Climate scenarios based on model estimates of future climate can be constructed either by adopting the direct model outputs or by combining model estimates of the changed climate with observational climate data. (ipcc.ch)
A further attraction of using 1961 to 1990 is that observational climate data coverage and availability are generally better for this period compared to earlier ones. (ipcc.ch)
A comparison of the changes and fluctuations in the three observational climate indicators (SLR, OHC, and GMST; Figure 2) clearly shows that both OHC and SLR are much better indicators of global warming than GMST. (eos.org)