Why isn’t increased CO2-levels positive for nature?

Question

The levels of CO2 in the atmosphere is increasing and have done so for many years. Shouldn’t this have a positive impact on plants etc.?

Maybe not nature including humans, but plants should thrive, right?

In: 2

Answer 1

I think most people have touched on the greenhouse gas effects, but CO2 also plays an important role in ocean acidification. The higher the CO2 content in air, the more acidic water exposed to that air will be. What this means for life, is any ocean organisms with shells (thing corals, some plankton, etc.) will die off, because their shells will dissolve (greatly oversimplifying the process, but that’s the end result). This then has a runaway effect where ocean organisms start to die off that produce most of the oxygen on earth, which then leads to mass extinction of land plants and animals as well.

This same effect of acidification is relevant not just to the ocean but to most life, as life has currently adapted to a specific CO2 content (and therefore a specific blood/internal fluids pH (acidity), so shifting that equilibrium faster than life can evolve leads to mass die offs.

In reality there’s no one single reason why increasing CO2 is bad, it’s a web of interconnected factors that can all be summed up as: life evolved to fit in with a CO2 concentration that is relatively steady (over thousands of years), and can’t adapt fast enough when humans start rapidly affecting the atmospheric CO2 concentration.

Edit: I saw in one of your other comments asking about what if oxygen increased instead. This would also be problematic for different reasons, as some organisms could take advantage of it more than others (think algae blooms). Also, life has evolved mechanisms to prevent damage due to oxidation, so increasing oxygen results in more oxidative stress/damage. The overall conclusion is that changing anything from the way it is now will be bad for currently living things, but if it’s done gradually enough (over millions of years), new organisms which have adapted to the changes conditions will flourish.