That might be available on company but not on a system level. So I don't think there is no way to compare it with the energy consumption of an entire blockchain.
Which block chains require sharing the amount of CO2 released while adding a new block? How do the non accepted blocks get counted?
The energy consumption of a blockchain is not publicly available anywhere. What are you talking about?
there are estimates available : https://www.forbes.com/sites/philippsandner/2021/11/19/bitco...
Most companies monitor their power bills in order to ensure they are not needlessly wasting money by leaving lights or air-conditioning on etc.
Once you know your power consumption it's a pretty simple calculation to get CO2 usage.