>> The CO2 increase of the past 300 years was caused by the temperature increase during the Medieval Climate Optimum.
The delay is counter-intuitive. Is there an explanation of this? Do similar properties exist for other elements?
What’s counter intuitive about it? The largest source and sink of CO2 is the oceans. Cool them down and they absorb gas, warm them up and they release it. They have a huge thermal mass and only respond slowly to warming and cooling.