Peter Laux has offered $10000 to anyone who can produce empirical evidence proving man-made global warming [AGW]. Peter’s offer is in the form of a Statutory Declaration, which is neither here nor there. Peter’s wording is:
This is an invitation to treat which differs fundamentally from a contract and being bound by contractual terms. An invitation to treat can be thought of as a prelude to entering a contract and being bound by contractual terms. Basically Peter is inviting people to submit offers about the proof for AGW which he may then convert into contractual terms.
As part of this invitation to treat people were invited to submit their offers to the Climate Guy blog site of Denis Rancourt.
The invitation has attracted the usual alarmists, well-meaning and not. John Byatt, blogging as Duchess Judy John Byatt, has claimed he has satisfied the terms of the contract and is eligible for the $10000 bounty.
John’s ‘proof’ is that
The RF for CO2 is currently 1.68Wm2
And that Peter has accepted this RF [radiative forcing] figure for CO2 by saying it is a:
statement of RF for CO2 nothing more
Obviously Peter has not accepted that the finding by the IPCC that the RF of CO2 is currently 1.68Wm2 is a fact. He has merely acknowledged that the RF for CO2 of 1.68W/m^2 is what the IPCC has most recently produced.
The history of the IPCC’s figures for the RF for CO2 is a dynamic one. The RF for CO2 is usually expressed in a temperature response to a doubling of CO2. This temperature response in turn is a measure of the climate sensitivity of CO2. Christopher Monckton has found this climate sensitivity of CO2 has changed over the history of AGW and in the various IPCC reports.
The current figure for the RF of CO2 was produced in 1998 in Myhre et al in Table 3. The formula in Myrhe et al for calculating the RF of CO2 is a logarithmic formula because Beers Law says that increases in CO2 will have a decreasing effect. CO2 in 1850 when the modern warming began as the Little Ice Age ended was about 280 parts per million [the same as it was in 1750 as shown in the above IPCC chart for RF from 1750]. The current concentration of CO2 is about 400 parts per million. Putting those amounts into Myhre et al’s formula gives the following result:
F (W/m^2) = 5.35 ln (CO2 / CO2 [starting]) = 1.91W/m^2
So even using the IPCC’s own formula for calculating the RF for CO2 we get a difference. Admittedly the RF of 1.91W/m^2 is within the error range of the IPCC which is 1.68W/m^2 [1.33 – 2.03]. But the temperature range this RF should have produced is outside the temperature range consistent with such a forcing. That range should have been between 1.14C – 1.33C. In fact the temperature increase since 1880 has been 0.7C.
The RF for CO2 and the climate sensitivity for CO2 has been all over the place in the AGW science. For instance, apart from the contradictions from the IPCC, the seminal AGW paper by Foster and Rahmstorf finds a ‘pure’ temperature response from CO2 RF ranging from 0.014 to 0.018 K yr−1
This finding translates to a climate sensitivity for CO2 RF of 1.4 – 1.8C which is markedly less than the IPCC range of 3.26 – 3.8ºC.
Also of interest is the comparison between the RF of CO2 and the RF of solar. Figure 9.1 from AR4 shows the result of RF from different sources including CO2 and solar:
Figure 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 (shown on right). See Appendix 9.C
The images clearly show the temperature result from solar (a) and CO2 [greenhouse gases but predominantly CO2, (c)] are different. This hasn’t stopped Real Climate, the major pro AGW and IPCC blog, from claiming there is an equivalence between RF from a doubling of CO2 and a 2% increase in solar.
But are 2XCO2 and a 2% increase in solar equivalent? Solar forcing is 341.5 W/m^2 of incident power [1366W/m^2/4 at the Top of Atmosphere] which heats the surface to 287K [384.7 W/m^2 of radiated power] for a net gain of 384.7/341.5 = 1.1 [solar forcing]. The IPCC claims that 3.7 W/m^2 of incremental forcing from 2XCO2 absorption causes a ~ 3C rise in the surface temperature. If you add 3C to 287K and convert to power, the Earth’s surface emits 401.1 W/m^2, which is an increase of 16.4 W/m^2. This means that the IPCC claim of gain, relative to power from CO2 forcing, is 16.4/3.7 = 4.43, which is about 4x higher than solar forcing which is not an equivalence.
The point of this is to show that the RF of CO2 is NOT a settled amount even in the AGW science.
For anyone to say a particular RF for CO2 proves AGW is therefore absurd.
In my opinion Peter’s invitation to treat does not have to be converted into a contract subject to verification any time yet.