the time scales.  Every time we dig it up, we've subtracted from the 'store' and added to our environment.  

Edited November 5, 2019 by richy_B

[Stere]

How about the carbon emission of felling and burying all theese trees?

 

Sounds abit crazy imo

 

Hand saws an shovels?

[Lucan]

I think there is some misunderstanding about how woodlands store carbon. The main store is not in the trees but in the soil. See the graph from Dewar and Cannel (1992)

 

 

Obviously if planting the potential to store carbon in the soil depends on the previous land use. If replanting a forest, organic soils or peatland than there would be little or negative storage, however if planting on agricultural land or heathland than there is substantial build up which remains even after clear fell harvesting, as the graph shows.

 

 

[saintsman54]

@lucan - what he said ?

[openspaceman]

4 hours ago, richy_B said:

Practically,  what are you proposing?  Deeply bury freshly felled trees etc?

Twenty years ago I was developing clean charcoal making, mainly to reduce the pollution and low thermal efficiency of making charcoal for cooking. At the same time scientists researching soils were talking about some fertile areas in the am'azon which appeared to have been be modified by humans, "terra preta des indios". These soils had a large char component and were produced centuries ago. So people looked at reproducing this terra preta to increase fertility and restore damaged soils in the tropics. An ex pat, the late Peter Reed, coined the term biochar to differentiate char used as  soil amelioration from that used for cooking.

 

As we were made more aware of the significance of increased CO2 emissions the second benefit of sequestering carbon by breaking into the photosynthesis to decay cycle and making a portion of the biomass recalcitrant became appealing.

Edited November 5, 2019 by openspaceman
Capatilising the south american river leads to it becoming a hyperlink to a well known and less than trustworthy marketing firm

[richy_B]

3 hours ago, Lucan said:

I think there is some misunderstanding about how woodlands store carbon. The main store is not in the trees but in the soil. See the graph from Dewar and Cannel (1992)

 

 

Obviously if planting the potential to store carbon in the soil depends on the previous land use. If replanting a forest, organic soils or peatland than there would be little or negative storage, however if planting on agricultural land or heathland than there is substantial build up which remains even after clear fell harvesting, as the graph shows.

 

 

That's some interesting data. 

 

So something more akin to a large scale move away from land inefficient agricultural activities such as sheep farming to woodland could deliver the best target results.