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Comment by jeffbee | Hacker News Reader

No because we aren't reliant on a model of atmospheric CO2 concentration. We directly measure it.

Yes because the models attempt to model feedback loops like the albedo difference created by greenery, the CO2 dampening effect of photosynthesis, the water content of the air and how that's affected by trees and so on.

Bear in mind, ESMs aren't trying to predict future CO2 levels. They're trying to predict future weather based on the effects of higher CO2, and vegetation is a part of that.

You measure the past, but you don't measure the future, right ?

Right, this new estimate can be useful for decision support: if we plant X acres, how much CO2 would it absorb? It's not very important outside of that, and it cant have caused significant past errors because to date humans have not undertaken large-scale planting for CO2 absorption reasons.

>It's not very important outside of that,

It's not very important outside of predicting the future of the climate accurately.

That's not the kind of thing I'd write "It's not very important outside of" before. This "mere" prediction and decision support is the reason we fund the sciences.

Several countries have implemented large-scale planting efforts: China, Ethiopia, India, Brazil, Australia, Pakistan, and Turkey to name a few. In 2019, Ethiopia claimed to have planted over 350 million trees in a single day as part of a broader initiative to plant 4 billion trees within a year to fight climate change.

Expected future CO2 concentration are a parameter for the climate models, and are generated by themselves by other models with different set of inputs accounting for a series of natural and socio-economic variables.

I assume they mean for things like offsetting programmes, predicting the continuing trend and effect of governments deciding to plant more/less, etc.

Don't we need models to make predictions about the future?

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