Fogdog
Well-Known Member
Ah the troposphere, I was hoping somebody would post that bit of skepticism.It seems logical at some point to evaluate model performance against observations. If the greatest warming is expected to occur in the troposphere above the tropics, and our best measurement tools are not seeing it taking place at expected levels, should we not get concerned about our assumptions at some point? If so, when?
Beginning at about 2:50, he gets into middle and upper troposphere temperatures, both predicted and measured.
The middle troposphere measurements above the tropics are not heating up as predicted in the models for the greenhouse gas effect But again, skeptics are cherry picking. Surface temperatures and upper troposphere temperature measurements are changing exactly as predicted.
As the narrator, Mark Richardson from NASA/JPL-Cal Tech says: "Using the (absence of a predicted) hot spot to cast doubt on greenhouse warming is a red herring. Its a sign of changing moisture in the tropics, not of greenhouse gas warming. A real fingerprint of greenhouse warming is warming near the surface while the atmosphere above 20 km cools this has already had a spectacular effect" as shown in satellite readings. (his words from the video are shown in italics.
The key point is, while it is true that the state of the science of global climate modelling and the science of measuring atmospheric temperatures at all elevations are not completely in synch. What is also true is the fingerprint showing greenhouse global warming are exactly in sync. Predicted and measured rising surface temperature and upper troposphere cooling are confirmed.
For example, the figure below shows a series of PCM global temperatures throughout all elevations. Compare (a), where elevated surface temperature is entirely due to solar forcing with (c) where elevated surface temperature is entirely due to elevated greenhouse gas emissions. The blue-violet region in the upper atmosphere in (c) is the fingerprint that Richardson refers to.
Fig 9.1: Zonal mean atmospheric temperature change from 1890 to 1999 (°C per century) as simulated by the PCM model from (a) solar forcing, (b) volcanoes, (c) well-mixed greenhouse gases, (d) tropospheric and stratospheric ozone changes, (e) direct sulphate aerosol forcing and (f) the sum of all forcings. Plot is from 1,000 hPa to 10 hPa (shown on left scale) and from 0 km to 30 km. (IPCCAR4 WG1)
Anyway, don't listen to me, listen to Richardson 'splain it better than I can.