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Author Topic: Carbon Cycle  (Read 86169 times)

AbruptSLR

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Re: Carbon Cycle
« Reply #350 on: November 29, 2016, 05:41:18 PM »
It's possible, but there's no direct evidence for it. I think that was the point of Tamino's article. It was perplexing to see a 12-year trend being used in a peer-reviewed paper, especially since we regularly lambast deniers for using such short intervals for spurious claims about global temperature trends. There's not even any evidence for a slowdown in the rate of acceleration.

My post was about a "pause" in the rate of increase of CO2 concentration in the atmosphere from 2002 to 2014 (due to a presumed increase in CO2 uptake by terrestrial plants); while Tamino's post was about a faux "pause" in the increase in GMSTA.  While the two can be related in a ESM projection, the two issues are different and offset in time by lag.
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AbruptSLR

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Re: Carbon Cycle
« Reply #351 on: December 08, 2016, 02:01:10 AM »
The linked article is entitled: "500-year-old clam reveals 'hugely worrying' evidence of climate change and its effects".  This indicates that changes in the ocean may soon accelerate to follow the rapidly changing atmosphere (as the clams indicate happened in the past).


http://www.independent.co.uk/news/science/climate-change-clam-effects-500-years-old-quahog-global-warming-oceans-atmosphere-cardiff-a7460376.html

Extract: "… since humans started emitting large amounts of greenhouse gases through industrialisation, a switch has taken place and changes in the ocean are now led by the atmosphere, according to the international team of biologists."

See also the linked article is entitled: "What 500-year-old clams can tell us about climate change".

https://theconversation.com/what-500-year-old-clams-can-tell-us-about-climate-change-69926

Extract: "Perhaps one of the most profound aspects of our research is the finding that human-driven climate change, resulting in an overall warming of surface air temperatures, has led to a reversal in the long-term natural coupling of the marine and atmospheric climate systems.
Evidence from the shells shows that over the modern industrial period (AD 1800-2000) changes in marine climate lagged behind the atmosphere. Surface air temperatures responded much faster to human-induced climate changes than the North Atlantic did."
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Bruce Steele

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Re: Carbon Cycle
« Reply #352 on: December 08, 2016, 06:00:33 AM »
"This study assesses the impact of ocean acidification (OA) on phytoplankton and its synthesis of the climate-active gas dimethylsulfide (DMS), as well as its modulation by two contrasting light regimes in the Arctic. The light regimes tested had significant impact on neither the phytoplankton nor DMS concentration whereas both variables decreased linearly with the decrease in pH. Thus, ocean acidification could significantly decrease the algal biomass and inhibit DMS production in the Arctic."
http://www.biogeosciences-discuss.net/bg-2016-501/

logicmanPatrick

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Re: Carbon Cycle
« Reply #353 on: December 22, 2016, 10:06:53 AM »
Pardon the plug.  ;-)

A bit of carbon cycle science history for anyone who is interested.

Carbon Cycles by Arvid G. Högbom
http://www.science20.com/the_chatter_box/blog/carbon_cycles_by_arvid_g_hoegbom-196827
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AbruptSLR

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Re: Carbon Cycle
« Reply #354 on: December 27, 2016, 12:51:30 AM »
The linked article is entitled: "How NASA’s space laser might help save the world".  This research clarifies the substantial risk that polar phytoplankton might absorb less CO₂ with continued global warming:

http://www.ntnews.com.au/technology/how-nasas-space-laser-might-help-save-the-world/news-story/54da1605bf4835687bdb0cd694b38a1d

Extract: "Last week, NASA released a study that culminated a decade’s worth of data and imagery giving new insight into the boom-and-bust cycles of polar phytoplankton — a building block to the entire coastal and oceanic food chain.

The results showed that even the slightest environmental changes in the polar food webs significantly influence the microalgae, which also have another significant impact on the environment with their ability, through photosynthesis, to suck out carbon dioxide from the atmosphere."
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Bruce Steele

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Re: Carbon Cycle
« Reply #355 on: January 14, 2017, 08:25:02 PM »
 
http://www.nature.com/ngeo/journal/v10/n1/full/ngeo2854.html

This abstract is from the nature.com  link above that doesn't seem to properly load.

Coccolithophores—single-celled calcifying phytoplankton—are an important group of marine primary producers and the dominant builders of calcium carbonate globally. Coccolithophores form extensive blooms and increase the density and sinking speed of organic matter via calcium carbonate ballasting.     Thereby, they play a key role in the marine carbon cycle. Coccolithophore physiological responses to experimental ocean acidification have ranged from moderate stimulation to substantial decline in growth and calcification rates, combined with enhanced malformation of their calcite platelets. Here we report on a mesocosm experiment conducted in a Norwegian fjord in which we exposed a natural plankton community to a wide range of CO2-induced ocean acidification, to test whether these physiological responses affect the ecological success of coccolithophore populations. Under high-CO2 treatments, Emiliania huxleyi, the most abundant and productive coccolithophore species, declined in population size during the pre-bloom period and lost the ability to form blooms. As a result, particle sinking velocities declined by up to 30% and sedimented organic matter was reduced by up to 25% relative to controls. There were also strong reductions in seawater concentrations of the climate-active compound dimethylsulfide in CO2-enriched mesocosms. We conclude that ocean acidification can lower calcifying phytoplankton productivity, potentially creating a positive feedback to the climate system.
« Last Edit: January 14, 2017, 08:36:11 PM by Bruce Steele »

Bruce Steele

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Re: Carbon Cycle
« Reply #356 on: January 15, 2017, 05:41:43 AM »
I would like to emphasize the importance of the paper with the failed link above.
Riebesell et al 2016 "Competitive fitness of a predominate pelagic calcified impaired by ocean acidification"

https://news-oceanacidification-icc.org/2016/12/16/a-small-change-with-a-large-impact-mesocosm-experiment-reveals-how-community-interactions-amplify-the-response-of-a-calcifying-phytoplankton-species-to-ocean-acidification/
 
The coccolith in the study is the most important calcifying phytoplankton in the oceans. Although I haven't read the paper in full a 25% reduction in organic carbon ballasted to depth is a very sobering figure. I assume this is based upon projected pCO2 levels for the turn of the century. Pteropods aren't the focus of this study but they are also likely to contribute less towards organic carbon transport due to their susceptibility to lowered pH. So the the # 1 and # 2 oceanic calcifying organisms in the ocean will not be as effective at transporting surface Co2 to depth.
 The sediment carbon sink is about .2 Gt per year and although that doesn't sound like a huge number it is the most effective way to put carbon into a very long term sink. There won't be calcifying phytoplankton or animals to replace the carbon sink contributions of these two organisms, a plant and a mollusk.
 So while the arctic soils contribute an ever increasing amount of carbon to the atmosphere  the oceans will be less capable of absorbing the excess. More Co2 will stay in the atmosphere for longer periods of time.
 

 



 

Bruce Steele

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Re: Carbon Cycle
« Reply #357 on: February 23, 2017, 04:44:50 AM »


https://news-oceanacidification-icc.org/2017/02/22/development-and-application-of-foraminiferal-carbonate-system-proxies-to-quantify-ocean-acidification-in-the-california-current/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+wordpress%2FlRgb+%28Ocean+acidification%29

Development and application of foraminiferal carbonate system proxies to quantify ocean acidification in the California Current

The oceanic uptake of anthropogenic carbon has mitigated climate change, but has also resulted in a global average 0.1 decline in surface ocean pH over 20th century known as ocean acidification. The parallel reduction in carbonate ion concentration ([CO32-]) and the saturation state of seawater (Ω) has caused many major calcium carbonate-secreting organisms such as planktonic foraminifera to exhibit impaired calcification. We develop proxy calibrations and down core records that use calcification and geochemical characteristics of planktonic foraminifera as proxies for the marine carbonate system. This study focuses specifically on the surface ocean chemistry of the California Current Ecosystem (CCE), which has been identified as a region of rapidly progressing ocean acidification due to natural upwelling processes and the low buffering capacity of these waters. The calibration portion of this study uses marine sediments collected by the Santa Barbara Basin (SBB), California sediment-trapping program located in the central region of the CCE. We calibrate the relationships of Globigerina bulloides calcification intensity to [CO3 2-] and the B/Ca ratios of G. bulloides, Neogloboquadrina dutertrei and Neogloboquadrina incompta shells to Ω calcite using in situ measurements and model simulations of these independent variables. By applying these proxy methods to down core, our records from the SBB indicate a 20% reduction in foraminiferal calcification since ~1900, translating to a 35% decline in [CO 32-] in the CCE over this period. Our high-resolution calcification record also reveals a substantial interannual to decadal modulation of ocean acidification in the CCE related to the sign of Pacific Decadal Oscillation and El Niño Southern Oscillation. In the future we can expect these climatic modes to both enhance and moderate anthropogenic ocean acidification. Based on our historic record, we predict that if atmospheric CO2 reaches 540 ppm by the year 2100 as predicted by a conservative CO3 pathway, [CO32-] will experience a net reduction of 55%, resulting in at least a 30% reduction in calcification of planktonic foraminifera that will likely be mirrored by other adversely affected marine calcifiers.

Osborne E. B., 2016. Development and application of foraminiferal carbonate system proxies to quantify ocean acidification in the California Current. PhD thesis, University of South Carolina, 182 p. Thesis (restricted access).

Archimid

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Re: Carbon Cycle
« Reply #358 on: February 25, 2017, 01:35:18 PM »
Scrutinizing the carbon cycle and CO2 residence time in the atmosphere

http://www.sciencedirect.com/science/article/pii/S0921818116304787

Abstract(my emphasis):
Climate scientists presume that the carbon cycle has come out of balance due to the increasing anthropogenic emissions from fossil fuel combustion and land use change. This is made responsible for the rapidly increasing atmospheric CO2 concentrations over recent years, and it is estimated that the removal of the additional emissions from the atmosphere will take a few hundred thousand years. Since this goes along with an increasing greenhouse effect and a further global warming, a better understanding of the carbon cycle is of great importance for all future climate change predictions. We have critically scrutinized this cycle and present an alternative concept, for which the uptake of CO2 by natural sinks scales proportional with the CO2 concentration. In addition, we consider temperature dependent natural emission and absorption rates, by which the paleoclimatic CO2 variations and the actual CO2 growth rate can well be explained. The anthropogenic contribution to the actual CO2 concentration is found to be 4.3%, its fraction to the CO2 increase over the Industrial Era is 15% and the average residence time 4 years.



I don't have the full article, but it seems to me that another scientist lost his nerve. How can he possibly assume that all carbon sinks will perfectly accommodate the increase of CO2 in the atmosphere? How can all carbon sinks scale linearly with carbon concentration? Magic? Everything I know about the natural world tells me that there are limits to Carbon Sinks and all I know tells me that sinks can certainly become saturated.

Furthermore, meybe it says so in the full article, but how does he account for the historic increase in CO2 from 270 ppm's to the 400ppm's we have now? Magic again? Natural variability? arghh. 
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

logicmanPatrick

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Re: Carbon Cycle
« Reply #359 on: February 25, 2017, 04:26:23 PM »

... How can he possibly assume that all carbon sinks will perfectly accommodate the increase of CO2 in the atmosphere? How can all carbon sinks scale linearly with carbon concentration? Magic?  ...
how does he account for the historic increase in CO2 from 270 ppm's to the 400ppm's we have now? Magic again? Natural variability? arghh.


The author, Hermann Harde, oversimplifies his model of the planetary atmosphere such that feedbacks and delays are, not so much minimised as trivialised.

Please see, e.g. -
    
Dinner with global warming contrarians, disaster for dessert

Consider a Spherical Truncated Icosahedron

Residence Time of Carbon Dioxide in the Atmosphere

[Hermann Harde's] claim goes like this:

    (A) Predictions for the Global Warming Potential (GWP) by the IPCC express the warming effect CO2 has over several time scales; 20, 100 and 500 years.
    (B) But CO2 has only a 5 year life time in the atmosphere.
    (C) Therefore CO2 cannot cause the long term warming predicted by the IPCC.

This claim is false. (A) is true. (B) is also true. But B is irrelevant and misleading so it does not follow that C is therefore true.

source: Skeptical Science


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Bruce Steele

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Re: Carbon Cycle
« Reply #360 on: February 25, 2017, 05:49:48 PM »
I should read logicman links before I comment but I only gave the Herman harder link a cusory look and the graphic offered makes it look like there are no deep sinks or that they are all on some sort of ? 4 year cycle. That is of course ridiculous.
 There are deep sinks. We can date them with radiocarbon from our testing years. We know there are ~38,000 gigatonnes of carbon in the deep oceans . DIC dissolved inorganic carbon.
 Understanding how carbon is delivered into this sink and how carbon is then returned back into the atmosphere is of critical import . Time of circulation is on thousand year timeframes.
 For some further reading about carbon dating and for some more on radiocarbon dating of water masses and the carbon ages associated.

https://www.iaea.org/About/Policy/GC/GC51/GC51InfDocuments/English/gc51inf-3-att3_en.pdf



wili

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Re: Carbon Cycle
« Reply #361 on: February 25, 2017, 06:20:16 PM »
Good points, Bruce and Patrick. Those were pretty much my first impressions. I asked about the paper over at RealClimate and this was Gavin Schmidt's response (He's the director of GISS, for those who don't know):

Oh dear me. Yes, it’s nonsense. But apparently it’s an “Invited” paper? (I’ve never heard of that either). Some questions are going to be raised about the peer review and editorial process here… – gavin]
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Bruce Steele

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Re: Carbon Cycle
« Reply #362 on: February 26, 2017, 07:17:57 PM »
Latest pan oceanic oxygen measurements show a 2% drop since the 1960's. In this study they are modeling a 7% decline by 2100 but in the models I inked in the first post on the " carbon cycle " page they projected an 8.6 % drop in the same timeframe.

https://www.washingtonpost.com/news/energy-environment/wp/2017/02/15/its-official-the-oceans-are-losing-oxygen-posing-growing-threats-to-marine-life/?utm_term=.b8fe6c02da97


wili

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Re: Carbon Cycle
« Reply #363 on: February 27, 2017, 07:07:47 AM »
GS has now opened a thread devoted to debunking the Harde study:

http://www.realclimate.org/index.php/archives/2017/02/something-harde-to-believe/#more-20160
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Laurent

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Re: Carbon Cycle
« Reply #364 on: February 28, 2017, 06:38:05 PM »
I have that graph about the residence time of CO2 showing up to 10.000 years remaining CO2 after a pulse. It is not clear to me, is it after a 100 year pulse ? I don't know. I have seen some of that king where you should count on 100.000 years before coming back to normal (but with uncertainties up to million years...).