  Quantitative estimates of the contributions of the anthropogenic forcing,
characterized by changes in the radiative forcing of atmospheric greenhouse
gases (CO2, in particular), and solar activity variations to the trends of the
global surface temperature on secular temporal horizons are obtained with the
aid of autoregressive models from simulations with climate models of the CMIP6
ensemble and from long-term observational data since the 19th century. The
results for the simulations with climate models characterized by low, medium
and high temperature sensitivity to changes in the CO2 content are compared. It
is found, in particular, that the estimates from observation data revealing the
determinative contribution of the CO2 content to the global surface temperature
trends on half-century and century-long time intervals are most consistent with
the estimates from simulations with the climate model with the lowest
sensitivity of the global surface temperature to doubling the CO2 atmospheric
content.
