PROFESSOR MARK MASLIN, CLIMATE SCIENTIST

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THIS POST IS A CRITICAL EVALUATION OF THE PAPER BY PROFESSOR MARK MASLIN CITED BELOW THAT DESCRIBES A ROLE FOR ATMOSPHERIC CARBON DIOXIDE IN GLACIATION CYCLES WITH RADICAL AND UNCONVENTIONAL CONCLUSIONS ABOUT A ROLE OF HUMAN ACTIVITY IN THE EVOLUTION AND CONTINUATION OF THE HOLOCENE 

MASLIN, MARK: Tying celestial mechanics to Earth’s ice ages; Physics Today 73, 5, 48 (2020); https://doi.org/10.1063/PT.3.4474: There is no abstract. The last paragraph appears to sum up the findings. It says “The extended interglacial period caused by persistently high GHG emissions produced an unusually stable climate and may have helped human empires emerge. Those emissions, however, are small compared to what humans have emitted since the start of the industrial revolution. Atmospheric carbon dioxide has increased by 47% to more than 410 ppm and methane by some 250% to more than 1860 ppb. Depending on future carbon emissions, global temperatures could rise 1.5–5.6 ˚C during the next century. The GHGs already emitted have delayed the next ice age for 60 000 years, as shown in figure 5, according to climate models. If the emissions reach the highest predicted level, glaciation would be delayed for 0.5 million years. Human fossil-fuel use has created a super-interglacial period that has overridden the effect of orbital forcing on Earth’s climate.  [FULL TEXT PDF] 

SUMMARY OF THE CLAIMS MADE IN THE PAPER

The paper describes the Milankovitch theory of glaciation cycles and then concludes that the change in the period of the glaciation cycle to 100,000 years in the last million years from 40,000 years prior to that is inconsistent with the Milankovitch eccentricity argument and goes on to propose a theory of glaciation cycles in terms of the greenhouse effect of atmospheric CO2 and CH4 and ice albedo and other proposed feedback systems.

The modified theory of glaciation cycles is presented as follows: First, to get glaciation started, “(1) summer temperatures must first decrease a little bit” but does not explain how or why that happens. Perhaps it is a random event in which case there would be no periodicity in glaciation cycles. (2) The decrease in summer temperature causes ice formation and that gets the (3) ice albedo feedback started because the more ice there is the more ice there can be. This goes on until the (4) ice sheets are big enough to deflect high elevation Rossby wave wind patterns depicted graphically in the video below provided by NOAA. Glaciation ice sheets can be 2,000 to 3,000 meters high and therefore assumed to be an atmospheric anomaly in terms of elevation such that they can change the climate by altering Rossby wave wind patterns. As a way of comparison the major  peaks in the Rockies are more than 4,000 meters high and those in Europe are 5,000 meters and higher. Rossby wave winds are also called planetary waves because they are created by the rotation of the earth.

The proposed climate impact mechanism of the Rossby wave deflection by ice sheets is that (5) the deflected Rossby wave takes storms to the North Atlantic and dumps cold water on the Gulf Stream. This prevents it from going too far north and thus acts as yet another feedback system that causes even more cooling in the Northern Hemisphere and even more ice to form. Glaciation ice formation is thus presented as a feedback system that gets started because “summer temperatures must first decrease a little bit” and is then propagated by two different feedback systems – ice albedo and Rossby wave deflection.

It is suggested that during glaciation, atmospheric GHG concentration (CO2+CH4) deceases by a half or a third ahead of the cooling implying that the glaciation cooling is an atmospheric phenomenon driven by the GHG effect of CO2 and CH4. It appears therefore that what gets the glaciation feedback system started is an unexplained loss of atmospheric CO2 and CH4 “by a half or a third” that causes “summer temperatures to decrease a little bit” which in turn causes ice formation and activates the albedo and Rossby wave deflection feedback systems to create the full glaciation state of the climate. A further role for GHGs in glaciation is described in terms of reinforcing ice sheet albedo feedbacks. Ice core data show that atmospheric GHG at that time had decreased in a sequence that implies that falling GHG causes cooling and not that cooling causes falling GHG. The Milankovitch theory is thus modified with the insertion of two new variables – the GHG concentration of the atmosphere and the Rossby wave deflection by ice sheets to accommodate the large differences in glaciation periods from 40,000 years to 100,000 years.

However, details of the GHG effect are not provided in terms of their concentrations and the value of the climate sensitivity parameter used in the evaluation of the temperature effect of the observed changes in atmospheric GHG concentration. It is also noted that the author insists on including CH4 as a separate and independent GHG forcing agent over the very long time scales in glaciation and deglaciation processes even though CH4 is unstable in the atmosphere with a half life of about 5 years. It spontaneously oxidizes to form CO2 and therefore its greenhouse warming effect over much longer time scales should take this instability into consideration.

The author explains that ice formation is a slow process that took 80,000 years to form in the most recent glaciation but that the melt is much faster. He says that summer sunshine at 65 degrees North Latitude gets the melting started and rising GHG concentration of the atmosphere causes warming and ice melt to accelerate. Once the melt starts, 80% of the ice can be gone in 4,000 years. The implication is sunshine alone initially gets  both warming and GHG release from the ocean started and the heat trapping effect of the GHG then acts as a feedback loop and accelerates the rate of warming and that in turn increases atmospheric GHG concentration even further.

The author then claims that the whole of the current interglacial, the Holocene, is an unusual and exceptionally warm interglacial that he calls a Super-Interglacial, made that way by the presence of humans and by the nature of human activity since the Neolithic Revolution 10,000 years ago. In contrast, mainstream climate science theory traces human caused global warming (AGW) and climate change to the Industrial Revolution about 200 years ago years ago, when the Little Ice Age (LIA) is thought to have been ended and the current warm period started by the fossil fuel emissions of the industrial economy of the humans. Also, mainstream climate science holds that the the natural interglacial warming had caused the Holocene Climate Optimum (HCO) 10,000 years ago and that it was this warmth that had caused the Neolithic Revolution and the rise of human civilization {described in a related post on this site [LINK] }. In the revisionist history of the Holocene Climate Optimum (HCO) presented here, the causation is reversed. The HCO did not give rise to the the Neolithic Revolution but rather it was the Neolithic Revolution that had caused the HCO by way of the CO2 emissions of human activity presumably in the form of cutting down trees, building homes, farming, and raising farm animals. However, no estimate is given for the amount of  CO2 and/or CH4 emissions of the Neolithic Revolution farmers and/or the climate sensitivity or TCRE values that were used to determine that the warming seen is explained in terms of these emissions. It is an innovative and creative conjecture by the author that is consistent with the super-interglacial hypothesis of the author but no data is provided and no empirical support is found in the paper.

The author may have used climate models to make these determinations as he had done in predicting the future of the Super Interglacial. In a forward  projection of the Super Interglacial hypothesis into the future, climate models show the temperature could rise by 1.5C to 5.6C in the next century and that the GHGs already emitted by humans have locked in enough long term future warming to push the next glaciation cycle 60,000 years into the future. If emissions continue to rise at the high end of the forecast, the next glaciation cycle will be delayed by 500,000 years according to climate models.

CRITICAL COMMENTARY 

THE CLIMATE CHANGE EVALUATIONS AND SCENARIOS DESCRIBED IN THE PAPER ARE DERIVED FROM CLIMATE MODELS. CLIMATE MODELS TELL US THE IMPLICATIONS OF THE CLIMATE THEORY BEING PROPOSED BY THE AUTHOR. IT IS UNCLEAR WHETHER THESE THEORIES HAVE BEEN TESTED WITH EMPIRICAL DATA. NO CLEAR PRESENTATION OF EMPIRICAL SUPPORT IS FOUND IN THE THE PAPER. THE THEORIES PROPOSED ARE MOSTLY INCONSISTENT WITH CLIMATE  SCIENCE AS IT EXISTS AND AS IT IS BEING USED BY THE IPCC AND BY MAINSTREAM CLIMATE SCIENCE IN THE EVALUATION OF FUTURE SCENARIOS AND THE DESIGN AND PROPOSAL OF CLIMATE ACTION PLANS. THE RADICAL THEORIES, SCENARIOS, AND FORECASTS PRESENTED HERE, AS FOR EXAMPLE THE HUMAN CAUSED SUPER INTERGLACIAL, ARE A FORM OF CLIMATE DENIAL EXCEPT THAT IT IS DENIAL ON THE HIGH END OF THE ALARMISM SCALE UNLIKE THE LOW END DENIAL THAT WE NORMALLY SEE IN CLIMATE SKEPTICISM.

PERHAPS THE ANOMALOUS FINDINGS REPORTED BY THIS AUTHOR ARE BEST UNDERSTOOD IN TERMS OF THE EXTREME ALARMISM OF HIS “HUMAN IMPACT” POSITION PRESENTED IN HIS EVALUATION OF THE ANTHROPOCENE IN THE VIDEO BELOW. IT IS NOT POSSIBLE FOR A RESEARCHER TO CARRY OUT OBJECTIVE AND UNBIASED SCIENTIFIC INQUIRY WHEN HE HAS AN ACTIVISM INTEREST IN THE SUBJECT MATTER OF THE RESEARCH QUESTION. 

A COMMENTARY ON THE ANTHROPOCENE IS OFFERED IN A RELATED POST ON THIS SITE [LINK]  . IN TERMS OF THE CLASSIFICATION OF THE HOLOCENE AS A HUMAN CAUSED EXCEPTIONALLY WARM SUPER INTERGLACIAL, SOME EXPLANATION IS NEEDED FOR THE CHAOTIC PATTERN OF THE HOLOCENE AS CYCLICAL ALTERNATIONS BETWEEN COLD AND WARM PERIODS AT MILLENNIAL AND CENTENNIAL TIME SCALES SEEN IN PALEO DATA [LINK]

THESE ARE THE PEOPLE WHO HAVE NOW TAKEN CHARGE OF OUR ENERGY FUTURE THAT IS COMMANDED TO BE RENEWABLE ENERGY AND NOTHING MORE LEST THERE BE ICE MELT AND SEA LEVEL RISE AND EXTREME WEATHER AND FOREST FIRES AND VIOLENT STORMS.