Those clay tablets needed to be fired and had a negative carbon footprint.
Handmade parchment, or leather carvings if you don’t mind.
Those both require cattle farming, which is a major contributor to greenhouse gas emissions (at least 10%, perhaps as high as 19.6%, per https://thebreakthrough.org/issues/food-agriculture-environm...). Stick with papyrus or wax, please.
Why fire them when you can just reuse them?