Climate Change Debate

Professor Michael E. Mann, Distinguished Professor of Atmospheric Science at Penn State University, creator of the (in)famous hockey stick and self-appointed spokesperson of the consensed climate science community, apparently has no interest in participating in the Red Team / Blue Team exercise regarding climate change proposed by EPA Administrator Scott Pruitt. Mann recently opined, during a lecture on (of all things) academic and intellectual freedom at the University of Michigan, that climate was not debatable. It would be just as well that Mann would choose not to participate, since he should not be allowed to participate, as he has failed to share the data and calculations underlying his seminal “contribution” to climate science; and has, in fact, aggressively used the court system to avoid disclosing the underlying data and calculations.

The Red Team / Blue Team debate should focus on:

• the degree to which the near-surface temperature data currently being collected represent climate, as opposed to the effects of localized heat islands;
• the legitimacy and objectivity of the processes being used to “adjust” the data;
• the frequency of recalibration of the sensors used to collect the data;
• the influence of data “infilling” and “homogenization”;
• the justification for periodic “reanalysis” of historic data;
• recent research results for climate sensitivity;
• recent research regarding cloud formation and cloud forcing;
• recent research regarding solar influences on earth’s climate;
• the causes of the recent temperature “hiatus” or “pause”;
• the causes of the recent 12 year major landfalling hurricane respite;
• the causes of the decrease in major tornado frequency and intensity;
• changes in drought and flood frequency and magnitude;
• the difference between the land-based and satellite sea level rise measurements;
• the growing disparity between measured and modeled anomalies;
• the Social Cost of Carbon;
• recent research on the social benefits of carbon; and,
• the influences of natural phenomena on climate (El Nino, La, Nina, AMO, PDO)

All the above issues are clearly debatable; and, are subjects of active debate, even within the consensed climate science community.

Perhaps the most difficult aspect of the proposed debate will be the necessity to separate fact from belief in the presentations of various positions. We know that CO2, Methane and several other gases are “greenhouse gases”. We know that human activities result in the emissions of these gases. We know that the effects of these gases in the atmosphere are logarithmic, with declining effect as concentrations increase. We know that earth’s atmospheric, near-surface and sea surface temperatures have increased.

However, we do not know the sensitivity of earth’s climate to a doubling of atmospheric CO2 concentration. We do not know the magnitude of climate forcings and feedbacks. We do not have a model which allows us to know what climate will be like in the future. We do not have accurate temperature measurements of the near-surface, with the exception of the United States Climate Reference Network. There is even recent disagreement between the two primary sources of satellite temperature measurements. There is also continuing disagreement between the surface-based and satellite sea level measurements.

Dr. Mann was correct when he stated that “climate is not debatable”. Earth has a climate. He would still have been right if he had stated that climate change was not debatable. Climate has clearly changed throughout earth’s history. He might even have been correct if he had stated that some human contribution to climate change is not debatable. However, he was almost certainly not correct in stating that climate change “is human-caused”, since that would exclude any involvement of natural variation, which clearly continues.