There is an established belief in science that there are roughly 20-to-30-year time lags between a year of emissions and the perceptible appearance of their effects. Therefore we are currently seeing the consequences of carbon concentrations 40 to 60 ppm less than at present. Furthermore, the signature of positive feedback loops is acceleration – it is apparent that in the last two or so years we are witnessing that acceleration in spades, as heat records are broken right and left, wildfires rage, etc. etc.