Carbon Cycle

[kassy]

Warming of 2°C would release billions of tonnes of soil carbon

Global warming of 2°C would lead to about 230 billion tonnes of carbon being released from the world's soil, new research suggests.

Global soils contain two to three times more carbon than the atmosphere, and higher temperatures speed up decomposition - reducing the amount of time carbon spends in the soil (known as "soil carbon turnover").

The new international research study, led by the University of Exeter, reveals the sensitivity of soil carbon turnover to global warming and subsequently halves uncertainty about this in future climate change projections.

The estimated 230 billion tonnes of carbon released at 2°C warming (above pre-industrial levels) is more than four times the total emissions from China, and more than double the emissions from the USA, over the last 100 years.

"Our study rules out the most extreme projections - but nonetheless suggests substantial soil carbon losses due to climate change at only 2°C warming, and this doesn't even include losses of deeper permafrost carbon," said co-author Dr Sarah Chadburn, of the University of Exeter.

...

State-of-the-art models suggest an uncertainty of about 120 billion tonnes of carbon at 2°C global mean warming.

The study reduces this uncertainty to about 50 billion tonnes of carbon.

https://www.eurekalert.org/pub_releases/2020-11/uoe-wo2103020.php

[nanning]

^^
How much extra global heating would that produce?
How much extra soil carbon would be emitted by that extra global heating?
Etcetera...   Oh hey hellooo, look who's here to help out... Lord Methane! And he's brought his little friend Rev. Albedo.

[GeoffBeacon]

For 2°C:

Can 232 GtC (851 CO2) of soil carbon be used to update remaining carbon budgets in SR15, Ch 2, Table 2.2?

For 50% chance in Table 2.2, budget to keep below 2°C is 1500 GtCO2 (less Earth System Feedbacks less emissions since 1/1/2018).

Taking 851 from 1500 gives 650 GtCO2 (less Earth System Feedbacks less emissions since)

Earth system feedbacks include CO2 released by permafrost thawing or methane released by wetland. These in Table 2.2 given as 100 GtCO2 for  a 1.5°C rise, but will  be more for 2°C rise.
Guess 150GtCO2?

Emissions since date in SR15 (1/1/2018) about 100 GtCO2?

That gives remaining carbon budget of 650-150-100 = 400 Gt CO2.

That's a remaining budget of 53 tonnes CO2 per human for 2°C rise.

Crude but this it at all realistic?

How much does non-CO2 climate forcing reduce this?

[nanning]

Geoff, in my opinion the 'budget' is already empty.
I refer to the many tipping points, but also to interglacial paleoclimate records that show ca. +3°C for 410ppm CO₂ GHG and that's without CH₄ & N₂0  (and ca.20m SLR).

All of this FF anthropogenic CO2 is of course from outside the long-term carbon cycle.

[GeoffBeacon]

nanning

I agree but I'm searching for ways to test the 'official' view.

e.g. On this twitter thread.

https://twitter.com/richardabetts/status/1323333437068070912

[Tom_Mazanec]

Geoff, in my opinion the 'budget' is already empty.
I refer to the many tipping points, but also to interglacial paleoclimate records that show ca. +3°C for 410ppm CO₂ GHG and that's without CH₄ & N₂0  (and ca.20m SLR).

All of this FF anthropogenic CO2 is of course from outside the long-term carbon cycle.

This is why you need to remember CO2e which, IIRC, is about 500 ppm right now.

[nanning]

Geoff, that twitter thread has made it to the Guardian:

https://www.theguardian.com/business/2020/nov/03/shells-climate-poll-on-twitter-backfires-spectacularly


Shell’s climate poll on Twitter backfires spectacularly

Oil giant accused of gaslighting after asking users: ‘What are you willing to change?’

Sorry for off-topic

[kassy]

Krill could be vital in climate change battle, say British Antarctic Survey researchers

They could turn out to be a significant accomplice in the battle against climate change.

Vast swarms of krill in the Southern Ocean are now believed to remove double the amount of carbon from the atmosphere than previously assumed by global models.

Scientists have been aware that krill produce carbon-rich faecal pellets that sink in the water column and transfer carbon from the atmosphere to the deep ocean.

But now researchers at the British Antarctic Survey in Cambridge have found that the process of moulting, in which they shred their exoskeletons, performs a similar function.

Dr Clara Manno, a marine ecologist at BAS and lead author of the paper published in Nature Communications last Friday, says: “This is exciting news because it almost doubles the previous estimate of how much atmospheric carbon is transported into deep ocean layers by krill.

...

Antarctic krill (Euphausia superba) represent some of the highest concentrations of animal biomass in the world’s oceans – estimated to be more than 150 million tonnes. They are the main diet for whales, penguins and seals and also harvested for food by humans

...

Co-author and ecologist Prof Geraint Tarling said: “Krill are really unusual crustaceans in moulting so frequently. In fact, they renew their exoskeleton every 10 to 14 days, releasing their old ones to sink towards the seabed, and taking carbon with it.

https://www.cambridgeindependent.co.uk/news/krill-could-be-vital-in-climate-change-battle-say-british-antarctic-survey-researchers-9143897/

Open access:
Continuous moulting by Antarctic krill drives major pulses of carbon export in the north Scotia Sea, Southern Ocean

Abstract
Antarctic krill play an important role in biogeochemical cycles and can potentially generate high-particulate organic carbon (POC) fluxes to the deep ocean. They also have an unusual trait of moulting continuously throughout their life-cycle. We determine the krill seasonal contribution to POC flux in terms of faecal pellets (FP), exuviae and carcasses from sediment trap samples collected in the Southern Ocean. We found that krill moulting generated an exuviae flux of similar order to that of FP, together accounting for 87% of an annual POC flux (22.8 g m−2 y−1). Using an inverse modelling approach, we determined the krill population size necessary to generate this flux peaked at 261 g m−2. This study shows the important role of krill exuviae as a vector for POC flux. Since krill moulting cycle depends on temperature, our results highlight the sensitivity of POC flux to rapid regional environmental change.

https://www.nature.com/articles/s41467-020-19956-7

[vox_mundi]

The Greening of the Earth is Approaching Its Limit
https://phys.org/news/2020-12-greening-earth-approaching-limit.html

An international study published today in Science concludes that the fertilizing effect of CO2 is decreasing worldwide, and that the reduction has reached 50% progressively since 1982 due basically to two key factors: the availability of water and nutrients.

"There is no mystery about the formula, plants need CO2, water and nutrients in order to grow. However much the CO2 increases, if the nutrients and water do not increase in parallel, the plants will not be able to take advantage of the increase in this gas", explains Professor Josep Peñuelas. In fact, three years ago Prof. Peñuelas already warned in an article in Nature Ecology and Evolution that the fertilizing effect of CO2 would not last forever, that plants cannot grow indefinitely, because there are other factors that limit them.

... "These unprecedented results indicate that the absorption of carbon by vegetation is beginning to become saturated. This has very important climate implications that must be taken into account in possible climate change mitigation strategies and policies at the global level. ... If the fertilizing capacity of CO2 decreases, there will be strong consequences on the carbon cycle and therefore on the climate.

The team based it's conclusions on data obtained from hundreds of forests studied over the last 40 years. "This data show that concentrations of essential nutrients in the leaves, such as nitrogen and phosphorus, have also progressively decreased since 1990," explains researcher Songhan Wang, the first author of the article.

The team has also found that water availability and temporal changes in water supply play a significant role in this phenomenon. "We have found that plants slow down their growth, not only in times of drought, but also when there are changes in the seasonality of rainfall, which is increasingly happening with climate change," explains researcher Yongguan Zhang.





S. Wang el al., "Recent global decline of CO2 fertilization effects on vegetation photosynthesis," Science (2020)
https://science.sciencemag.org/content/370/6522/1295

... Our analyses showed a significant and spatially extensive decline in β, which implies a substantial reduction of the positive effects of increasing atmospheric CO2 on terrestrial carbon uptake.

[kassy]

Thanks! Another interesting puzzle piece.

[kassy]

Muddying the waters: Weathering might remove less atmospheric CO2 than thought

The weathering of rocks at the Earth's surface may remove less greenhouse gases from the atmosphere than previous estimates, says new research from the University of Cambridge.

The findings, published in PNAS, suggest Earth's natural mechanism for removing carbon dioxide (CO2) from the atmosphere via the weathering of rocks may in fact be weaker than scientists had thought -- calling into question the exact role of rocks in alleviating warming over millions of years.

The research also suggests there may be a previously unknown sink drawing CO2 from the atmosphere and impacting climate changes over long timescales, which researchers now hope to find.

Weathering is the process by which atmospheric carbon dioxide breaks down rocks and then gets trapped in sediment. It is a major part of our planet's carbon cycle, shuttling carbon dioxide between the land, sea and air, and influencing global temperatures.

"Weathering is like a planetary thermostat -- it's the reason why Earth is habitable. Scientists have long suggested this is why we don't have a runaway greenhouse effect like on Venus," said lead author Ed Tipper from Cambridge's Department of Earth Sciences. By locking carbon dioxide away in sediments, weathering removes it from the atmosphere over long timescales, reducing the greenhouse effect and lowering global temperatures.

The team's new calculations show that, across the globe, weathering fluxes have been overestimated by up to 28%, with the greatest impact on rivers in mountainous regions where rocks are broken down faster.

They also report that three of the largest river systems on Earth, including the neighbouring Yellow and Salween Rivers with their origins on the Tibetan Plateau and the Yukon River of North America, do not absorb carbon dioxide over long timescales -- as had been thought.

For decades the Tibetan plateau has been invoked as a long term sink for carbon and mediator of climate. Some 25% of the sediment in the world's oceans originate from the plateau.

"One of the best places to study the carbon cycle are rivers, they are the arteries of the continents. Rivers are the link between the solid Earth and oceans -- hauling sediments weathered from the land down to the oceans where their carbon is locked up in rocks," said Tipper.

"Scientists have been measuring the chemistry of river waters to estimate weathering rates for decades," said co-author Victoria Alcock "Dissolved sodium is one of the most commonly measured products of weathering -- but we've shown that it's not that simple, and in fact sodium often comes from elsewhere."

Sodium is released when silicate minerals, the basic building blocks of most of Earth's rocks, dissolve in carbonic acid -- a mix of carbon dioxide in the atmosphere and rainwater.

However, the team found not all sodium comes from this weathering process. "We've found an additional source of sodium in river waters across the globe," said co-author Emily Stevenson. "That extra sodium is not from weathered silicate rocks as other studies assume, but in fact from very old clays which are being eroded in river catchments."

Tipper and his research group studied eight of the largest river systems on Earth, a mission involving 16 field seasons and thousands of lab analyses in search of where that extra sodium was coming from.

They found the answer in a soupy 'gel' of clay and water -- known as the cation exchange pool -- which is carried along by muddy river sediment.

The exchange pool is a reactive hive of cations -- positively charged ions like sodium -- which are weakly bonded to clay particles. The cations can easily swap out of the gel for other elements like calcium in river water, a process that can take just a few hours.

Although it has been described in soils since the 1950s, the role the exchange pool plays in supplying sodium to rivers has been largely neglected.

"The chemical and isotopic makeup of the clays in the exchange pool tell us what they are made of and where they've come from," said co-author Alasdair Knight. "We know that many of the clays carried by these rivers come from ancient sediments, and we suggest that some of the sodium in the river must come from these clays."

The clays were originally formed from continental erosion millions of years ago. On their journey downstream they harvested cations from the surrounding water -- their exchange pool picking up sodium on reaching the sea. Today, after being uplifted from the seafloor, these ancient clays -- together with their sodium -- are now being eroded by modern rivers.

This old sodium, which can switch out of the clays in the exchange pool and into river water, has previously been mistaken as the dissolved remnants of modern weathering.

"Generating just one data point took a huge amount of work in the lab and we also had to do a lot of maths," said Stevenson. "It's like unmixing a cake, using a forensic approach to isolate key ingredients in the sediments, leaving behind the exchange pool and the clays. People have used the same methods for a really long time -- and they work -- but we've been able to find an extra ingredient that provides the sodium and we need to account for this."

"It's thanks to the hard work of many collaborators and students over many years that our samples had the scope to get to grips with this complex chemical process at a global scale," said Tipper.

Scientists are now left to puzzle over what else could be absorbing Earth's carbon dioxide over geological time. There are no certain candidates -- but one controversial possibility is that life is removing carbon from the atmosphere. Another theory is that silicate dissolution on the ocean floor or volcanic arcs may be important. "People have spent decades looking on the continents for weathering -- so maybe we now need to start expanding where we look," said Tipper.

https://www.sciencedaily.com/releases/2020/12/201221160459.htm

[Tor Bejnar]

Thanks, Kassy.

Eroded uplifted sedimentary rocks (not just "clays" - e.g., ever heard of salt domes?) is an obvious source of cations in river water, and I presumed this source was already in the calculations demonstrating that weathering was a significant long-term device for removing CO2 from the atmosphere.  I guess what is special about eroding clay minerals is that carbon is released when clay minerals 'dissolve' in river water (or if not dissolved, not taking into account some cations 'in the water' have been in a long-term relationship with carbon), whereas there is functionally no carbon in mafic igneous rocks.

one controversial possibility is that life is removing carbon from the atmosphere

This one floors me!  Where do they think peat, oil, coal, odiferous shales and submerged log furniture come from?

[kassy]

Climate and carbon cycle trends of the past 50 million years reconciled

Predictions of future climate change require a clear and nuanced understanding of Earth's past climate. In a study published today in Science Advances, University of Hawai'i (UH) at Mānoa oceanographers fully reconciled climate and carbon cycle trends of the past 50 million years--solving a controversy debated in the scientific literature for decades.

Throughout Earth's history, global climate and the global carbon cycle have undergone significant changes, some of which challenge the current understanding of carbon cycle dynamics.

Less carbon dioxide in the atmosphere cools Earth and decreases weathering of rocks and minerals on land over long time scales. Less weathering should lead to a shallower calcite compensation depth (CCD), which is the depth in the ocean where the rate of carbonate material raining down equals the rate of carbonate dissolution (also called "snow line"). The depth of the CCD can be traced over the geologic past by inspecting the calcium carbonate content of seafloor sediment cores.

...

Contrary to expectations, the deep-sea carbonate records indicate that as atmospheric carbon dioxide (CO2) decreased over the past 50 million years, the global CCD deepened (not shoaled), creating a carbon cycle conundrum.

"The variable position of the paleo-CCD over time carries a signal of the combined carbon cycle dynamics of the past," said Komar, lead author of the study. "Tracing the CCD evolution across the Cenozoic and identifying mechanisms responsible for its fluctuations are therefore important in deconvolving past changes in atmospheric CO2, weathering, and deep-sea carbonate burial. As CO2 and temperature dropped over the Cenozoic, the CCD should have shoaled but the records show that it actually deepened."

Komar and Zeebe's computer model allowed them to investigate possible mechanisms responsible for the observed long-term trends and provide a mechanism to reconcile all the observations.

"Surprisingly, we showed that the CCD response was decoupled from changes in silicate and carbonate weathering rates, challenging the long-standing uplift hypothesis, which attributes the CCD response to an increase in weathering rates due to the formation of the Himalayas and is contrary to our findings," said Komar.

Their research suggests that the disconnect developed partially because of the increasing proportion of carbonate buried in the open ocean relative to the continental shelf due to the drop in sea level as Earth cooled and continental ice sheets formed. In addition, ocean conditions caused the proliferation of open-ocean carbonate-producing organisms during that period of time.

https://www.eurekalert.org/pub_releases/2021-01/uoha-cac012121.php

[Bruce Steele]

Kassy, The Komar/ Zeebe paper is open access.

https://advances.sciencemag.org/content/7/4/eabd4876

Thanks for the news article, now for some deep reading.

[kassy]

Fishes contribute roughly 1.65 billion tons of carbon in feces and other matter annually
Study estimates fishes contribute about 16 percent of the sinking carbon in upper ocean waters

Scientists have little understanding of the role fishes play in the global carbon cycle linked to climate change, but a Rutgers-led study found that carbon in feces, respiration and other excretions from fishes - roughly 1.65 billion tons annually - make up about 16 percent of the total carbon that sinks below the ocean's upper layers.

https://www.eurekalert.org/pub_releases/2021-02/ru-fcr021721.php

Paper:
Toward a better understanding of fish‐based contribution to ocean carbon flux
https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.11709

This article explains the research , good start if it is new to you:
Why Scientists Just Ran Numbers on All The Fish Poop in The World's Oceans
https://www.sciencealert.com/scientists-calculated-all-the-fish-poo-in-the-ocean-for-climate-research

[kassy]

Effects of past ice ages more widespread than previously thought

A new study suggests that cold temperatures in unglaciated North America during the last ice age shaped past and modern landscape as far south as Texas and Arkansas.

...

The findings help shape understanding of the earth's "Critical Zone," the relatively thin layer of the planet that extends from where vegetation meets the atmosphere to the lowermost extent of weathered bedrock. "Climate and ecosystems determine how quickly bedrock weathers, how soil is produced, how sediment moves on land and in rivers and other factors that shape the landscape," the authors wrote.

In cold lands, such as Alaska today, frost can crack or weather rock that is at or near the surface of the earth -- making it more porous and turning solid rock into sediment. By applying a frost-weathering model to North America paleoclimate simulations tracking temperatures during the Last Glacial Maximum approximately 21,000 years ago, Marshall and her team determined that a large swath of North America, from Oregon to Georgia and as far south as Texas and Arkansas, were likely affected by such periglacial processes.

While permafrost landscapes like the modern Arctic experience frozen ground for two years or more, periglacial landscapes, though not permanently frozen, experience below-freezing temperature for much of the year. Though the evidence of past periglacial processes is easily hidden by vegetation and/or erased by subsequent geological processes, the teams' results suggest that frost weathering (and by extent other periglacial processes) covered an area about 3.5 times larger than the mapped extent of permafrost during the Last Glacial Maximum. This predicted influence of past cold climates on below ground weathering may significantly influence modern landscape attributes that we depend on such as soil thickness and water storage.

...

https://www.sciencedaily.com/releases/2021/02/210222192830.htm

[vox_mundi]

Forests' Long-Term Capacity to Store Carbon is Dropping In Regions With Extreme Annual Fires
https://phys.org/news/2021-02-forests-long-term-capacity-carbon-regions.html

Researchers have analyzed decades' worth of data on the impact of repeated fires on ecosystems across the world. Their results, published today in the journal Nature Ecology and Evolution, show that repeated fires are driving long-term changes to tree communities and reducing their population sizes.

Savannah ecosystems, and regions with extreme wet or dry seasons were found to be the most sensitive to changes in fire frequency. Trees in regions with moderate climate are more resistant. Repeated fires also cause less damage to tree species with protective traits like thicker bark.

These effects only emerge over the course of several decades: the effect of a single fire is very different from repeated burning over time. The study found that after 50 years, regions with the most extreme annual fires had 72% lower wood area—a surrogate for biomass—with 63% fewer individual trees than in regions that never burned. Such changes to the tree community can reduce the forest's long-term ability to store carbon, but may buffer the effect of future fires.

... Past studies have found that frequent fires reduce levels of nutrients—including nitrogen—in the soil. The new study demonstrates that this can favor slower-growing tree species that have adaptations to help them survive with less nutrients. But these tree species also slow down nutrient cycling in the soil—they hold onto what they have. This can limit the recovery of the forest as a whole by reducing the nutrients available for plant growth after an intense fire.

In the past, the majority of carbon released by wildfires was recaptured as ecosystems regenerated. But the more frequent fires of recent years, driven by changes in climate and land use, don't always allow time for this.

Pellegrini, A.F.A. et al: 'Decadal changes in fire frequencies shift tree communities and functional traits.' Nature Ecology & Evolution, February 2021
https://www.nature.com/articles/s41559-021-01401-7

[gerontocrat]

Yet another possibility for AGW to accelerate.

https://www.theguardian.com/environment/2021/mar/24/soils-ability-to-absorb-carbon-emissions-may-be-overestimated-study
One of Earth’s giant carbon sinks may have been overestimated - study

The potential of soils to slow climate change by soaking up carbon may be less than previously thought

The storage potential of one of the Earth’s biggest carbon sinks – soils – may have been overestimated, research shows. This could mean ecosystems on land soaking up less of humanity’s emissions than expected, and more rapid global heating.

Soils and the plants that grow in them absorb about a third of the carbon emissions that drive the climate crisis, partly limiting the impact of fossil-fuel burning. Rising carbon dioxide levels in the atmosphere can increase plant growth and, until now, it was assumed carbon storage in soils would increase too.

But the study, based on over 100 experiments, found the opposite. When plant growth increases, soil carbon does not. The finding is significant because the amount of organic carbon stored in soils is about three times that in living plants and double that in the atmosphere. Soils can also store carbon for centuries, whereas plants and trees rot quickly after they die.

It is not yet known how big the effect of lower carbon storage in soils might be on the speed of climate change, and experts cautioned that other impacts of the climate emergency such as drought would also affect how well plants and soils store carbon.

“We found that when rising CO2 increases plant growth, there is a decrease in soil carbon storage. That’s a very important conclusion,” said César Terrer, who led the research while at Stanford University in the US. He said that if soils do absorb less in future, “the speed of global warming could be higher”.

Terrier said soils, plants and trees were important for carbon levels, but that ending the burning of fossil fuels remains essential. “If we really want to stop global warming, we need to stop emissions, because ecosystems only take up a fraction of all the CO2 emissions,” he said.

The study, published in the journal Nature, analysed more than 100 experiments from across the world in which soils, plants and trees were exposed to higher CO2 levels than in today’s atmosphere. The biomass growing in forests rose by 23% in experiments where the CO2 level used was double pre-industrial atmospheric levels. It is 50% higher today. But the forest soils did not store any more organic carbon at all.

It was thought that biomass and soil carbon would increase in tandem, as more plant biomass falls to the ground and turns into organic matter. But increased plant and tree growth requires more nutrients from the soil, which may explain the new finding, the scientists said. Extracting the extra nutrients requires the plants to increase the symbiotic microbial activity in their roots, which then releases CO2 to the atmosphere that might otherwise have remained locked in the soil.

The researchers found that in grasslands, elevated CO2 led to 9% plant growth – less than forests – but soil carbon rose by 8%. Terrier said there has been a lot of discussion about tree planting as a way to tackle the climate crisis. “What I found very concerning in that debate is that people were suggesting planting trees in natural grasslands, savannah, and tundra,” he said. “I think that would be a terrible mistake because, as our results imply, there is a very large potential to increase soil carbon storage in grasslands.”

Open access article - cannot download pdf
https://www.nature.com/articles/s41586-021-03306-8.epdf?sharing_token=TmGNRC-Kphbf-zH7cCY8_9RgN0jAjWel9jnR3ZoTv0N2nuYqS5Si1oM85m9uPVbHtSoElmnSOceF_iSQhP1hfFAkwk2zkiuCDFYLMQUcWZ449oya-b_b0UwO-hnx_pjFJ9gmuFo7O9lrCLLifZ20c-ZUT3DZBSpOHb0b5Fqvp24p_KRkyABFbdQ1hqI_6thGftvWq4mOuSbtzwO5bbFqfwUKqJGWN8vrTjBiiyPdetYtiWWVN-8L521MmwBg1eZXB1F1oO9dbULOJm_v6RHa_mHW0Dy9Ace4IWWVVTMYb8nzBuZcqt3iekOpS8b8vFrA6QMXj942FKewZV_veXZJTXtsTgOmMoyOaaZPmKZAl1E%3D&tracking_referrer=www.theguardian.com

[kassy]

Here we synthesized data from 108 eCO2 experiments and found that the effect of eCO2 on SOC stocks is best explained by a negative relationship with plant biomass: when plant biomass is strongly stimulated by eCO2, SOC storage declines; conversely, when biomass is weakly stimulated, SOC storage increases. This trade-off appears to be related to plant nutrient acquisition, in which plants increase their biomass by mining the soil for nutrients, which decreases SOC storage. We found that, overall, SOC stocks increase with eCO2 in grasslands (8±2 per cent) but not in forests (0±2 per cent), even though plant biomass in grasslands increase less (9±3 per cent) than in forests (23±2 per cent). Ecosystem models do not reproduce this trade-off, which implies that projections of SOC may need to be revised.

The relationship is simple enough.

We take soils for granted which we should not do especially since we are degrading them.

[kassy]

Risk that the terrestrial carbon sink declines in the future

Climate consequences can in the future become even bigger than thought, because the capacity of the land vegetation to absorb carbon dioxide is likely to decline. This is the conclusion of a large international study with contribution by Umeå University. So far the vegetation has dampened climate change by taking up a significant fraction of carbon dioxide emissions, but it is uncertain if this effect will persist.

...

The land carbon sink has been around 11 billion tons carbon dioxide per year, compared to emissions of 35 billion tons. That's now, but to look into the future, to predict the carbon sink decades ahead, for our greatgrandchildren, the authors had to figure out the physiological mechanisms of the sink. That concerns what fraction of the carbon sink is due to carbon dioxide fertilization of photosynthesis, and if models of photosynthesis properly describe its increase. And finally one has to gauge if the current effects will persist over coming decades.

https://phys.org/news/2021-04-terrestrial-carbon-declines-future.html

Open source but very technical article:
https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.16866

From Conclusions:

Evidence for the CO2‐fertilization hypothesis suggests a highly valuable ecosystem service that is buying us time in the fight against climate change, although the size of this subsidy remains unclear. Based on diminishing theoretical GPP responses, probable increasing nutrient limitations, increasing mortality, and other negative temperature‐related effects (Peñuelas et al., 2017) it is highly likely that increases in terrestrial carbon storage as a result of iCO2 will decline into the future. A decline in this subsidy will result in accelerated climate change on the current trajectory of anthropogenic CO2 emissions.

[kassy]

Study Reveals Uncertainty In How Much Carbon The Ocean Absorbs Over Time

The ocean’s “biological pump” describes the many marine processes that work to take up carbon dioxide from the atmosphere and transport it deep into the ocean, where it can remain sequestered for centuries. This ocean pump is a powerful regulator of atmospheric carbon dioxide and an essential ingredient in any global climate forecast.

But a new MIT study points to a significant uncertainty in the way the biological pump is represented in climate models today. Researchers found that the “gold standard” equation used to calculate the pump’s strength has a larger margin of error than previously thought, and that predictions of how much atmospheric carbon the ocean will pump down to various depths could be off by 10 to 15 parts per million.

Given that the world is currently emitting carbon dioxide into the atmosphere at an annual rate of about 2.5 parts per million, the team estimates that the new uncertainty translates to about a five-year error in climate target projections.

“This larger error bar might be critical if we want to stay within 1.5 degrees of warming targeted by the Paris Agreement,” says Jonathan Lauderdale, a research scientist in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “If current models predict we have until 2040 to cut carbon emissions, we’re expanding the uncertainty around that, to say maybe we now have until 2035, which could be quite a big deal.”

...

In the new study, Lauderdale and Cael looked at how much difference it would make to estimates of carbon stored deep in the ocean if they changed the mathematical description of the biological pump.

*The martin curve was discovered in the 80ies but we do not know if this curve is correct and we can not really tell. There are 6 alernative equations see text for detail*

They started with the same six alternative equations, or remineralization curves, that Cael had previously studied. The team looked at how climate models’ predictions of atmospheric carbon dioxide would change if they were based on any of the six alternatives, versus the Martin curve’s power law.

https://scienceblog.com/522108/study-reveals-uncertainty-in-how-much-carbon-the-ocean-absorbs-over-time

Paper:
Reconciling the Size‐Dependence of Marine Particle Sinking Speed
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL091771

Even knowing what we do not know is quite a bit of work. 

[kassy]

Southern Ocean anthropogenic carbon sink constrained by sea surface salinity

Abstract
The ocean attenuates global warming by taking up about one quarter of global anthropogenic carbon emissions. Around 40% of this carbon sink is located in the Southern Ocean. However, Earth system models struggle to reproduce the Southern Ocean circulation and carbon fluxes. We identify a tight relationship across two multimodel ensembles between present-day sea surface salinity in the subtropical-polar frontal zone and the anthropogenic carbon sink in the Southern Ocean. Observations and model results constrain the cumulative Southern Ocean sink over 1850-2100 to 158 ± 6 petagrams of carbon under the low-emissions scenario Shared Socioeconomic Pathway 1-2.6 (SSP1-2.6) and to 279 ± 14 petagrams of carbon under the high-emissions scenario SSP5-8.5. The constrained anthropogenic carbon sink is 14 to 18% larger and 46 to 54% less uncertain than estimated by the unconstrained estimates. The identified constraint demonstrates the importance of the freshwater cycle for the Southern Ocean circulation and carbon cycle.

https://advances.sciencemag.org/content/7/18/eabd5964.full

[vox_mundi]

Climate Change: Amazon Turning From Friend to Foe
https://phys.org/news/2021-04-climate-amazon-friend-foe.html

The Brazilian Amazon released nearly 20 percent more carbon dioxide into the atmosphere over the last decade than it absorbed, according to a stunning report that shows humanity can no longer depend on the world's largest tropical forest to help absorb manmade carbon pollution.

From 2010 through 2019, Brazil's Amazon basin gave off 16.6 billion tonnes of CO2, while drawing down only 13.9 billion tonnes, researchers reported Thursday in the journal Nature Climate Change.

"We half-expected it, but it is the first time that we have figures showing that the Brazilian Amazon has flipped, and is now a net emitter," said co-author Jean-Pierre Wigneron, a scientist at France's National Institute for Agronomic Research (INRA).

"We don't know at what point the changeover could become irreversible," he told AFP in an interview.

... The study also showed that deforestation—through fires and clear-cutting—increased nearly four-fold in 2019 compared to either of the two previous years, from about one million hectares (2.5 million acres) to 3.9 million hectares, an area the size of the Netherlands.

"Brazil saw a sharp decline in the application of environmental protection policies after the change of government in 2019," the INRA said in a statement.

Brazilian President Jair Bolsonaro was sworn into office on January 1, 2019.

Yuanwei Qin et al. Carbon loss from forest degradation exceeds that from deforestation in the Brazilian Amazon, Nature Climate Change (2021)
https://www.nature.com/articles/s41558-021-01026-5

[Bruce Steele]

Ocean acidification in polar regions. The timeframes of reversing acidification > 60,000 years.
Most humans just can’t wrap their heads around the timeframes involved.
I have been looking at OA since 2005 and nothing in any scenario projected for what happens to our world at 450-550 ppm CO2 seems to get through to people. It’s like we can go extinct with a smile on our face. We can send ,and are willing to send , thousands of other species into extinction and not even lose sleep over it.
 I find myself getting angry far too often anymore and feel my attempts at educating others are like thrashing the air with my hands. Frustrated, sad , angry, and not who I once was. I don’t know how to walk away and I don’t know how to help. My mother , who has since passed , summed it up as “ the weight of the world”.

https://www.50x30.net/polar-ocean-acidification

[kassy]

The 'grand tour' Atlantic Ocean water takes around the world

...

The researchers found that about one-third of the water parcels left the Atlantic, then took a trip around the Pacific, Indian, and Southern oceans and needed about 300 years to return home. About 20% made roughly the same journey but traveled to greater depths and made a detour into the Weddell Sea off Antarctica. Those parcels needed 700 years to get back to the Atlantic.

The largest number, nearly half, needed 2,800 years to get back, diving for roughly 1,000 years into the abyssal Pacific Ocean. Those, Cessi said, took the "grand tour" of the world's oceans, visiting nearly every basin at varying depths before returning.

...

https://www.nsf.gov/discoveries/disc_summ.jsp?WT.mc_id=USNSF_1&cntn_id=302904

Not directly the Carbon cycle but these cycles play a role in where acidification manifests (at least the shorter ones).

[morganism]

Sulfur enhances carbon storage in the Black Sea

"The researchers posit that reactions with hydrogen sulfide play an important role in stabilizing carbon compounds. "This mechanism apparently contributes to the fact that there is more than twice as much organic carbon in the waters of the Black Sea as in oxygen-rich marine areas," says Niggemann. "This provides a negative feedback in the climate system that could counteract global warming over geological periods."

Hydrogen sulfide reacts with dissolved organic matter

As the new study shows, this highly reactive molecule binds with substances from a diverse group of carbonaceous materials that are present in every liter of seawater. These substances are known as dissolved organic matter (DOM) – a complex mixture of countless different molecules that are the product of decomposed organic matter or bacterial metabolic processes. "We were able to show very clearly that hydrogen sulfide reacts with the extremely diluted organic matter directly in the water," Niggemann explains. The products of the reaction are potentially more durable than the starting materials and therefore accumulate in the water."

https://phys.org/news/2021-06-sulfur-carbon-storage-black-sea.html

More information: Gonzalo V. Gomez-Saez et al, Sulfurization of dissolved organic matter in the anoxic water column of the Black Sea, Science Advances (2021). DOI: 10.1126/sciadv.abf6199

[vox_mundi]

Amazon Rainforest Now Emitting More CO2 Than It Absorbs
https://www.theguardian.com/environment/2021/jul/14/amazon-rainforest-now-emitting-more-co2-than-it-absorbs

The Amazon rainforest is emitting a billion tonnes of carbon dioxide a year, according to a study. The giant forest had been absorbing the emissions driving the climate crisis but is now causing its acceleration, researchers said.

Most of the emissions are caused by fires, many deliberately set to clear land for beef and soy production. But even without fires, hotter temperatures and droughts mean the south-eastern Amazon has become a source of CO2, rather than a sink.

The research used small planes to measure CO2 levels up to 4,500m above the forest over the last decade, showing how the whole Amazon is changing. Previous studies indicating the Amazon was becoming a source of CO2 were based on satellite data, which can be hampered by cloud cover, or ground measurements of trees, which can cover only a tiny part of the vast region.

The research, published in the journal Nature, involved taking 600 vertical profiles of CO2 and carbon monoxide, which is produced by the fires, at four sites in the Brazilian Amazon from 2010 to 2018. It found fires produced about 1.5bn tonnes of CO2 a year, with forest growth removing 0.5bn tonnes. The 1bn tonnes left in the atmosphere is equivalent to the annual emissions of Japan, the world’s fifth-biggest polluter.

https://www.nature.com/articles/s41586-021-03629-6

The scientists said the discovery that part of the Amazon was emitting carbon even without fires was particularly worrying.

Luciana Gatti, at the National Institute for Space Research in Brazil and who led the research, said: “The first very bad news is that forest burning produces around three times more CO2 than the forest absorbs. The second bad news is that the places where deforestation is 30% or more show carbon emissions 10 times higher than where deforestation is lower than 20%.”

Prof Scott Denning, at Colorado State University, said the aerial research campaign was heroic. “In the south-east, the forest is no longer growing faster than it’s dying. This is bad – having the most productive carbon absorber on the planet switch from a source to a sink means we have to eliminate fossil fuels faster than we thought.”

A satellite study published in April found the Brazilian Amazon released nearly 20% more carbon dioxide into the atmosphere over the past decade than it absorbed. Research that tracked 300,000 trees over 30 years, published in 2020, showed tropical forests were taking up less CO2 than before. Denning said: “They’re complementary studies with radically different methods that come to very similar conclusions.”

https://www.theguardian.com/environment/2021/apr/30/brazilian-amazon-released-more-carbon-than-it-absorbed-over-past-10-years

https://www.theguardian.com/environment/2020/mar/04/tropical-forests-losing-their-ability-to-absorb-carbon-study-finds

https://www.sciencedirect.com/science/article/pii/S0305750X21001972

Research published on Friday estimated that Brazil’s soy industry loses $3.5bn a year due to the immediate spike in extreme heat that follows forest destruction.

https://www.sciencedirect.com/science/article/pii/S0305750X21001972

[Bruce Steele]

NOAA wrote up a story on the beginnings of C-CAN , Calif. Current Acidification Network. Our group formed to help monitor ocean acidification in the coastal waters of Washington, Oregon, and Calif. ,involving a collaboration between science and industry. Story from NOAA OAP.

https://spark.adobe.com/page/Y6GRDuqVaQvpF/

[kassy]

A lack of fish faeces is changing the flow of carbon in the ocean

A shortage of fish faeces is contributing to shifts in the ocean’s carbon cycle of an equivalent magnitude to that of the impact of climate change on the ocean.

Fish-produced faecal pellets are one of the most efficient natural mechanisms of carbon storage, locking it deep in the ocean for up to 600 years. But the rise of industrial fishing has seen the number of fish in the sea fall, so Daniele Bianchi at the University of California, Los Angeles, and his colleagues decided to investigate how this has affected the flow of faeces.

The team developed a model of the global marine ecosystem that quantifies how the production of fish faeces has changed over time. The model is based on estimates of historical and present-day numbers of fish caught, as well as broader human-driven impacts on marine ecosystems, such as climate change.

...

Almost all of the biomass on Earth is ultimately the product of photosynthesis by plants, so one way to measure an animal’s influence on the ecosystem is to look at how much of this mass, known as global primary production, cycles through it.

The team found that the species that industrial fishers try to catch cycled 2 per cent of this mass before the 1900s, but by the time the number of fish caught industrially peaked in the 1990s, this had halved, as had the rate at which carbon locked up in fish faeces sank into the sea.

These figures suggest that the effect of industrial fishing on the ocean’s carbon cycle is comparable in magnitude to the impact of climate change on the ocean’s carbon, says Bianchi. “We should consider fish as an integral part of the ocean’s biogeochemical cycles.”

https://www.newscientist.com/article/2293190-a-lack-of-fish-faeces-is-changing-the-flow-of-carbon-in-the-ocean/

Paper:
Estimating global biomass and biogeochemical cycling of marine fish with and without fishing
https://www.science.org/doi/10.1126/sciadv.abd7554

[jai mitchell]

I remember doing some analytics trying to look at carbon pools and capture mechanisms during the previous interglacial and compared to today.

I estimated that terrestrial biomass was now about 25% that of the primordial old growth forests and that large bony fish ocean biomass is now 1/10th of that (the primary mechanism for this form of carbon sequestration).

Just another way of recognizing the lack of relevant paleoclimate analog to today's conditions.

[Freegrass]

Bottom trawling releases as much carbon as air travel, landmark study finds
https://www.theguardian.com/environment/2021/mar/17/trawling-for-fish-releases-as-much-carbon-as-air-travel-report-finds-climate-crisis

Dragging heavy nets across seabed disturbs marine sediments, world’s largest carbon sink, scientists report

Fishing boats that trawl the ocean floor release as much carbon dioxide as the entire aviation industry, according to a groundbreaking study.

Bottom trawling, a widespread practice in which heavy nets are dragged along the seabed, pumps out 1 gigaton of carbon every year, says the study written by 26 marine biologists, climate experts and economists and published in Nature on Wednesday.

The carbon is released from the seabed sediment into the water, and can increase ocean acidification, as well as adversely affecting productivity and biodiversity, the study said. Marine sediments are the largest pool of carbon storage in the world.

The report – Protecting the global ocean for biodiversity, food and climate – is the first study to show the climate impacts of trawling globally. It also provides a blueprint outlining which areas of the ocean should be protected to safeguard marine life, boost seafood production and reduce climate emissions.

Only 7% of the ocean is under some kind of protection. The scientists argue that, by identifying strategic areas for stewardship – for example, regions with large-scale industrial fishing and major economic exclusion zones or marine territories – nations could reap “significant benefits” for climate, food and biodiversity. Protecting “strategic” ocean areas could produce 8m tonnes of seafood, they say.

“Ocean life has been declining worldwide because of overfishing, habitat destruction and climate change,” said Dr Enric Sala, explorer-in-residence at the National Geographic Society and lead author of the paper. “In this study, we’ve pioneered a new way to identify the places that – if strongly protected – will boost food production and safeguard marine life, all while reducing carbon emissions.

“It’s clear that humanity and the economy will benefit from a healthier ocean. And we can realise those benefits quickly if countries work together to protect at least 30% of the ocean by 2030.”

The scientists identified marine areas where species and ecosystems face the greatest threats from human activities. They developed an algorithm to identify regions where safeguarding would deliver the greatest benefits across three goals: biodiversity protection, seafood production and climate mitigation. They then mapped these to create a practical “blueprint” that governments can use, depending on their priorities.

The top 10 countries with the most carbon emissions from bottom trawling, and therefore the most to gain, were China, Russia, Italy, UK, Denmark, France, the Netherlands, Norway, Croatia and Spain.

The analysis shows that the world must protect a minimum of 30% of the ocean in order to provide multiple benefits. The scientists say their results lend credence to the ambition of protecting at least 30% of the ocean by 2030, which is part of the target adopted by a coalition of 50 countries this year to slow the destruction of the natural world.

Zac Goldsmith, the UK minister for Pacific and the environment, described the paper as “an important contribution to the science on ocean protection and highlights the need for countries to work together to protect at least 30% of the global ocean by 2030”.

He said the UK was playing a leading role in a global ocean alliance supporting this target and promised: “We will do all we can to deliver it at the UN biodiversity conference in China.”

“There is no single best solution to save marine life and obtain these other benefits. The solution depends on what society – or a given country – cares about, and our study provides a new way to integrate these preferences and find effective conservation strategies,” said Dr Juan S Mayorga, a report co-author and a marine data scientist with the Environmental Market Solutions Lab at the University of California, Santa Barbara and Pristine Seas at the National Geographic Society.

The study calculates that eliminating 90% of the present risk of carbon disturbance due to bottom trawling would require protecting only about 4% of the ocean, mostly within national waters.

Dr David Mouillot, a report co-author and a professor at the Université de Montpellier in France, said: “One notable priority for conservation is Antarctica, which currently has little protection, but is projected to host many vulnerable species in the near future due to climate change.”

The study estimated the emissions at between 0.6 and 1.5 gigatons of carbon dioxide a year, or an average of 1 gigaton annually. Aviation emissions of carbon dioxide in 2019 were 918m tons.

The UN’s biodiversity conference, Cop15, which is to be held in Kunming, China, this year, is expected to produce a global agreement for nature, building on the targets already set by some nations to protect at least 30% of the ocean by 2030.

[Bruce Steele]

It would be nice if such a grand reach at closing fishing grounds was based upon some actual pH, alkalinity, and omega measurements about the effects of bottom disturbances rather than formulas and models not tested.
 Along with organic carbon released that could potentially oxidize there would also be calcium carbonate resuspended that would increase alkalinity as it dissolved. Increased alkalinity would increase the omega and counteract potential negative biological impacts of resuspended organics and carbonates.
 It wouldn’t be difficult to actually place pH meters or take water samples while disturbances are occurring to get some real world numbers about chemical characteristics of water in areas fished. But when your goal is to close fishing you wouldn’t want to spend some money and  effort to fact base your claims.
 
 

[Freegrass]

Why didn't CO2 level go up much in the early '90? Where did all that CO2 go to? I know Pinatubo cooled the planet, but CO2 should have still gone up. Where did it go? Did the ash from the Pinatubo eruption cause a plankton bloom that sucked CO2 out of the atmosphere? If we can replicate what happened back then, we could stop CO2 levels from going up, no?

[J Cartmill]

The collapse of the Soviet Union in 1991 led to a huge drop in greenhouse-gas emissions because the resulting economic crisis meant many people stopped eating meat.


https://www.nature.com/articles/d41586-019-02024-6

https://science.ku.dk/english/press/news/2019/soviet-collapse-saved-the-atmosphere-from-7-billion-tonnes-of-co2/

[Freegrass]

The collapse of the Soviet Union in 1991 led to a huge drop in greenhouse-gas emissions because the resulting economic crisis meant many people stopped eating meat.


https://www.nature.com/articles/d41586-019-02024-6

https://science.ku.dk/english/press/news/2019/soviet-collapse-saved-the-atmosphere-from-7-billion-tonnes-of-co2/

That's impressive, but it doesn't make any sense. We had a similar reduction of CO2 because of the pandemic, yet CO2 levels kept going up at the same rate. Not even a little blip to be seen in the graph...

What shows up in that graph must have another reason. The rest of the world kept producing CO2, so something caused a big uptake of CO2 in those years. And the only thing I can think of that could accomplish this is massive ocean seeding by the Pinatubo eruption.

[oren]

It has been known for a long time that the '90s blip was a result of the Soviet Union collapse. While it may not make any sense to you I wouldn't throw this explanation out the window and stick to a new one of your choice without reading a lot on the subject.

[El Cid]

The collapse of the Soviet Union in 1991 led to a huge drop in greenhouse-gas emissions because the resulting economic crisis meant many people stopped eating meat.

While agriculture changes might also be important, it is worth noting, that Eastern Europe had a huge economic depression during 1990-1994 leading to a complete collapse of industry as well. Unemployment rates reached 20-40% and GDP collapsed by 20-40% as well. This is equivalent to the Great Depression (1929-33) in the USA!
Most of the heavy industry  closed while energy consumption also was reduced by a lot (20-30%).

I know, I lived through it. Basically everybody was poor. Not African poor but very little "extra"-consumption during those years by anyone.

[Freegrass]

It has been known for a long time that the '90s blip was a result of the Soviet Union collapse. While it may not make any sense to you I wouldn't throw this explanation out the window and stick to a new one of your choice without reading a lot on the subject.

Sorry, but I'm not convinced. The drop in Russia is too insignificant to register on a global scale. All other countries just kept pumping out CO2. What was lost in the USSR got compensated by the rise in China.

Scroll down a little and look at the graph.

https://www.wri.org/insights/history-carbon-dioxide-emissions

[oren]

Stubborn people might not be convinced, but the data is there (thanks for the source you provided). A similar drop happened in other Eastern Europe countries not shown in the chart, as can be seen in the Europe-wide data.

[Freegrass]

You're welcome. Just stumbled on it...

It's stubborn people that change the world, right? How long did it take before someone took Einstein's theory of relativity serious? Not saying I'm Einstein! But sometimes you just have to challenge conventional group thinking... It worked predicting the ice minimum this year, didn't it? 

I just can't believe that this little dip in Russia could cause a global stall on atmospheric CO2. It's impossible... During that same period the CO2 from other countries kept going up. Especially in China! And so I absolutely can't believe that reduced emission in the USSR - which are only a small portion of global CO2 emissions - could cause a stall in atmospheric CO2 like we see in that graph. Especially because we just had a global pandemic that didn't register at all. It just doesn't make any sense to me... The 1991 Pinatubo eruption that cooled the entire planet for a few years makes a lot more sense to me...

Edit: added a snipped screenshot of the amount of CO that was lost by Russia, and gained by China. They basically cancel eachother out...

Edit 2: And don't forget that this reduction in Europe and Asia didn't mean that CO2 emissions stopped. It was only the rate of additional CO2 that went down a little. What was there stayed there, and so CO2 levels should have still gone up. Maybe at a slower rate, but they still should have gone up. A stall like we see in that graph means no addition of CO2 for 3 years. And that's impossible... Addition and reduction is the only way that graph could have flattened... The world didn't stop emitting all of a sudden...

[gerontocrat]

Looks to me like a confusion between CO2 emissions and CO2 ppm concentration.

If by some miracle annual CO2 emissions dropped by 45% from now to 2030 CO2 ppm concentration would continue to rise but at a slower rate.

[The Walrus]

Looks to me like a confusion between CO2 emissions and CO2 ppm concentration.

If by some miracle annual CO2 emissions dropped by 45% from now to 2030 CO2 ppm concentration would continue to rise but at a slower rate.

Good catch gerontocrat.  All the previous graphs show the slowdown in the growth of atmospheric concentration.  While China and other countries kept emitting CO2 at a roughly constant rate from 1990-1994, Russia and the eastern bloc decreased dramatically.  The overall effect was a slowdown in the RISE of atmospheric CO2, as evident from the graphs provided.

[Freegrass]

Looks to me like a confusion between CO2 emissions and CO2 ppm concentration.

If by some miracle annual CO2 emissions dropped by 45% from now to 2030 CO2 ppm concentration would continue to rise but at a slower rate.

I totally agree. That's why I don't believe that a drop in annual emission from the USSR could cause a stagnation of atmospheric CO2 concentrations in the early the '90s. Something else must have happened that put a break on global annual emission for 3 years (mostly in summer). And the only thing that would be significant enough to do this, is Pinatubo...

And then I assume it could be all that ash that fell into the ocean that caused a massive algae bloom and extracted CO2 from the atmosphere. But I'm not sure about that. That's just an assumption... But I'm pretty sure it's Pinatubo. Not Russia...

[Freegrass]

Looks like I was wrong. Is it a 40 year lag time?

The best estimate for the thermal lag delay is that it takes very roughly forty years from the time we increase CO2 levels for most of warming to occur in response to that extra CO2.

https://www.anthropocenemagazine.org/2021/11/poo-from-the-worlds-largest-animals-have-a-stunning-effect-on-ocean-ecosystems-and-even-carbon-capture/

Help me out here! I need the right facts so I don't say stupid things on twitter. And no, I'm not gonna read that entire thread... Too much... Just tell me please!

[kassy]

At the time is was the Soviet Union and basically the whole Warschaupact that collapsed .
The growth in China only took off later.

There is also a difference between human emissions which we can easily if crudely calculate and the atmospheric concentrations.

Pinatubo:
The effects of the 1991 eruption were felt worldwide. It ejected roughly 10 billion tonnes (1.1×1010 short tons) or 10 km3 (2.4 cu mi) of magma, and 20 million tonnes (22 million short tons) of SO2, bringing vast quantities of minerals and toxic metals to the surface environment. It injected more particulate into the stratosphere than any eruption since Krakatoa in 1883. Over the following months, the aerosols formed a global layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C (0.9 °F) in the years 1991–1993,[8] and ozone depletion temporarily saw a substantial increase.[9]

 A paper about CO2 and Pinatubo:

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.

...

"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."

...

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

And just a part of it:

There's variability in the rate at which the ocean takes up carbon dioxide, which isn't fully understood. In particular, the scientific community has puzzled over why the ocean briefly absorbed more carbon dioxide in the early 1990s and then slowly took up less until 2001, a phenomenon verified by numerous ocean observations and models.

McKinley and her coauthors addressed this question by using a diagnostic model to visualize and analyze different scenarios that could have driven greater and lesser ocean carbon uptake between 1980 and 2017. They found the reduced ocean carbon sink of the 1990s can be explained by the slowed growth rate of atmospheric carbon dioxide early in the decade. Efficiency improvements and the economic collapse of the Soviet Union and Eastern European countries are thought to be among the causes of this slowdown.

But another event also affected the carbon sink: The massive eruption of Mount Pinatubo in the Philippines in 1991 caused the sink to temporarily become much larger coincident with the eruption.

"One of the key findings of this work is that the climate effects of volcanic eruptions such as those of Mount Pinatubo can play important roles in driving the variability of the ocean carbon sink," said coauthor Yassir Eddebbar, a postdoctoral scholar at Scripps Institution of Oceanography.

Pinatubo was the second-largest volcanic eruption of the 20th century. The estimated 20 million tons of ash and gases it spewed high into the atmosphere had a significant impact on climate and the ocean carbon sink. The researchers found that Pinatubo's emissions caused the ocean to take up more carbon in 1992 and 1993. The carbon sink slowly declined until 2001, when human activity began pumping more carbon dioxide into the atmosphere. The ocean responded by absorbing these excess emissions.

PS: How can you know the right facts without context? Maybe you should do more reading.

[Freegrass]

Pinatubo was the second-largest volcanic eruption of the 20th century. The estimated 20 million tons of ash and gases it spewed high into the atmosphere had a significant impact on climate and the ocean carbon sink. The researchers found that Pinatubo's emissions caused the ocean to take up more carbon in 1992 and 1993. The carbon sink slowly declined until 2001, when human activity began pumping more carbon dioxide into the atmosphere. The ocean responded by absorbing these excess emissions.

Thanks Kassy! That confirms my suspicion. I'll try to read the paper later.

[kassy]

Poo from the world’s largest animals have a stunning effect on ocean ecosystems—and even carbon capture

A million additional whales defecating close to the surface would be like having massive ocean fertilizer machines—absorbing as much carbon as forests covering a continent


The Southern Ocean that encircles Antarctica has, for decades, been home to a mystery known as the “krill paradox.” It goes like this: tiny shrimp-like krill have been in decline there for decades, even though the population of one of their chief predators—whales—fell dramatically during the 20th century. With fewer whales, shouldn’t krill numbers boom? Now, scientists think they have an answer: Whale poop.

Thanks to an elaborate decade-long investigation involving whale-mounted trackers, drones and sonar, scientists have found that the planet’s largest animals eat and poop far more than previously thought. This gluttony has the potential to ripple through entire ecosystems—including krill—as the whales vacuum up vast amounts of nutrients, then spread them back into the water as feces.

“Just this idea that if you remove large whales, there’s actually less productivity and potentially less krill and fish is amazing,” said Jeremy Goldbogen, a Stanford University biologist who supervised much of the work.

The insight came from a simple question: How much do baleen whales eat?

The animals, which can grow as large as a commercial airliner in the case of the blue whale, feed on some of the smallest animals in the sea by sucking vast amounts of ocean water through comb-like structures in their mouths called baleen. The baleen catches krill or small fish such as anchovies, which the whales then swallow.

...

The results were stunning. These whales, it turns out, eat approximately triple the amount of food previously estimated. For the eastern North Pacific blue whale, that amounted to roughly 16 metric tons per day—the equivalent of eating 3 adult African elephants. To grasp the difference from previous studies, the researchers noted that in 2008 scientists predicted that each year whales off the west coast of North America ate approximately 2 million metric tons in total. The new study found that individual blue, fine and humpback whales in the area ate that amount, according to the study, published today in the journal Nature.

“Think of these large whales as mobile krill processing plants,” said Matthew Savoca, a marine ecologist and postdoctoral fellow at Stanford University who was the study’s lead author.

...

The researchers suspect the answer is in whale poop, or, more specifically, the iron contained in the poop. The growth of phytoplankton in the Southern Oceans is limited by a lack of iron, so having more than a million additional whales defecating relatively close to the ocean surface would be like having fertilizer machines crisscrossing the region. At pre-hunting numbers, Antarctic minke, humpback, fin and blue whales combined would have injected as much as 1500 metric tons of iron back into the environment, much of which otherwise would have sunk to the ocean floor as krill died.

...

https://www.anthropocenemagazine.org/2021/11/poo-from-the-worlds-largest-animals-have-a-stunning-effect-on-ocean-ecosystems-and-even-carbon-capture/

Oh look another lost sink.

On a more positive note lets plant a million more wales. 

[Richard Rathbone]

Surely green whales must be better at this than blue whales?

[Freegrass]

Surely green whales must be better at this than blue whales?

I wouldn't know mate... I'm a sperm whale... 😂🤣😂

[Freegrass]

CO2 emissions per capita by country in 2020, based on new @gcarbonproject data.
https://twitter.com/SeppalaVilleEN/status/1458076684134100992