Updated climate sensitivity estimates using aerosol-adjusted forcings and various oce

[ScienceRocks]

Updated climate sensitivity estimates using aerosol-adjusted forcings and various ocean heat uptake estimates

Posted on May 24, 2013 by Anthony Watts
Updated climate sensitivity estimates using aerosol-adjusted forcings and various ocean heat uptake estimates | Watts Up With That?

Guest essay by Nic Lewis

The Otto et al. paper has received a great deal of attention in recent days. While the paper’s estimate of transient climate response was low, the equilibrium/effective climate sensitivity figure was actually slightly higher than that in some other recent studies based on instrumental observations. Here, Nic Lewis notes that this is largely due to the paper’s use of the Domingues et al. upper ocean (0–700 m) dataset, which assesses recent ocean warming to be faster than other studies in the field. He examines the effects of updating the Otto et al. results from 2009 to 2012 using different upper ocean (0–700 m) datasets, with surprising results.

Last December I published an article here entitled ‘Why doesn’t the AR5 SOD’s climate sensitivity range reflect its new aerosol estimates?‘ (Lewis, 2012). In it I used a heat-balance (energy-budget) approach based on changes in mean global temperature, forcing and Earth system heat uptake (ΔT, ΔF and ΔQ) between 1871–80 and 2002–11. I used the RCP 4.5 radiative forcings dataset (Meinshausen et al, 2011), which is available in .xls format here, conformed it with solar forcing and volcanic observations post 2006 and adjusted its aerosol forcing to reflect purely satellite-observation-based estimates of recent aerosol forcing.

I estimated equilibrium climate sensitivity (ECS) at 1.6°C,with a 5–95% uncertainty range of 1.0‑2.8°C. I did not state any estimate for transient climate response (TCR), which is based on the change in temperature over a 70-year period of linearly increasing forcing and takes no account of heat uptake. However, a TCR estimate was implicit in the data I gave, if one makes the assumption that the evolution of forcing over the long period involved approximates a 70-year ramp. This is reasonable since the net forcing has grown substantially faster from the mid-twentieth century on than previously. On that basis, my best estimate for TCR was 1.3°C. Repeating the calculations in Appendix 3 of my original article without the heat uptake term gives a 5–95% range for TCR of 0.9–2.0°C.

 

[Mr. H.]

Oh noze, this is ba bound to have an adverse effect on agriculture.
Right, Old Rocks?

 

[skookerasbil]

[ame=http://www.youtube.com/watch?v=NBO2IstMi2A]CO2 is a trace gas. - YouTube[/ame]

 

[IanC]

Isn't it odd how CAGWers believe in strong positive feedbacks even though they lead to out of control warming for a small disruption?