The figure below incorporates elements of figures from Keeling (1976), Hersoug et al (2012), and IPCC(2001). It is a time series of atmospheric CO2 (ppmv; parts per million by volume)

data from 2 icecores (black and green), the Moana Loa Observatory (blue), and an IPCC model (red). Based on this figure, answer the following questions:

Fig: 1

Fig: 2