THIS POST IS A CRITICAL REVIEW OF A 2020 CLIMATE SCIENCE RESEARCH PAPER THAT CLAIMS TO HAVE REVISED THE CLIMATE SCIENCE POSITION OF MORE THAN 20 YEARS WITH RESPECT TO THE AIRBORNE FRACTION OF CO2 IN FOSSIL FUEL EMISSIONS.

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THE AIRBORNE FRACTION ISSUE IN CLIMATE SCIENCE

IN THE FOURTH IPCC REPORT 2007 LINK https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/ch7s7-3-1-3.html we find the climate science position on the airborne fraction, the portion of carbon dioxide in fossil fuel emissions that contributes to the observed rise in atmospheric CO2 concentration. It says that fossil fuel emissions have caused AtmosCO2 to rise by 3.2GTC/year in the 1990s and that the rate of increase has gone up to 4.1GtC/year in 2000-2005. It is noted that at 8 gigatons per year of fossil fuel emissions at that time, the airborne fraction is approximately 50%. The human cause implication here is that about half of the CO2 in fossil fuel emissions cause global warming by raising atmospheric CO2 concentration while the other half of the CO2 in fossil fuel emissions is removed by the carbon cycle identified by the IPCC as mostly in photosynthesis and in oceanic absorption.

The ‘airborne fraction’ is the portion of fossil fuel emissions that explains the observed rise in atmospheric CO2 concentration. It serves as the basis for attributing the rise to fossil fuel emissions; and as a benchmark for measuring the impact of the industrial economy on climate. It is the key foundational argument for human cause in climate change. Without an airborne fraction there can be no human cause.

Yet, we note here that conceptually and in computational procedure, the airborne fraction is computed not from measurements of carbon cycle flows but from circular reasoning that begins and ends with the measured increase in atmospheric CO2 concentration. As noted in related posts on this site, without the use of circular reasoning, the large uncertainties in carbon cycle flows would make the computation of the airborne fraction an impossibility LINK#1: https://tambonthongchai.com/2018/05/31/the-carbon-cycle-measurement-problem/ LINK#2: https://tambonthongchai.com/2020/06/10/a-monte-carlo-simulation-of-the-carbon-cycle/https://tambonthongchai.com/2020/06/10/a-monte-carlo-simulation-of-the-carbon-cycle/

THE 2020 UPDATE TO THE AIRBORNE FRACTION BY CLIMATE SCIENCE

SOURCE ARTICLE FROM EUREKALERT LINK https://www.eurekalert.org/pub_releases/2020-09/uoe-ocu090320.php

“The world’s oceans soak up more carbon than most scientific models suggest, according to new research. Previous estimates of the movement of carbon (known as “flux”) between the atmosphere and oceans have not accounted for temperature differences at the water’s surface and a few metres below. The new study, led by the University of Exeter, includes this – and finds significantly higher net flux of carbon into the oceans. It calculates CO2 fluxes from 1992 to 2018, finding up to twice as much net flux in certain times and locations, compared to uncorrected models. Half of the carbon dioxide we emit doesn’t stay in the atmosphere but is taken up by the oceans and land vegetation ‘sinks. “Researchers have assembled a large database of near-surface carbon dioxide measurements – the “Surface Ocean Carbon Atlas” (http://www.socat.info) – that can be used to calculate the flux of CO2 from the atmosphere into the ocean. “Previous studies that have done this have, however, ignored small temperature differences between the surface of the ocean and the depth of a few metres where the measurements are made. “Those differences are important because carbon dioxide solubility depends very strongly on temperature. “We used satellite data to correct for these temperature differences, and when we do that it makes a big difference – we get a substantially larger flux going into the ocean. “The difference in ocean uptake we calculate amounts to about 10 per cent of global fossil fuel emissions.” Dr Jamie Shutler, of the Centre for Geography and Environmental Science on Exeter’s Penryn Campus in Cornwall, added: “Our revised estimate agrees much better than previously with an independent method of calculating how much carbon dioxide is being taken up by the ocean. “That method makes use of a global ocean survey by research ships over decades, to calculate how the inventory of carbon in the ocean has increased. “These two ‘big data’ estimates of the ocean sink for CO2 now agree pretty well, which gives us added confidence in them.”

CRITICAL COMMENTARY ON THE 2020 UPDATE TO THE AIRBORNE FRACTION

In 2020, climate scientists used measurements of CO2 concentrations of air at the ocean surface and from these partial pressure computations over time they were able to determine that the airborne fraction is 50% just as the IPCC had said.

But perhaps the contribution of this effort is that the claim to the 50% airborne fraction is no longer circular reasoning computed only from the observed increase in atmospheric CO2. Here actual measurements of CO2 partial pressure at the ocean surface verifies the carbon cycle flow from atmosphere to ocean and that computation in turn verifies the 50% airborne fraction without the use of circular reasoning.

If this were true, it would indeed be a significant research finding but this finding is undone by two details. First, though the data and research methodology is exclusively on ocean surface CO2 concentration, the finding of 50% airborne fraction is reported as what remains after absorption by the ocean and by photosynthesis but no measurement details or data are provided for photosynthesis – and that takes us right back to circular reasoning. A second factor is that changes in oceanic CO2 concentration is interpreted purely in terms of the atmosphere with the atmosphere designated as the only source of CO2. This assumption contains an extreme form of the atmosphere bias in climate science. As described in related posts, the ocean’s own sources of carbon are many orders of magnitude greater than atmospheric CO2 or fossil fuel emissions. Changes in oceanic CO2 concentration cannot be interpreted purely in atmospheric terms. Such interpretations imply confirmation bias and circular reasoning.

LINK#1 https://tambonthongchai.com/2020/08/14/ocean-volcanism/ LINK#2: https://tambonthongchai.com/2020/02/27/a-co2-nightmare-hydrothermal-vents/

LINK#3: https://tambonthongchai.com/2020/03/20/an-atmosphere-bias-part-2/

LINK#4: https://tambonthongchai.com/2020/03/14/atmosphere-bias/