If it has been underestimated then that means climate models have been using the bad, underestimated data, so they need to be updated and run to see where we are at, corrrect?
I expect climate models contain a lot of parameters that aren't related to plant uptake of CO2, and some that are. I expect that, until now, the latter have been based on the 1980 study, because otherwise this latest result would not be news.
I also expect that the contribution of plant CO2 uptake is a large factor in these models, so a significant change like this will potentially have a significant effect on predictions.
Are any of these expectations wrong? If so, which ones?
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.
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.