Nitrous oxide - laughing gas - is a much more heating gas than carbon dioxide and where carbon dioxide is happily absorbed by plants I don't know of anything that actively absorbs nitrous oxide.

However, levels of carbon dioxide in the atmosphere are far higher than a few thousand years ago. Even if the life of a molecule of it is not all that long, the number of molecules has been is increased.

I'd think that we really should be covering every square foot of soil with things that grow. When the permafrost melts and the dead plants and animals it contains start to decompose then the level of carbon dioxide is really going to rise.