Gordon: “How does the decade since 1998 compare with the decade of 1931-1940?”
According to the UK’s Climate Research Unit, the decade since 1998 is between 0.4 deg C and 0.6 deg C higher than the decade 1931-1940.
“Is it not true that showing a trend of temperature on a chart is affected by the start date of the data?”
The temperature trend can be affected by the start date, which is why 1998 is such an obvious cherry pick. So run the data from, say, 1850, and you’ll get a more accurate indication of the long-term trend.
“As more CO2 is added to the atmosphere, it’s effect diminishes.”
Not so much as sceptics claim. The calculations of sensitivity ignore the lag between CO2 entering the atmosphere and the final equilibrium temperature. This lag is explained by the high heat capacity of water, enabling the oceans to act as a giant heat sink.
