We Don't Depend on Climate Models Alone

....to see the possible effects of higher carbon dioxide levels.

https://arstechnica.com/science/2018...ing-something/

It's possible to observe what similar carbon dioxide levels had in the past.

As the article notes, the situation is different. The increased carbon dioxide
levels had time to have their full ultimate effects - and because they didn't
happen rapidly, they didn't lead to carbon dioxide being dissolved by the ocean,
causing temporary acidification. (So we can expect all that carbon dioxide now
dissolved in the ocean to soon enough come out again...)

John Savard