Energy consumption ≠ Carbon emission

The energy consumption to mine is easy to estimate: You can just look at its hashrate (i.e. the total combined computational power used to mine Bitcoin and process transactions), and then make some educated guesses as to the energy requirements of the hardware that miners are using.

To calculate associated carbon emission you need to know energy mix i.e the makeup of different energy sources used by computers mining bitcoin. Mining is an intensely competitive business, and miners tend not to be particularly forthcoming around the details of their operations making it even harder to calculate.