Paul Biggs from the University of Birmingham, UK, sent me the following summary of a presentation by Roger Pielke Sr. There is so much interesting information on the potential human impact on climate beyond a focus on carbon dioxide:
“Roger Pielke Sr, a respected climatologist of some 30 years, gave an interesting presentation of his perspective on climate science entitled ‘Regional and Global Climate Forcings – The Need to Move Beyond a Focus of the Radiative Forcing of the Well-Mixed Greenhouse Gases’ at the The 2006 Earth’s Radiative Energy Budget Related to SORCE Meeting in Washington.
The general conclusions that I draw from Pielke’s work are as follows:
Humans are significantly altering the global climate, but in a variety of diverse ways beyond the radiative effect of carbon dioxide.
In terms of climate change and variability on the regional and local scale, the IPCC Reports, the CCSP Report on surface and tropospheric temperature trends, and the U.S. National Assessment, have all overstated the role of the radiative effect of the anthropogenic increase of CO2 relative to the role of the diversity of other human climate climate forcing on global warming, and more generally, on climate variability and change.
Pielke calculates the fraction of global warming due to the radiative forcing of increased atmospheric CO2, using the current IPCC framework on climate forcings:
This includes new findings on artic ozone, methane, albedo, and aerosols/black carbon with forcing calculated to be about 26.5%. This contrasts with the IPCC view of 48%.
He suggests new or under-recognized human climate forcings including:
biogeochemical effect of CO2, nitrogen deposition, land-use/land-cover change, glaciation effect of aerosols, thermodynamic effect of aerosols, surface energy budget effect.
Global and regional climate models have not demonstrated skill at predicting climate change and variability on multi-decadal time scales.
A postitive feedback is required in order to significantly amplify the radiative forcing of added carbon dioxide.
There is, as of yet, no evidence that atmospheric water vapor concentrations have increased (see http://climatesci.atmos.colostate.edu/2006/04/03/new-global-precip-papers-trend-is-zero-or-positive/).
Moreover, water vapor also changes phase (into liquid and ice clouds and precipitation) which greater complicates the actual climate response to added CO2 and other well-mixed greenhouse gases.
Attempts to significantly influence regional and local-scale climate based on controlling CO2 emissions alone is an inadequate policy for this purpose.
The needed focus for the study of climate change and variability is on the regional and local scales. Global and zonally averaged surface temperature trend assessments, besides having major difficulties in terms of how this metric is diagnosed and analyzed, do not provide significant information on climate change and variability on the regional and local scales.
It is this instrumental data that gives the plot of a hockey stick shape, grafted onto proxy data. Furthermore, if, for example, the temperature of an area of the desert were to increase from plus 40 degrees celsius to 41 degrees, while at the same time an equal area of the Antarctic decreased from minus 40 to minus 41, the average temperature of the earth would stay constant.
However, under the Stephan-Boltzman equation, more radiation would be emitted by increasing the temperature of the desert, than the radiation loss from Antarctica. Pielke will shortly have a paper published in JGR, which introduces this problem.
Global warming is not equivalent to climate change. Significant, societally important climate change, due to both natural and human climate forcings, can occur without any global warming or cooling.
The spatial pattern of ocean heat content change is the appropriate metric to assess climate system heat changes including global warming. Pielke examines the significant upper ocean cooling from 2003 reported by Lyman et al, 2006 (http://www.noaanews.noaa.gov/stories2006/s2704.htm) to a depth of at least 750m, which was not predicted by climate models.
He cites 2 papers which support the diagnosis: A 2004 Science article by E. Pallé, P. R. Goode, P. Montañés-Rodríguez, and S. E. Kooninentitled ‘Changes in Earth’s Reflectance Over the Past Two Decades’ and a follow-on 2005 Geophysical Research Letters paper by Pallé E., P. Montañés-Rodriguez, P. R. Goode, S. E. Koonin, M. Wild, and S. Casadio entitled ‘A multi-data comparison of shortwave climate forcing changes’ (http://www.agu.org/pubs/crossref/2005…/2005GL023847.shtml ).
Finally, I must point out that Pielke says all of this is not a reason not to seek to reduce CO2 emissions.”
Thanks Paul for the summary and also to Luke, for emphasising to me the importance of getting this information up as a new post/thread.