Saturn’s Climate Change And Its Lessons For Earth

Written by Koen Vogel, Ph.D. on December 12, 2022. Posted in Current News

Alternate models for planetary processes, part1

Physical processes that are able to distribute and focus energy on planetary scales are rare, so planetary data sets that show significant spatial covariation – such as Earth’s geomagnetic and geothermal data – strongly suggest that a single process is responsible for their shared geometry.

The characterization of a planetary process, such as climate change, usually relies on the analysis of relatively easily-acquired Earth data. Models of planetary processes however should be evaluated against the physical, chemical, and geological observations of all planets, as extraterrestrial data can often improve Earth-inspired models. An analysis of Saturn’s climate change provides a good example.

This post is the first of seven in support of the PROM article “An integrated physical model characterizing planetary magnetism and heat”, which proposes an alternate origin of the geomagnetic field versus the consensus geodynamo theory. The alternate model better explains the magnetic field geometry and heat anomalies of all planets, including such “problematic” planets such as Saturn and Neptune, and accurately predicts their magnetic field strengths from best-estimate input data.

Seven PSI posts dealing with general interest topics, such as climate change, continental drift, and magnetic field generation are posted in support of the PROM article. Each post documents an alternate model to the existing scientific consensus on planetary processes. This post deals with climate change.

The consensus theory on climate change: the IPCC attribution study

The principal focus of the most recent IPCC climate change attribution study ^[1] was to determine the relative contributions of Natural versus Anthropogenic forcings to the Global Mean Surface Temperature (GMST) variability, with special attention dedicated to the observed warming of 0.6 °C in the 1951-2010 period. Two main Natural Forcings are recognized: Solar Irradiation Forcing, which actively heats the Earth, and Volcanic Forcing, which limits the solar radiation that reaches the Earth’s surface at irregular time intervals.

The Anthropogenic Forcings include Radiative Forcing due to Greenhouse Gasses (RFGHG), whose main effect is to allow the Earth to recover some of its emitted heat energy, and Other Anthropogenic Forcing, a catchall that includes e.g. anthropogenic aerosols, and that mainly acts to limit Solar Irradiation in a manner similar to Volcanic Forcing. Other climate forcings were investigated but deemed insignificant relative to these four main ones and were therefore not simulated by the IPCC climate models during the attribution study ^[1]. The attribution analysis employed a unique-to-IPCC technique termed Optimal Fingerprint Analysis and concluded that RFGHG is the forcing mainly responsible for the 1951-2010 GMST increase.

Saturn’s Climate Change

The IPCC analysis focused solely on Earth, yet Saturn’s recent global temperature changes can provide some valuable insights into the IPCC-ignored Natural forcings that demonstrably play a significant role in Saturn’s – and Earth’s – climate change. Saturn’s distance to the Sun is an order of magnitude larger than Earth’s (1 AU vs 10 AU) so its mean incident solar irradiance (measured in W/m²) is roughly two orders of magnitude lower. However: (https://www.science20.com/news_articles/why_does_saturn_radiate_twice_energy_it_absorbs_sun)

• Saturn radiates twice the energy it receives from solar irradiation; this is termed Saturn’s “energy crisis”
• Saturn’s original formational heat is likely not powering the energy crisis: Kelvin-Helmholtz’s modeling indicates Saturn lost all this heat over 2 billion years ago^[2].
• Saturn emitted less energy each year from 2005 to 2009: the planet suffered global cooling in the period after its southern summer solstice in 2002 up to its equinox in 2009.
• In 2010 Saturn’s heat radiation was asymmetrical: its southern hemisphere radiated about one-sixth more energy than its northern one. The effective northern hemisphere temperature gradually dropped between 2005 to 2008 but started to warm up again by 2009 during the run-up to the northern hemisphere summer. The temperatures cooled in the southern hemisphere between 2005 to 2009 during its southern fall season.
• Saturn’s heat anomalies also shifted with its seasons, mirroring the hemispherical temperature shifts: an equatorial heat anomaly during the 1997 equinox migrated to the south pole in 2006 during the southern hemisphere’s summer (Fig. 1). The anomaly then migrated to the north, causing northern hemisphere heat anomalies following the 2009 equinox (Fig. 2), and terminated at Saturn’s north pole by the 2017 northern hemisphere summer.

Figure 1: Left: Infrared telescope images of Saturn for two dates (Source. Right: VLT image of Saturn’s giant vortex at mid-infrared wavelengths. (December 2010 – October 2012 timeframe) (Source)

Figure 2: Cassini Composite Infrared Spectrometer images of Saturn’s North Pole. SourceSaturn’s thermosphere is 200-400 K hotter than what can be expected from solar heating alone, and a study determined that an extra 2.5 TW of heating power per hemisphere is needed to explain observed temperatures ^[3].

Saturn’s climate change – on a decennial time scale – is consistent with its seasonal changes: the northern hemisphere warmed and the southern hemisphere cooled during its transition to summer in the north between 2009 (equinox) and 2017 (northern summer solstice). Its polar heat anomalies, however (Figs. 1-2) are more difficult to explain, as the poles are more distant to the sun than the equator, and their solar irradiance incidence angles are lower: the poles receive less net solar irradiation energy than the equator. Saturn radiates more energy than it receives from solar irradiation, yet Saturn’s internal (formational) heat was expended 2 billion years ago, and anthropogenic and volcanic forcings can reliably be assumed to be absent.

An IPCC-similar analysis, therefore, indicates a major, enigmatic Natural climate forcing is at play. This enigmatic climate forcing is very likely solar-powered, as Saturn’s radiated energy and heat anomalies follow the seasons from hemisphere to hemisphere, and heat anomalies peak at the poles during their summer solstice. Apart from solar irradiation, the only significant solar power reaching Saturn is the solar wind, which fortunately fits the observations very well. The 5 TW of power^[3] required for Saturn’s 200-400 K higher thermosphere temperature represents roughly 18% of the 28 TW of incident solar wind power (PROM article, Table 2), so the incident solar wind is a credible power source for both Saturn’s energy crisis, and its enigmatic climate forcing. The PROM article demonstrates that Saturn’s migrating heat anomalies in fact originate as magnetogenic waste heat from Saturn’s solar wind-powered magnetogenic process.

All Gas Giants suffer a similar climate forcing

Figure 3: Infrared images of Uranus (a), Jupiter (b), and Neptune (c) showing heat anomalies at their poles (Source: a&c [8]; b [9])

• Neptune and Jupiter radiate significantly more energy than they receive from solar irradiation; Uranus radiates slightly more than it receives
• The Gas Giants often show heat anomalies at their poles. Saturn, Uranus, and Neptune’s heat anomalies are likely related to seasonal variations, but Jupiter – with an axial tilt of 0° – has no seasons in the Earth sense of the word.
• Neptune’s southern hemisphere heat anomaly peaked during its summer solstice ^[7]

The PROM article details the large number of highly speculative planet-internal heat sources that have been proposed that could – under a variety of highly speculative assumptions – solve the planetary energy crises. Some authors for example suggest a helium rain falling through Saturn’s atmosphere is generating friction and supplying the missing heat. These speculations usually do not include any energy calculations demonstrating the feasibility of such sources (>5 TW needed for Saturn), and generally cannot explain such observations as local (migrating) heat anomalies, or hemisphere-wide temperature variations.

Most authors do not attempt to link the various planetary processes and their energy exchanges, which is rather short-sighted: a planetary process that distributes and focuses one energy form (e.g. magnetic energy) likely interacts – energy-wise – with other such processes (e.g. heat). It is commonly accepted that planetary magnetic fields are generated in a planet’s interior, though most authors fail to make the link between the magnetogenic process, which must also generate waste heat and a planet’s internal heat budget.

For example, Wikipedia states both Uranus and Neptune lack an internal energy source, despite the fact that some planetary process must internally be generating their magnetic fields, as well as magnetogenic waste heat. Neptune and Uranus radiate 2.6 and 1.1 times resp. as much energy as they receive from solar irradiation, so some of this excess heat is very likely magnetogenic waste heat.

The PROM article explains the planetary magnetic and heat anomalies in terms of a newly proposed magnetogenic process – the Solar Wind Induced Electromagnet (SWIEM) – that is powered by the incident solar wind. The SWIEM model is able to predict planetary magnetic field strengths from best estimates of solar wind strength and planetary geometries (Fig. 4) and accounts for the temporal variation of planetary heat anomalies.

Fig. 4: SWIEM model-predicted versus observed planetary magnetic field strength (Note: log scales).

… and so does Earth

Earth is the only other planet in the solar system – apart from Gas Giants – to have a significant (> 10 µT) magnetic field. Similar to the Gas Giants:

• Earth is warmer than it should be from solar irradiance alone: it radiates more heat than it receives from solar irradiation (https://www.nasa.gov/feature/langley/what-is-earth-s-energy-budget-five-questions-with-a-guy-who-knows; Retrieved 2022 November 27). It was this observation that led Fourier to propose the greenhouse effect: he reasoned that a planetary process was regulating the Earth’s temperature.
• Over the past 150 years, Earth has experienced 2 prolonged north pole heat anomalies that were largely responsible for the 1950-2010 and 1900-1945 GMST increases (Fig. 5), a fact which is documented by the IPCC [1].

It is somewhat surprising that many IPCC climate models – for example the GISS model – can simulate the observed north pole heating (Fig. 6 left), as the asserted dominance of the RFGHG climate forcing implies that global temperature increases should largely mirror the heat energy emitted by the Earth (Fig. 6 right): more emitted heat implies more energy captured by greenhouse gasses and therefore higher temperatures. Locally, this appears to be the case: the GISS-modeled temperature increases do reflect the southern hemisphere’s high emitted-heat band connecting Brazil, southern Africa, and Australia. For the Arctic, however, an inverse relationship exists (Fig. 6): the higher measured Arctic temperatures and low emitted Arctic heat energy contradict that RFGHG is the dominant Arctic climate forcing. The IPCC climate models, therefore, include highly-speculative climate feedback loops termed “Polar Amplification” [4; Box 5.1]. These feedback loops are modeled as polar albedo changes caused by retreating sea ice.

“The resulting ocean warming contributes to further sea ice melting. The sea ice/ocean surface albedo feedback can exhibit threshold behavior when temperatures exceed the freezing point of sea ice. This may also translate into a strong seasonality of the response characteristics.” [4]

Fig. 5: North Pole heat anomalies during 1900-1944 (left) and the current (right) global temperature increases. (Source 1; Source 2)

Fig. 6: Left: 2005-2009 simulated temperature increase from the GISS climate model simulation made for the IPCC Fourth Assessment Report; Right: 2003-2010 Earth outgoing longwave radiation (Sources: https://climate.nasa.gov/news/2943/study-confirms-climate-models-are-getting-future-warming-projections-right/; https://en.wikipedia.org/wiki/Outgoing_longwave_radiation)

However, observations indicate the GISS-modeled Polar amplification process is not occurring in reality:

1. Arctic temperature increases do not occur during the summer “when temperatures exceed the freezing point of sea ice” [4], but during the winter (Fig. 7). In addition, these temperature increases appear to have started around 1995-2000, and are therefore apparently uncorrelated to anthropogenic GHG or aerosol increases

2. The 2000-2011 changes in polar reflectivity appear to be relatively uniform over the Arctic, and in no way reflect the observed changes in summer ice cover (Fig. 8), but do reflect the observed changes in temperature (Fig. 5 right; Fig 6 left). The diminishing sea ice cover seems to primarily occur near the Asian continent, not the North American continent, indicating Arctic heating is largely asymmetrical. Polar Amplification cannot, therefore, explain the rise in temperature over the North American Arctic.

Note that it is commonly accepted that the Arctic has warmed nearly three to four times faster than the globe since 1979 and that the IPCC climate models systematically tend to underestimate this heating, even under the incorrect assumption of Polar amplification feedback loops [6].

Fig. 7: Temperature anomalies of the Arctic +80N region: annual mean (black line), summer anomaly (red line; averaged over June, July, August), and winter anomaly (blue line; averaged over December, January, February). (Source). Reference climate is ECMWF-ERA40 1958-2002.

Fig. 8: Left: CERES-measured change in Arctic reflectivity for the March 2000 – December 2011 period; Right: Sea ice extent on September 9, 2011, the date of minimum extent for the year. (Sources: https://earthobservatory.nasa.gov/images/84499/measuring-earths-albedo; https://www.climate.gov/news-features/understanding-climate/state-climate-2011-arctic-sea-ice-minimum)

Polar Amplification is therefore very likely not causing the Arctic anomaly on Earth, and definitely not causing the polar anomalies on the Gas Giants. The only possible explanation for the Arctic temperature increase during winter is a climate forcing that acts on the Arctic Ocean, that is acts below the ice not above it. The Earth’s albedo is notoriously difficult to measure at the Earth’s surface, so albedo analyses use satellite radiometer data measuring the Earth’s outgoing (shortwave) solar energy reflected by the planet (albedo) as well as its outgoing longwave thermal energy. Albedo calculations reflect the balance between the measured incoming solar energy and outgoing shortwave and longwave energies. Therefore, if an unrecognized below-the-ice climate forcing is heating the Arctic over the 2000-2011 period, then any change in emitted heat energy is interpreted as a decrease in albedo, i.e. more longwave emitted energy signifies a larger portion of the incoming energy is absorbed, meaning a lower portion of the incoming energy is reflected, so a lower calculated albedo. The entire Arctic shows a pronounced lower calculated reflectivity (Fig. 8 left) between 2000-2011, suggesting identical “albedo changes” for both long-lasting sea ice and open sea water, which directly refutes the GISS-modeled “Polar Amplification” mechanism [4].

The fact that the ice cover is asymmetrically melting to the north of the Asian continent is very likely explained by a local, year-round offshore-Asia heat source that helps to melt the local ice cover during the summer, but whose heat is also re-distributed year-round throughout the basin by the Arctic currents. The “decrease in albedo” is therefore likely due to an increase in radiated Arctic ocean heat fueled by an increase in near-Asia Arctic sea floor heat flux.

The attempts to explain the Arctic heat anomaly as anthropogenic climate change have led to a plethora of highly speculative (and unsupported by data) explanations [6]:

• enhanced oceanic heating and ice-albedo feedback due to diminishing sea ice
• Planck feedback [essentially invoking RFGHG]
• lapse-rate feedback
• near-surface air temperature inversion
• cloud feedback
• ocean heat transport
• meridional atmospheric moisture transport
• reduced air pollution in Europe
• reductions of Asian aerosols

In effect, the analysis [6] strongly implies that the IPCC climate models are missing an important climate forcing, as the IPCC has gone to great lengths to demonstrate the above explanations cannot affect a temperature increase that is larger than the RFGHG effect. Therefore, the IPCC climate models are incorrectly modeling the largest temperature anomaly on Earth, one that’s responsible for a significant part of the average 1951-2010 global GMST increase.

The incorrectly ignored Natural climate forcing

The attempts to explain the Arctic anomaly as anthropogenic climate change have led to the above list of speculative climate forcings that the IPCC attribution study itself [1]  dismisses as insignificant. Occam’s razor suggests Earth’s polar temperature anomalies are caused by the same planetary process as the Gas Giants’ polar anomalies. The polar heat anomalies of all planets, as well as the 1900-1944 Arctic heat anomaly, provide some insights into this missing, solar wind-driven climate forcing.

The heat anomalies of the planets with significant magnetic fields (Gas Giants + Earth) are more alike than different: all show polar temperature anomalies that are impossible to explain by the main IPCC-modeled Earth Natural and Anthropogenic climate forcings. Fig. 9 demonstrates that the 1900-1944 Arctic heat anomaly was not caused by Polar Amplification or RFGHG forcing: the Arctic heated between 1900 and 1944, but the higher Arctic temperatures had disappeared by 1964, despite the fact that RFGHG had increased significantly between 1944 and 1964 [1]. Note that the 1944-1964 temperature reduction must have been due to Arctic heat energy being radiated to space despite increasing RFGHG levels. The 1900-1944 Arctic heat anomaly was therefore caused by an unrecognized-by-IPCC Natural climate forcing that disappeared between 1944-1964, but very likely returned and played a significant role during the 1964-2010 temperature increase.

Fig. 9: North Pole heat anomalies between 1900-present. Upper left: no anomaly in 1919; Upper right: an anomaly in 1944; Lower left: no anomaly in 1964;  Lower right: a large anomaly in 2020. (Source)

A likely cause of Earth’s Arctic heat anomaly is an Arctic seafloor thermal anomaly, similar to the polar anomalies of the Gas Giants that are fueled by internal heat: high Arctic ocean floor heat flux is warming the Arctic ocean and causing Arctic temperature increases (Fig. 6), mainly during the winter (Fig. 7) when solar irradiation forcing is low and therefore not dominating measured temperatures. This extra heat is generated as a byproduct of the magnetogenic process (see PSI Post 2) and redistributed by Arctic ocean sea currents (e.g. Beaufort Gyre), resulting in a larger-than-expected outgoing heat flow over the entire Arctic (Fig. 5-9). This interpretation is supported by heat flow measurements of 104-127 mW/m2 for the Arctic Amundsen Basin, which is over double the magnitude predicted by ocean heat flow models and that is not readily explainable by sediment, crustal or lithospheric scale effects [5].

The PROM article, and the next PSI Post (2), explain that planetary magnetogenesis is responsible for the polar heat anomalies on Earth and the Gas Giants.

Alternate model: A significant part of Earth’s 1951-2010 and 1900-1944 global warming is due to an Earth-internal heat source that is powered by its magnetogenic process. This significant climate forcing has not been modeled by the IPCC.

[1]  Bindoff, N.L., Stott, P.A.,  AchutaRao, K.M. et al., 2013: Detection and Attribution of Climate Change: from Global to Regional. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., et al. (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

[2] Marley, M.S., Fortney, J.J., 2014, Interiors of the Giant Planets. In: Encyclopedia of the Solar System (Third Edition), Academic Press, p. 743-758, ISBN: 978-0-12-415845-0

[3] Cowley, S. W. H., Bunce, E. J., and O’Rourke, J. M., 2004, A simple quantitative model of plasma flows and currents in Saturn’s polar ionosphere, J. Geophys. Res., 109, A05212, doi:10.1029/2003JA010375, 2004b.

[4] Intergovernmental Panel on Climate Change, 2014, Information from Paleoclimate Archives. In Climate Change 2013 – The Physical Science Basis: Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (pp. 383-464). Cambridge: Cambridge University Press. doi:10.1017/CBO9781107415324.013

[5] Urlaub, M., Schmidt-Aursch, M. C., Jokat, W., and Kaul, N., 2009, Gravity crustal models and heat flow measurements for the Eurasia Basin, Arctic Ocean. Marine Geophysical Researches, 30, 277-292.

[6] Rantanen, M., Karpechko, A.Y., Lipponen, A. et al., 2022, The Arctic has warmed nearly four times faster than the globe since 1979., Commun Earth Environ 3, 168, https://doi.org/10.1038/s43247-022-00498-3

[7] Roman, M.T., Fletcher, L.N., Orton, G.S., Vatant d’Ollone, J., Sinclair, J.A., Rowe-Gurney, N., Moses, J.I., & Irwin, P.J., 2020, Sub-Seasonal Variations in Neptune’s Stratospheric Infrared Emission from VLT-VISIR, 2006-2018. The Planetary Science Journal, 3, 41 pp, https://doi.org/10.3847/PSJ/ac5aa4

[8] de Pater, I, Kurth, W.S, 2014, The Solar System at Radio Wavelengths. In: Encyclopedia of the Solar System (Third Edition), Academic Press ISBN: 978-0-12-415845-0, 1107-1132

[9] UPI; Retrieved: 2022 December 3)

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