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Bruce Steele

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Re: Carbon Cycle
« Reply #550 on: January 29, 2020, 03:35:58 AM »
Kasy, Your question about the source of the waters upwelled in the other eastern boundary current systems and the time between formation and upwelling are important to understanding each of those currents . They will each be different, I am sure , and in general they will pull up water from <300 meters. I don’t know enough physical oceanography to give a description of each upwelling system and the formation processes of the waters upwelled.

 

kassy

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Re: Carbon Cycle
« Reply #551 on: January 29, 2020, 02:35:59 PM »
Thanks! I will see what i can dig up at a later date.
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gerontocrat

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Re: Carbon Cycle
« Reply #552 on: February 11, 2020, 09:03:45 PM »
Perhaps this post belongs in the "World of 2030" thread?

https://www.bbc.co.uk/news/science-environment-51464694
Amazon: Parts of rainforest 'emitting more CO2 than they absorb'
Quote
Results from a decade-long study of greenhouse gasses over the Amazon basin appear to show around 20% of the total area has become a net source of carbon dioxide in the atmosphere.

One of the main causes is deforestation. While trees are growing they absorb carbon dioxide from the atmosphere; dead trees release it again. Millions of trees have been lost to logging and fires in recent years.

They suggest that the Amazon rainforest - a vital carbon store, or "sink", that slows the pace of global warming - may be turning into a carbon source faster than previously thought.

Gatti's research suggests this south-eastern part of the forest, about 20% of the total area, has become a carbon source. "Each year is worse," she told Newsnight. "We observed that this area in the south-east is an important source of carbon. And it doesn't matter whether it is a wet year or a dry year. 2017-18 was a wet year, but it didn't make any difference."

For decades, scientists have warned of an "Amazon tipping-point": the point at which the forest loses its ability to renew itself and begins to emit more carbon than it absorbs.

"It [the Amazon] used to be, in the 1980s and '90s, a very strong carbon sink, perhaps extracting 2bn tons of carbon dioxide a year from the atmosphere," says Professor Nobre, who is also a researcher at the University of Sao Paulo's Institute for Advanced Studies and Brazil's leading expert on the Amazon.

"Today, that strength is reduced perhaps to 1-1.2bn tons of carbon dioxide a year."

To put that in context, a billion tonnes of carbon dioxide is almost three times what the UK said it officially emitted in 2018.

For decades, scientists have warned of an "Amazon tipping-point": the point at which the forest loses its ability to renew itself and begins to emit more carbon than it absorbs.

"Some people think that it won't be until three degrees warming - so towards the end of the century, whereas other people think that we could get [it with] deforestation up above 20% or so and that might happen in the next decade or two. So it's really really uncertain," explained Simon Lewis, professor of Global Change Science at UCL.
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TerryM

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Re: Carbon Cycle
« Reply #553 on: February 12, 2020, 02:49:37 AM »
^^
With the ESAS, permafrost melt, & now the possibility of the Amazon becoming a source not a sink, we soon won't need to turn down the AC or fire up the F-150 to produce enough GHG to fry us all!


Keep it Cool!
Terry

Bruce Steele

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Re: Carbon Cycle
« Reply #554 on: February 12, 2020, 05:22:33 PM »
“ We find that the largest contribution to the interior ocean pH gradient comes from organic matter remineralization, with CaCO3 cycling being the second most important process. The estimates of the impact of anthropogenic CO2 changes on pH reaffirm the large and well‐understood anthropogenic impact on pH in the surface ocean, and put it in the context of the natural pH gradient in the interior ocean. We also show that in the depth layer 500–1,500 m natural processes enhance ocean acidification by on average 28 ± 15%, but with large regional gradients.”

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GB006229

Open access,  Processes driving global interior ocean pH distribution

sidd

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Re: Carbon Cycle
« Reply #555 on: February 13, 2020, 08:46:55 AM »
Excluding herbivores increases sequestration in arid savanna in Kenya: doi: 10.1002/ecy.3008

Grasses continue to do more than trees, even after herbivores are gone.

" Large herbivore exclusion, which included a diverse community of grazers, browsers, and mixed‐feeding ungulates, resulted in significant increases in grass cover (~22%), woody basal area (~8 m2 ha‐1) and woody canopy cover (31%), translating to a ~8.5 t ha‐1 increase in aboveground carbon over two decades. Herbivore exclusion also led to a 54% increase (20.5 t ha‐1) in total soil carbon to 30 cm depth, with ~71% of this derived from C4 grasses (vs. ~76% with herbivores present) despite substantial increases in woody cover."

"study was conducted from 1999-2017 at the Mpala Research Centre (MRC) and Mpala Ranch which together encompass 190 km 2 of semiarid savanna within the Laikipia County in central Kenya (37°53’ E, O°17’ N)."

"The most common native ungulates include impala (Aepyceros melampus, c. 20 km -2 ), Günther’s dik-dik (Madoqua guentheri c. 140 km -2 ) and elephant (Loxodonta africana c. 1.7 km -2 ), while giraffe (Giraffa camelopardalis), greater kudu (Tragelaphus strepsiceros), zebra (Equus burchellii), waterbuck (Kobus ellipsiprymnus), buffalo (Syncerus caffer) and eland (Taurotragus oryx) occur at lower densities"

"Two paired ~0.5 ha (70 x 70 m) plots were demarcated at three sites located on red sandy soils in central and southern MRC in 1999. For each pair of these plots, one was retained as a control while the other fenced to exclude herbivores. These were protected using a 3 m tall electrified fence, consisting of 11 wire strands with additional mesh and electrified wires from ground level to half a meter above ground level (Augustine and McNaughton 2004). The exclosures were designed to exclude all herbivores larger than 2 kg."

"herbivore exclusion increased soil carbon pools to at least 30 cm (~20 t ha -1 )"

"exclusion resulted in much higher woody canopy cover compared to where herbivores were present (~70% at the end of the experiment inside exclosures vs. 27% where herbivores were present)."

"we found herbivore exclusion to have no effect on soil carbon under bare soil patches. If the direct effects of herbivores (e.g., trampling, addition of carbon in dung) were strong, we would have expected these differences to be evident (i.e. higher soil C) in the bare patches where herbivores were present."

"grass cover significantly increased with herbivore exclusion, even below tree canopies, both soil carbon originating from grass litter as well as soil carbon inputs from grass roots likely increased with herbivore removal"

"Our results also suggest a facilitative role of trees on grasses in this fine-leaved semi-arid savanna"

"the fine-leaved woody species with ‘sparse open’ canopies (e.g. Acacia etbaica and A. mellifera) that dominate this semi-arid savanna did not suppress grass cover. Similar responses may not be expected in more dense, broad-leaved savannas where high woody canopy cover can result in canopy closure and the exclusion of grasses."

"While we see an overall decrease in soil and aboveground carbon with herbivory, this result may be specific to the combination of herbivore species, densities and soil nutrient status at our study site. We know from a range of other systems that herbivores can sometimes increase soil carbon because they stimulate grasses (and grass roots) to grow faster and therefore result in greater carbon sequestration (Frank et al. 1995, Derner et al. 2006). However, in this system, herbivore offtake of carbon appears to exceed any enhancement through increased herbaceous production (Sankaran & Augustine 2004; Augustine & McNaughton 2006). While our results suggest that herbivores reduce both above- and belowground carbon in this ecosystem, these carbon losses must be evaluated against the biodiversity and livelihood benefits"

sidd

kassy

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Re: Carbon Cycle
« Reply #556 on: February 15, 2020, 11:52:41 AM »
Forest soils release more carbon dioxide than expected in rainy season

Current carbon cycle models may underestimate the amount of carbon dioxide released from the soil during rainy seasons in temperate forests like those found in the northeast United States, according to Penn State researchers.

Tree roots and microbes use oxygen to convert organic carbon in the soil to carbon dioxide (CO2) for energy through a process called aerobic respiration. This release of CO2 from soils to the atmosphere represents the largest flux of carbon from terrestrial ecosystems, making it a key component of the global carbon budget. Aerobic respiration is the dominant process contributing to this flux, but the researchers found that under wet conditions, anaerobic respiration—or respiration without oxygen—also significantly contributes to the flux.

"In current models, amounts of carbon dioxide and oxygen are controlled by the consumption of oxygen and the production of carbon dioxide through aerobic respiration," said Caitlin Hodges, a doctoral candidate in the Department of Ecosystem Science and Management. "It's usually a one-to-one relationship of consumption and production. But we found that, especially in summer, there was a significant signal of anaerobic respiration caused by the roots having a higher demand for oxygen and outcompeting the microbes. The microbes then have to switch over to using anaerobic respiration."

...

The researchers also calculated the total amount of carbon dioxide—36 grams per meter squared—that leaves the soil system every year due to anaerobic respiration. They said the conservative estimate constitutes 10% of all respiration done by soil microbes at their research sites, which is a large number since scientists don't think of these humid temperate forests as posting much anaerobic respiration.

"It's expected that the northeastern United States will have increased rainfall with climate change," said Hodges. "We expect that this anaerobic respiration will become a more dominant process in these forest systems, and our soil carbon models don't yet take this into account."

https://phys.org/news/2020-02-forest-soils-carbon-dioxide-rainy.html

DOI: 10.2136/sssaj2019.02.0049
full article needs subsricption
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wili

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Re: Carbon Cycle
« Reply #557 on: February 15, 2020, 03:33:11 PM »
I'm confused--How could ANaerobic respiration (without access to oxygen) create more CO2 (which is, of course, 2 parts oxygen) than aerobic respiration, which has access to lots of oxygen.

Do they mean that, since the anaerobic process creates methane, the CO2equivalent is much higher in rainy season? If so, the headline (at least) is misleading.
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kassy

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Re: Carbon Cycle
« Reply #558 on: February 16, 2020, 12:54:12 AM »
The processes work together. Under certain conditions the soil microbes switch to anaerobic respiration so you get the normal aerobic version and extra CO2 from the other process.

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Florifulgurator

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Re: Carbon Cycle
« Reply #559 on: February 16, 2020, 02:35:41 AM »
Aerobic methanotrophs in upper soil can transform the methane from deeper soil into CO2. It all depends how fast the methane diffuses upward. E.g. thawing permafrost covered with soil emits less methane than thermokarst lakes where the methane bubbles out into the atmosphere. Soil microbiology is quite a tangled web.
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vox_mundi

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Re: Carbon Cycle
« Reply #560 on: March 04, 2020, 08:40:59 PM »
Tropical Forests' Carbon Sink is Already Rapidly Weakening
https://phys.org/news/2020-03-tropical-forests-carbon-rapidly-weakening.html

The ability of the world's tropical forests to remove carbon from the atmosphere is decreasing, according to a study tracking 300,000 trees over 30 years, published today in Nature.

The global scientific collaboration, led by the University of Leeds, reveals that a feared switch of the world's undisturbed tropical forests from a carbon sink to a carbon source has begun.

The new analysis of three decades of tree growth and death from 565 undisturbed tropical forests across Africa and the Amazon has found that the overall uptake of carbon into Earth's intact tropical forests peaked in the 1990s.

By the 2010s, on average, the ability of a tropical forest to absorb carbon had dropped by one-third. The switch is largely driven by carbon losses from trees dying


In the 1990s intact tropical forests removed roughly 46 billion tonnes of carbon dioxide from the atmosphere, declining to an estimated 25 billion tonnes in the 2010s.

The lost sink capacity in the 2010s compared to the 1990s is 21 billion tonnes carbon dioxide, equivalent to a decade of fossil fuel emissions from the UK, Germany, France and Canada combined.

Overall, intact tropical forests removed 17% of human-made carbon dioxide emissions in the 1990s, reduced to just 6% in the 2010s.

The study by almost 100 institutions provides the first large-scale evidence that carbon uptake by the world's tropical forests has already started a worrying downward trend.

"By combining data from Africa and the Amazon we began to understand why these forests are changing, with carbon dioxide levels, temperature, drought, and forest dynamics being key."

"Extra carbon dioxide boosts tree growth, but every year this effect is being increasingly countered by the negative impacts of higher temperatures and droughts which slow growth and can kill trees.

Quote
"Our modelling of these factors shows a long-term future decline in the African sink and that the Amazonian sink will continue to rapidly weaken, which we predict to become a carbon source in the mid-2030s."

Senior author Professor Simon Lewis, from the School of Geography at Leeds, said: "Intact tropical forests remain a vital carbon sink but this research reveals that unless policies are put in place to stabilise Earth's climate it is only a matter of time until they are no longer able to sequester carbon.

"One big concern for the future of humanity is when carbon-cycle feedbacks really kick in, with nature switching from slowing climate change to accelerating it.



Asynchronous carbon sink saturation in African and Amazonian tropical forests, Nature (2020)
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

kassy

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Re: Carbon Cycle
« Reply #561 on: March 19, 2020, 02:38:55 PM »
Chronicling 23 Years of Acidification in the Beaufort Sea

The term ocean acidification was coined in 2003, but in the Beaufort Sea scientists have been tracking its effects since 1997.

Over the past 23 years, the Arctic Ocean has become increasingly acidic. While most of the increase has been driven by rising carbon emissions, a recent paper shows how acidification has been intensified by an influx of fresh water from melting sea ice. In 2006, the Beaufort Sea passed a crucial tipping point: ever since, the water has been corrosive to animals’ shells.

Among the victims of this shift are Arctic sea butterflies—small marine snails with delicate shells. In Beaufort Sea fjords, 70 percent of sea butterflies have weakened shells.

...

When seawater freezes, salt and calcium carbonate are pushed out, resulting in sea ice that is basically fresh water. The older the ice, the fresher it is. So when multi-year Arctic sea ice began disappearing rapidly in the late 1990s and early 2000s, it sent a pulse of fresh water into the sea that diluted calcium carbonate and rapidly turned the Beaufort Sea corrosive.

In the future, melting permafrost and rising rivers will push more fresh water into the Arctic Ocean, which could further dilute calcium carbonate—especially in coastal areas.

“Organisms have some ability to flex their body systems,” says Zhang. But like most high-latitude systems, the Beaufort Sea food web is highly dependent on a relatively small number of species. “Once one [species] is gone, the impact will be bigger than in other oceans.”

https://www.hakaimagazine.com/news/chronicling-23-years-of-acidification-in-the-beaufort-sea/
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Hefaistos

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Re: Carbon Cycle
« Reply #562 on: April 16, 2020, 02:41:05 AM »
"The ocean’s ‘biological pump’ captures more carbon than expected"

In a paper published April 6 in Proceedings of the National Academy of Sciences, WHOI geochemist Ken Buesseler and colleagues demonstrated that the depth of the sunlit area where photosynthesis occurs varies significantly throughout the ocean. This matters because the phytoplankton’s ability to take up carbon depends on amount of sunlight that’s able to penetrate the ocean’s upper layer. By taking account of the depth of the euphotic, or sunlit zone, the authors found that about twice as much carbon sinks into the ocean per year than previously estimated.

The paper relies on previous studies of the carbon pump, including the authors’ own. “If you look at the same data in a new way, you get a very different view of the ocean’s role in processing carbon, hence its role in regulating climate,” says Buesseler.

“Using the new metrics, we will be able to refine the models to not just tell us how the ocean looks today, but how it will look in the future,” he adds. “Is the amount of carbon sinking in the ocean going up or down? That number affects the climate of the world we live in.”

https://www.whoi.edu/press-room/news-release/the-oceans-biological-pump-captures-more-carbon-than-expected/

Full paper:
"Metrics that matter for assessing the ocean biological carbon pump" by Buesseler et al
https://www.pnas.org/content/early/2020/04/03/1918114117

kassy

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Re: Carbon Cycle
« Reply #563 on: May 01, 2020, 11:44:45 AM »
Ocean acidification prediction now possible years in advance

CU Boulder researchers have developed a method that could enable scientists to accurately forecast ocean acidity up to five years in advance. This would enable fisheries and communities that depend on seafood negatively affected by ocean acidification to adapt to changing conditions in real time, improving economic and food security in the next few decades.

...

"We've taken a climate model and run it like you would have a weather forecast, essentially - and the model included ocean chemistry, which is extremely novel," said Riley Brady, lead author of the study, and a doctoral candidate in the Department of Atmospheric and Oceanic Sciences.

For this study the researchers focused on the California Current System, one of four major coastal upwelling systems in the world, which runs from the tip of Baja California in Mexico all the way up into parts of Canada. The system supports a billion-dollar fisheries industry crucial to the U.S. economy.

"Here, you've got physics, chemistry, and biology all connecting to create extremely profitable fisheries, from crabs all the way up to big fish," said Brady, who is also a graduate student at the Institute of Arctic and Alpine Research (INSTAAR). "Making predictions of future environmental conditions one, two, or even three years out is remarkable, because this is the kind of information that fisheries managers could utilize."

...

"Ocean acidification is proceeding at a rate 10 times faster today than any time in the last 55 million years," said Lovenduski.

Within decades, scientists are expecting parts of the ocean to become completely corrosive for certain organisms, which means they cannot form or maintain their shells.

https://www.eurekalert.org/pub_releases/2020-05/uoca-oap043020.php

Preprint available at:
https://eartharxiv.org/3m2h7/
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kassy

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Re: Carbon Cycle
« Reply #564 on: May 01, 2020, 01:34:53 PM »
And we move onto land...

CO2 emissions from dry inland waters globally underestimated

Inland waters such as rivers, lakes and reservoirs play an important role in the global carbon cycle. Calculations that scale up the carbon dioxide emissions from land and water surface areas do not take account of inland waters that dry out intermittently. This means that the actual emissions from inland waters have been significantly underestimated - as shown by the results of a recent international research project led by scientists at the Helmholtz Centre for Environmental Research (UFZ) in Magdeburg and the Catalan Institute for Water Research (ICRA). The study was published in Nature Communications.

"It all began in 2013, during a measurement campaign in Catalonia in Spain," says Dr Matthias Koschorreck, a biologist in the Department of Lake Research at UFZ. Together with a Spanish team, he was studying the release of greenhouse gases in the catchment of a small river. "It was summer and parts of the riverbed were dry. On a whim, we decided to take some measurements in those areas too," Koschorreck explains. "The results surprised us - these dry, gravelly areas of the riverbed released unexpectedly high levels of carbon dioxide." Koschorreck and his colleague Dr Rafael Marcé from ICRA in Girona (Spain), decided to investigate that further. Results from various locations in Spain and Germany all produced the same finding: dry inland waters released readily measurable and sometimes considerable levels of carbon dioxide. "We wondered whether this might be the case in other regions of the world, and whether greenhouse gas emissions from inland waters might be fundamentally underestimated," says Koschorreck. "In studies that scale up emissions of greenhouse gases from land and water surface areas, inland waters that dry out intermittently haven't previously been taken into account."

To investigate these questions, in 2016 Koschorreck and Marcé together with a core team of six German and Spanish scientists launched the dryflux research project, with the aim of measuring greenhouse gas emissions from dry inland waters. As part of a workshop held at the UFZ's Magdeburg site, they developed a measurement and sampling concept for their study. They then engaged the help of their international networks. "Every participant at the workshop got in touch with research teams all over the world to see whether they would be interested in taking part in measurement campaigns on freshwater systems in their area," explains Koschorreck. "The response was amazing. Twenty four research teams from all over the world took part, which meant that we were able to collect data from 196 different sites on every continent except Antarctica." Each team carried out three closed-chamber measurements in dry areas of at least three freshwater systems in their region - a river, lake, reservoir or pond. This involves placing a special measuring container with its open end downwards on the ground, separating the air inside the container from the ambient air. An analytical device is then used to measure the change in the amount of carbon dioxide inside the container. At the same location, the project partners also took samples of the dry sediment and measured its moisture, organic matter and salt content, temperature, and pH.

The large, complex dataset was evaluated by Philipp Keller, a doctoral researcher in the Department of Lake Research at the UFZ and first author of the study, who came to some interesting conclusions. "We found significant carbon dioxide emissions from dry areas of inland waters across all climate zones," says Keller. "So this really is a global phenomenon." The researchers also discovered that these emissions are in fact often higher than typical emissions from water surfaces of the same size. "We were able to show that dry areas of inland waters actually account for a significant proportion of total carbon dioxide emissions from these freshwater systems," says Koschorreck. "If you take account of this in global calculations for inland waters, the carbon dioxide emissions increase by six percent."


...

https://www.eurekalert.org/pub_releases/2020-05/hcfe-cef043020.php

Emissions from dry inland waters are a blind spot in the global carbon cycle

https://www.sciencedirect.com/science/article/pii/S0012825218301971
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Bruce Steele

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Re: Carbon Cycle
« Reply #565 on: May 01, 2020, 04:18:42 PM »
Kassy, The ability to predict future acidification in the the Calif. Current from modeling has been accurate for over a decade but it’s effects on various species at all of their life stages of development is still ongoing science.
 I spent my life as a fisherman and a fisheries manager. We have taken some very painful management decisions ,like closing 25-30% of state waters to both recreational and commercial catch. Those closures were not a specific response to acidification but there were plenty of us involved , in the closures, who knew what was on our doorstep. There are less fishermen as a result and acidification progresses apace . I get pissed every time I see someone say some modeling exercise predicting acidification can help fisheries “ adapt “. We can manage our fisheries to a zero yield but that isn’t adapting. How otherwise do fishery managers use the information ? There are no new fish stocks to switch into and we can’t change ocean conditions to make them more productive.
 Finally the acidification will continue its deleterious effects for a millennia . There currently is undersaturated water at depth year round but the entire water column will be undersaturated year round within a couple decades. How do you adapt to such a thing ? There will still be fisheries but they will be seriously truncated . Some of the most valuable fisheries may disappear entirely . Managing towards zero is brutal work , who those managers are and how they hold up to the psychological impacts of decline stretching through their entire careers is anyone’s guess . This ends with human extinction so adapt to that.

Hefaistos

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Re: Carbon Cycle
« Reply #566 on: May 26, 2020, 10:41:30 AM »
"The ocean’s ‘biological pump’ captures more carbon than expected"

In a paper published April 6 in Proceedings of the National Academy of Sciences, WHOI geochemist Ken Buesseler and colleagues demonstrated that the depth of the sunlit area where photosynthesis occurs varies significantly throughout the ocean. This matters because the phytoplankton’s ability to take up carbon depends on amount of sunlight that’s able to penetrate the ocean’s upper layer. By taking account of the depth of the euphotic, or sunlit zone, the authors found that about twice as much carbon sinks into the ocean per year than previously estimated.

The paper relies on previous studies of the carbon pump, including the authors’ own. “If you look at the same data in a new way, you get a very different view of the ocean’s role in processing carbon, hence its role in regulating climate,” says Buesseler.

“Using the new metrics, we will be able to refine the models to not just tell us how the ocean looks today, but how it will look in the future,” he adds. “Is the amount of carbon sinking in the ocean going up or down? That number affects the climate of the world we live in.”

https://www.whoi.edu/press-room/news-release/the-oceans-biological-pump-captures-more-carbon-than-expected/

Full paper:
"Metrics that matter for assessing the ocean biological carbon pump" by Buesseler et al
https://www.pnas.org/content/early/2020/04/03/1918114117

A nice read by the same author.

https://theconversation.com/tiny-plankton-drive-processes-in-the-ocean-that-capture-twice-as-much-carbon-as-scientists-thought-136599

vox_mundi

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Re: Carbon Cycle
« Reply #567 on: June 02, 2020, 02:59:09 AM »
Study Shows Today's Atmospheric Carbon Dioxide Levels Greater Than 23 Million-Year Record
https://phys.org/news/2020-06-today-atmospheric-carbon-dioxide-greater.html

A common message in use to convey the seriousness of climate change to the public is: "Carbon dioxide levels are higher today than they have been for the past one million years!" This new study by Brian Schubert (University of Louisiana at Lafayette) and coauthors Ying Cui and A. Hope Jahren used a novel method to conclude that today's carbon dioxide (CO2) levels are actually higher than they have been for the past 23 million years.

The team used the fossilized remains of ancient plant tissues to produce a new record of atmospheric CO2 that spans 23 million years of uninterrupted Earth history. They have shown elsewhere that as plants grow, the relative amount of the two stable isotopes of carbon, carbon-12 and carbon-13 changes in response to the amount of CO2 in the atmosphere. This research, published this week in Geology, is a next-level study measuring the relative amount of these carbon isotopes in fossil plant materials and calculating the CO2 concentration of the atmosphere under which the ancient plants grew.

Furthermore, Schubert and colleagues' new CO2 "timeline" revealed no evidence for any fluctuations in CO2 that might be comparable to the dramatic CO2 increase of the present day, which suggests today's abrupt greenhouse disruption is unique across recent geologic history.

Another point, important to geological readers, is that because major evolutionary changes over the past 23 million years were not accompanied by large changes in CO2, perhaps ecosystems and temperature might be more sensitive to smaller changes in CO2 than previously thought. As an example: The substantial global warmth of the middle Pliocene (5 to 3 million years ago) and middle Miocene (17 to 15 million years ago), which are sometimes studied as a comparison for current global warming, were associated with only modest increases in CO2.

Ying Cui et al. A 23 m.y. record of low atmospheric CO2, Geology (2020).
https://pubs.geoscienceworld.org/gsa/geology/article/586769/A-23-my-record-of-low-atmospheric-CO2
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kassy

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Re: Carbon Cycle
« Reply #568 on: June 04, 2020, 03:02:00 PM »
Some new research with troubling consequences:

Ocean uptake of CO2 could drop as carbon emissions are cut

Volcanic eruptions and human-caused changes to the atmosphere strongly influence the rate at which the ocean absorbs carbon dioxide, says a new study. The ocean is so sensitive to changes such as declining greenhouse gas emissions that it immediately responds by taking up less carbon dioxide.

The authors say we may soon see this play out due to the COVID-19 pandemic lessening global fuel consumption; they predict the ocean will not continue its recent historic pattern of absorbing more carbon dioxide each year than the year before, and could even take up less in 2020 than in 2019.

"We didn't realize until we did this work that these external forcings, like changes in the growth of atmospheric carbon dioxide, dominate the variability in the global ocean on year-to-year timescales. That's a real surprise," said lead author Galen McKinley, a carbon cycle scientist at Columbia University's Lamont-Doherty Earth Observatory. "As we reduce our emissions and the growth rate of atmospheric carbon dioxide slows down, it's important to realize that the ocean carbon sink will respond by slowing down."

The paper, published today in the journal AGU Advances, largely resolves the uncertainty about what caused the ocean to take up varying amounts of carbon over the last 30 years. The findings will enable more accurate measurements and projections of how much the planet might warm, and how much the ocean might offset climate change in the future.

...

Nearly 40 percent of the carbon dioxide added to the atmosphere by fossil fuel burning since the dawn of the industrial era has been taken up by the ocean.

...

the Pinatubo eruption impacted global climate, and thus the ocean carbon sink, and whether the drop in emissions due to COVID-19 is reflected in the ocean are among the research team's next plans.

By understanding variability in the ocean carbon sink, the scientists can continue to refine projections of how the ocean system will slow down.

McKinley cautions that as global emissions are cut, there will be an interim phase where the ocean carbon sink will slow down and not offset climate change as much as in the past. That extra carbon dioxide will remain in the atmosphere and contribute to additional warming, which may surprise some people, she said.
https://www.eurekalert.org/pub_releases/2020-06/eiac-ouo060320.php

Paper:
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019AV000149
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gerontocrat

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Re: Carbon Cycle
« Reply #569 on: June 04, 2020, 08:16:11 PM »
It's bad news both ways...

As CO2 ppm increases - "Elevated CO2 concentrations increase photosynthesis and, potentially, net ecosystem production (NEP), meaning a greater CO2 uptake."

BUT...
as CO2 ppm increases, so do global temperatures, and "increased temperatures were negatively associated with NEP (net ecosystem production)."

i.e. as temperatures increase overall photosynthesis activity declines. (See 2nd extract below - Rainforests are at least one  culprit).

https://www.nature.com/articles/s41558-018-0367-7 (paywalled)
Global trends in carbon sinks and their relationships with CO2 and temperature
Abstract

Quote
Elevated CO2 concentrations increase photosynthesis and, potentially, net ecosystem production (NEP), meaning a greater CO2 uptake. Climate, nutrients and ecosystem structure, however, influence the effect of increasing CO2. Here we analysed global NEP from MACC-II and Jena CarboScope atmospheric inversions and ten dynamic global vegetation models (TRENDY), using statistical models to attribute the trends in NEP to its potential drivers: CO2, climatic variables and land-use change. We found that an increased CO2 was consistently associated with an increased NEP (1995–2014). Conversely, increased temperatures were negatively associated with NEP. Using the two atmospheric inversions and TRENDY, the estimated global sensitivities for CO2 were 6.0 ± 0.1, 8.1 ± 0.3 and 3.1 ± 0.1 PgC per 100 ppm (~1 °C increase), and −0.5 ± 0.2, −0.9 ± 0.4 and −1.1 ± 0.1 PgC °C−1 for temperature. These results indicate a positive CO2 effect on terrestrial C sinks that is constrained by climate warming.

h
ttps://www.nature.com/news/2007/070806/full/070806-13.html#:~:text=The%20effect%20%E2%80%94%20so%20far%20largely,the%20air%20as%20they%20grow.
Rising temperatures "will stunt rainforest growth"
Quote
Global warming could cut the rate at which trees in tropical rainforests grow by as much as half, according to more than two decades' worth of data from forests in Panama and Malaysia. The effect — so far largely overlooked by climate modellers — could severely erode or even remove the ability of tropical rainforests to remove carbon dioxide from the air as they grow.

The study shows that rising average temperatures have reduced growth rates by up to 50% in the two rainforests, which have both experienced climate warming above the world average over the past few decades. The trend is shown by data stretching back to 1981 collected from hundreds of thousands of individual trees.

If other rainforests follow suit as world temperatures rise, important carbon stores such as the pristine old-growth forests of the Amazon could conceivably stop storing as much carbon, says Ken Feeley of Harvard University's Arnold Arboretum in Boston, who presented the research at the annual meeting of the Ecological Society of America in San Jose, California.
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Freegrass

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Re: Carbon Cycle
« Reply #570 on: June 16, 2020, 03:23:41 AM »
Visualizing the Deep Carbon Cycle

Geoscientists have created animations to help visualize different components of Earth’s carbon cycle.


This image of Pangaea illustrates some familiar features of Earth’s carbon cycle. The seafloor spreading of ocean crust is in pink, terminating at light blue subduction zones. Orange represents orogeny in the yellow continental crust, while black spots represent the eruption of large igneous provinces. Credit: Sabin Zahirovic


12 June 2020
https://eos.org/articles/visualizing-the-deep-carbon-cycle
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kassy

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Re: Carbon Cycle
« Reply #571 on: June 16, 2020, 02:55:57 PM »
In the Slab Flux one you can see the world drift into it´s current set up. It´s pretty cool. 
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kassy

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Re: Carbon Cycle
« Reply #572 on: July 08, 2020, 10:48:41 AM »
Light A Critical Factor In Limiting Carbon Uptake, Especially In North

Most projections about climate change assume that, as temperatures rise, regions in the north high latitudes may become more suitable for the growth of vegetation, turning into cropland to feed increasing populations while also fixing more carbon dioxide (CO2) and slowing down climate change. Plants require appropriate temperature, water, and light conditions for photosynthesis and growth, so it seems logical that as temperatures increase in the northern high latitudes, plant photosynthesis, which uses CO2 to release oxygen, should also increase.

At the same time, plant respiration, which uses oxygen to release CO2 and is also highly dependent on temperature, is expected to increase, too. The critical question still under debate is whether autumn warming might lead to an increase in carbon uptake, i.e., the difference between photosynthesis and respiration.

A new Columbia Engineering study demonstrates that even when temperatures warm and cold stress is limited, light is still a major factor in limiting carbon uptake of northern high latitudes. The team, led by Pierre Gentine, associate professor of earth and environmental engineering, analyzed satellite observations, field measurements, and model simulations and showed that there is a prevalent radiation limitation on carbon uptake in northern ecosystems, especially in autumn. Using a new dataset, Gentine’s group developed an algorithm to map global plant photosynthesis and then developed a framework to quantify the limitation of light on photosynthesis. The study is published in Nature Climate Change.

....

Gentine’s team found that, at northern latitudes that are more than 30N, the end-of-season photosynthesis response to warming is mostly dictated by light. In some of those regions in the fall, the length of daily light shortens very quickly. Less light leads to weaker photosynthesis, which in turn cannot offset the increased respiration induced by global warming. Because northern high latitudes have stronger light limitation, their vegetation will release more carbon in the fall if warming continues.

In the future, light limitation will increase as the vegetation growing season lengthens due to global warming. Earlier starts of the season in spring and later ends of the season in fall correspond to shorter day lengths and less solar radiation, posing a stronger light limit on vegetation photosynthesis.

“This light limitation increase will lower the potential ability of northern ecosystems to act as a continuous carbon sink,” says Zhang. “Our study highlights the important role of solar radiation, which is usually ignored in climate change studies.”

....

https://www.eurasiareview.com/08072020-light-a-critical-factor-in-limiting-carbon-uptake-especially-in-north/


Paywalled:
Light limitation regulates the response of autumn terrestrial carbon uptake to warming

https://www.nature.com/articles/s41558-020-0806-0
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Re: Carbon Cycle
« Reply #573 on: July 08, 2020, 11:54:37 AM »
Paywalled:
Light limitation regulates the response of autumn terrestrial carbon uptake to warming

https://www.nature.com/articles/s41558-020-0806-0

Without paywall here >> https://outline.com/jMtZ6g

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Re: Carbon Cycle
« Reply #574 on: July 28, 2020, 10:49:03 AM »
Scientists Record Rapid Carbon Loss from Warming Peatlands
https://phys.org/news/2020-07-scientists-rapid-carbon-loss-peatlands.html

Scientists at the Department of Energy's Oak Ridge National Laboratory have demonstrated a direct relationship between climate warming and carbon loss in a peatland ecosystem. Their study published in AGU Advances provides a glimpse of potential futures where significant stores of carbon in peat bogs could be released into the atmosphere as greenhouse gases.

... The study found that in just three years, all warmed bog plots turned from carbon sinks into carbon sources—marking the first time whole-ecosystem plots have been used to document such changes. This fundamental shift in the nature of the bog occurred even at the most modest level of warming (about 4 degrees F (2.25°C) above ambient temperature), and showed carbon loss rates five to nearly 20 times faster than historical rates of accumulation.

Warmer temperatures directly translated into greater carbon emissions, with the warmest of the experimentally heated plots emitting the most carbon dioxide and methane. The scientists were surprised to find such a linear relationship between heat and carbon loss.

"This is a very tight relationship for biological data," Hanson said. "These results were within the range of hypotheses that we allowed ourselves to think about, but the sensitivity of carbon loss to temperature was a bit of a surprise."

The decline of sphagnum moss, a key species in this ecosystem, contributed notably to the net carbon loss. A previous study by ORNL colleague Richard Norby detailed sphagnum's role in accumulating carbon in peat and its potentially irreversible decay as warming dries out bogs.



Paul J. Hanson et al, Rapid Net Carbon Loss From a Whole‐Ecosystem Warmed Peatland, AGU Advances (2020)
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020AV000163
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Tom_Mazanec

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Re: Carbon Cycle
« Reply #575 on: August 05, 2020, 07:15:54 PM »
What is the absolute minimum CO2 a person can emit into the atmosphere, assuming he lives 100 years and his only emissions are respiratory exhalation?
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Richard Rathbone

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Re: Carbon Cycle
« Reply #576 on: August 05, 2020, 08:49:08 PM »
What is the absolute minimum CO2 a person can emit into the atmosphere, assuming he lives 100 years and his only emissions are respiratory exhalation?
Its quite large, but also quite misleading. Thats because it comes from eating food, and that food took CO2 out of the atmosphere as it was made. What hurts the climate isn't the carbon in the carbohydrates of your food, its the carbon in the methane that was used to make the fertiliser applied to the fields where your food was grown, and the carbon in the oil that was used to drive the tractor that harvested it, and the carbon in the trees that were cut down to clear the field.
The carbon you breathe out is genuinely renewable, its the carbon that went into manufacturing your food, rather than the carbon in the food itself, that isn't.

Assume almost but not quite starvation level is 1000 calories per day. (2000-2500 is the generally recommended level for a healthy diet that avoids a relatively sedentary westerner becoming obese)
Thats 250g of sugar, which is 40% carbon, so 100g carbon per day, 36.5 kg per year, 3.65 tonnes per century. Round because this is a really rough estimate and not worth more than 1 sig fig.

4 tonnes.

Tom_Mazanec

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Re: Carbon Cycle
« Reply #577 on: August 06, 2020, 12:09:00 AM »
Quote
The carbon you breathe out is genuinely renewable, its the carbon that went into manufacturing your food, rather than the carbon in the food itself, that isn't.

Why would some carbon be renewable and some not? Because the not renewable was taken from out of the carbon cycle as fossil fuel and put into it as exhaust? Is that what you mean?
How much non-renewable carbon is an average American who lives a Middle Class lifestyle for 100 years responsible for adding to the carbon cycle?
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Bruce Steele

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Re: Carbon Cycle
« Reply #578 on: August 06, 2020, 12:39:23 AM »
Tom, Long term carbon sinks are not the same as short term sinks. A short term carbon sink like vegetables grown in a field will yield almost all the carbon they store when you eat them. Your CO2 emissions can be reabsorbed again by other plants but the cycle is short and very little carbon is put into any long term sinks in the process. Animal and plants cycle carbon back and forth and the process is renewable unless you start utilizing carbon obtained from long term sinks, like lime for concrete, or buried fossil fuels.  Whether human causes or natural causes like “ the Deccan traps “ release of CO2 from long term sinks results in an unbalanced system where added CO2 can cause atmospheric heating and potentially catastrophic positive feedbacks.
 Renewable implies a cycle that can be repeated but if you tinker too long with burning carbon from long term sinks the system can go haywire. The earth can no longer absorb the extra carbon supplied and you get a runaway system. It has happened before.
 
So Richard is correct animals, including humans, can eat plant life and the plant life can reabsorb the CO2 emitted. Renewable
But earth can’t reabsorb carbon at an unlimited rate when carbon is released from deep time sinks.

Bruce Steele

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Re: Carbon Cycle
« Reply #579 on: August 06, 2020, 12:48:43 AM »

The recent state and variability of the carbonate system of the Canadian Arctic Archipelago and adjacent basins in the context of ocean acidification

Alexis Beaupré-Laperrière1, Alfonso Mucci1, and Helmuth Thomas
https://bg.copernicus.org/articles/17/3923/2020/
“ The prominent pathway for the eastward flow of Canada Basin water masses into Baffin Bay extends along the 74th parallel from M'Clure Strait to Lancaster Sound. A shallow 125 m sill at Barrow Strait, located centrally in the archipelago, inhibits the eastward flow of Atlantic waters, so that only surface and Pacific-origin waters reach Baffin Bay (Bidleman et al., 2007). “

New paper on OA in the CAA and the CAB. Interesting in the context of a potential garlic press starting this season.

Bruce Steele

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Re: Carbon Cycle
« Reply #580 on: August 06, 2020, 12:57:19 AM »
Also a link to a paper by Tremblay et al 2011
Linked in article above.
Upwelling and productivity eastern cab
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL048825

Shows locations of upwelling of halocline water 2007.


Florifulgurator

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Re: Carbon Cycle
« Reply #581 on: August 06, 2020, 02:54:53 AM »
What is the absolute minimum CO2 a person can emit into the atmosphere, assuming he lives 100 years and his only emissions are respiratory exhalation?
Its quite large, but also quite misleading.
 [...].
4 tonnes.
4tC x 44/12 ~ 15tCO2

How much of that would have fossil C isotopes (vs. the CO2 emitted elsewhere by Haber-Bosch nitrogen fertilizer production)?


Hmmm... is that really large?

Counterquestion: How much CO2 does one cubic meter of horse manure ((*) vs. vegetable compost) emit in 1 year while composting?

(*) Seriously. This can give a nice qualitative picture of the natural carbon cycle.
« Last Edit: August 06, 2020, 03:24:10 AM by Florifulgurator »
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Bruce Steele

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Re: Carbon Cycle
« Reply #582 on: August 14, 2020, 05:42:32 PM »
“Rapid deep ocean deoxygenation and acidification threaten life on Northeast Pacific seamounts. “
“Anthropogenic climate change is causing our oceans to lose oxygen and become more acidic at an unprecedented rate, threatening marine ecosystems and their associated animals. In deep‐sea environments, where conditions have typically changed over geological time scales, the associated animals, adapted to these stable conditions, are expected to be highly vulnerable to any change or direct human impact. Our study coalesces one of the longest deep‐sea observational oceanographic timeseries, reaching back to the 1960s, with a modern visual survey that characterizes almost two vertical‐kilometers of benthic seamount ecosystems. Based on our new and rigorous analysis of the Line P oceanographic monitoring data, the upper 3000 m of the Northeast Pacific has lost 15% of its oxygen in the last 60 years. Over that time, the oxygen minimum zone (OMZ), ranging between approximately 480 and 1700 m has expanded at a rate of 3.0±0.7 m/year (due to deepening at the bottom). Additionally, carbonate saturation horizons above the OMZ have been shoaling at a rate of 1‐2 m/year since the 1980s. Based on our visual surveys of four Northeast Pacific seamounts, these deep‐sea features support ecologically important taxa typified by long lifespans, slow growth rates, and limited mobility, including habitat‐forming cold‐water corals and sponges, echinoderms, and fish. By examining the changing conditions within the narrow realized bathymetric niches for a subset of vulnerable populations, we resolve chemical trends that are rapid in comparison to the lifespan of the taxa and detrimental to their survival. If these trends continue as they have over the last 3‐6 decades, they threaten to diminish regional seamount ecosystem diversity and cause local extinctions. This study highlights the importance of mitigating direct human impacts as species continue to suffer environmental changes beyond our immediate control.”

https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15307

One more time for emphasis.” The upper three thousand meters of the Northeastern Pacific has lost 15% of it’s oxygen in the last sixty years. “

« Last Edit: August 14, 2020, 05:55:44 PM by Bruce Steele »

kassy

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Re: Carbon Cycle
« Reply #583 on: August 14, 2020, 06:29:04 PM »
I have wondered about the effect the rate of change of our carbon push ever since the paper that showed we were actually outpacing the PETM.

That does sound bad.

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NotaDenier

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Re: Carbon Cycle
« Reply #584 on: August 16, 2020, 02:41:20 PM »
https://thenextweb.com/syndication/2020/08/16/heres-why-you-need-to-start-worrying-about-the-worlds-frozen-peatlands/

Peatlands cover just a few percent of the global land area but they store almost one-quarter of all soil carbon and so play a crucial role in regulating the climate. My colleagues and I have just produced the most accurate map yet of the world’s peatlands – their depth, and how much greenhouse gas they have stored. We found that global warming will soon mean that these peatlands start emitting more carbon than they store.

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Re: Carbon Cycle
« Reply #585 on: August 16, 2020, 03:06:18 PM »
What do you mean by “soon”, NotaDenier? In climatology soon could be in a couple centuries.
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kassy

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Re: Carbon Cycle
« Reply #586 on: August 16, 2020, 07:42:47 PM »
The underlined thing is a link and you could actually just go read that.
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Re: Carbon Cycle
« Reply #587 on: August 17, 2020, 12:13:39 AM »
Quote
We found that the thaw projected from future global warming will cause releases of greenhouse gas that overshadow and reverse the carbon dioxide sink of all northern peatlands for several hundred years. The exact timing of this switch is still highly uncertain, but it is likely to happen in the later half of this century.
So perhaps as soon as 2051? I will turn 93 that year if I survive.
Scary.
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kassy

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Re: Carbon Cycle
« Reply #588 on: August 17, 2020, 01:20:15 PM »
Yes. And maybe we do not even have to wait that long because the failure of Arctic summer ice will kick things up a notch.
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Re: Carbon Cycle
« Reply #589 on: August 17, 2020, 01:40:00 PM »
Quote
We found that the thaw projected from future global warming will cause releases of greenhouse gas that overshadow and reverse the carbon dioxide sink of all northern peatlands for several hundred years. The exact timing of this switch is still highly uncertain, but it is likely to happen in the later half of this century.
So perhaps as soon as 2051? I will turn 93 that year if I survive.
Scary.

That's a poorly written sentence and it's hard to know exactly what it means. But I don't think the "exact timing of this switch" actually matters. When a sink begins to fail and head toward a source, it has an immediately and ongoing impact on the net flux of CO2 to the atmosphere. The moment it passes through the boundary between sink and source isn't especially important.

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Re: Carbon Cycle
« Reply #590 on: August 17, 2020, 03:15:29 PM »
<Took out the part not about the carbon cycle. kassy>

What do you mean by “soon”, NotaDenier? In climatology soon could be in a couple centuries.
Current climatology is about decades meanwhile.
« Last Edit: August 17, 2020, 03:47:35 PM by kassy »
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kassy

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Re: Carbon Cycle
« Reply #591 on: August 17, 2020, 03:37:18 PM »
The exact timing does not matter but this is the way that people think about these things.

Of course key questions are: can we stop this or is it already locked in? And what does it mean for the rest.

The paper:
https://www.pnas.org/content/pnas/early/2020/08/04/1916387117.full.pdf



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Re: Carbon Cycle
« Reply #592 on: August 21, 2020, 09:02:57 AM »
Sometimes research is incredibly interesting:

" Fossil leaves show high atmospheric carbon spurred ancient 'global greening'
A unique New Zealand deposit opens insights into how modern climate change may proceed"

"Scientists studying leaves from a 23-million-year-old forest have for the first time linked high levels of atmospheric carbon dioxide with increased plant growth, and the hot climate off the time. The finding adds to the understanding of how rising CO2 heats the earth, and how the dynamics of plant life could shift within decades, when CO2 levels may closely mirror those of the distant past.

Scientists retrieved the leaves from a unique onetime New Zealand lake bed that holds the remains of plants, algae, spiders, beetle, flies, fungi and other living things from a warm period known as the early Miocene. Scientists have long postulated that CO2 was high then, and some plants could harvest it more efficiently for photosynthesis. This is the first study to show that those things actually happened in tandem. The findings were published this week in the journal Climate of the Past.

"The amazing thing is that these leaves are basically mummified, so we have their original chemical compositions, and can see all their fine features under a microscope," said lead author Tammo Reichgelt, an adjunct scientist at Columbia University's Lamont-Doherty Earth Observatory and assistant professor of geosciences at the University of Connecticut. "Evidence has been building that CO2 was high then, but there have been paradoxes."

The so-called "carbon fertilization effect" has vast implications. Lab and field experiments have shown that when CO2 levels rise, many plants increase their rate of photosynthesis, because they can more efficiently remove carbon from the air, and conserve water while doing so. Indeed, a 2016 study based on NASA satellite data shows a "global greening" effect mainly due to rising levels of manmade CO2 over recent decades; a quarter to a half of the planet's vegetated lands have seen increases in leaf volume on trees and plants since about 1980. The effect is expected to continue as CO2 levels rise."

https://www.eurekalert.org/pub_releases/2020-08/eiac-fls081720.php

Hefaistos

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Re: Carbon Cycle
« Reply #593 on: August 21, 2020, 09:05:28 AM »

On the global greening effect mentioned in the paper in previous post:

"... a 2016 study based on NASA satellite data shows a "global greening" effect mainly due to rising levels of manmade CO2 over recent decades; a quarter to a half of the planet's vegetated lands have seen increases in leaf volume on trees and plants since about 1980. The effect is expected to continue as CO2 levels rise."

Interesting regional distribution.

kassy

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Re: Carbon Cycle
« Reply #594 on: August 21, 2020, 08:33:42 PM »
The thing that will bite that is the actual rate of change we are forcing on the planet (and chopping the Amazon down for soy will not help acreage).

A lot of forests are struggling with the current local climate and we will lose a whole bunch. Plants can´t move fast enough and there are people in the way in many places.

The Oligocene plants developed under totally different conditions.   

Yes plants can capture a shit ton of carbon if you actually let them and you have the time.

Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

oren

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Re: Carbon Cycle
« Reply #595 on: August 24, 2020, 04:44:30 AM »
Sometimes research is incredibly interesting:

You somehow cut the next paragraph from the article:
Quote
This might seem like good news, but the reality is more complex. Increased CO2 absorption will not come close to compensating for what humans are pouring into the air. Not all plants can take advantage, and among those who do, the results can vary depending on temperature and availability of water or nutrients. And, there is evidence that when some major crops photosynthesize more rapidly, they absorb relatively less calcium, iron, zinc and other minerals vital for human nutrition. Because much of today's plant life evolved in a temperate, low-CO2 world, some natural and agricultural ecosystems could be upended by higher CO2 levels, along with the rising temperatures and shifts in precipitation they bring. "How it plays out is anyone's guess," said Reichgelt. "It's another layer of stress for plants. It might be great for some, and horrible for others."

nanning

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Re: Carbon Cycle
« Reply #596 on: August 24, 2020, 09:37:05 AM »
Re: forests
Higher latitude forests are degrading already and many trees will die because of parasites and diseases that are moving north with global heating. On top of that, the increasing extreme temperatures, droughts and frequency of forest fires.
I fear that most of the high latitude forests will go up in flames eventually after having crossed some physical/ecosystem tresholds. After a number of forest fire years with increasing max temps, most trees will die. The forests die and burn up, releasing massive amounts of carbon. All the forest fires will release massive amounts of aerosol pollution/black carbon/GHG.

Is there something wrong with this simplistic line of thinking?
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
"It is preoccupation with what other people from your groups think of you, that prevents you from living freely and nobly" - Nanning
Why do you keep accumulating stuff?

Hefaistos

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Re: Carbon Cycle
« Reply #597 on: September 05, 2020, 10:49:26 PM »
"The ocean’s ‘biological pump’ captures more carbon than expected"

In a paper published April 6 in Proceedings of the National Academy of Sciences, WHOI geochemist Ken Buesseler and colleagues demonstrated that the depth of the sunlit area where photosynthesis occurs varies significantly throughout the ocean. This matters because the phytoplankton’s ability to take up carbon depends on amount of sunlight that’s able to penetrate the ocean’s upper layer. By taking account of the depth of the euphotic, or sunlit zone, the authors found that about twice as much carbon sinks into the ocean per year than previously estimated.

The paper relies on previous studies of the carbon pump, including the authors’ own. “If you look at the same data in a new way, you get a very different view of the ocean’s role in processing carbon, hence its role in regulating climate,” says Buesseler.

“Using the new metrics, we will be able to refine the models to not just tell us how the ocean looks today, but how it will look in the future,” he adds. “Is the amount of carbon sinking in the ocean going up or down? That number affects the climate of the world we live in.”

https://www.whoi.edu/press-room/news-release/the-oceans-biological-pump-captures-more-carbon-than-expected/

Full paper:
"Metrics that matter for assessing the ocean biological carbon pump" by Buesseler et al
https://www.pnas.org/content/early/2020/04/03/1918114117

New research confirms the finds by Buesseler et al. The world's oceans soak up more carbon than most scientific models suggest. Previous estimates of the 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 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. Also, the flux is significantly increasing over time.

Paper in Nature Communications: "Revised estimates of ocean-atmosphere CO2 flux are consistent with ocean carbon inventory."

"Abstract
The ocean is a sink for ~25% of the atmospheric CO2 emitted by human activities, an amount in excess of 2 petagrams of carbon per year (PgC yr−1). Time-resolved estimates of global ocean-atmosphere CO2 flux provide an important constraint on the global carbon budget. However, previous estimates of this flux, derived from surface ocean CO2 concentrations, have not corrected the data for temperature gradients between the surface and sampling at a few meters depth, or for the effect of the cool ocean surface skin. Here we calculate a time history of ocean-atmosphere CO2 fluxes from 1992 to 2018, corrected for these effects. These increase the calculated net flux into the oceans by 0.8–0.9  PgC yr−1, at times doubling uncorrected values. We estimate uncertainties using multiple interpolation methods, finding convergent results for fluxes globally after 2000, or over the Northern Hemisphere throughout the period. Our corrections reconcile surface uptake with independent estimates of the increase in ocean CO2 inventory, and suggest most ocean models underestimate uptake."

full paper at:
https://www.nature.com/articles/s41467-020-18203-3

See also:
https://www.eurekalert.org/pub_releases/2020-09/uoe-ocu090320.php

Figure 3 byline:
The net flux into the ocean is shown as negative, following convention.

The black line is our standard case global ocean-atmosphere flux increased by −0.57 PgC Cyr−1 to account for pre-industrial and Arctic fluxes as described in the text. The shading gives one and two standard deviations of estimates around this value, including the uncertainty in gas transfer rates as assessed by Woolf et al.20. Red horizontal line and uncertainty is a recent estimate of the global inventory increase of anthropogenic carbon in the ocean between 1994 and 200717. Dashed lines: two previous estimates of global uptake based on surface data: blue dashed line from Landschützer et al.8, red dashed line from Rödenbeck et al.10, both as quoted in Le Quéré et al.31. Both are increased by the pre-industrial flux correction and Landschützer et al.8 also increased by Arctic correction.

Simon

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Re: Carbon Cycle
« Reply #598 on: September 06, 2020, 08:25:41 AM »
Interesting paper. Not sure why or how there is such a huge variation in the ocean sink in the past twenty years. ????

The conventional wisdom has been that the oceans have been sinking 2.5PgC per year As this paper assumes

https://essd.copernicus.org/articles/11/1783/2019/essd-11-1783-2019.pdf

This paper may have the best carbon cycle illustration I have seen (page 5)