Temperature Anomaly is the measure used to show that the earth is warming. The formula for temperature anomaly involves in the subtraction of average temperature measurement over 30 years considered as a base line temperature . Usually temperature anomaly graphs starts from 1880, was the average taken from 1850 or which 30 years was used in the baseline or average temperature calculation?
can you suggest places that i can learn about these and get these data?
even though subtracting the baseline temperature reduces the influence of errors in measurement, still how are these error accounted for in these graphs? even modern thermometer have +/- 0.5 deg error how are these error removed from the dataset?