Daily Archives: September 8, 2017

The ECS is not the ECS with constant feedbacks.

“The black line is the case in which we assume feedbacks remain constant; this produces what is typically referred to as the Effective Climate Sensitivity.”

The ECS is not the ECS with constant feedbacks. It is the ECS for a doubling of CO2 whatever the CO2 level is and in the particular group of cases we are talking about it is for the current earth atmosphere in the 21st century. Hence such a figure includes all known feedbacks some of which vary depending on the starting CO2 point.
This in effect removes the wriggle room for forcing definitions such as changing warming patterns, earth system feedbacks and temperature dependent feedbacks. They are for the most part already included in an ECS or it would not be the ECS. Some of these are part of natural variation anyway. Natural variation after all is only the envelope of uncertainty.
The comment “The consensus on the ‘likely’ range for climate sensitivity of 1.5 °C to 4.5 °C today is the same as given by Jule Charney in 1979” gives it away.38 years of satellites and better world wide monitoring and mapping for what? Certainly not an improvement in diagnostics.
As I said before graphs with results only on one side of a 50% projection are suspect either in maths or motivation.
Your graph should include another line to the left giving a lower surface anomaly for the fact that temperature dependent feedbacks and the pattern of warming can also, one expects lead to less warming in future.

“We expect, however, that temperature dependent feedbacks and the pattern of the warming could lead to more warming in future than we would expect based on an assumption of constant feedbacks”. Expectation is not science.