And if you accidentally just vent the refrigerant lines instead of draining then you can release a year's worth of global warming in about 20 seconds. Best not to try.
What does this mean? I know you’re not saying that it leaks that much refrigerant over a year normally.
(I have no idea if this comparison is accurate, but I do know that coolers commonly contain gasses that you don't want to release)
For example, the refrigerant R-410A does about 2000 more greenhouse warming over a 100 year period. So a leak of 1 kg of R-410A is equivalent to about 2 metric tons of CO2 emissions.
10 years ago I bought an expensive tumble drier with a heap pump in order to be nice to the environment. After a few years there was an issue with it and I called a repairman. He vented the refrigerant and refilled it as part of his repair.
My calculation said it was an equivalent emission of about 1300kg CO2. Environmental impact immediately went negative.
This will be an issue when everyone is heating their house with heat pumps. They are amazing, but you have to follow the rules when repairing and scrapping them.
But…
At least in the US kitchen refrigerators have moved to hydrocarbon refrigerants (R600a a.k.a. isobutane) which have a much lower global warming potential of around 3.3x that of CO2. Prior to that it was R134a, and I'm pretty sure R410a was mostly limited to HVAC applications. More to the point a modern refrigerator has on the order of a couple ounces (so maybe 50 grams) of refrigerant not an entire kilo.
Don't fuck around with the sealed system unless you've the proper training. It's not rocket science but there are any number of non-obvious ways for things to go wrong. R600a is (in)flammable, R134a decomposes into hydrogen fluoride when exposed to flame, and R410a is a blend of things so you can't really top it off.
Edit: Copper fittings if you're lucky. We're starting to see some bits made out of aluminum now so (assuming you want to do the job correctly) you'll either have to get real good at brazing aluminum to copper or you'll have to invest the $$$ in the crimp tools.