Climate

Our climate work has been led by Professor Emeritus Jackson Davis, University of California with our first papers published in 2017, 2018, 2019 and 2020. In 2019, Peter Taylor was invited to give a keynote address on this work in February 2019 at an international climate science conference in Prague.

These Open Access papers are listed below, with download links:


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The Relationship between Atmospheric Carbon Dioxide Concentration and Global Temperature for the Last 425 Million Years

W. Jackson Davis

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Published in Climate 2017, 5, 76; doi:10.3390/cli5040076  https://www.mdpi.com/2225-1154/5/4/76

 

Abstract: Assessing human impacts on climate and biodiversity requires an understanding of the relationship between the concentration of carbon dioxide (CO2) in the Earth’s atmosphere and global temperature (T). Here I explore this relationship empirically using comprehensive, recently-compiled databases of stable-isotope proxies from the Phanerozoic Eon (~540 to 0 years before the present) and through complementary modeling using the atmospheric absorption/transmittance code MODTRAN. Atmospheric CO2 concentration is correlated weakly but negatively with linearly-detrended T proxies over the last 425 million years. Of 68 correlation coefficients (half non-parametric) between CO2 and T proxies encompassing all known major Phanerozoic climate transitions, 77.9% are non-discernible (p > 0.05) and 60.0% of discernible correlations are negative. Marginal radiative forcing (DRF co2) change in forcing at the top of the troposphere associated with a unit increase in atmospheric CO2 concentration, was computed using MODTRAN. The correlation between DRFCO2

and linearly-detrended T across the Phanerozoic Eon is positive and discernible, but only 2.6% of variance in T is attributable to variance in DRFCO2. Of 68 correlation coefficients (half non-parametric) between DRFCO2 and T proxies encompassing all known major Phanerozoic climate transitions, 75.0% are non-discernible and 41.2% of discernible correlations are negative. Spectral analysis, auto and cross-correlation show that proxies for T, atmospheric CO2 concentration and DRFCO2 oscillate across the Phanerozoic, and cycles of CO2 and DRFCO2 are antiphasic. A prominent 15 million-year CO2 cycle coincides closely with identified mass extinctions of the past, suggesting a pressing need for research on the relationship between CO2, biodiversity extinction, and related carbon policies.

This study demonstrates that changes in atmospheric CO2 concentration did not cause temperature change in the ancient climate.

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The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature

W. Jackson Davis, Peter J. Taylor  and W. Barton Davis

 

Published in Climate 2018, 6, 3; doi:10.3390/cli6010003   www.mdpi.com/journal/climate

 

Abstract: We report a previously-unexplored natural temperature cycle recorded in ice cores from Antarctica—the Antarctic Centennial Oscillation (ACO)—that has oscillated for at least the last 226 millennia. Here we document the properties of the ACO and provide an initial assessment of its role in global climate. We analyzed open-source databases of stable isotopes of oxygen and hydrogen as proxies for paleo-temperatures. We find that centennial-scale spectral peaks from temperature-proxy records at Vostok over the last 10,000 years occur at the same frequencies (2.4%)

in three other paleoclimate records from drill sites distributed widely across the East Antarctic Plateau (EAP), and >98% of individual ACOs evaluated at Vostok match 1:1 with homologous cycles at the other three EAP drill sites and conversely. Identified ACOs summate with millennial periodicity to form the Antarctic Isotope Maxima (AIMs) known to precede Dansgaard-Oeschger (D-O) oscillations recorded in Greenland ice cores. Homologous ACOs recorded at the four EAP drill sites during the last glacial maximum appeared first at lower elevations nearest the ocean and centuries later on the high EAP, with latencies that exceed dating uncertainty >30-fold. ACO homologs at different drill sites became synchronous, however, during the warmer Holocene. Comparative spectral analysis suggests that the millennial-scale AIM cycle declined in period from 1500 to 800 years over the last 70 millennia. Similarly, over the last 226 millennia ACO repetition period (mean 352 years) declined by half while amplitude (mean 0.67 C) approximately doubled. The period and amplitude of ACOs oscillate

in phase with glacial cycles and related surface insolation associated with planetary orbital forces. We conclude that the ACO: encompasses at least the EAP; is the proximate source of D-O oscillations in the Northern Hemisphere; therefore affects global temperature; propagates with increased velocity as temperature increases; doubled in intensity over geologic time; is modulated by global temperature

variations associated with planetary orbital cycles; and is the probable paleoclimate precursor of the contemporary Antarctic Oscillation (AAO). Properties of the ACO/AAO are capable of explaining the current global warming signal.

 

Note the final sentence of  the Abstract – Professor Davis had become convinced by the data that cycles in global temperature were capable of explaining current global warming. The second paper explored the way in which Antarctic cycles were capable of driving all the ocean cycles, as if the dynamics of the circumpolar ocean currents were the engine of global temperature change.

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The Origin and Propagation of the Antarctic Centennial Oscillation

W. Jackson Davis.  Peter J. Taylor and W. Barton Davis

 

Published in Climate 2019, 7, 112; doi:10.3390/cli7090112   www.mdpi.com/journal/climate

 

Abstract: The Antarctic Centennial Oscillation (ACO) is a paleoclimate temperature cycle that originates in the Southern Hemisphere, is the presumptive evolutionary precursor of the contemporary Antarctic Oscillation (AAO), and teleconnects to the Northern Hemisphere to influence global temperature. In this study we investigate the internal climate dynamics of the ACO over the last 21 millennia using stable water isotopes frozen in ice cores from 11 Antarctic drill sites as temperature proxies. Spectral and time series analyses reveal that ACOs occurred at all 11 sites over all time periods evaluated, suggesting that the ACO encompasses all of Antarctica. From the Last Glacial Maximum through the Last Glacial Termination (LGT), ACO cycles propagated on a multi-centennial time scale from the East Antarctic coastline clockwise around Antarctica in the streamline of the Antarctic Circumpolar Current (ACC). The velocity of teleconnection (VT) is correlated with the geophysical characteristics of drill sites, including distance from the ocean and temperature. During the LGT, the VT to coastal sites doubled while the VT to inland sites decreased fourfold, correlated with increasing solar insolation at 65N. These results implicate two interdependent mechanisms of

teleconnection, oceanic and atmospheric, and suggest possible physical mechanisms for each. During the warmer Holocene, ACOs arrived synchronously at all drill sites examined, suggesting that the VT increased with temperature. Backward extrapolation of ACO propagation direction and velocity places its estimated geographic origin in the Southern Ocean east of Antarctica, in the region of the strongest sustained surface wind stress over any body of ocean water on Earth. ACO period is correlated with all major cycle parameters except cycle symmetry, consistent with a forced, undamped

oscillation in which the driving energy affects all major cycle metrics. Cycle period and symmetry are not discernibly different for the ACO and AAO over the same time periods, suggesting that they are the same climate cycle. We postulate that the ACO/AAO is generated by relaxation oscillation of Westerly Wind velocity forced by the equator-to-pole temperature gradient and propagated regionally by identified air-sea-ice interactions.

 

Following a session at ESI in 2018, whilst examining the accumulated data, we noticed an extra-ordinary pattern in the data on dust deposition in the ice-cores – this being a proxy for both wind strength and changes of direction. Similar proxies had been used for the Greenland ice-core record by Bond at the Lamont Docherty Laboratories in the USA where he deduced that major changes in wind direction in the North Atlantic were driving temperature and precipitation on the Greenland ice-cap. We worked on a third paper together, but for various reasons I could not participate fully and it was published in 2020.

 

Antarctic Winds: Pacemaker of Global Warming, Global Cooling, and the Collapse of Civilizations

W. Jackson Davis and W. Barton Davis

 

Published in Climate 2020, 8, 130; doi:10.3390/cli8110130    www.mdpi.com/journal/climate

 

Abstract: We report a natural wind cycle, the Antarctic Centennial Wind Oscillation (ACWO), whose properties explain milestones of climate and human civilization, including contemporary global warming. We explored the wind/temperature relationship in Antarctica over the past 226 millennia using dust flux in ice cores from the European Project for Ice Coring in Antarctica (EPICA) Dome C (EDC) drill site as a wind proxy and stable isotopes of hydrogen and oxygen in ice cores from EDC and ten additional Antarctic drill sites as temperature proxies. The ACWO wind cycle is coupled 1:1 with the temperature cycle of the Antarctic Centennial Oscillation (ACO), the paleoclimate precursor of the contemporary Antarctic Oscillation (AAO), at all eleven drill sites over all time periods evaluated. Such tight coupling suggests that ACWO wind cycles force ACO/AAO temperature cycles. The ACWO is modulated in phase with the millennial-scale Antarctic Isotope Maximum (AIM) temperature cycle. Each AIM cycle encompasses several ACWOs that increase in frequency and amplitude to a Wind Terminus, the last and largest ACWO of every AIM cycle. This historic wind pattern, and the heat and gas exchange it forces with the Southern Ocean (SO), explains

climate milestones including the Medieval Warm Period and the Little Ice Age. Contemporary global warming is explained by venting of heat and carbon dioxide from the SO forced by the maximal winds of the current positive phase of the ACO/AAO cycle. The largest 20 human civilizations of the past four millennia collapsed during or near the Little Ice Age or its earlier recurrent homologs. The Eddy Cycle of sunspot activity oscillates in phase with the AIM temperature cycle and therefore may force the internal climate cycles documented here. Climate forecasts based on the historic ACWO wind pattern project imminent global cooling and in ~4 centuries a recurrent homolog of the Little Ice Age. Our study provides a theoretically-unified explanation of contemporary global warming and other climate milestones based on natural climate cycles driven by the Sun, confirms a dominant role for climate in shaping human history, invites reconsideration of climate policy, and offers a method to project future climate.

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We would argue that this work provides the basis for cycles of wind-driven ocean currents and surfacing of warm/cold waters drives a variable millennial cycle. Furthermore, extrapolation of the wave-form shows that the cycles peak during this current ‘warm period’. The question then remains as to how much of a contribution is made by the main anthropogenic greenhouse gas – carbon dioxide. The answer has major policy implications, of course.

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In 2019, on the basis of the three then published papers, I took up an invitation to speak at a major global summit on climate science, held in Prague. I was invited as keynote speaker and to chair some sessions. Here is the abstract upon which the invitation was based:

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Natural drivers of global warming: ocean cycles, anthropogenic greenhouse gases and the question of percentages.

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Peter J. Taylor. (2025). Natural Drivers of Global Warming: Ocean Cycles, Anthropogenic Greenhouse Gases and the Question of Percentages. Journal of Environmental & Earth Sciences, 7(2), 262–290. https://doi.org/10.30564/jees.v7i2.7683

 

Abstract: At present, there is a widespread policy assumption that anthropogenic greenhouse gases are the main driver of the observed 1°C rise in global surface air temperatures since ‘pre-industrial’ times. This paper demonstrates that the onset of the current warming trend began in the mid-19th century and is consistent with the rising phase of a variable 800-1200 year global warming and cooling cycle evident in the Northern Hemisphere and a 750-year cycle in the Southern Hemisphere. The last trough of these cycles, known as the Little Ice Age, coincides with the baseline of pre-industrial times used to calculate the impact of Anthropogenic Global Warming. Yet, half of the observed 20th century temperature rise occurred before 1950 when carbon dioxide levels remained low, with the remaining half happening at a similar rate of warming despite the much higher concentrations of greenhouse gases in the atmosphere. This study shows that when the amplitudes and rates of change of the long-term global cycles are considered, the anthropogenic component of warming can be reduced to 38% (using factors derived from the latest IPCC Working Group reports) or as little as 25% (using observational flux data of dominant Short Wave Absorbed Surface Radiation). These long-term global cycles can be extrapolated into the future and the implications for policy of a large natural component to climate change are explored – in particular, the potential for mitigation strategies to have minimal impact and for the climate to cool as a consequence of a cyclic down-phase.

 

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Further work led to a closer study of ocean-initiated mass extinctions:

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Mass Extinctions and Their Relationship With Atmospheric Carbon Dioxide Concentration: Implications for Earth's Future

W. Jackson Davis

Citation: Davis, W. J. (2023). Mass extinctions and their relationship with atmospheric carbon dioxide concentration : Implications for Earth's future.

Earth's Future, 11, e2022EF003336. https://doi.org/10.1029/2022EF003336

 

Abstract

Industrialization has raised the concentration of carbon dioxide (CO2) in Earth's atmosphere by half since 1770, posing a risk from ocean acidification to global biodiversity, including phytoplankton that synthesize approximately (∼) 50% of planetary oxygen. This risk is estimated here from the fossil record and implications for our energy and economic future are explored. Over the last 534 million years (Myr), 50

extinction events present as peaks of genus loss-and-recovery cycles, each spanning ∼3–40 Myr. Atmospheric CO2 concentration oscillates with percent genus loss, leading in phase by ∼4 Myr and sharing harmonic periodicities at ∼10, 26 and 63 Myr. Over the last 210 Myr, where data resolution is highest, biodiversity loss is correlated with atmospheric CO2 concentration, but not with long-term global temperature nor with marginal radiative forcing of temperature by atmospheric CO2. The end-Cretaceous extinction of the dinosaurs is anomalous, occurring during a 20-million year depression in atmospheric CO2 concentration and rising global temperature. Today's atmospheric CO2 concentration, ∼421 parts per million by volume (ppmv), corresponds in the most recent marine fossil record to a biodiversity loss of 6.39%, implying that contemporary anthropogenic CO2 emissions are killing ocean life now. The United Nations Intergovernmental Panel on Climate Change projects that unabated fossil fuel use could elevate atmospheric CO2 concentration to 800 ppmv by 2100, approaching the 870 ppmv mean concentration of the last 19 natural extinction events. Reversing this first global anthropogenic mass extinction requires reducing net anthropogenic CO2 emissions to zero, optimally by 2% per year starting immediately.

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This is a seminar paper delivered to the World Congress of Anthropology's special meeting on climate issues in June 2016 at the British Museum in London.​

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Cycles, irregular periods and the unpredictable vs linear extrapolation, prediction and control: are there social and psychological issues in the construction of climate knowledge?

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Short Abstract
As a natural scientist working in policy fields relevant to climate change: e.g energy strategies, resilient systems and environmental impacts, the author invites social anthropologists to consider a potential major sociological bias in methodologies used to construct climate science knowledge.​