For the first part of your quesition, to quote wikipedia (feel free to check the primary sources yourself): > Atlantic overturning is not a static feature of g

For the first part of your quesition, to quote wikipedia (feel free to check the primary sources yourself): > Atlantic overturning is not a static feature of global circulation, but rather a sensitive function of temperature and salinity distributions as well as atmospheric forcings. Paleoceanographic reconstructions of AMOC vigour and configuration have revealed significant variations over geologic time [34][35] complementing variation observed on shorter scales.[36][14] https://en.wikipedia.org/wiki/Atlantic_meridional_overturning_circulation#AMOC_stability https://en.wikipedia.org/wiki/Atlantic_meridional_overturnin...