> Basically you have to do the exact opposite of what we've been doing with coal and oil for over a century

There's a nugget of a story in the Carboniferous being the result of a civilisation trying, but failing, to sequester carbon by burying trees and plankton.

Why not build houses from trees that will take carbon out 100-200 years from cycle.

Not just houses but any kind of building. There is an architectural movement called Mass Timber where the buildings are not just framed in wood but are virtually solid wood. It actually solves a lot of problems around building cavity thermodynamics, by eliminating the cavities. A large scale mass timber building sequesters a huge amount of carbon.

Carbon sequestration is a nice side benefit, but wood-into-durable-products can absorb only a small fraction of present anthropogenic CO2 emissions. We're emitting about 37 billion tonnes of CO2 per year at present (10 billion tonnes of carbon) and wood is about 50% carbon. To offset a quarter of human CO2 emissions, we'd need to turn about 5 billion tonnes of wood per year into long-lasting buildings and other manufactured objects. As of 2014, the world was producing about 0.8 billion tonnes of wood products that could be used in long lasting applications (sawnwood and wood paneling).

https://www.co2.earth/global-co2-emissions

https://blog.forest2market.com/fao-report-highlights-resurge...

I see what you're saying, but that doesn't actually strike me as too crazy of a goal. 0.8 is 16% of 5, and 6x-ing an industry seems within reach, given sufficient incentives.

Also concrete industry produces huge amounts co2 so chancing concrete to less co2 intense options helps lot.

There is enough landmass in Northern Canada / Russia to do this on a mass scale. Could you coat the trees in something to greatly reduce their likelihood of burning? Therefore not having to use biochar or some other form of carbon storage.

You would also have to coat them in something to prevent decomposition. Assuming that worked, over time you would take a ton of nutrients out of the system and the primary forest would eventually become grassland.

Maybe if you were growing trees specifically for this purpose on degraded land it could work.

Could we sink the trees in the ocean? The water would prevent them both from rotting and burning.

This doesn't make sense, the trees themselves are valuable. Why flood the market with cheep tree's and make useful stuff out of them. As suggested earlier, we can use way more trees in our building materials ( https://news.ycombinator.com/item?id=18286855 )