"Temperature estimates" refers to calculations or approximations made to determine the level of heat or coldness in a particular place or object. Full definition
* The claim that 95 % of the greenhouse effect is caused by water vapor (this fallacy is the primary way he gets very low temperature estimates for reducing CO2). (judithcurry.com)
It's in variations («anomalies») a base temperature — I'd start at the bottom of the chart to get that straight and also get the base temperature estimate. (owlcation.com)
The graphs compare the global mean temperature estimated by the models with that estimated from the data. (realclimate.org)