Roy Clark: A null hypothesis for CO2

Roy Clark phd has spent the last three years researching and writing this paper. It confirms my own research on the average sunspot number and the ocean equilibrium value, as well as extending my thoughts on the multi-decadal retention of heat energy in the worlds oceans into properly quantified analysis. This has enabled Roy to make much more detailed and definite statements about the relative importance of co2 in the atmosphere as an agent of climate change than I could. The paper is pay for, but at least the journal (Energy and Environment) has been consistently open minded about reviewing and publishing those scientists whose research findings are sometimes at odds with the so called mainstream consensus on this issue. The paper runs to 30 pages with many graphs and digrams and represents much better value and more bang for your buck than any other published paper on the subject I know of.  A version of the CA climate article should be published on the SSPI (Science and Public Policy Institute) website quite soon and I will revisit this paper after that has gone online.

Journal: Energy & Environment
Publisher: Multi Science Publishing
ISSN 0958-305X Issue Volume 21, Number 4 / August 2010
Category: Research Article DOI 10.1260/0958-305X.21.4.171 Pages 171-200
Date Tuesday, June 29, 2010
Author: Roy Clark, Ph.D.1 1
1336 N. Moorpark Road #224, Thousand Oaks, CA 91360 USA

Abstract:

Energy transfer at the Earth’s surface is examined from first principles. The effects on surface temperature of small changes in the solar constant caused by the sunspot cycle and small increases in downward long wave infrared (LWIR) flux due to a 100 ppm increase in atmospheric CO2 concentration are considered in detail. The changes in the solar constant are sufficient to change ocean temperatures and alter the Earth’s climate.

Figure 4

The surface temperature changes produced by an increase in downward LWIR flux are too small to be measured and cannot cause climate change. The assumptions underlying the use of radiative forcing in climate models are shown to be invalid. A null hypothesis for CO2 is proposed that it is impossible to show that changes in CO2 concentration have caused any climate change, at least since the current composition of the atmosphere was set by ocean photosynthesis about one billion years ago.

http://multi-science.metapress.com/content/9p72043270187318/?p=2c519815645444e4ae47651096f785d4&pi=2

Via email, Roy has added an extra summary:

The energy transfer at the surface is dynamic.  The heat flux and the temperature are always changing.  The total daily heat flux from the sun can be up to 30 MJ/day.  The night time cooling can reach about 360 kJ/hour.  The ground surface temperature can reach 50 C or more and the heat is coupled into about the first meter of the ground.  The total increase in downward long wave IR (LWIR) flux for a 100 ppm increase in atmospheric CO2  is about 1.7 W.m-2 or 0.15 MJ/day.  When this is mixed in with the rest of the surface flux it simply makes no difference to the surface temperature.  Oceans behave a little differently.  There is more evaporation, and a lot more subsurface transport. The end result is the same.  The LWIR flux change from CO2 is too small to detect.

The next point is that all of the surface energy is moved up through atmosphere by convection at some point during the ascent, except for the LWIR radiation that is transmitted directly to space through the LWIR atmospheric transmission window.

There is also a downward LWIR flux from the atmosphere that helps to keep the surface warm, but almost all of this originates in first km above the surface.  This layer is reheated by convection on a daily basis.  This is the ‘traditional greenhouse effect’. It is there, but it is not controlled by CO2.

As the warm air rises through the atmosphere, it cools because of expansion.  This is controlled by the (moist) lapse rate.  This is set by the bulk thermodynamics of the convection.  The rising air controls the temperature and the LWIR radiation in the troposphere.

Now we have to get down into the spectroscopic details.  The molecular lines in the atmosphere are broadened by molecular collisions. This is known as pressure broadening.  As the pressure (and temperature) decrease with altitude, the molecular lines become narrower and the LWIR radiation can ‘escape’ between the lines.  This is like looking through a comb.  The water vapor concentration also decreases rapidly with altitude and this ‘amplifies’ the line narrowing for water.

The LWIR radiation does not magically appear at the top of the atmosphere, it is produced gradually by line narrowing on the way up.  This is controlled mainly by water vapor.  The emission band just moves up and down in the atmosphere as the surface temperature and the height of the tropopause change.

As the air rises through the atmosphere it also has to do mechanical work against the force of gravity.  This is the underlying cause of the lapse rate.  This is where the ’33 K’ greenhouse effect really comes from.

Update: In reply to my question at the top of the comments section below, Roy sent me this via email:

As far as heat flow is concerned, the surface temperature is set by the dynamic balance of the energy flow at the surface.  Energy flow includes convection and evaporation as well as just radiation.

There are very few weather stations that measure the various energy flux terms.  These are usually called micrometeorological stations and they have a lot more instrumentation than the usual wind, temperature and humidity sensors.  The Department of Energy has funded the operation of some of these stations as part of its Ameriflux Program.  http://public.ornl.gov/ameriflux/dataproducts.shtml Figure 1 shows the average daily night time IR flux for one of the UC Irvine stations for 2008. (‘Grasslands’ site).  Cooling flux is negative, heating flux is positive.  At night, the surface is cooling, so the flux is usually negative.  The average annual night time flux is about -43 W.m-2 +/-15 W.m-2.  (one sigma standard deviation).  This is the net cooling flux through the LWIR atmospheric window.  When there are clouds around, the flux is between ~0 and -30 W.m-2.   (These are night time averages, so they include cloud free periods as well).  When the humidity is low, the LWIR cooling flux is between -60 and -100 W.m-2.  The night time ground temperature will decrease more slowly when there are clouds present than when the air is clear and the humidity is low.  However, when the magnitude and variation of these fluxes is compared to the 1.7 W.m-2 ‘clear sky’ increase in flux from a 100 ppm of CO2, over 200 years, the change in CO2 flux is too small to make any measurable difference.

Usually, at this site these clouds are from a low altitude marine layer, so the cloud temperature is near the surface temperature.  This means that the upward flux from the surface is balanced by the downward flux from the cloud.   As the clouds move up to higher altitudes, they become cooler and there is less downward LWIR flux from the cloud that reaches the surface.  There is less LWIR flux to ‘fill’  the LWIR window.

Figure 2 is a calculation of the downward LWIR flux at the surface from H2O and CO2 at a surface air temperature of 300K and 50% RH.  Superimposed on this are black body radiators at 292 and 277 K.  These are relative flux values, normalized to the 300 K black body curve.  For a lapse rate of -6.5K.km-1 these would be clouds at about 1 km and 3.5 km altitude.  (Note: the calculation is only for CO2 and H2O.  Other greenhouse gases in the LWIR transmission window such as ozone and methane are not included).

Over the oceans, the cooling is dominated by surface evaporation.  As the air becomes warmer, the increase in LWIR flux is absorbed very close to the ocean surface, within 100 micron. This just adds to the evaporation, which increases  almost exponentially with temperature.  Evaporation also depends on humidity and wind speed and usually local fluctuations in wind speed will cause larger changes in evaporation than the LWIR flux.  Again, this gets back to that dynamic energy balance.  Convection and evaporation have to be included as well as radiation.

The reference is

L. Yu, X. Jin & R. A. Weller, OAFlux Project Technical Report (OA-2008-01) Jan 2008, “Multidecade Global Flux Datasets from the Objectively Analyzed Air-sea Fluxes (OAFlux) Project: Latent and Sensible Heat Fluxes, Ocean Evaporation, and Related Surface Meteorological Variables”

It is a NOAA publication.