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| Fig. 1 Who's on first |
I. Background
There is some contrast among the statements of impact that atmospheric warming has on oceanic warming:
"In 2022, the world’s oceans, as given by OHC, were again the hottest in
the historical record and exceeded the previous 2021 record maximum."
(Another Year of Record Heat for the Oceans, Cheng et al. 2023, emphasis added).
"Earth's average surface temperature in 2022 tied with 2015 as the fifth warmest on record, according to an analysis by NASA. "
NASA Says 2022 Fifth Warmest Year on Record, Warming Trend Continues
There is quite a difference between first place and fifth place (Fig. 1), so what does the difference in the two contrasting sources mean?
II. Various Reasons
I don't know, but the general scientific understanding is that about 90-93% of global warming that takes place in the atmosphere flows into the oceans (Wikipedia, IUCN).
That would mean, at first blush, that in 2022 the oceans received the fifth most global warming induced heat, and that another year received the most.
I do know that the paper Cheng et al. 2023 (linked-to above) does not use the international standard (TEOS-10) for calculating ocean heat content (Wikipedia).
Improper nomenclature and practice has been removed by those who use TEOS-10:
"Here, we are concerned with issues related to the properties of seawater that have only recently been widely recognized because of research resulting in the Thermodynamic Equation of Seawater 2010 (TEOS-10). These issues mean that the intercomparison of different models, and comparison with ocean observations, needs to be undertaken with care.
In particular, it is widely recognized that the traditional measure of heat content per unit mass in the ocean (with respect to an arbitrary reference state), the so-called potential temperature, is not a conservative variable (McDougall, 2003). Hence, the time change in potential temperature at a point in space is not determined solely by the convergence of the potential temperature flux at that point. Furthermore, the non-conservative nature of potential temperature means that the potential temperature of a mixture of water masses is not the mass average of the initial potential temperatures since potential temperature is “produced” or “destroyed” by mixing within the ocean’s interior. This empirical fact is an inherent property of seawater (e.g. McDougall, 2003; Graham and McDougall, 2013), so treating potential temperature as a conservative tracer (as well as making certain other assumptions related to the modelling of heat and salt) results in contradictions, which have been built into most numerical ocean models to varying degrees.
These contradictions have existed since the beginning of numerical ocean modelling but have generally been ignored or overlooked because many other oceanographic and numerical factors were of greater concern. However, as global heat budgets and their imbalances are now a critical factor in understanding climate changes, it is important to examine the consequences of these assumptions and perhaps correct them even at the cost of introducing problems elsewhere. These concerns are particularly important when heat budgets are being compared between different models
and with similar calculations made with observed conditions in the real ocean."
"This document describes the International Thermodynamic Equation Of Seawater – 2010 (TEOS-10 for short). TEOS-10 defines the thermodynamic properties of seawater, of ice Ih, and of humid air, and has been adopted by the Intergovernmental Oceanographic Commission at its 25 th Assembly in June 2009, replacing EOS-80 as the official description of seawater and ice properties in marine science."
(TEOS-10 Manual, emphasis added). When a non-standard is used the results have, historically, ended up with some degree of confusion.
The conclusion of Cheng et al. 2023 in its broadest sense, which is that the oceans continue to warm at a dangerous pace, is entirely correct, even though the specifics that scientists use for minute detail is not.
In today's Appendices (Appendix A, Appendix B, Appendix C, Appendix D) I present graphs concerning Antarctica that were generated using the C++ TEOS-10 library (available at the TEOS-10 website here).
IV. Content of The Appendices
The depths featured today are Pelagic depths:
mesopelagic (201-1000 m)
bathypelagic (1001-4000m)
abyssopelagic (4001-5500m)
hadopelagic (5501-6000m)
(See In Search Of Ocean Heat - 7). The World Ocean Database (WOD) uses a 33 level depth system, so I converted the 33 levels into pelagic levels for viewing purposes (95 or so percent of the data used is WOD, the rest is SOCCOM, Woods Hole, and OMG.
Appendix A shows graphs of Antarctica (Sectors A,B,C,D,E and F); the data types are Conservative Temperature (CT), Potential Enthalpy (Ho), and Photon Count (mol).
CT and Ho are explained by Dr. McDougall in the paper above ("The
interpretation of temperature and salinity variables in numerical ocean
model output and the calculation of heat fluxes and heat content").
Appendix B shows ice melt in terms of gigatons.
Appendix C shows the temperature at which ice melts (TEOS-10 calculations) as well as the temperature of the seawater touching or in 1 meter proximity to the glacier.
Appendix D shows the same as Appendix C but has more detail explaining the graph's lines.
V. Closing Comments
The grounding lines in the sectors total about 53,239 km in length (7,446 km, 6,724 km, 12,694 km, 8,594 km 3,814 km, and 13,967 km).
That length changes in small percentages of increase and decrease as the tidewater glaciers melt, calve, and flow into the Southern Ocean.
But all along that length the ice is being melted at various rates because the ambient seawater is above the melting point of the ice (Appendix C, D).
Papers that ignore these realities, such as Inter-decadal climate variability induces differential ice response along Pacific-facing West Antarctica leaning on aforementioned models ("We attribute this to ... suppression of westerly winds in the Amundsen Sea, which reduced warm water inflow to the Amundsen Sea Embayment ... Thus, model projections accounting for regionally resolved ice-ocean-atmosphere interactions will be important for predicting accurately the short-term evolution of the Antarctic Ice Sheet.").
The authors Christie et al. are following the same pattern Hansen et al. have warned about for decades:
"I suspect the existence of what I call the `John Mercer effect'. Mercer (1978) suggested that global warming from burning of fossil fuels could lead to disastrous disintegration of the West Antarctic ice sheet, with a sea level rise of several meters worldwide. This was during the era when global warming was beginning to get attention from the United States Department of Energy and other science agencies. I noticed that scientists who disputed Mercer, suggesting that his paper was alarmist, were treated as being more authoritative.
It was not obvious who was right on the science, but it seemed to me, and I believe to most scientists, that the scientists preaching caution and downplaying the dangers of climate change fared better in receipt of research funding. Drawing attention to the dangers of global warming may or may not have helped increase funding for relevant scientific areas, but it surely did not help individuals like Mercer who stuck their heads out. I could vouch for that from my own experience. After I published a paper (Hansen et al 1981) that described likely climate effects of fossil fuel use, the Department of Energy reversed a decision to fund our research, specifically highlighting and criticizing aspects of that paper at a workshop in Coolfont, West Virginia and in publication (MacCracken 1983).
I believe there is a pressure on scientists to be conservative. Papers are accepted for publication more readily if they do not push too far and are larded with caveats. Caveats are essential to science, being born in skepticism, which is essential to the process of investigation and verification. But there is a question of degree. A tendency for `gradualism' as new evidence comes to light may be ill-suited for communication, when an issue with a short time fuse is concerned."
(The Warming Science Commentariat - 12, quoting Dr. James Hansen). As Dr. Rignot points out in the video below, the melt that matters is taking place 1000-2000 meters below the ocean surface at the grounding line.
The next post in this series is here, the previous post in this series is here.
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