 So I've spoken a bit about residence time and I just might cover what residence time is if you think of a bank account You'll all have probably have bank accounts and money flows in and out of that bank account The residence time for that money in the bank account is how long it stays there. So if you have You spend a lot very quickly the reasons the residence time of your money in the bank account would be short If you let it build up and accumulate will be long time The same sort of concepts can be used for the ocean and we think about carbon in the ocean and it's residence time so a short-term residence time would be in the with the surface ocean communicating with the atmosphere carbon is exchanged and that that occurs on timescales of weeks to months Whereas if we think about the residence time of carbon in the deep ocean, it's usually on Years to centuries even to thousands of years so that that's quite a big difference in residence time between the surface and the deep ocean