Carbon Cycle

[kassy]

It is. And we should really stop treating this as something we can solve later instead of doing what we can now. Of course in there we have a big chance that our current society will not actually survive this but that does not mean we have to make things worse then they could be.

[glennbuck]

10 Celsius! So Sam Carana from Arctic news forum was closer to the truth than people thought? http://arctic-news.blogspot.com/

[Richard Rathbone]

My initial read of the paper.

Hansen's hanging an awful lot of his argument on a feature that has only just emerged in his latest GCM and he doesn't have much idea why its different. The change between models of the y-axis intercept on Fig 5b is a genuinely big deal, but my reading of the paper is that this could be a model artefact and is not as solid a result as Hansen would like it to be.

If its real and only appeared because the model got better, then all the consequences follow. If its an artefact and only appeared because the model got more detail (and hence more opportunity to be overfitted) they don't.

Hansen's sided with the wolf pack rather than pack in the current generation of climate models. There are two strands to this. Clouds and paleo. He argues that clouds respond fast to reduce energy imbalances and that there are large errors in the reconstruction of the LGM climate. And aerosols, which are the reason its hard to model clouds and work on them in the last decade is why he has confidence his new model effect is genuine and the paleo constraints are wrong.

James Annan did a blog on the paleo argument earlier this year. He thinks the paleo reconstruction that Hansen is relying on in this paper is the consequence of bad statistics. https://bskiesresearch.wordpress.com/2022/05/24/egu-2022/

[El Cid]

In the paper, they claim an equilibrium climate sensitivity of a least 4C, (range 3.5-5.5).  Currently, atmospheric carbon dioxide is approaching a 50% increase from pre-industrial levels.  Based on a 4C climate sensitivity, temperatures in the pipeline, based on current CO2 levels,  amount to less than 2C increase over pre-industrial.   How did they come up with 10C?

I also did not understand how they came up with the 10 C, though I read the paper

To oversimplify it, this is how I understand what they say:

- new evidence points to higher ECS than previously thought
- previous models underestimated aerosol negative forcing, and to counterbalance that they had too fast deep ocean warming, both are wrong
- they think that ECS is 4 C or even more, and roughly half of that is "fast", half of that happens slower
- since we have already increased CO2 by 50%, we should have warmed by cca 2 C but aerosols had a big negative forcing and that is why we are just above 1 C
- but aerosols are quickly phased out, so we are in for very fast warming during the next decades and will hit 2 C in 20-30 years

Now, this is all clear and reasonable (though I do not know how right they are)

Now, that 10 C...I do not understand

[The Walrus]

In their paper, they use a larger negative aerosol forcing, thus the ECS must be higher to offset the aerosols.  One of their biggest uncertainties is the following, "The indirect forcing caused by aerosol-induced cloud changes must be extracted from natural (unforced) cloud variability and cloud changes caused by ongoing global warming."

They conclude that when other GHG forces, besides CO2, are allowed to change, the ECS increases 25% to 5C.  They then make this broad sweeping statement, without clarifying how they get there:

"When all feedbacks, including ice sheets, are allowed to respond to the climate forcing, the equilibrium response is approximately doubled, i.e., ESS is ~ 10°C."

[Sublime_Rime]

In the paper, they claim an equilibrium climate sensitivity of a least 4C, (range 3.5-5.5).  Currently, atmospheric carbon dioxide is approaching a 50% increase from pre-industrial levels.  Based on a 4C climate sensitivity, temperatures in the pipeline, based on current CO2 levels,  amount to less than 2C increase over pre-industrial.   How did they come up with 10C?

- since we have already increased CO2 by 50%, we should have warmed by cca 2 C but aerosols had a big negative forcing and that is why we are just above 1 C

Here things get confusing for me, because they cite that total GHG forcing estimates are 4.1W/m^2, equivalent to 2xCO2 and ~4C of warming, but also say that expected warming is ~2.2C currently without aerosols. I interpreted this as that when aerosols are subtracted and other ultrafast, fast and slow feedbacks are considered, we're up to 4C with current levels of warming (with short-mid term changes in albedo, ocean mixing, etc). Where they get to 10C is still uncertain to me, unless that refers to "very slow feedbacks" on the century time-scale, such as with secondary CO2 and methane sources (so 4C is decadal with no aerosols, 2.2 ultrafast w/o aerosols).

Does this make sense to others? I have to admit I haven't had time for a really deep dive here, but seems worth it at some point.

[kassy]

The 10C is longer term and also not that important.
One question was cloud modelling and the recent developments don´t look good. Post from the clouds thread below.

The other long term problem is albedo loss. If our CO2eq mix declines slower then the loss of albedo then that will lead to long term warming when that overpowers the decline

One of climate change's great mysteries is finally being solved


For over a decade, the largest scientific uncertainty about how the planet will respond to warming temperatures hasn’t come from how much carbon dioxide will be soaked up by the ocean or absorbed by the trees. It’s come, instead, from clouds.

The fluffy, whimsical collections of water droplets floating in the air have, for some time, confounded climate scientists and models alike. Scientist have long known that depending on how clouds respond to warming temperatures, the world could become even warmer or a little bit cooler. They just haven’t known which.

But in the past few years, scientists have begun to nail down exactly how clouds will change shape and location in the rapidly warming world. The result is good news for science – but not good news for humanity.

“We’ve found evidence of the amplifying impact of clouds on global warming,” said Paulo Ceppi, a climate scientist at Imperial College London.

Scientists have long known that clouds have two primary influences on the global climate. First, clouds are reflective – their white surfaces reflect the sun’s rays away from Earth, creating a cooling effect. (If the planet were suddenly devoid of these fluffy parasols, the planet would be roughly five times hotter than even the most disastrous global warming projections.)

But clouds also create a warming effect – certain types of clouds insulate the Earth’s radiation, keeping the planet warm much like carbon dioxide released from the burning of fossil fuels.

Which effect is stronger depends on the type of cloud. Cirrus clouds – high, wispy clouds visible in the distant atmosphere on relatively clear days – absorb and trap more radiation, warming the Earth. Stratus or stratocumulus clouds – plump, fluffy clouds that often hover over the ocean on overcast days – reflect more sunlight, cooling the Earth.

How exactly those two factors will balance out as the world warms has been uncertain. That’s mostly because, even though clouds can look gigantic – when you are flying through them in a plane or looking up at them from the ground – they form at microscopic levels, when water vapour condenses around a particle of dust or a droplet.

As a result, they are essentially impossible to model in the standard big climate models. (Clouds form at the micrometer level, while the models that most climate scientists use separate the world into blocks hundreds of kilometres in width.)

“We have a really tough time simulating with any fidelity how clouds actually behave in the real world,” said Timothy Myers, a postdoctoral researcher at the Lawrence Livermore National Laboratory in California.

But in recent years, scientists have gained increasing clarity on what will happen – and what is already happening – to clouds as the planet warms.

First, the high, wispy cirrus clouds that trap the Earth’s radiation are expected to shift upward in the atmosphere, to lower temperature zones. Thanks to a complicated relationship between clouds and the radiation of the Earth, that will increase the amount of radiation that the cirrus clouds trap in the atmosphere.

“When they rise, their greenhouse effect, or warming effect, on the Earth tends to increase,” Myers said.

That result has been known for about a decade, and indicates that clouds are likely to amplify global warming. But just in the past few years, researchers have also discovered that the number of low-level stratus or stratocumulus clouds are expected to decrease as the planet continues to warm.

One study, in the journal Nature Climate Change, used satellite observations to discover how cloud formation is affected by ocean temperatures, wind speed, humidity and other factors – and then analysed how those factors will change as the world warms.

“We concluded that as the ocean warms, the low-level clouds over the oceans tend to dissipate,” said Myers, one of the authors of the study. That means that there are fewer clouds to reflect sunlight and cool the earth – and the change in low-level clouds will also amplify global warming.

Another paper, in the Proceedings of the National Academy of Sciences, found a similar result, also using observational techniques. Research based on high resolution models – which are better able to model cloud formation than general, larger-scale climate models – have also concluded that clouds are likely to amplify global warming.

...

According to another study released last month in the Proceedings of the National Academy of Sciences, sulfate aerosols have spurred cloud formation, thus masking some of the global warming that has already occurred.

...

Scientists once estimated that if CO2 reached 560 ppm, the temperature would increase between 1.5 and 4C – a range that spans a “still very liveable planet” to “near-apocalypse levels of warming”.

A great deal of that uncertainty has stemmed from the question of clouds. Because clouds are so influential on the Earth’s climate already, even small changes in clouds as the world warms can have large effects on future temperature change.

The new cloud research indicates that the lower estimates for warming are highly unlikely. Instead, the recent papers estimate that CO2 levels of 560 ppm would probably result in at least 3 or 3.5 degrees of warming.

...

https://www.stuff.co.nz/environment/climate-news/300763418/one-of-climate-changes-great-mysteries-is-finally-being-solved

All in all this tells a simple tale. So we are warming since the seventies. Then we added more then ever before in the last thirty years.

If you use 2C global increase so the signal without dampening then you have to keep in mind that a part of it is the sea which is cooler and the other part is the land where it is even warmer.

For the Netherlands you can do a quick translation to double global so at 2C we would be at around 4C above the historical norm. This would be problematic for a lot we try to grow because heat waves will be higher and not that nice in the cities either. Should also bring interesting rain events.

Up in the Arctic the effect is even bigger and once we start a partial blue ocean event you are looking at a quick 0,2-0,6C rise in global temperatures on a short scale plus some wild weather effects. 

The effects are unavoidable and you can add them. The big question is how much we can handle and that is way below 10C anyway.

[Sublime_Rime]

The 10C is longer term and also not that important.

Thanks Kassy, I always appreciate your perspective. I'm just curious as to why you said the10C doesn't matter. I interpreted that statement as: "Its so highly catastrophic that it doesn't need to be very precise." Is that correct?

I'd say the fact that Hansen et al., found such a large long-term forcing just as disturbing as their shorter term findings. While I agree its not important whether its 8C, 10C or even 12C with all the feedbacks incorporated, just the fact that we could already be committed to that level of warming CURRENTLY, is pretty frightening. Of course not for myself, or even my non-existent grand-children, but the stability of this civilization that I feel compassion for.

That aside, I'd like to highlight that this is a preprint, and should therefore be taken with handful of salt until it makes it past peer review. I'm even doubting whether its good policy to post preprints on public forums where they might get confused with peer reviewed work (though one could argue such a forum could function as a form of peer review).

[The Walrus]

Other studies on clouds have come to different conclusions. 

https://www.nature.com/articles/s41558-021-01038-1

Another study showed that deforestation will decrease low-level clouds, leading to greater warming.

https://www.nature.com/articles/s41467-021-24551-5

[Richard Rathbone]

There is something in Hansen's model that is temporarily suppressing warming. I couldn't find an explanation of the physical mechanism behind it in the paper, I'm going to have to read it more closely, but there is some sort of ultra fast negative feedback in his latest model that pushes a lot more of the warming into the pipeline than Hansen previously thought. Something like cloud structure rearranging itself in a way that cools as long as the earth is getting warmer. e.g. Add enough CO2 to instantly generate 2 W/m2 of imbalance and that imbalance in turn generates enough extra reflective clouds to drop it back to 1.2 W/m2. Crucially this is short term and a consequence of there being an imbalance. As the earth warms up to a new equilibrium, it goes away. Its an ultrafast negative feedback that slows warming but it doesn't avert it.

Initial warming going slower means that the ratio of what's in the pipeline to what's already observed is smaller than Hansen previously thought, and that the future trajectory is going to go up more steeply and to a higher level than he previously thought.

If he's right, there's a nasty shock coming over the next decade because emission reductions are going to have much less of an effect than anticipated. The feedback will act to reduce their immediate effect, just as it acts to reduce the immediate warming effect of additional emissions.

[El Cid]

If he's right, there's a nasty shock coming over the next decade because emission reductions are going to have much less of an effect than anticipated. The feedback will act to reduce their immediate effect, just as it acts to reduce the immediate warming effect of additional emissions.

Yes, I think the main point is that (if he is right and aerosols have a much bigger negative forcing than previously thought - a theme he's been pounding for a while) the next 2-3 decades should see accelerated warming, instead of 0,2C /decade we could see 0,3-0,4 C or even 0,5 C.

And yes, kassy is right that this is a global average and NH warms faster than SH, and NH land warms faster than NH oceans, and the closer to the pole, the bigger the warming, so Europe will likely see 0,6-1C/decade (once again: if Hansen is right).

However contrary to kassy, I still think the main problem is NOT Europe or NH midlatitudes.  If London (or the Hague for that matter) becomes Madrid, or Milan becomes Malaga you can adapt to that. But what happens to Cairo or Baghdad or Delhi? That is the real problem. It's strange that it is mostly the US and Europe responsible for most of the emissions historically but they are not the ones who will suffer the most...

[Richard Rathbone]

If he's right, there's a nasty shock coming over the next decade because emission reductions are going to have much less of an effect than anticipated. The feedback will act to reduce their immediate effect, just as it acts to reduce the immediate warming effect of additional emissions.

Yes, I think the main point is that (if he is right and aerosols have a much bigger negative forcing than previously thought - a theme he's been pounding for a while) the next 2-3 decades should see accelerated warming, instead of 0,2C /decade we could see 0,3-0,4 C or even 0,5 C.

Hansen is saying aerosols have a much bigger effect than HE previously thought and is upping how much warming he expects as a result.

He was surprised by the ultrafast feedback in his new model, so he asks why didn't he already see it had to be there from existing data. His answers are i) aerosols are an even bigger deal, ii) LGM was even colder than people think, iii) it might be an artefact of his model.

I don't know enough about aerosols to evaluate i). ii) looks like confirmation bias to me. iii) another thing he has been banging on about for ages is that modellers should publish more details of their results, and its possible there's a whole bunch of other models out there (what Gavin at realclimate calls the wolf pack) that have the same thing in their current models as him, but they aren't publishing enough detail for him to know. This preprint is a challenge to them to publish the same details of their results that he's put in it about his. I guess they are scared they might be wrong, and he's scared he might be right.

[kassy]

Thanks Kassy, I always appreciate your perspective. I'm just curious as to why you said the10C doesn't matter. I interpreted that statement as: "Its so highly catastrophic that it doesn't need to be very precise." Is that correct?

Yes indeed. There are two reasons for this.
1 is time. It is the final outcome but that is for really long term. We won´t see Greenland melt completely either but it´s the extra SLR now which is our problem. The aerosol fallout is quick but the 10C is also the result of some long term albedo effects.
2 On the way to 10C we will hit a temperature where it will be really problematic. We don´t know
what value that is exactly but it is way below 10C. It could very well be around 2C. We are moving from an equilibrium to another state. At some point the temperatures get to high for the local plants.

The Arctic sea ice will go at some point which will bring some interesting weather and a rapid boost for global temperatures.

I still think the main problem is NOT Europe or NH midlatitudes.  If London (or the Hague for that matter) becomes Madrid, or Milan becomes Malaga you can adapt to that. But what happens to Cairo or Baghdad or Delhi?

While the effect of aerosol drop out will be gradual a thing the onset of a partial BOE is not.

The future speed of change will be problematic everywhere.

[kassy]

We conclude that peak aerosol climate forcing – in the first decade of this century – was of a
(negative) magnitude of at least 1.5-2 W/m2. We estimate that the GHG plus aerosol climate
forcing during the period 1970-2010 grew +0.3 W/m2 per decade (+0.45 from GHG, – 0.15 from
aerosols), which produced observed warming of 0.18°C per decade. With current policies, we
expect climate forcing for a few decades post-2010 to increase 0.5-0.6 W/m2
per decade and produce global warming at a rate at least +0.27°C per decade. In that case, global warming should reach 1.5°C by the end of the 2020s and 2°C by 2050 (Fig. 19).

Well i finally read the paper. It was interesting to see how Ruddimans theory came into it. We really do underestimate what we did earlier.

Testing 1.5°C by the end of the 2020s is something we can watch in real time. It is also quite likely as is the rest which is really problematic.

[Richard Rathbone]

More from Hansen on this subject at

https://mailchi.mp/caa/earths-energy-imbalance-and-climate-response-time

(flagged in the Energy Imbalance thread by jai)

I reckon its a rather shorter and better written account and well worth reading even if you've slogged though the preprint.

[The Walrus]

More from Hansen on this subject at

https://mailchi.mp/caa/earths-energy-imbalance-and-climate-response-time

(flagged in the Energy Imbalance thread by jai)

I reckon its a rather shorter and better written account and well worth reading even if you've slogged though the preprint.

From this article, they conclude that ECS is at least 4, but their figure shows a warming of closer to 3.5, but that takes 2000 years to reach.

[kassy]

That is the GISS model outputs so just one of the inputs. Just read the whole paper:

https://arxiv.org/abs/2212.04474

And yes the whole measure is about the result of instantly doubling CO2. The end result of that always takes time which runs into millenia. The difference between the model results lead them to recalculate ECS. This involves many more factors.

The end result is also not important:

With current policies, we expect climate forcing for a few decades post-2010 to increase 0.5-0.6 W/m2per decade and produce global warming at a rate at least +0.27°C per decade.
In that case, global warming should reach 1.5°C by the end of the 2020s and 2°C by 2050 (Fig. 19).

This is what matters and the wait is not a thousand years. This is an interesting prediction because we can check it with a little patience.

[Sublime_Rime]

More from Hansen on this subject at

https://mailchi.mp/caa/earths-energy-imbalance-and-climate-response-time

Thanks again Richard, this has been helpful in particular with the role of ocean mixing modeling.

I'm still having trouble with the ultrafast feedback, assumed to be from changes in cloud formation. This ultrafast feedback, whatever it is caused by, is reducing the EEI almost instantly, but not leading to a more precipitous increase in temperature in the near-term. Hansen et al. also state that they suspect the cloud feedback is part of a higher estimation of ECS they see in their models.

So is the theory that the cloud feedback is rapidly counterbalancing the warming produced by GHGs by ~1/3, but then also leading to increased warming over the fast-feedback timescale included in ECS? Essentially "hiding" the warming produced by GHGs in the short term, slowing the ocean heating, which will eventually diminish the cloud feedback as mixing occurs?

[The Walrus]

More from Hansen on this subject at

https://mailchi.mp/caa/earths-energy-imbalance-and-climate-response-time

Thanks again Richard, this has been helpful in particular with the role of ocean mixing modeling.

I'm still having trouble with the ultrafast feedback, assumed to be from changes in cloud formation. This ultrafast feedback, whatever it is caused by, is reducing the EEI almost instantly, but not leading to a more precipitous increase in temperature in the near-term. Hansen et al. also state that they suspect the cloud feedback is part of a higher estimation of ECS they see in their models.

So is the theory that the cloud feedback is rapidly counterbalancing the warming produced by GHGs by ~1/3, but then also leading to increased warming over the fast-feedback timescale included in ECS? Essentially "hiding" the warming produced by GHGs in the short term, slowing the ocean heating, which will eventually diminish the cloud feedback as mixing occurs?

The cloud feedback would only diminish in the absence of future warming.  The model assumption is an instantaneous doubling, but no further increase.  That would lead to the fast-feedback indicated.  In the real world, the feedback is in response to the warming, and not “hiding” it at all.  The cloud feedback will remain, as long as atmospheric conditions remain.

[Richard Rathbone]

So is the theory that the cloud feedback is rapidly counterbalancing the warming produced by GHGs by ~1/3, but then also leading to increased warming over the fast-feedback timescale included in ECS? Essentially "hiding" the warming produced by GHGs in the short term, slowing the ocean heating, which will eventually diminish the cloud feedback as mixing occurs?

Yes.

I could hypothesise a mechanism for how that might happen, because clouds have both heating and cooling effects and one might be temporary and associated with an imbalance while the other might be permanent and associated with a temperature change. However I'd expect a description of it in the paper and the absence makes we wonder just how robust the finding is.

[The Walrus]

So is the theory that the cloud feedback is rapidly counterbalancing the warming produced by GHGs by ~1/3, but then also leading to increased warming over the fast-feedback timescale included in ECS? Essentially "hiding" the warming produced by GHGs in the short term, slowing the ocean heating, which will eventually diminish the cloud feedback as mixing occurs?

Yes.

I could hypothesise a mechanism for how that might happen, because clouds have both heating and cooling effects and one might be temporary and associated with an imbalance while the other might be permanent and associated with a temperature change. However I'd expect a description of it in the paper and the absence makes we wonder just how robust the finding is.

There is quite a bit of hand waving, which makes me wonder too.  While clouds do have both heating and cooling effects, depending on time and location, the net effect is cooling.  They have not shown how this effect is only temporary.

[kassy]

What matters for the experiment is the behavior of clouds over time under a warming scenario.

Physics behind ultrafast change in the GISS model likely involves cloud change. Indeed, Kamae
et al.81 review rapid cloud adjustments separate from surface temperature-mediated changes.
Clouds respond to radiative forcing, e.g., via effects on cloud particle phase, cloud cover, cloud
albedo and precipitation.82 The GISS (2020) model alters glaciation in stratiform mixed-phase
clouds, which increases the amount of supercooled water in stratus clouds, especially over the
Southern Ocean [Fig. 1 in GISS (2020) GCM description34]. The portion of supercooled cloud
water drops changes from too little in GISS (2014) to too much in GISS (2020). Although
neither model realistically simulates stratocumulus clouds – which are important for accurate
simulation of Earth’s albedo and climate sensitivity – that modeling deficiency does not affect
our assessment of climate sensitivity and it does not prevent use of the two GISS models to help
expose real-world physics affecting climate sensitivity and climate response times.

It is the timing and location of the clouds effects which change with temperature.

What they model is still not correct but as our modelling of clouds gets better it might show that we underestimated the strengths of these responses which was always a possibility.

[kassy]

Climate warming reduces organic carbon burial beneath oceans

Painstaking study of 50-plus years of seafloor sediment cores has surprise payoff


An international team of scientists painstakingly gathered data from more than 50 years of seagoing scientific drilling missions to conduct a first-of-its-kind study of organic carbon that falls to the bottom of the ocean and gets drawn deep inside the planet.

Their study, published this week in Nature, suggests climate warming could reduce organic carbon burial and increase the amount of carbon that's returned to the atmosphere, because warmer ocean temperatures could increase the metabolic rates of bacteria.

Researchers from Rice University, Texas A&M University, the University of Leeds and the University of Bremen analyzed data from drilled cores of muddy seafloor sediments that were gathered during 81 of the more than 1,500 shipboard expeditions mounted by the International Ocean Discovery Program (IODP) and its predecessors. Their study provides the most detailed accounting to date of organic carbon burial over the past 30 million years, and it suggests scientists have much to learn about the dynamics of Earth's long-term carbon cycle.

"What we're finding is that burial of organic carbon is very active," said study co-author Mark Torres of Rice. "It changes a lot, and it responds to the Earth's climatic system much more than scientists previously thought."

The paper's corresponding author, Texas A&M oceanographer Yige Zhang, said, "If our new records turn out to be right, then they're going to change a lot of our understanding about the organic carbon cycle. As we warm up the ocean, it will make it harder for organic carbon to find its way to be buried in the marine sediment system."

Carbon is the main component of life, and carbon constantly cycles between Earth's atmosphere and biosphere as plants and animals grow and decompose. Carbon can also cycle through the Earth on a journey that takes millions of years. It begins at tectonic subduction zones where the relatively thin tectonic plates atop oceans are dragged down below thicker plates that sit atop continents. Downward diving oceanic crust heats up as it sinks, and most of its carbon returns to the atmosphere as carbon dioxide (CO2) from volcanoes.

Scientists have long studied the amount of carbon that gets buried in ocean sediments. Drilled cores from the ocean floor contain layers of sediments laid down over tens of millions of years. Using radiometric dating and other methods, researchers can determine when specific sediments were laid down. Scientists can also learn a lot about past conditions on Earth by studying minerals and microscopic skeletons of organisms trapped in sediments.

"There are two isotopes of carbon -- carbon-12 and carbon-13," said Torres, an assistant professor in Rice's Department of Earth, Environmental and Planetary Sciences. "The difference is just one neutron. So carbon-13 is just a bit heavier.

"But life is lazy, and if something's heavier -- even that tiny bit -- it's harder to move," Torres said. "So life prefers the lighter isotope, carbon-12. And if you grow a plant and give it CO2, it will actually preferentially take up the lighter isotope. That means the ratio of carbon-13 to -12 in the plant is going to be lower -- contain less 13 -- than in the CO2 you fed the plant."

For decades scientists have used isotopic ratios to study the relative amounts of inorganic and organic carbon that was undergoing burial at specific points in Earth's history. Based on those studies and computational models, Torres said scientists have largely believed the amount of carbon undergoing burial had changed very little over the past 30 million years.

Zhang said, "We had this idea of using the actual data and calculating their organic carbon burial rates to come up with the global carbon burial. We wanted to see if this 'bottom-up' method agreed with the traditional method of isotopic calculations, which is more 'top down.'"

The job of compiling data from IODP expeditions fell to study first author, Ziye Li of Bremen, who was then a visiting student in Zhang's lab at A&M.

Zhang said the study findings were shocking.

"Our new results are very different -- they're the opposite of what the isotope calculations are suggesting," he said.

Zhang said this is particularly the case during a period called the mid-Miocene, about 15 million years ago. Conventional scientific wisdom held that a large amount of organic carbon was buried around this interval, exemplified by the organic-rich "Monterey Formation" in California. The team's findings suggest instead that the smallest amount of organic carbon was buried during this interval over the last 23 million years or so.

He described the team's paper as the beginning of a potentially impactful new way to analyze data that may aid in understanding and addressing climate change.

"It's people's curiosity, but I also want to make it more informative about what's going to happen in the future," Zhang said. "We're doing several things quite creatively to really use paleo data to inform us about the present and future."

...

https://www.sciencedaily.com/releases/2023/01/230104154234.htm

[Bruce Steele]

Kassy, Warmer water increases metabolic rates of bacteria so they need to consume more organic matter which results in increased remineralization ( CO2 nitrogen phosphorus etc ) and less organic matter makes it into bottom sediments . Reduced carbon sink
Warmer water also results in stratification so upwelling is reduced in surface waters and as a result less nutrients necessary for photosynthetic production move from intermediate or bottom water back to the surface. Less production , less organic matter.
Warmer water also carries less oxygen so respiratory demands of forage fish increase due to water temperature while oxygen availability decreases. Also results in reduced carbon sink IMO. Fecal pellets.
 
 Thanks for posting carbon sink articles.

[kassy]

Increased droughts are disrupting carbon-capturing soil microbes, concerning ecologists

Soil stores more carbon than plants and the atmosphere combined, and soil microbes are largely responsible for putting it there. However, the increasing frequency and severity of drought, such as those that have been impacting California, could disrupt this delicate ecosystem. In a perspective publishing in the journal Trends in Microbiology on April 12, microbial ecologist Steven Allison warns that soil health and future greenhouse gas levels could be impacted if soil microbes adapt to drought faster than plants do. He argues that we need to better understand how microbes respond to drought so that we can manage the situation in both agricultural and natural settings.

"Soil microbes are beneficial, and we couldn't live without their cycling of carbon and nutrients, but climate change and drought can tweak that balance, and we have to be aware of how it's changing," says Allison of the University of California, Irvine.

Some soil microbes take carbon from decomposing plants and store it in the soil, while others release plant carbon back into the atmosphere. The carbon that ends up in the soil is beneficial in multiple ways. "The carbon in the soil has these reverberating effects out to the rest of the world in terms of the infrastructure in our natural and managed ecosystems," says Allison. "Carbon-rich soils hold more nutrients, so plants growing in those soils tend to be more productive, and the carbon changes the physical properties of the soil, which prevents erosion."

"In California now, we have this system where the droughts are more intense, and then the rainfall is more intense," he says. "So, if you're losing your soil carbon, when it rains really hard it could carry away your soil and cause erosion, landslides, mudslides, sediments, and all kinds of problems that we're actually seeing right now."

The carbon that is released back into the atmosphere is another story. "From a climate mitigation standpoint, what we want is for more carbon to be in plants and soils and less carbon to be in the atmosphere, so the more carbon we can absorb into plants through photosynthesis and the more we can transfer and keep in the soil, the better off we're going to be in terms of climate change," says Allison. "That's why it's really important to know how the balance of incoming versus outflowing carbon changes with drought, or warming, or any other climate factor."

Plants and microbes will both be impacted by the increasing frequency of drought, but Allison suspects that microbes will be able to bounce back faster. "Microbes are really adaptable -- they can change their physiology, they can change their abundances so that more drought-adapted microbes take over, and they can potentially evolve -- so we expect that they are going to resist or bounce back from drought," says Allison. "All those different processes can happen pretty quickly with microbes, and much more quickly than with plants."

If more carbon-releasing microbes survive than carbon-sequestering microbes, we could end up with carbon-depleted soils, which would have serious negative implications for plant productivity and future greenhouse gas levels.

...

https://www.sciencedaily.com/releases/2023/04/230412131133.htm

[kassy]

Viruses could reshuffle the carbon cycle in a warming world

Viruses may have unanticipated consequences for ecosystem responses to climate change


Microbes play important roles in ecosystems, and these roles are changing with global warming. Scientists also now know that most types of microbes are infected by viruses, but they know relatively little about how these viral infections could change how microbes react to warming. In this study, scientists describe many different ways that increasing temperatures could affect viruses and their microbial hosts. These changes could ultimately affect the responses of whole ecosystems to warming. The work exposes several important gaps in researchers' current knowledge about the connections between viruses, warming, and ecosystem functioning. Filling these gaps is crucial for understanding and predicting the effects of climate change on ecosystems.

This study creates a roadmap for understanding the many different ways that viruses could modify the effects of warming on communities of microbes. Viruses likely have strong effects on processes with microbes and the ways ecosystems function. Incorporating these previously ignored effects into ecosystem models will help scientists improve their predictions of how ecosystems could respond to climate change.

Microorganisms play integral roles in ecosystems by controlling the flow of energy and matter through processes like photosynthesis (carbon uptake), respiration (carbon release), and decomposition (carbon recycling). Climate change is currently altering how ecosystems function by changing how organisms operate within microbial food webs. Scientists know that viruses can have strong impacts on microbial processes, but they have less knowledge of how these impacts will change with future warming.

In this study, scientists from Duke University, the University of Tennessee Knoxville, the Netherlands Institute of Ecology, and Oak Ridge National Laboratory reviewed the potential impacts of warming on viruses and how these might alter scientific understanding of ecosystem responses to climate change. Warming likely affects several different stages of the viral infection cycle, as well as virus-host dynamics. However, there are still many gaps in our understanding about these effects. Because viruses are ubiquitous across all habitats and have strong effects on microbial functioning, filling these gaps is critical to understanding how warming will affect the flow of energy and matter within ecosystems. The researchers' preliminary models show that viruses could potentially tip the scales on natural carbon balances, causing some ecosystems to switch from being net carbon sources (releasing more carbon than they store) to being net carbon sinks (absorbing carbon). This study shows how incorporating viruses into predictive models can lead to new and unexpected effects on ecosystems in response to climate change.

https://www.sciencedaily.com/releases/2023/05/230508190613.htm

[kassy]

'Sea butterfly' life cycle threatened by climate change may impact Southern Ocean ecosystem

The world's oceans absorb approximately a quarter of all carbon dioxide (CO2) emissions. During absorption, CO2 reacts with seawater and oceanic pH levels fall. This is known as ocean acidification and results in lower carbon ion concentrations. Certain ocean inhabitants use carbon ion to build and sustain their shells. Pteropods, which are important components of the marine ecosystem, are among them.

Certain aspects about pteropods, including life cycles and population dynamics, are not well-studied. This is partly due to their size—some sea butterfly species measure less than a millimeter—and poor long-term survival in captivity. Now, a team of marine scientists has examined life cycles, abundance, and seasonal variability of shelled sea butterflies in the north-east Scotia Sea, a region undergoing some of the fastest climate change in the Southern Ocean.

"Decline in Antarctic Ocean pteropod populations could have cascading ramifications to the food web and carbon cycle," said Dr. Clara Manno, a researcher at the British Antarctic Survey and corresponding author of the study published in Frontiers in Marine Science. "Knowledge about the life cycle of this keystone organism may improve prediction of ocean acidification impacts on the Antarctic ecosystem."

Population stability essential for species survival
For their work, the scientists collected sea butterflies in a sediment trap, a sampling device moored at 400 meters depth. "It is impossible to observe the full life cycle of sea butterflies in a laboratory setting, so we had to piece together information about their spawning, growth rate and population structure," added Dr. Vicky Peck, a researcher at the British Antarctic Survey and co-author of the study. "Using sediment trap samples, we successfully reconstructed their life cycle over a year."

For the two dominant species collected—Limacina rangii and Limacina retroversa—the scientists observed contrasting life cycles, leading to different vulnerabilities to changing oceans. L. rangii, a polar species, can be found as both adults and juveniles during the winter months. L. retroversa, a subpolar species, appear to occur only as adults during the winter.

During the coldest season, ocean water is more acidic than during other times of the year because cooler temperatures increase CO2 dissolution in the ocean. The life stages of sea butterflies that exist then are more exposed and vulnerable to increased levels of ocean acidification, the researchers wrote.

The fact that L. rangii adults and juveniles coexist over winter may give them a survival advantage. If one cohort is vulnerable, the overall population stability is not at risk. With L. retroversa, however, if one cohort is removed, the whole population may be vulnerable.

Prolonged exposure is a survival challenge
The researchers noted that despite species being impacted differently, neither is likely to remain unharmed if exposed to unfavorable conditions for extended time periods.

As the intensity and duration of ocean acidification events increase, they begin to overlap with spawning events in the spring. This may put the most vulnerable life stage, the larvae, particularly at risk and could jeopardize future populations, the scientists warned.

To learn how such a scenario might play out in the Scotia Sea, the research team will continue to study sea butterflies dwelling there. "A next step will be to focus on multiyear sediment trap samples to identify potential inter-annual variability in the life cycle associated with environmental change," said Dr. Jessie Gardner of the British Antarctic survey, lead author of the study.

https://phys.org/news/2023-05-sea-butterfly-life-threatened-climate.html

[kassy]

Since it is general science i put it in the Geology thread but here is the link:

Phenomenal phytoplankton: Scientists uncover cellular process behind oxygen production
...

https://www.sciencedaily.com/releases/2023/05/230531150117.htm

[kassy]

Warming climate could turn ocean plankton microbes into carbon emitters

New research finds that a warming climate could flip globally abundant microbial communities from carbon sinks to carbon emitters, potentially triggering climate change tipping points. The findings are published in Functional Ecology.

Mixotrophic microbes are organisms that can switch between photosynthesizing like plants (absorbing carbon dioxide) and eating like animals (releasing carbon dioxide). They are globally abundant, commonly found in freshwater and marine environments, and estimated to make up the majority of marine plankton.

By developing a computer simulation that modeled how mixotrophic microbes acquire energy in response to warming, researchers at Duke University and the University of California Santa Barbara, have found that under warming conditions, mixotrophic microbes shift from being carbon sinks to carbon emitters.

The findings mean that as temperatures increase, these highly abundant microbial communities could change from having a net cooling effect on the planet to a net warming effect.

Dr. Daniel Wieczynski of Duke University and lead author of the study said, "Our findings reveal mixotrophic microbes are much more important players in ecosystem responses to climate change than previously thought. By converting microbial communities to net carbon dioxide sources in response to warming, mixotrophs could further accelerate warming by creating a positive feedback loop between the biosphere and the atmosphere."

Dr. Holly Moeller of University of California Santa Barbara and co-author of the study added, "Because mixotrophs can both capture and emit carbon dioxide, they are like 'switches' that could either help reduce climate change or make it worse. These bugs are tiny, but their impacts can really scale up. We need models like this to understand how."

Dr. Jean-Philippe Gibert of Duke University and another co-author of the study said, "State-of-the-art predictive models of long-term climate change currently only account for microbial action in an extremely reductive, partial, or sometimes plain wrong fashion. Research like this is therefore much needed to improve our broader understanding of the biotic controls on Earth's atmospheric processes."

An early warning system
The researchers' model also revealed that right before mixotrophic microbe communities switch to emitting carbon dioxide, their abundance starts to fluctuate wildly. These changes could be detected in nature by monitoring mixotrophic microbe abundance and offers hope that these microbes could act as early warning signals for climate change tipping points.

Dr. Wieczynski said, "These microbes may act as early indicators of the catastrophic effects of rapid climate change, which is especially important in ecosystems that are currently major carbon sinks like peatlands, where mixotrophs are highly abundant."

However, the researchers also found these early warning signals can be muted by increases of nutrients like Nitrogen to the environment, typically caused by run off from agriculture and wastewater treatment facilities.

When higher amounts of such nutrients were included in the simulations, the researchers found that the range of temperatures over which the tell-tale fluctuations occur starts to shrink until eventually the signal disappears and the tipping point arrives with no apparent warning.

In the study, the researchers ran simulations using a 4-degree span of temperatures, from 19 to 23 degrees Celsius. Global temperatures are likely to surge 1.5 degrees Celsius above pre-industrial levels within the next five years, and are on pace to breach 2 to 4 degrees before the end of this century.

The researchers caution that the mathematical modeling used in the study draws on limited empirical evidence to investigate the effects of warming on microbial communities. Dr. Wieczynski said, "Although models are powerful tools theoretical results must ultimately be tested empirically. We strongly advocate for further experimental and observational testing of our results."

https://phys.org/news/2023-05-climate-ocean-plankton-microbes-carbon.html

Paper:
https://besjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/1365-2435.14350

The bolded part. That masking effect exists in many places. Can´t remember the exact gist of it but if you look at European soils over a longer time some finds where weird until they figured out that back in the days there was was more sulphur coming down which changed the whole balance.

[neal]

proposed new rule to make national forests permanent carbon capture repositories for prvate carbon capture compnies...

..Abstract:
To support responsible deployment of Carbon Capture, Utilization, and Sequestration (CCUS), the Forest Service is proposing an amendment to its regulations at 36 CFR 251.54 -- Proposal and Application Requirements and Procedures to allow exclusive or perpetual right of use or occupancy (36 CFR 251.54(e)(1)(iv)) of National Forest System (NFS) lands for CCUS. This proposed rulemaking would amend initial screen criteria in existing regulations to allow for permanent carbon dioxide sequestration on NFS lands to support CCUS-related activities and will help meet the Administration's priority of tackling the climate crisis....

https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=0596-AD55

[Alexander555]

From the University of Australia. If you look at it from the " total capacity " angle.

https://www.anu.edu.au/news/all-news/plants-release-more-carbon-dioxide-into-atmosphere-than-expected

[kassy]

A Multidecadal View of Oceanic Storage of Anthropogenic Carbon

A decline in the ratio of ocean carbon accumulation to atmospheric carbon dioxide growth between 1994-2004 and 2004-2014 suggests a reduction in the sensitivity of the ocean carbon sink.

The trend of the global ocean sink for anthropogenic carbon dioxide (CO2) is a topic of current debate. Using three decades of observations of inorganic carbon in the ocean, Müller et al. [2023] find that ocean storage since 1994 grew at a constant rate of ~28 Pg carbon (C) per decade. However, greater increases in atmospheric CO2 from 2004 to 2014 indicate that ocean uptake in the recent decade was 15 ± 11% lower than expected based on the relationship between ocean uptake and atmospheric increase from 1994 to 2004. The authors attribute this to both a decrease in the ocean buffer capacity and changes in ocean circulation. The latter is also reflected in the decadal variability of accumulation patterns. Estimates of changes in ocean C storage were significantly greater than those derived from air-sea CO2 fluxes, suggesting changes in the ‘natural’ C inventory. These results emphasize the vulnerability of the ocean C sink to climate change.

https://eos.org/editor-highlights/a-multidecadal-view-of-oceanic-storage-of-anthropogenic-carbon

OA paper:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023AV000875

[gerontocrat]

A Multidecadal View of Oceanic Storage of Anthropogenic Carbon

A decline in the ratio of ocean carbon accumulation to atmospheric carbon dioxide growth between 1994-2004 and 2004-2014 suggests a reduction in the sensitivity of the ocean carbon sink.

This is really, really bad news, made clearer in the plain language summary. A declining ocean sink means a lower proportion of CO2 emissions captured by the oceans so a higher rate of increase in atmospheric CO2ppm.

A recent paper concluded that the effectiveness of a significant land sink in much of Eastern Europe is in decline. If the ocean and the land sinks are both becoming less effective then the outlook for CO2 ppm looks bleak indeed.

Plain Language Summary
The ocean takes up about 30% of the anthropogenic CO2 that is emitted to the atmosphere by human activities. The removal of this anthropogenic CO2 from the atmosphere counteracts climate change.

The rate at which the ocean takes up anthropogenic CO2 is controlled by its transport from the surface to the depth of the ocean, where most of it accumulates. Thus, we can quantify and understand the oceanic uptake by keeping track of the accumulation of anthropogenic CO2 in the ocean interior. In this study, we use a global collection of measurements of CO2 in seawater to infer the temporal evolution of this accumulation between 1994 and 2014. We find that the ocean continued to act as a strong sink for CO2 over this period, removing, on average, nearly 30 billion tons of carbon per decade. However, we also detect a possible weakening of this uptake, since the accumulation of anthropogenic CO2 during the second decade was not as large as expected from the increase in atmospheric CO2.

Our findings suggest that the ocean sink for CO2 might further shrink as climate change progresses.

[kiwichick16]

@  kassy   ..... the 30 % reduction in AABW  is leaving both more heat and more CO2 in the Antarctic region .... less heat is being driven down to the ocean depths to start the oceanic circulation  ....surely this must be a factor both in declining sea ice and acceleration of CO2 levels in the atmosphere

[kassy]

A Multidecadal View of Oceanic Storage of Anthropogenic Carbon

A decline in the ratio of ocean carbon accumulation to atmospheric carbon dioxide growth between 1994-2004 and 2004-2014 suggests a reduction in the sensitivity of the ocean carbon sink.

This is really, really bad news, made clearer in the plain language summary. A declining ocean sink means a lower proportion of CO2 emissions captured by the oceans so a higher rate of increase in atmospheric CO2ppm.

It is also something we knew we would run into at some point but when? We find all these things in the rearview mirror. Oh the fish stocks are emigrating, the trigger points for Greenland and Antarctic melt were under 1C etc.

This find along with some others (the AABW, the EEI etc) are hints that we have a big problem.

And this:

We could be 16 years into a methane-fueled 'termination' event significant enough to end an ice age

A dramatic spike in atmospheric methane over the past 16 years may be a sign that Earth's climate could flip within decades, scientists have warned.

Large amounts of methane wafting from tropical wetlands into Earth's atmosphere could trigger warming similar to the "termination" events that ended ice ages, replacing frosty expanses of tundra with tropical savanna, a new study finds. Researchers first detected a strange peak in methane emissions in 2006, but until now, it was unclear where the gas was leaking from and if it constituted a novel trend.

"A termination is a major reorganization of the Earth's climate system," study lead author Euan Nisbet, a professor emeritus of Earth sciences at Royal Holloway, University of London, told Live Science. "These repeated changes have taken the world from ice ages into the sort of interglacial we have now."

Ice age terminations typically occur in three phases, which are recorded in ice cores going back 800,000 years. The initial phase is characterized by a gradual rise in methane and CO2, leading to global warming over a few thousand years. This is followed by a sharp increase in temperatures fueled by a burst of methane, leveling off in a third phase lasting several thousand years.

"Within the termination, which takes thousands of years, there's this abrupt phase, which only takes a few decades," Nisbet said. "During that abrupt phase, the methane soars up, and it's probably driven by tropical wetlands."

more details:
https://www.space.com/climate-change-termination-event-end-ice-age

More details and the link to the paper are on the CH4 thread. What is described here is consistent with the EEI prediction. The other things are hints of really big changes which have mostly been underappreciated.

[Sublime_Rime]

The trend of the global ocean sink for anthropogenic carbon dioxide (CO2) is a topic of current debate. Using three decades of observations of inorganic carbon in the ocean, Müller et al. [2023] find that ocean storage since 1994 grew at a constant rate of ~28 Pg carbon (C) per decade. However, greater increases in atmospheric CO2 from 2004 to 2014 indicate that ocean uptake in the recent decade was 15 ± 11% lower than expected based on the relationship between ocean uptake and atmospheric increase from 1994 to 2004. The authors attribute this to both a decrease in the ocean buffer capacity and changes in ocean circulation. The latter is also reflected in the decadal variability of accumulation patterns. Estimates of changes in ocean C storage were significantly greater than those derived from air-sea CO2 fluxes, suggesting changes in the ‘natural’ C inventory. These results emphasize the vulnerability of the ocean C sink to climate change.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023AV000875

Indeed, bad news, especially in combination with a potential termination event methane release. So if the changes in ocean carbon uptake were a linear process (of course they wouldn't be), than at maximum we'd have until 2060s before the ocean sink declined to nil? Or perhaps never there would always be some uptake, but just drastically reduced with warmer surface temps and a collapse of overturning circulation?

[kassy]

We've Been Overlooking a Major Part of Climate Change, And It's Sending Warning Signs

...

Soil temperatures have drawn relatively little attention overall in studies of human-induced climate change, the researchers say. Partly because measurement complexities make it hard to find enough reliable data on soil temperatures compared with near-surface air temperatures.

In the new study, however, a team of researchers from across Germany gathered soil-temperature data from a wide range of sources, including meteorological monitoring stations, remote-sensing satellites, the ERA5-Land data reanalysis set, and simulations from Earth-system models.

The team relied on the TX7d index, which is meant to capture the intensity of heat extremes by averaging the daily maximum temperatures during the hottest week per year.

They calculated this index for the upper 10 centimeters (3.9 inches) of soil, and for air up to 2 meters (6.5 feet) above the surface, at 118 weather stations across Europe, using temperature data from between 1996 and 2021 to provide 160 pairs of air and soil measurements.

At two-thirds of these sites, the researchers found a stronger trend in heat extremes within the soil than in the air above it, they report.

"This means that heat extremes develop much faster in the soil than in the air," says study co-author Almudena García-García, a remote-sensing researcher at the Helmholtz Centre for Environmental Research (UFZ).

The study revealed regional variations in this phenomenon across Europe, with heat extremes becoming more intense more quickly in Central Europe, namely in Germany, Italy, and southern France.

In these areas, the intensity of heat extremes is increasing 0.7 degrees Celsius per decade faster in the soil than in air near the surface, the study found.

The researchers investigated the frequency of soil heat extremes as well as their intensity, using a different index – TX90p – that factors in the percentage of days per month when the daily maximum temperature exceeds a given statistical threshold.

They found the number of days with heat extremes is increasing twice as quickly in the soil as it is in the air.

...

https://www.sciencealert.com/weve-been-overlooking-a-major-part-of-climate-change-and-its-sending-warning-signs

[FredBear]

Observations in my locality:-
On a local reserve (made from reused farmland for 30 years) last year herbage generally was hit hard by shortage of water, meadows short and trees losing leaves early (less CO₂ used).
This year growth has been good with fruiting excellent. But leaves seem to be falling early, elm and ash trees are dying from disease and brambles have not grown large to replace the very old stems.
Are things catching up with us even in leafy Surrey (England)

[kassy]

Yes as in Canada.

Ancient carbon in rocks releases as much carbon dioxide as the world's volcanoes


A new study led by the University of Oxford has overturned the view that natural rock weathering acts as a CO2 sink, indicating instead that this can also act as a large CO2 source, rivalling that of volcanoes. The results, published today in the journal Nature, have important implications for modelling climate change scenarios.

Rocks contain an enormous store of carbon in the ancient remains of plants and animals that lived millions of years ago. This means that the "geological carbon cycle" acts as a thermostat that helps to regulate the Earth's temperature. For instance, during chemical weathering rocks can suck up CO2 when certain minerals are attacked by the weak acid found in rainwater. This process helps to counteract the continuous CO2 released by volcanoes around the world, and forms part of Earth's natural carbon cycle that has helped keep the surface habitable to life for a billion years or more.

However, for the first time this new study measured an additional natural process of CO2 release from rocks to the atmosphere, finding that it is as significant as the CO2 released from volcanoes around the world. Currently, this process is not included in most models of the natural carbon cycle.

The process occurs when rocks that formed on ancient seafloors (where plants and animals were buried in sediments) are pushed back up to Earth's surface, for example when mountains like the Himalayas or Andes form. This exposes the organic carbon in the rocks to oxygen in the air and water, which can react and release CO2. This means that weathering rocks could be a source of CO2, rather than the commonly assumed sink.

Up to now, measuring the release of this CO2 from weathering organic carbon in rocks has proved difficult. In the new study, the researchers used a tracer element (rhenium) which is released into water when rock organic carbon reacts with oxygen. Sampling river water to measure rhenium levels makes it possible to quantify CO2 release. However, sampling all river water in the world to get a global estimate would be a significant challenge.

To upscale over Earth's surface, the researchers did two things. First, they worked out how much organic carbon is present in rocks near the surface. Second, they worked out where these were being exposed most rapidly, by erosion in steep, mountain locations.

Dr Jesse Zondervan, the researcher who led the study at the Department of Earth Sciences, University of Oxford, said: "The challenge was then how to combine these global maps with the river data, while considering uncertainties. We fed all of our data into a supercomputer at Oxford, simulating the complex interplay of physical, chemical, and hydrological processes. By piecing together this vast planetary jigsaw, we could finally estimate the total carbon dioxide emitted as these rocks weather and exhale their ancient carbon into the air."

This could then be compared to how much CO2 could be drawn down by natural rock weathering of silicate minerals. The results identified many large areas where weathering was a CO2 source, challenging the current view about how weathering impacts the carbon cycle. Hotspots of CO2 release were concentrated in mountain ranges with high uplift rates that cause sedimentary rocks to be exposed, such as the eastern Himalayas, the Rocky Mountains, and the Andes. The global CO2 release from rock organic carbon weathering was found to be 68 megatons of carbon per year.

Professor Robert Hilton (Department of Earth Sciences, University of Oxford), who leads the ROC-CO2 research project that funded the study, said: "This is about 100 times less than present day human CO2 emissions by burning fossil fuels, but it is similar to how much CO2 is released by volcanoes around the world, meaning it is a key player in Earth's natural carbon cycle."

These fluxes could have changed during Earth's past. For instance, during periods of mountain building that bring up many rocks containing organic matter, the CO2 release may have been higher, influencing global climate in the past.

Ongoing and future work is looking into how changes in erosion due to human activities, alongside the increased warming of rocks due to anthropogenic climate changes, could increase this natural carbon leak. A question the team are now asking is if this natural CO2 release will increase over the coming century. "Currently we don't know -- our methods allow us to provide a robust global estimate, but not yet assess how it could change'' says Hilton.

"While the carbon dioxide release from rock weathering is small compared to present-day human emissions, the improved understanding of these natural fluxes will help us better predict our carbon budget" concluded Dr. Zondervan.

https://www.sciencedaily.com/releases/2023/10/231004132437.htm

[kassy]

What phytoplankton physiology has to do with global climate

New insights into the nitrogen-phosphorus ratio in the ocean

Newswise — Phytoplankton in the ocean are central to the global carbon cycle as they perform photosynthesis, capturing and transporting carbon (C) to the deep ocean. The growth of phytoplankton relies not only on carbon but also on nitrogen (N) and phosphorus (P), which are crucial for their cellular functioning. Phytoplankton stoichiometry defines the relative proportions of different elements such as C, N, and P in these organisms. Key connections exist between phytoplankton stoichiometry and climate through interdependencies between the oceanic carbon pump, nutrient cycling, food web dynamics, and responses to climate-related factors like atmospheric carbon dioxide (CO2) concentration and temperature.

In the 1930s, the American oceanographer Alfred C. Redfield made an important discovery: he found that the concentrations of the elements C, N, and P in the marine phytoplankton roughly follow a fixed ratio of approximately 106:16:1 - the ratio now named after him, the Redfield ratio. Surprisingly, Redfield’s research also revealed that in the seawater samples he collected, the concentration of nitrate, a primary nitrogen nutrient source, was, on average, 16 times higher than the concentration of phosphate, a primary phosphorus nutrient source. The nitrogen-to-phosphorus (N:P) ratios in both phytoplankton and seawater are remarkably similar, indicating a strong connection between the particulate (phytoplankton) and dissolved (seawater) nutrient pools.

The question of whether the N:P ratio of the dissolved pool controls the ratio in particulate material, or vice versa, has long puzzled the marine science community. "It's a chicken-and-egg question," says Dr Chia-Te Chien, a researcher in the Biogeochemical Modelling Research Unit at the GEOMAR Helmholtz Centre for Ocean Research in Kiel, who is investigating the role of variable stoichiometry of phytoplankton in the marine biogeochemistry. Together with his colleagues, he has now carried out a modelling study that examines the relationship between the ratios of nitrogen and phosphorus in dissolved inorganic and particulate organic matter in seawater. The study, now published in the journal Science Advances, emphasizes the importance of variable C:N:P ratios of phytoplankton for regulating dissolved oceanic nutrient ratios on a global scale and highlights marine oxygen levels as a critical regulator in the Earth system.

To investigate these relationships, the authors used a computer model of algal physiology coupled to an Earth system model, wherein phytoplankton dynamically optimize their C:N:P ratios in response to varying environmental conditions. In the computer model, they could alter the characteristics of phytoplankton and observe how this changed the nitrogen and phosphorus ratios in the water.

They carried out an ensemble of 400 simulations, which differ in the minimal nitrogen and phosphorus contents required by algae to stay alive. The model results reveal intricate feedback mechanisms involving changes in the nitrogen and phosphorus content of phytoplankton, oceanic oxygen levels, N2 fixation by nitrogen-fixing phytoplankton, and denitrification. These model results challenge the commonly hypothesized strong link between phytoplankton and seawater nutrient ratios. Rather than attempting to uncover the reasons behind the resemblance in the currently observed ratios between phytoplankton and seawater, the results highlight that these ratios are not inherently similar. In other words, the similarity, as it is observed these days, is a specific state, and this state may be subject to change, at least on a time scale that is not covered by the many decades of ocean in situ observations.

Additionally, the analysis highlights the potentially substantial influence of phytoplankton subsistence nitrogen and phosphorus quotas on atmospheric CO2 levels on geological time scales. Traditionally, stoichiometric variations of the phytoplankton and within the marine ecosystem were considered to have a relatively minor impact on marine biogeochemistry and, consequently, atmospheric CO2 levels. This view could now be questioned, because this study points to the potential importance of a physiological detail for climate conditions on our planet.

The authors explain the significance of the findings: "Our results demonstrate that the concentration of atmospheric CO2 as well as the ocean and air temperature are remarkably sensitive to variations in elemental stoichiometry induced by changes in phytoplankton physiology." Understanding these connections could help scientists make more accurate predictions about how our planet's ecosystems and climate will evolve in the future

https://www.newswise.com/articles/the-link-between-phytoplankton-physiology-and-global-climate

Effects of phytoplankton physiology on global ocean biogeochemistry and climate
https://www.science.org/doi/10.1126/sciadv.adg1725

Implication for the role of phytoplankton physiology in marine nutrient cycling and global climate

Our simulations encompass a very wide spread in pCO2 (≈100 to >350 ppm; Fig. 2J), which, in this case, obviously originates from differences in the biological soft tissue pump (42), as phytoplankton is the only model component directly affected by the subsistence quotas. This may appear unexpected because changes in the biological pump usually are considered a minor contribution to variations in ocean C storage in the current climate change context, albeit with widely differing estimates (43, 44). Analyses of anthropogenic CO2 uptake by the ocean concern transient behavior on a time scale of decades to centuries, however, whereas our results refer to equilibrium Earth system states on a time scale of 104 (10000 years, see below) .years. In addition, wide-spread air-sea CO2 disequilibria have recently been shown to amplify effects of a changed biological pumping to such an extent that it could be considered a major contributor to the glacial-interglacial pCO2 difference (45).

Reference 45:
Air-sea disequilibrium enhances ocean carbon storage during glacial periods

Abstract
The prevailing hypothesis for lower atmospheric carbon dioxide (CO2) concentrations during glacial periods is an increased efficiency of the ocean’s biological pump. However, tests of this and other hypotheses have been hampered by the difficulty to accurately quantify ocean carbon components. Here, we use an observationally constrained earth system model to precisely quantify these components and the role that different processes play in simulated glacial-interglacial CO2 variations. We find that air-sea disequilibrium greatly amplifies the effects of cooler temperatures and iron fertilization on glacial ocean carbon storage even as the efficiency of the soft-tissue biological pump decreases. These two processes, which have previously been regarded as minor, explain most of our simulated glacial CO2 drawdown, while ocean circulation and sea ice extent, hitherto considered dominant, emerge as relatively small contributors.

https://www.science.org/doi/full/10.1126/sciadv.aaw4981

[Bruce Steele]

https://caseagrant.ucsd.edu/news/birth-c-can

Sometimes in life you are lucky enough to be in the right place at the right time. Once upon a time I helped save the Pacific Northwest Oyster industry.
And rarer still does one meeting have such effect. We collective all walked into a room intent on starting a discussion on how as biologists, industry, and biogeochemists we could address the coming anticipated problems and walked out confident that the problem wasn’t some future problem but one already on our doorstep. Ocean acidification was killing the juvenile oysters.
 Oyster aquaculture requires heated water for larval propagation. You can’t keep heating the tanks, inoculating them and watch all the baby oysters die. Well sometimes they lived but sometimes not and after filtering, and UV treating the incoming water to eliminate bacterial threats, and seeing no improvement you begin to reach the end of the line.  And cleaning the tanks, heating the water again and crashing again the oyster spat the rest of the grow out industry needed to maintain the outer beds, they had almost run out of time.
 We walked out knowing the omega that killed the larva was 1.7 , because a smart educated technician at a hatchery ( Alan Barton ) realized that the larval mortalities coincided with strong offshore winds . He also had a paper about acidification by Dick Feely on his desk in front of him , he put it together, he was first.we also learned  that we didn’t have the instrumentation to monitor omega ( carbonate saturation state ) real time in the hatchery intake pipes. The instrumentation that was closest to that objective got the funding and the expertise needed to keep them running in the hatcheries. Both Dick and Alan were at the meeting , so was I but my part was mostly already done. Just a spark that my wife managed to move forward. Butterfly wings flapping

[RoxTheGeologist]

https://caseagrant.ucsd.edu/news/birth-c-can

Sometimes in life you are lucky enough to be in the right place at the right time. Once upon a time I helped save the Pacific Northwest Oyster industry.
And rarer still does one meeting have such effect. We collective all walked into a room intent on starting a discussion on how as biologists, industry, and biogeochemists we could address the coming anticipated problems and walked out confident that the problem wasn’t some future problem but one already on our doorstep. Ocean acidification was killing the juvenile oysters.
 Oyster aquaculture requires heated water for larval propagation. You can’t keep heating the tanks, inoculating them and watch all the baby oysters die. Well sometimes they lived but sometimes not and after filtering, and UV treating the incoming water to eliminate bacterial threats, and seeing no improvement you begin to reach the end of the line.  And cleaning the tanks, heating the water again and crashing again the oyster spat the rest of the grow out industry needed to maintain the outer beds, they had almost run out of time.
 We walked out knowing the omega that killed the larva was 1.7 , because a smart educated technician at a hatchery ( Alan Barton ) realized that the larval mortalities coincided with strong offshore winds . He also had a paper about acidification by Dick Feely on his desk in front of him , he put it together, he was first.we also learned  that we didn’t have the instrumentation to monitor omega ( carbonate saturation state ) real time in the hatchery intake pipes. The instrumentation that was closest to that objective got the funding and the expertise needed to keep them running in the hatcheries. Both Dick and Alan were at the meeting , so was I but my part was mostly already done. Just a spark that my wife managed to move forward. Butterfly wings flapping

Great work, Bruce.

[oren]

+1

[Sigmetnow]

The Global Carbon Project has released its 2023 edition of the Global Carbon Budget, a comprehensive assessment of our perturbation of the carbon cycle and the balance of sources and sinks of CO₂. 1/🧵

12/5/23, https://x.com/robbie_andrew/status/1731919435705839752
Extensive thread discussion with graphs and data for emissions, countries, projections.

[Florifulgurator]

What phytoplankton physiology has to do with global climate
(...)

Effects of phytoplankton physiology on global ocean biogeochemistry and climate
https://www.science.org/doi/10.1126/sciadv.adg1725

(...) 104 years. (...)

(...)

Classical copy-paste typo: It is 10000 years.

[kassy]

Thanks for pointing that out. That is indeed unhelpful. Everybody gets CO2 with no subscript for the 2 but in this case with numbers it hides a whole bunch of powers of 10.

[kassy]

Trillions of tonnes of carbon locked in soil has been left out of environmental models – and it’s on the move

We all know about the carbon in Earth’s atmosphere, and probably about the carbon contained in plants and the bodies of animals. But a substantial fraction of the carbon in the planet’s land-based ecosystems is held in something so obvious we might overlook it: soil.

Even if we do think about carbon in soil, we are usually thinking of carbon in organic matter in the soil, such as plant litter, bacteria or animal waste. However, the inorganic, mineral component of soil also contains carbon.

In a new study just published in Science, we show there is much more soil inorganic carbon than anybody realised – and that it may be a surprisingly big player in Earth’s carbon cycle.

We analysed more than 200,000 soil measurements from around the world to calculate that the top two metres of soil globally holds about 2.3 trillion tonnes of inorganic carbon. This is about five times more carbon than found in all the world’s terrestrial vegetation. We estimate some 23 billion tonnes (1%) of this carbon may be released over the next 30 years, with poorly understood effects on Earth’s lands, waters and atmosphere.

What is soil inorganic carbon?
Inorganic carbon exists in soils in various forms. It can be trapped carbon dioxide gas, dissolved in water or other liquids, or it can be in solid form as carbonate minerals.

Most of the inorganic carbon by weight is solid carbonates, often calcium carbonate (a common substance found in materials such as limestone, marble and chalk). They give soil a whitish look, while organic carbon makes it dark.

Soil carbonates can come either from weathering of rocks or from the reaction of soil minerals with atmospheric carbon dioxide.

Inorganic carbon tends to build up more in soil in arid and semi-arid environments such as Australia. That’s because when water runs through soil it tends to carry away some of the carbonates with it.

Our estimates show the top two metres of Australia’s soil harbours some 160 billion tonnes (7%) of the world’s inorganic carbon. This makes Australia home to the fifth-largest pool of soil inorganic carbon in the world.

In wetter regions, soil carbonates may also be found along rivers and around lakes and coastal areas, in the form of calcium-rich alluvial deposits or calcareous rocks. Soils in karst regions – areas rich in rocks like limestone, and often characterised by caves and sinkholes – typically contain carbonate in rocks. In areas such as central Asia large deposits of wind-blown sediments (loess) contribute to the accumulation of carbonate minerals.

Why should we care?
This huge pool of carbon is affected by changes in the environment, especially soil acidification. Acids dissolve calcium carbonate, meaning the carbon dissolves in water or is released as carbon dioxide gas.

Soil in many regions of the globe (such as China and India) is becoming more acidic due to acid rain and other pollution from industrial activities and intense farming.

Scientists have viewed carbonates in soil as a relatively stable pool of carbon that changes only slowly over time. However, human activities have made soil inorganic carbon more mobile.

more:
https://theconversation.com/trillions-of-tonnes-of-carbon-locked-in-soil-has-been-left-out-of-environmental-models-and-its-on-the-move-227597

[kassy]

Non carbon but a similar mechanism as the study above:

Warming climate is putting more metals into Colorado's mountain streams

Warming temperatures are causing a steady rise in copper, zinc and sulfate in the waters of Colorado mountain streams affected by acid rock drainage. Concentrations of these metals have roughly doubled in these alpine streams over the past 30 years, presenting a concern for ecosystems, downstream water quality and mining remediation, according to a new study. Natural chemical weathering of bedrock is the source of the rising acidity and metals, but the ultimate driver of the trend is climate change, the report found, and the results point to lower stream volumes and exposure of rock once sealed away by ice as the likely causes.

...

https://www.sciencedaily.com/releases/2024/04/240423155758.htm

[kassy]

The warming climate shifts the dynamics of tundra environments and makes them release trapped carbon, according to a new study published in Nature. These changes could transform tundras from carbon sinks into a carbon source, exacerbating the effects of climate change.

A team of over 70 scientists used open-top chambers (OTCs) to experimentally simulate the effects of warming on 28 tundra sites around the world. OTCs basically serve as mini-greenhouses, blocking wind and trapping heat to create local warming.

The warming experiments led to a 1.4°C increase in air temperature and a 0.4°C increase in soil temperature, along with a 1.6% drop in soil moisture. These changes boosted ecosystem respiration by 30% during the growing season, causing more carbon to be released because of increased metabolic activity in soil and plants. The changes persisted for at least 25 years after the start of the experimental warming – which earlier studies hadn’t revealed.

‘We knew from earlier studies that we were likely to find an increase in respiration with warming, but we found a remarkable increase – nearly four times greater than previously estimated, though it varied with time and location,’ says Sybryn Maes of Umeå University, the study’s lead author.

The increase in ecosystem respiration also varied with local soil conditions, such as nitrogen and pH levels. This means that differences in soil conditions and other factors lead to geographic differences in the response – some regions will see more carbon release than others. Understanding the links between soil conditions and respiration in response to warming is important for creating better climate models.

...


https://www.newswise.com/articles/understanding-climate-warming-impacts-on-carbon-release-from-the-tundra
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