I am fairly familiar with the meanings of the word 'bolt', but I struggle to understand this sentence from a recent BBC article. If something is "bolted on to" something else, what does it mean? Please refer to a specific sense in the corresponding Lexico entry if possible (or another authoritative dictionary of your choosing).
"The COP itself is a consensus process, so it's a lowest common denominator. What we're seeing is other initiatives bolted on to the COP - there's real momentum."
I haven't found a dictionary that lists this meaning, but it's a clear metaphor to English speakers.
Something bolted on is "attached to the outside" - not part of the original design of something, but somebody has added it to the design, possibly without much consideration of the overall design.
So in this case, it means initiatives that were not intended to be part of COP, but which some people have attached to COP.
It means it is not an original part, but has been attached later. It is strongly attached, but could be removed. Literally you could have a car and use bolts to attach a decoration to the front of the car. The decoration would be literally "bolted on".
In this sense it is metaphorical. There is the COP (a structure of meetings and agreements between countries about climate) and then there may be other initiatives that are not part of the COP process.
For example There's a pact to cut emissions of methane, by 30% by 2030. It is not part of the COP because China and Russia haven't agreed it. But some other countries say that they will. This pact is attached to the main COP agreement as if it were attached by bolts.
