Peter Fiekowsky
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Does this paper, which also addresses the role of Pinatubo, impact your ideas Peter? Doing some review of the literature may suggest alternative explanations to OIF.- Peter JenkinsExternal Forcing Explains Recent Decadal Variability of the Ocean Carbon Sink
Peer Review: The peer review history for this article is available as a PDF in the Supporting Information.
Abstract
The ocean has absorbed the equivalent of 39% of industrial-age fossil carbon emissions, significantly modulating the growth rate of atmospheric CO2 and its associated impacts on climate. Despite the importance of the ocean carbon sink to climate, our understanding of the causes of its interannual-to-decadal variability remains limited. This hinders our ability to attribute its past behavior and project its future. A key period of interest is the 1990s, when the ocean carbon sink did not grow as expected. Previous explanations of this behavior have focused on variability internal to the ocean or associated with coupled atmosphere/ocean modes. Here, we use an idealized upper ocean box model to illustrate that two external forcings are sufficient to explain the pattern and magnitude of sink variability since the mid-1980s. First, the global-scale reduction in the decadal-average ocean carbon sink in the 1990s is attributable to the slowed growth rate of atmospheric pCO2. The acceleration of atmospheric pCO2 growth after 2001 drove recovery of the sink. Second, the global sea surface temperature response to the 1991 eruption of Mt Pinatubo explains the timing of the global sink within the 1990s. These results are consistent with previous experiments using ocean hindcast models with variable atmospheric pCO2 and with and without climate variability. The fact that variability in the growth rate of atmospheric pCO2 directly imprints on the ocean sink implies that there will be an immediate reduction in ocean carbon uptake as atmospheric pCO2 responds to cuts in anthropogenic emissions.
Plain Language Summary
Humans have added 440 Pg of fossil fuel carbon to the atmosphere since 1750, driving up the atmospheric CO2 concentration. But not all of this carbon remains in the atmosphere. The ocean has absorbed 39%, substantially mitigating anthropogenic climate change. Though this “ocean carbon sink” is a critical climate process, our understanding of its mechanisms remains limited. Of great interest is the unexplained slow-down of the ocean carbon sink in the 1990s and a subsequent recovery. In this work, we use a simple globally-averaged model to show that two processes external to the ocean are sufficient to explain the slowing of the ocean carbon sink in the 1990s. First, a reduced rate of accumulation of carbon in the atmosphere after 1989 reduced the atmosphere–ocean gradient that drives the ocean sink. Second, the eruption of Mt Pinatubo led to changes in ocean temperature that modified the timing of the sink from 1991 to 2001. We illustrate that the most important control on the decade-averaged magnitude of the ocean sink is variability in the growth rate of atmospheric CO2. This implies that as future fossil fuel emission cuts drive reduced growth of atmospheric CO2, the ocean sink will immediately slow down.
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It would be helpful to read the NASEM ocean CDR study chapter on ocean fertilization, which includes some good analysis about why natural releases of iron may not be analogous to OIF. It also suggests why we should take the link between the Haida intervention and fish production with a grain of salt.
The study also suggests that nutrient robbing could eliminate all of the benefits of OIF, as well as engender international tensions. Finally, the study outlines a number of other risks of this approach that need to be seriously considered before one would fulsomely endorse ocean fertilization.
wil
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WIL BURNS Visiting Professor Environmental Policy & Culture Program Northwestern University
Email: william...@northwestern.edu Mobile: 312.550.3079
1808 Chicago Ave. #110 Evanston, IL 60208 https://epc.northwestern.edu/people/staff-new/wil-burns.html
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I acknowledge and honor the Ojibwe, Potawatomi, and Odawa, as well as the Menominee, Miami and Ho-Chunk nations, upon whose traditional homelands Northwestern University stands, and the Indigenous people who remain on this land today.
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Have you heard other explanations?
Yes, I recall claims that the 1991 El Niño dropped exceptional amounts of rain in South America, the deserts of Peru bloomed, but it was wet in the Amazonia too, and so there was unusually high tropical biomass drawdown, much of which was respired or oxidized in the drier years that followed.
From:
carbondiox...@googlegroups.com <carbondiox...@googlegroups.com> on behalf of Peter Fiekowsky <pfi...@gmail.com>
Date: Tuesday, May 3, 2022 at 11:02 AM
To: peter jenkins <jenkinsb...@gmail.com>
Cc: Healthy Climate Alliance <healthy-clim...@googlegroups.com>, Carbon Dioxide Removal <carbondiox...@googlegroups.com>
Subject: [CDR] Re: [HCA-list] OIF and Mt. Pinatubo 1991
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Peter,
Transient micronutrient enrichment of the surface ocean can enhance phytoplankton growth rates and alter microbial community structure with an ensuing spectrum of biogeochemical feedbacks. Strong phytoplankton responses to micronutrients supplied by volcanic ash have been reported recently. Here we: (i) synthesize findings from these recent studies; (ii) report the results of a new remote sensing study of ash fertilization; and (iii) calculate theoretical bounds of ash-fertilized carbon export. Our synthesis highlights that phytoplankton responses to ash do not always simply mimic that of iron amendment; the exact mechanisms for this are likely biogeochemically important but are not yet well understood. Inherent optical properties of ash-loaded seawater suggest rhyolitic ash biases routine satellite chlorophyll-a estimation upwards by more than an order of magnitude for waters with <0.1 mg chlorophyll-a m−3, and less than a factor of 2 for systems with >0.5 mg chlorophyll-a m−3. For this reason post-ash-deposition chlorophyll-a changes in oligotrophic waters detected via standard Case 1 (open ocean) algorithms should be interpreted with caution. Remote sensing analysis of historic events with a bias less than a factor of 2 provided limited stand-alone evidence for ash-fertilization. Confounding factors were poor coverage, incoherent ash dispersal, and ambiguity ascribing biomass changes to ash supply over other potential drivers. Using current estimates of iron release and carbon export efficiencies, uncertainty bounds of ash-fertilized carbon export for three events are presented. Patagonian iron supply to the Southern Ocean from volcanic eruptions is less than that of windblown dust on 1000 year timescales but can dominate supply at shorter timescales. Reducing uncertainties in remote sensing of phytoplankton response and nutrient release from ash are avenues for enabling assessment of the oceanic response to large-scale transient nutrient enrichment.
On the Haida OIF/salmon hypothesis, I recall there is zero published science and we've seen no supporting opinions from any recognized fisheries scientists supporting that hypothesis. Or can you point to some new info? The southeast AK salmon fishery is one of the most carefully studied fisheries in the world. Logic is not enough to offer conclusions on causation of annual run sizes.- Peter J
There’s good indications from the satellite Infrared data of large scale greening events following exceptionally wet years in the tropics, which are large enough to make a couple year hiccup on the CO2 curve.
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Has anyone digested Jeng 2022 to understand why a reduction of
atmospheric CO2 does not reduce ocean impacts? Is it a bias of
the model or experiment design or? It doesn't make sense (to me,
yet) that if the driver of increased CO2-caused ocean degradation
is reduced, ocean degradation will not be reduced. This is a
common theme across CDR modeling that I have yet to understand.
"Compared to the RCP8.5 simulation without SRM, by the year 2100,
SRM reduces atmospheric CO2 by 65 ppm mainly as a result of
increased CO2 uptake by the terrestrial biosphere. However,
SRM-induced change in atmospheric CO2 and climate has a small
effect in mitigating ocean acidification."
Cheers,
B
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Sorry all. I meant Jin 2022 (not Jeng 2022). The paper Andrew sent -
Effects of solar radiation modification on the ocean carbon cycle:
An earth system modeling study
Author links open overlay panelXiaoyuJinJingyuZhang
https://doi.org/10.1016/j.aosl.2022.100187
B
Has anyone digested Jeng 2022 to understand why a reduction of atmospheric CO2 does not reduce ocean impacts? Is it a bias of the model or experiment design or? It doesn't make sense (to me, yet) that if the driver of increased CO2-caused ocean degradation is reduced, ocean degradation will not be reduced. This is a common theme across CDR modeling that I have yet to understand.
"Compared to the RCP8.5 simulation without SRM, by the year 2100, SRM reduces atmospheric CO2 by 65 ppm mainly as a result of increased CO2 uptake by the terrestrial biosphere. However, SRM-induced change in atmospheric CO2 and climate has a small effect in mitigating ocean acidification."
Cheers,
B
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