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How would I compensate 250 tons of CO₂ emissions that I've created in my life? Is there a sustainable way?

I know trees can absorb a lot of CO₂, but once they die, the absorbed CO₂ is back in the cycle.

Please try to avoid answers which refer to current lifestyle or habits.

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    Not all carbon goes back into the atmosphere when a tree dies, otherwise we wouldn't have coal, oil and gas deposits underground. I'm not sure what percentage of a tree ends up permanently stored underground though... – Highly Irregular Jan 28 '18 at 1:47
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Each offset program is problematic in its own way. We can't (feasibly) put carbon back; we can only try to store away what's already out there, or give more people more options to develop without hydrocarbons.

Consider giving to organizations that protect forests and other natural areas to preserve existing trees through policy action or by buying land, especially in places like the Amazon.

If you don't like reforestation, there are companies that take offset money and use it to set up small-scale windmill/hydro/methane systems in developing countries. The goal is to ensure people have access to power without using hydrocarbons. Of course, you have to be sure the governance is good and that the money is going where you think it is.

There's no such thing as a true "offset;" any action can try and reduce future emissions, via saving a tree or offering someone renewable power, but you can't really take back your carbon.

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If you restore the ecology of barren earth so that it continues to sustain and increase total biomass, then you've made a big step in that direction. As soil improves, the total carbon contained or sequestered in it will rise. When a tree dies, or when it is thinned, trimmed, or pruned, the wood can be converted to biochar and most of the carbon removed from the atmosphere will be locked up for hundreds, or even thousands, of years. If you return the biochar to the soil, it will continue to assist your local biology as it naturally increase the total biomass of your ecosystem.

Where I live in Arizona highly degraded land can be purchased for a few hundred USD per acre. Due to overgrazing and erosion, the total carbon content can be negligible (less than 1%) which establishes a reasonable baseline. For the cost of a few Kg of carbon I can spread 250 tons of a manure and wood chip waste product on an acre of barren dirt to increase the temporary carbon content of the topsoil to a target of 10% which will itself return to the atmosphere in a few years, but the lasting effect is much more significant. The aim is to create a carbon cycle where none previously existed.

A perpetual organic carbon cycle requires water, a scarce resource in the desert. This temporary organic layer acts as a mulch that increases rainfall penetration, prevents erosion, and reduces evaporation. The available moisture in the soil often increases by a factor of 10, and sometimes considerably more. This gives native grasses a chance to gain a foothold, which in turn enables the establishment of shrubs and hardwood trees such as mesquite and other leguminous species. This continually increases the carbon maintained in the soil and in the biomass of living organisms sustained by the system. Broadcasting appropriate seeds greatly increases the speed of establishment.

For the most part, you wouldn't say that the carbon is locked up or sequestered. Rather, it would be more accurate to say it is engaged in an ecosystem of living and otherwise stored solids instead of primarily floating around in the atmosphere. The added benefit, of course, is that it now becomes a valuable source of food, fuel, and fodder. This is the only workable solution I have found to compensate for my personal carbon footprint.

  • Welcome to Sustainable Living! I think your answer is informative, but I do wonder if it's possible to "compensate 250 tons of CO₂ emissions" this way. – THelper Aug 4 at 9:33
  • I found this article that indicates that biochar can indeed be used as a carbon negative technology. There can however also be some drawbacks as is discussed in this article – THelper Aug 4 at 9:49
  • 250 tons of CO2 is only 85 tons of Carbon, or 85 trees which can easily fit into an acre of land. Even without the trees its still only 20g of Carbon per square metre over an acre. – Christopher Gilmour Aug 5 at 10:06
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My approach is the following:

I bought shares of a young joint forest. Young, because the forest has relatively small existing trees. These trees will continue to grow for the next 50 years or so. For the next 50 years, they will be a major carbon sink.

I understand that occasionally the forest is partially or fully harvested. When partially harvested, the pulpwood is used to make pulp and paper, which are relatively short-lived products, returning the carbon to the atmosphere. However, a partial harvesting only releases some of the carbon sequestered back. On the other hand, it makes the biggest trees more room to grow to the full length.

In the full harvest at the end of the lifecycle of the forest, a large portion of the wood is sawlogs, which are used to make sawmill products: lumber that can be used to construct wooden houses. In contrast to a house constructed from concrete (CO2 is released to the atmosphere), a house constructed from lumber is actually a carbon sink.

Now, if you want to permanently sequester the carbon dioxide, to calculate how much of the wood actually ends in lumber, you need to take into account that one cubic meter of lumber (that sequesters about one tonne of carbon dioxide from the atmosphere) requires about 2.3 cubic meters of sawlogs. Only about half of the wood in an old forest are sawlogs (the rest is pulpwood), so one cubic meter of lumber requires 4.6 cubic meters of raw wood.

So, to sequester 250 tons of CO2, you need 250 cubic meters of lumber, which requires 1150 cubic meters of raw wood. 100 cubic meters of growth per year will remove the emissions in 11.5 years. Then, after that, you own a carbon sink worth of 21.7 tonnes per year.

How much hectares is needed for 100 m3 / year growth, then? In the southern Finland, one hectare grows at about 7 m3 / year. This means 14.3 hectares is needed. One hectare costs about 6000 euros (depends on the age of the forest; for carbon sequestration purposes you might want to prefer young forests that are fortunately cheaper), so about 86 000 euros will buy you the sink.

Now the fun part. Where I live, car drivers pay 500 EUR / tonne of carbon dioxide emitted in the form of quite many various taxes (at the same time carbon emission rights at the European emission trading scheme trade at 20 - 30 EUR / tonne). That has not caused car drivers to switch to electric cars in a major manner. If you believe one tonne of carbon dioxide emitted is worth 500 EUR, then your sink of 21.7 tonnes per year is worth 10 850 euros per year. That's a whopping return rate of 12.6%! Ok, that return rate is very speculative, because currently forest owners are not compensated for the carbon sink they create, and if they will be in the future, it's far from certain the rate is 500 EUR / tonne.

However, do note that forest growth rate varies depending on the location of the forest. So, I don't intend the figures in this answer to be absolute universally valid truth. You need to analyze the local forest growth rates if you buy the forest in your local country.

Somebody might protest that if you buy forest, some other person is selling it at the same time, creating no new forest. This is false. By buying forest, you are affecting the price of forest: the increased demand causes a very minor increase of price. Because forest increases in price as you buy it (although in a very minor manner), it becomes more profitable for someone to buy land that doesn't have forest in it, and plant a new forest. Much of the forests of this planet have been destroyed because people aren't interested in owning forest. If everyone was interested in owning forest, the destruction of forest would cease, and much new forest would be planted.

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