Tree planting: Where can I do it and which type is best?

Is the carbon sequestered when the paper bags are sent to landfil, or do the bags rot releasing a mix of co2 and methane, making this a negative result because of the extra warming effects of methane?

Please provide numbers.

Numbers are important and should be discussed transparently. Lots of variation in guesstimates, fudging, simplifications, etc cloud the issue and give drastically different "good ways forward". So, please, correct my back-of-the-envelope estimate below:

E.g. from [1]: "Following the estimations of carbon stock including above ground biomass, the total stock in the studied chestnut forests could be ordered as follows: CF3 (105.8 t C ha-1) > CF1 (102.1 t C ha-1) > CF2 (76.3 t C ha-1). The pure chestnut forest CF3 characterized with the highest total carbon stock per hectare and only 20.6 % from it is accumulated in the aboveground tree biomass."

Chestnut is one of the best carbon sequestering forest options we have. Estimate (overly positively) that this capacity cycles over 100y. Fudge down the CO2 and CH4 release from decomposition. That gives ca 100 tC/ha over 100y, aka 1tC/(ha y) or 100tC/(km2 y).

Globally we have ca 35GtCO2 or 10GtC carbon emission per year. Current forests store about 15% of that, but we are currently loosing forests at a rapid rate, and we need to not only reach neutral but also sink the 100y or so of spewing we've already fucked up. So let's keep the number at 10GtC/y.

10GtC/y would then require 100E6km2 of NEW perfect assumption chestnut forest.

We have ca 500E6km2 of total land surface on earth. That means we need to set aside 20% of all land on earth for our NEW chestnut forest. But we don't have that much land that can sustain something like this. Forest grows less well outside of humid temperate to tropical regions. E.g. Antarctica, Sahara, the steppes, boreal forest regions, etc. E.g: All agricultural land, both fields and grazing, is 11% of total land area but over one third of all culturable land, the rest of which is already mostly forest. Even if we covered all growth-possible land area that is not already forest we simply don't have enough land. And we would be out of farmland.

Based on this back of envelope calculation tree planting is not a viable solution. It's a good step in the right direction, but nothing to get the crowds overly excited about.

Instead, e.g. azolla is around 15x more potent as sequestering growth stock than forests, and it grows floating on water. Genetically engineering azolla to grow fast in higher salinity would be a better way to combat climate change. We have plenty of ocean surface area. There will be downsides to such a solution, but compare with other solutions or the horrors of what will be if we don't act...

And I'm sure someone can cook up some gm-franken-algae that is even more potent.

My point, if any, is to make sure to actually run the numbers. Get different estimates then pay skilled scientists to get better estimates. Discuss the numbers, assumptions, simplifications. Don't get the general population stuck on low worth paths when they could start fighting for more valuable ones.

And I don't propose "stop planting trees". I argue that planting trees is a good thing, but only a minor item that is overshadowing more valuable options in the general debate. We need to get people to start facing reality to the point where they can start thinking about compromises. There is no "solution" that don't require drastic changes in how we use our land and live our lives.

Side note: nuclear is the only short term low land-usage footprint solution I can see, and drastic genetic manipulation biomass or vast nuclear powered direct capture are the only long term solutions I can guesstimate. Anyone that can show me interesting alternatives?

[1]: https://www.researchgate.net/publication/285516686_Carbon_st...

Plants not only make wood, they make nectar, sugars, ambar, they make alkaloids, and they make thousands of seeds also.

Some hard nuts remains have been found after 3000 years. They will survive for as many time than wood or longer. A big walnut can produce 160 Kg of nuts each year. A sequoia can produce a number of pine cones that I can't quantify, but would be probably measurable in thousands of Kg/year. Easily

Even more, upper members of the Plant kingdom produce a very special substance. One of the most inert polymers found in the nature that is much more desirable than wood for our needs of stabilising climate. Its degradation time can be measured in millions of years and appears fosilized or semifosilized in all continents and all ecosystems, with or without trees. Is called sporopollenin, and is the extra hard and waterproof material that makes the outer layer of pollen grains.

You don't need a tree to produce really hard pollen. A humble daisy can sequester carbon in a powder that will easily remain structurally intact for the next 1000 years. Everybody that has a garden and has cultured a big conifer knows that males of this creatures release copious amounts of the substance each year. Also old plants. _Specially_ old decaying plants that are about to die and invest all its reserves on reproduction. Maybe its time to start quantifying it.

Therefore your statement that plants only sequester CO2 when they grow is clearly false. If your maths and calculus do not include nuts and pollen, and do not include soft herbs, flowers and annual weeds they are incomplete, and most probably wrong, IMHO.

Processing and transport requires energy which is unlikely to be renewable. To maximize impact I think we need to find some efficient system, perhaps algae or GMO plants or weeds, that sinks carbon straight into the earth. Perhaps very verdant places like Minnesota, residents could be encouraged to collect deciduous leaves each year and round them up for sequestration (which again requires energy). Or renewable and nuclear power plants could use all of their excess power toward some kind of machine that scrubs co2, which becomes a solid at relatively high temperature of -75C (compared to liquid o2 or n2).

We could artificially capture arbitrary amounts of carbon using nuclear and renewable power, but I think it's important to consider how such activities would be paid for.

It seems more politically feasible to me, to incentivise ecologically healthy consumption through taxation (e.g. carbon tax; fuel duties; severance taxes), than to fund grand reparative projects.