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Richard Rathbone

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Re: Carbon Cycle
« Reply #750 on: May 14, 2024, 03:22:06 PM »
Hansen reckons that this type of  mixing is over-represented in current models,  not under-represented. This is an underlying reason he is confident that his modelling is better and IPCC underestimates the level of  warming that will happen as aerosol pollution diminishes. I think it  might be relevant to Atlantic salinity calculations and differing opinions on AMOC stability too.

Continental shelf edges  generate  up/down currents. The Med has a high density of them so is a good place to go if you want to find surface organisms at depth. Its a bad place to go if you want to estimate global effects.

kassy

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Re: Carbon Cycle
« Reply #751 on: May 14, 2024, 11:23:15 PM »
Do you have any link for that? Not seen him discuss this part. If it would be important he would be wrong but i think that you are mixing up things. It´s completely unclear what this find means for climate.
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Richard Rathbone

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Re: Carbon Cycle
« Reply #752 on: May 15, 2024, 03:42:42 PM »
Do you have any link for that? Not seen him discuss this part. If it would be important he would be wrong but i think that you are mixing up things. It´s completely unclear what this find means for climate.

Its a common theme of his modelling papers. There's not enough data to independently set ocean mixing parameters, aerosol parameters, and ECS. Consequently uncertainties in them are correlated. He makes this point frequently for ECS and aerosols, but brings in mixing as well when there's a more technically detailed discussion.
I haven't seen him make the link between overmixing in the CMIP ocean models, and their salinity bias in the Atlantic yet, thats my speculation. I might not have noticed it, I haven't gone back and reread them since the recent AMOC stability paper that showed a salinity bias was making the CMIP AMOC too stable. Overmixing would make concentrations too uniform but I've no idea whether this is a significant factor in their salinity bias or not. Its something I'm hoping to see discussed when the second part of Hansen's Pipeline paper gets published.

e.g from Hansen's last email where he gets a lot more technical than he usually does in them.
https://www.columbia.edu/~jeh1/mailings/2024/Hopium.MarchEmail.2024.03.29.pdf
Quote
There were two reasons that the GCM modelers did not want to include the full aerosol
forcing in their models. First, many of the oceans in the GCMs tended to mix heat into the
deep ocean too effectively, which meant that the GCM needed a slightly exaggerated forcing
to match observed surface warming. Increased net forcing could be achieved with a smaller
(less negative) aerosol forcing

kassy

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Re: Carbon Cycle
« Reply #753 on: May 27, 2024, 07:27:24 PM »
Drought, soil desiccation cracking, and carbon dioxide emissions: an overlooked feedback loop exacerbating climate change


Soil stores 80 percent of carbon on earth, yet with increasing cycles of drought, that crucial reservoir is cracking and breaking down, releasing even more greenhouse gases creating an amplified feedback loop that could accelerate climate change.

The accuracy of climate models depends on many factors -- greenhouse gas emissions from industrial and transportation activity, farm animal "emissions," urban growth and loss of forests, and solar reflections off snow and ground cover. Natural phenomena like volcanic eruptions also contribute and are incorporated into models.

However, some other natural processes have been overlooked. Farshid Vahedifard, professor and Louis Berger Chair in civil and environmental engineering, points to an important one that lies directly beneath our feet and covers most of our planet above water.

In a study published in Environmental Research Letters, Vahedifard notes that soil stores 80 percent of carbon on Earth, and with increasing cycles and severity of droughts in several regions, that crucial reservoir is cracking and breaking down, releasing even more carbon dioxide and other greenhouse gases into the atmosphere. In fact, it may be creating an amplified feedback loop that could accelerate climate change well beyond current predictions.

"This process has not been sufficiently evaluated in the existing literature or incorporated into models," said Vahedifard. "If we don't consider the interplay of drought, soil desiccation cracking, and CO2 emissions, that could result in significant inaccuracies when modeling and predicting climate change. There are other repercussions as well. Poorer soil health can lead to reduced photosynthesis and lower carbon dioxide uptake, and it can compromise the structural integrity of earthen dams that protect against floods."

...

But soil changes caused by drought could be as significant, if not more significant, than any of those factors. Drought, manifested by long periods of low soil moisture content and high temperature, leads to cracking in fine-grained soils, sometimes extending meters below the surface. The cracks result in more exposure to the air, increased microbial activity and breakdown of organic matter, released carbon dioxide, and loss of nutrients and ability to support plant growth, reducing carbon dioxide sequestering.

The deep cracks expose much older reserves of carbon that had previously been stable and protected. The permeation of air into the soil accelerates the release of not only carbon dioxide from organic matter but also other greenhouse gases like nitrous oxide.

Small animals like earthworms and millipedes that help turn the soil over are also affected by the reduced moisture and increased air exposure, being less able to play active roles in nutrient cycling and soil structure maintenance. That, in turn, increases the likelihood of soil cracking and aeration.

"The amplifying effect of soil carbon feedback loops and its interactions with other loops could carry us across tipping points and lead to even more severe and permanent shifts in climate," said Vahedifard.

more:
https://www.sciencedaily.com/releases/2024/03/240313135541.htm
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kassy

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Re: Carbon Cycle
« Reply #754 on: June 01, 2024, 07:44:00 PM »
Study suggests faster decomposition rates in waterways could exacerbate greenhouse gas emissions, threaten biodiversity


Humans may be accelerating the rate at which organic matter decomposes in rivers and streams on a global scale, according to a new study from the University of Georgia, Oakland University and Kent State University.

That could pose a threat to biodiversity in waterways around the world and increase the amount of carbon in Earth's atmosphere, potentially exacerbating climate change.

Published in Science, the study is the first to combine a global experiment and predictive modeling to illustrate how human impacts to waterways may contribute to the global climate crisis.

...

Global warming, urbanization, increased nutrients altering global carbon cycle

Rivers and streams play a key role in the global carbon cycle by storing and decomposing large amounts of leaves, branches and other plant matter.

Typically, the process would go something like this: Leaf falls into river. Bacteria and fungi colonize the leaf. An insect eats the bacteria and fungi, using the carbon stored in the leaf to grow and make more insects. A fish eats the insect.

The study found that this process is changing in areas of the world impacted by humans.

Rivers impacted by urbanization and agriculture are changing how quickly leaf litter decomposes.

And when the process speeds up, that insect doesn't have a chance to absorb the carbon from the leaf. Instead, the carbon is released into the atmosphere, contributing to greenhouse gas pollution and ultimately disrupting the food chain.

"When we think of greenhouse gas emissions, we tend to think of tailpipes and factories," said Scott Tiegs, co-author of the study and a professor of biological sciences at Oakland.

"But a lot of carbon dioxide and methane comes from aquatic ecosystems. This process is natural. But when humans add nutrient pollution like fertilizer to fresh waters and elevate water temperatures, we increase the decomposition rates and direct more CO2 into the atmosphere."

...

https://phys.org/news/2024-05-faster-decomposition-waterways-exacerbate-greenhouse.html
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morganism

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Re: Carbon Cycle
« Reply #755 on: June 06, 2024, 11:17:24 PM »
Ocean Floor Topography Found to Significantly Impact Carbon Sequestration

The carbon cycle, a key process regulating Earth's climate, involves the movement of carbon between the atmosphere, oceans, and continents. While volcanic eruptions and human activities release carbon dioxide, forests and oceans absorb it, maintaining a balanced system. Carbon sequestration has become a vital method in combating climate change.

A recent study reveals that the shape and depth of the ocean floor account for up to 50% of the changes in oceanic carbon sequestration depth over the past 80 million years. Previous explanations for these changes were attributed to other factors. It has been established that the ocean, the largest carbon absorber on Earth, controls atmospheric carbon dioxide levels. However, the impact of seafloor topography on the ocean's carbon sequestration ability had been unclear.

"We were able to show, for the first time, that the shape and depth of the ocean floor play major roles in the long-term carbon cycle," said Matthew Bogumil, the paper's lead author and a UCLA doctoral student of earth, planetary, and space sciences.

The long-term carbon cycle operates with various elements over different timescales. One significant element is seafloor bathymetry, which includes the mean depth and shape of the ocean floor. This factor is influenced by the positions of continents and oceans, sea levels, and mantle flow. Carbon cycle models, using paleoclimate datasets, form the basis of our understanding of the global marine carbon cycle and its response to natural disturbances.

"Typically, carbon cycle models over Earth's history consider seafloor bathymetry as either a fixed or a secondary factor," said Tushar Mittal, the paper's co-author and a professor of geosciences at Pennsylvania State University.

Published in Proceedings of the National Academy of Sciences, the study reconstructed bathymetry over the last 80 million years and used a computer model to measure marine carbon sequestration. Results showed that ocean alkalinity, calcite saturation state, and carbonate compensation depth were strongly affected by changes in shallow ocean areas (about 600 meters or less) and the distribution of deeper regions (greater than 1,000 meters). These factors are crucial in understanding how carbon is stored in the ocean floor.

The researchers found that, for the current geologic era, the Cenozoic, bathymetry alone explained 33%-50% of the variation in carbon sequestration. Ignoring bathymetric changes has led researchers to incorrectly attribute changes in carbon sequestration to other factors, such as atmospheric CO2, water column temperature, and silicates and carbonates from rivers.

"Understanding important processes in the long-term carbon cycle can better inform scientists working on marine-based carbon dioxide removal technologies to combat climate change today," Bogumil said. "By studying what nature has done in the past, we can learn more about the possible outcomes and practicality of marine sequestration to mitigate climate change."

This new insight into the influence of ocean floor shape and depth on carbon sequestration also has implications for the search for habitable planets.

"When looking at faraway planets, we currently have a limited set of tools to give us a hint about their potential for habitability," said co-author Carolina Lithgow-Bertelloni, a UCLA professor and department chair of earth, planetary and space sciences. "Now that we understand the important role bathymetry plays in the carbon cycle, we can directly connect the planet's interior evolution to its surface environment when making inferences from JWST observations and understanding planetary habitability in general."

The researchers' work is far from over.

"Now that we know how important bathymetry is in general, we plan to use new simulations and models to better understand how differently shaped ocean floors will specifically affect the carbon cycle and how this has changed over Earth's history, especially the early Earth, when most of the land was underwater," Bogumil said.

https://www.energy-daily.com/reports/Ocean_Floor_Topography_Found_to_Significantly_Impact_Carbon_Sequestration_999.html

https://www.pnas.org/doi/10.1073/pnas.2400232121
Kalingrad, the new permanent home of the Olympic Village

Bruce Steele

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Re: Carbon Cycle
« Reply #756 on: June 07, 2024, 01:32:49 AM »
https://www.pnas.org/doi/10.1073/pnas.2400232121

“The shape of the ocean floor (bathymetry) and the overlaying sediments provide the largest carbon sink throughout Earth’s history, supporting ~one to two orders of magnitude more carbon storage than the oceans and atmosphere combined”


How bathymetry affects paleo record of carbon cycle ,calcium compensation depth.
Paywalled, hat tip to morganism.

My guess is the ratio of shallow water and shelf verses deep waters ( below CCD ) affects efficacy of the oceans as sinks.

kassy

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Re: Carbon Cycle
« Reply #757 on: August 21, 2024, 07:03:06 PM »
Plants might not hold on to carbon as long as we thought

Earth’s plants aren’t holding onto carbon as long as we thought.

A new analysis of pulses of radioactive carbon-14 from 20th-century bomb tests reveals that plants stock more carbon in short-lived tissues such as leaves than previously estimated, scientists report in the June 21 Science. That means that this carbon is probably more vulnerable to re-release to the atmosphere — potentially altering estimates of how much anthropogenic carbon the biosphere can hold, the team says.

In July 1945, the United States detonated the first plutonium bomb. That “Trinity” test kicked off decades of nuclear weapon tests, particularly in the 1950s and early 1960s. Each detonation sent a large spike of radioactive carbon-14, a variant of carbon, into Earth’s atmosphere. The bomb radiocarbon then joined Earth’s carbon cycle, winding its way through Earth’s oceans and biosphere (SN: 4/14/20).

That fact became a scientific silver lining to the bomb tests: The bursts of radiocarbon circulating through Earth’s system, scientists realized, were a lot like pulses of radioactive medical tracers traveling through a human body. They offered a unique opportunity for scientists to follow the carbon, analyzing where and for how long it was being stored and released around the globe.

That intel is now crucial. As the climate heats up due to the accumulation of carbon dioxide and other greenhouse gases in the atmosphere, there is an acute need to understand just how long Earth’s biosphere — including its plants and soil — can sequester some of that carbon, says Heather Graven, an atmospheric scientist at Imperial College London (SN: 3/10/22).

Current computer models of the climate estimate that Earth’s vegetation and soils take up about 30 percent of human-caused carbon dioxide emissions. Graven and her colleagues were curious about that. “We were interested in looking at the models of the biosphere and how well they represented the radiocarbon from the bomb tests,” she says.

In the new study, Graven and her colleagues focused on a brief span of time, from 1963 to 1967, during which there weren’t any bomb tests. That meant no new pulses to confuse the data — only radiocarbon pulses already moving through the system. The team also focused just on the plant-growth part of the carbon storage.
...

The results were startling, Graven says. Most current computer simulations of vegetation and climate underestimate how fast plants are growing, they found. Current models suggest that plants are pulling in between 43 trillion and 76 trillion kilograms of carbon each year; the new study increases that to at least 80 trillion — possibly twice as much.

That sounds like good news, when it comes to hopes of storing excess carbon from human activities in the biosphere (SN: 7/9/21). But, the team found, there’s a downside. The bomb radiocarbon tracking also revealed that more carbon is being stored in short-lived biomass such as leaves and thin, fine roots than previously thought. Those tissues are far more vulnerable to degradation that releases carbon back to the atmosphere than longer-lived tissues such as stems and larger roots.

“The carbon going [into plants] now is not going to be there as long as we thought,” Graven says. And that, she says, reemphasizes how important it is to limit fossil fuel emissions. “There is a limit of how much we can store in vegetation.”

...

https://www.sciencenews.org/article/plants-might-not-hold-carbon-as-long
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kassy

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Re: Carbon Cycle
« Reply #758 on: September 11, 2024, 05:53:42 PM »
Oceans absorb 6% more carbon thanks to rain, study reveals


The ocean plays an important role in the global carbon cycle by absorbing about one-quarter of the carbon emitted by human activities every year. A study published recently in Nature Geoscience and co-authored by a University of Hawaiʻi at Mānoa oceanographer revealed about 6% of the total uptake of carbon dioxide (CO2) by the ocean is due to rainfall.

"The impact of rain on air-sea CO2 fluxes hasn't been systematically examined, but understanding it gives us a more complete picture," said David Ho, study co-author and professor in the UH Mānoa School of Ocean and Earth Science and Technology.

"This is especially important since rainfall patterns over the ocean are expected to shift with climate change, and that could impact the ocean carbon sink."

Ocean, atmosphere exchanges
Exchanges between the ocean and the atmosphere are governed by chemical, physical, and biological properties and processes. Rainfall alters these properties of the ocean surface, promoting the exchange of CO2 between the air and the sea.

Rain impacts this carbon exchange in three different ways. First, as it falls on the ocean surface, it generates turbulence that facilitates water just below the surface being in contact with the atmosphere. Secondly, it dilutes the seawater at the surface, altering the chemical equilibrium within the oceanic carbon cycle and enabling seawater to absorb greater quantities of CO2. Finally, raindrops directly inject into the ocean the CO2 absorbed during their fall through the atmosphere.

The new study, led by Laetitia Parc, a doctoral student at Ecole Normale Supérieure (ENS; France), is the first to provide a global estimate of these three effects of rain. The research team relied on an analysis of satellite observations and reanalysis of global climate and weather data over an 11-year period from 2008 to 2018.

Rain's effect on carbon sinks
Their investigation showed that rain increases the oceanic carbon sink by 140 to 190 million tons of carbon per year. This represents an increase of 5% to 7% in the 2.66 billion tons of carbon absorbed annually by the oceans. The increase in surface exchanges due to turbulence and seawater dilution plays a role of comparable order of magnitude to the direct injection of dissolved carbon in raindrops.

However, the regions where these processes are significant differ. Turbulence and dilution primarily increase the CO2 sink in tropical regions characterized by heavy rainfall events associated with weak winds, which induces noticeable salinity and CO2 dilution. In contrast, the deposition by raindrops is significant in all regions with heavy precipitation: the tropics, of course, but also the storm tracks and the Southern Ocean.

The results of this study suggest that the effect of rain should be explicitly included in the estimates used to construct the global carbon budget, which is compiled annually and integrates anthropogenic emissions, the growth of atmospheric CO2, and natural carbon sinks.

https://phys.org/news/2024-09-oceans-absorb-carbon-reveals.html

Paper:
https://www.nature.com/articles/s41561-024-01517-y
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kassy

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Re: Carbon Cycle
« Reply #759 on: October 13, 2024, 10:23:26 PM »
Hidden biological processes can affect how the ocean stores carbon

New Stanford-led research unveils a hidden factor that could change our understanding of how oceans mitigate climate change. The study, published Oct. 11 in Science, reveals never-before seen mucus "parachutes" produced by microscopic marine organisms that significantly slow their sinking, putting the brakes on a process crucial for removing carbon dioxide from the atmosphere. The surprising discovery implies that previous estimates of the ocean's carbon sequestration potential may have been overestimated, but also paves the way toward improving climate models and informing policymakers in their efforts to slow climate change.

"We haven't been looking the right way," said study senior author Manu Prakash, an associate professor of bioengineering and of oceans in the Stanford School of Engineering and Stanford Doerr School of Sustainability.

"What we found underscores the importance of fundamental scientific observation and the need to study natural processes in their true environments. It's critical to our ability to mitigate climate change."

The biological pump

Marine snow -- a mixture of dead phytoplankton, bacteria, fecal pellets, and other organic particles -- absorbs about a third of human-made carbon dioxide from the atmosphere and shuttles it down to the ocean floor where it is locked away for millennia.

Scientists have known about this phenomenon -- known as the biological pump -- for some time.

However, the exact manner in which these delicate particles fall (the ocean's average depth is 4 kilometers, or 2.5 miles) has remained a mystery until now.

The researchers unlocked the mystery using an unusual invention -- a rotating microscope developed in Prakash's lab that flips the problem on its head.

The device moves as organisms move within it, simulating vertical travel over infinite distances and adjusting aspects such as temperature, light, and pressure to emulate specific ocean conditions.

Over the past five years, Prakash and his lab members have brought their custom-built microscopes on research vessels to all the world's major oceans -- from the Arctic to Antarctica.

On a recent expedition to the Gulf of Maine, they collected marine snow by hanging traps in the water, then rapidly analyzed the particles' sinking process in their rotating microscope.

Since marine snow is a living ecosystem, it is important to make these measurements at sea.

The rotating microscope allowed the team to observe marine snow in its natural environment in exquisite detail -- instead of a distant lab -- for the first time.

The results stunned the researchers. They revealed that marine snow sometimes creates parachute-like mucus structures that effectively double the time the organisms linger in the upper 100 meters of the ocean.

This prolonged suspension increases the likelihood of other microbes breaking down the organic carbon within the marine snow particles and converting it back into readily available organic carbon for other plankton -- stalling carbon dioxide absorption from the atmosphere.


Beauty and complexity in the smallest details

The researchers point to their work as an example of observation-driven research, essential to understanding how even the smallest biological and physical processes work within natural systems.

"Theory tells you how a flow around a small particle looks like, but what we saw on the boat was dramatically different," said study lead author Rahul Chajwa, a postdoctoral scholar in the Prakash Lab.

"We are at the beginning of understanding these complex dynamics."

This work lays out an important fact. For the last 200 years, scientists have studied life, including plankton, in a two-dimensional plane, trapped in small cover slips under a microscope.

On the other hand, doing microscopy at high resolution is very hard on the high seas.

Chajwa and Prakash emphasize the importance of leaving the lab and conducting scientific measurements as close as possible to the environment in which they occur.

Supporting research that prioritizes observation in natural environments should be a priority for public and private organizations that fund science, the researchers argue.

"We cannot even ask the fundamental question of what life does without emulating the environment that it evolved with," Prakash said.

"In biology, stripping it away from its environment has stripped away any of our capacity to ask the right questions."

Beyond its importance in directly measuring marine carbon sequestration, the study also reveals the beauty in everyday phenomena.

Much like sugar dissolving in coffee, marine snow's descent into the depth of the ocean is a complex process influenced by factors we don't always see or appreciate.

"We take for granted certain phenomena, but the simplest set of ideas can have profound effects," Prakash said.

"Observing these details -- like the mucus tails of marine snow -- opens new doors to understanding the fundamental principles of our world."

The researchers are working to refine their models, integrate the datasets into Earth-scale models, and release an open dataset from the six global expeditions they have conducted so far.

This will be the world's largest dataset of direct marine snow sedimentation measurements.

They also aim to explore factors that influence mucus production, such as environmental stressors or the presence of certain species of bacteria.

Although the researchers' discovery is a significant jolt to how scientists have thought about tipping points in ocean-based sequestration, Prakash and his colleagues remain hopeful.

On a recent expedition off the coast of Northern California, they discovered processes that can potentially speed up carbon sequestration.

"Every time I observe the world of plankton via our tools, I learn something new," Prakash said.

https://www.sciencedaily.com/releases/2024/10/241010142521.htm

That´s some nice new angle.
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Bruce Steele

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Re: Carbon Cycle
« Reply #760 on: October 14, 2024, 12:51:43 AM »
Kassy, Yes the speed of sinking can have consequences in how much carbon is consumed by bacteria and viruses and remineralized before it sinks into the particulate sink or is remineralized at greater depths and converted into DIC. But it seems to me sediment traps at different depths would measure how much carbon reached various depths regardless of  how long it took to get there.
So I don’t think deep water sediment traps would in long term studies be affected by this newly observed process unless climate change somehow increases mucous production, but then again without long term data how would we know.

kassy

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Re: Carbon Cycle
« Reply #761 on: October 14, 2024, 11:59:01 AM »
I agree.

Here is some much clearer research:

Trees and land absorbed almost no CO2 last year. Is nature’s carbon sink failing?

...

In 2023, the hottest year ever recorded, preliminary findings by an international team of researchers show the amount of carbon absorbed by land has temporarily collapsed. The final result was that forest, plants and soil – as a net category – absorbed almost no carbon.

There are warning signs at sea, too. Greenland’s glaciers and Arctic ice sheets are melting faster than expected, which is disrupting the Gulf Stream ocean current and slows the rate at which oceans absorb carbon. For the algae-eating zooplankton, melting sea ice is exposing them to more sunlight – a shift scientists say could keep them in the depths for longer, disrupting the vertical migration that stores carbon on the ocean floor.

“We’re seeing cracks in the resilience of the Earth’s systems. We’re seeing massive cracks on land – terrestrial ecosystems are losing their carbon store and carbon uptake capacity, but the oceans are also showing signs of instability,” Johan Rockström, director of the Potsdam Institute for Climate Impact Research, told an event at New York Climate Week in September.

“Nature has so far balanced our abuse. This is coming to an end,” he said.

The 2023 breakdown of the land carbon sink could be temporary: without the pressures of drought or wildfires, land would return to absorbing carbon again. But it demonstrates the fragility of these ecosystems, with massive implications for the climate crisis.

...

The kind of rapid land sink collapse seen in 2023 has not been factored into most climate models. If it continues, it raises the prospect of rapid global heating beyond what those models have predicted.

‘We have been lulled – we cannot see the crisis’
For the past 12,000 years, the Earth’s climate has existed in a fragile equilibrium. Its stable weather patterns allowed the development of modern agriculture, which now supports a population of more than 8 billion people.

As human emissions rose, the amount absorbed by nature increased too: higher carbon dioxide can mean plants grow faster, storing more carbon. But this balance is beginning to shift, driven by rising heat.

“This stressed planet has been silently helping us and allowing us to shove our debt under the carpet thanks to biodiversity,” says Rockström. “We are lulled into a comfort zone – we cannot really see the crisis.”

Only one major tropical rainforest – the Congo basin – remains a strong carbon sink that removes more than it releases into the atmosphere. Exacerbated by El Niño weather patterns, deforestation and global heating, the Amazon basin is experiencing a record-breaking drought, with rivers at an all-time low. Expansion of agriculture has turned tropical rainforests in south-east Asia into a net source of emissions in recent years.

Emissions from soil – which is the second-largest active carbon store after the oceans – are expected to increase by as much as 40% by the end of the century if they continue at the current rate, as soils become drier and microbes break them down faster.

Tim Lenton, professor of climate change and Earth system science at Exeter University, says: “We are seeing in the biosphere some surprising responses that are not what got predicted, just as we are in the climate.

“You have to question: to what degree can we rely on them as carbon sinks or carbon stores?” he says.

“In 2023 the accumulation of CO2 in the atmosphere is very high and this translates into a very, very low absorption by the terrestrial biosphere,” says Philippe Ciais, a researcher at the French Laboratory of Climate and Environmental Sciences, who was an author of the most recent paper.

“In the northern hemisphere, where you have more than half of CO2 uptake, we have seen a decline trend in absorption for eight years,” he says. “There is no good reason to believe it will bounce back.”

...

‘None of the models have factored this in’
The flow of carbon through the land and ocean remains one of the least understood parts of climate science, say researchers. While human emissions are increasingly simple to measure, the sheer number and complexity of processes in the natural world mean there are important gaps in our understanding.

Satellite technology has improved monitoring of forests, peatlands, permafrost and ocean cycles, but assessments and forecasts in international reports often have large error margins. That makes it difficult to predict how the world’s natural carbon sinks will behave in future – and means many models do not factor in a sudden breakdown of multiple ecosystems.

“Overall, models agreed that both the land sink and the ocean sink are going to decrease in the future as a result of climate change. But there’s a question of how quickly that will happen. The models tend to show this happening rather slowly over the next 100 years or so,” says Prof Andrew Watson, head of Exeter University’s marine and atmospheric science group.

“This might happen a lot quicker,” he says. “Climate scientists [are] worried about climate change not because of the things that are in the models but the knowledge that the models are missing certain things.”

Many of the latest Earth systems models used by scientists include some of the effects of global heating on nature, factoring in impacts such as the dieback of the Amazon or slowing ocean currents. But events that have become major sources of emissions in recent years have not been incorporated, say scientists.

“None of these models have factored in losses like extreme factors which have been observed, such as the wildfires in Canada last year that amounted to six months of US fossil emissions. Two years before, we wrote a paper that found that Siberia also lost the same amount of carbon,” says Ciais.

“Another process which is absent from the climate models is the basic fact that trees die from drought. This is observed and none of the models have drought-induced mortality in their representation of the land sink,” he says. “The fact that the models are lacking these factors probably makes them too optimistic.”

‘What happens if the natural sinks stop working?’
The consequences for climate targets are stark. Even a modest weakening of nature’s ability to absorb carbon would mean the world would have to make much deeper cuts to greenhouse gas emissions to achieve net zero. The weakening of land sinks – which has so far been regional – also has the effect of cancelling out nations’ progress on decarbonisation and progress towards climate goals, something that is proving a struggle for many countries.

In Australia, huge soil carbon losses from extreme heat and drought in the vast interior – known as rangelands – are likely to push its climate target out of reach if emissions continue to rise, a study this year found. In Europe, France, Germany, the Czech Republic and Sweden have all experienced significant declines in the amount of carbon absorbed by land, driven by climate-related bark beetle outbreaks, drought and increased tree mortality.

Finland, which has the most ambitious carbon neutrality target in the developed world, has seen its once huge land sink vanish in recent years – meaning that despite reducing its emissions across all industries by 43%, the country’s total emissions have stayed unchanged.

...

https://uk.news.yahoo.com/trees-land-absorbed-almost-no-070018521.html

https://arxiv.org/pdf/2407.12447

So if the land sink failed in 2023 you can safely bet it will be worse in the near future...
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Bruce Steele

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Re: Carbon Cycle
« Reply #762 on: October 18, 2024, 10:44:22 PM »
https://arxiv.org/pdf/2407.12447
Same link as Kassy put up.
2023 land terrestrial land sink .41Gt C
        ocean sink.                  2.33Gt C
         Total                           2.74Gt C x 3.67 = 10.05Gt CO2  so roughly half of normal because we expect the combined land and ocean sinks to take up half of our emissions of 37.4Gt CO2 .
So like I said in another thread 18.7 expected 10.05 realized so about 8Gt went into the atmosphere instead.

Bruce Steele

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Re: Carbon Cycle
« Reply #763 on: October 18, 2024, 11:12:48 PM »
Liu J, Baker D et al  2024, The reduced net carbon uptake over Northern Hemisphere land.
https://www.science.org/doi/10.1126/sciadv.adl2201
This paper explores why 2021 ,a La Niña year , did not strengthen the carbon cycle as La Niña is expected to do .

This paper is very good. Nice graphics. Open access.
« Last Edit: October 19, 2024, 04:48:20 PM by Bruce Steele »

Bruce Steele

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Re: Carbon Cycle
« Reply #764 on: October 19, 2024, 11:24:21 PM »
https://www.reuters.com/world/americas/canadas-wildfire-season-ranks-among-worst-less-severe-than-feared-2024-09-12/

https://www.dw.com/en/brazil-faces-worst-fires-in-14-years/a-70475926

https://phys.org/news/2024-09-arctic-siberian-wildfires.html

So with both Arctic fires and the fires in the Amazon we will have issues with the terrestrial carbon sink in 2024 . There is the added effect of upwelling resuming in the Eastern Tropical Pacific after the El Niños end and the ocean to atmosphere source of CO2 it represents.
So CO2 sources from fires increase atmospheric  CO2 and negate any positives that global greening , CO2 fertilization , or increased in NO2 would otherwise have on plant growth and their contribution to the carbon sink.
 This issue has been repeating enough years now that maybe the loss of the terrestrial sink starts to bother the forecasters…
 What happens when we realize the CO2 required to reach doubling is already in the past ?
« Last Edit: October 20, 2024, 12:10:31 AM by Bruce Steele »

kiwichick16

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Re: Carbon Cycle
« Reply #765 on: October 26, 2024, 10:58:52 PM »
Most Australians call the interior of their country the "outback " or the "bush "  .....as in someone living in the outback has "gone bush "

https://en.wikipedia.org/wiki/Outback

gerontocrat

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Re: Carbon Cycle
« Reply #766 on: November 03, 2024, 04:03:02 AM »
I've taken a bit of time to look at biodiversity loss in relation to carbon sinks. Things were not looking good and now look a bit worse.

Opinion piece published by US National Academy of Sciences
https://www.pnas.org/doi/abs/10.1073/pnas.2115218118
Quote
We need biosphere stewardship that protects carbon sinks and builds resilience

Earth’s biosphere, its extraordinary and complex web of species and ecosystems on land and in the oceans, drives the life-sustaining cycles of water and other materials that enable all life on Earth to thrive. The biosphere is also a principal driver of immense negative feedback loops in the Earth system that stabilize atmospheric CO2 concentrations and thereby global climate—including carbon sequestration by vegetation, soils, and the oceans. As such, Earth’s ecosystems have played a central role in keeping our planet’s climate system unusually stable throughout the last 11,700 years (i.e., the inter-glacial Holocene).

During this epoch, global mean temperatures have oscillated only about 1 °C around the pre-industrial average, providing the unique conditions that allowed human civilizations to flourish. Today, ocean and land ecosystems remove around 50% of anthropogenic CO2 emissions from the atmosphere each year (1), an extraordinary biophysical feat, given that these emissions have risen from approximately 4 gigatonnes of carbon (GtC) per year in 1960 to around 11 GtC per year today. Put another way, half our “climate debt” is removed, for free, by the biosphere every year—a vast subsidy to the world economy.

the COP16 BioDiversity meeting has just finished and unfortunately  it basically was a failure

This BBC article is quite polite about it though the headline says it all - other sources howled in fury and frustration.
https://www.bbc.co.uk/news/articles/cy9jdpep4ydo
Quote
Politicians not ambitious enough to save nature, say scientists
Scientists say there has been an alarming lack of progress in saving nature as the UN biodiversity summit, COP 16, draws to a close.

The scale of political ambition has not risen to the challenge of reducing the destruction of nature that costs the economy billions, said one leading expert.

Representatives of 196 countries have been meeting in Cali, Colombia, to agree on how to halt nature decline by 2030.

The biodiversity summit is separate from the more well-known COP climate summit, which is set to take place in Baku later this month.

Countries were meant to come to the table with a detailed plan on how they intended to meet biodiversity targets at home, but most missed the deadline.

However, plans were agreed to raise money for conservation through making companies pay for using genetic resources from nature.

The summit comes as one million species face extinction and nature is declining at rates unprecedented in human history.

We are stuck in a "vicious cycle where economic woes reduce political focus on the environment" while the destruction of nature costs the economy billions, said Tom Oliver, professor of biodiversity at the University of Reading.
"I wasn't expecting that quite so soon" kiwichick16
"Para a Causa do Povo a Luta Continua!"
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"Damn, I wanted to see what happened next" (Epitaph)

kassy

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Re: Carbon Cycle
« Reply #767 on: December 05, 2024, 08:20:51 PM »
Warming temperatures may shrink wetland carbon sinks

A major global study using teabags as a measuring device shows warming temperatures may reduce the amount of carbon stored in wetlands.

The international team of scientists buried 19,000 bags of green tea and rooibos in 180 wetlands across 28 countries to measure the ability for wetlands to hold carbon in their soil, known as wetland carbon sequestration.

While tea bags may seem an unusual instrument to measure this phenomenon, it is a proven proxy method to measure carbon release from soil into the atmosphere. However, this is the first time teabags have been used for a large-scale, long-term study and the tea leaves have revealed which types of wetlands are leaking the most carbon.

...

Reading the tea leaves

Tea bags provide a simple and standardised way to identify how climate, habitat type and soil type influence carbon breakdown rates in wetlands.

At each site, scientists buried between 40 and 80 tea bags about 15 cm underground and collected these at various time intervals over three years, tagging their GPS location. They then measured their remaining organic mass to assess how much carbon had been preserved in the wetlands.

The project used the two types of tea bags (green and rooibos) as measures for different kinds of organic matter found in soils. Green tea consists of organic matter that decomposes easily, whereas rooibos decomposes more slowly. Using both types of tea bags in this project enabled the researchers to gain a more comprehensive picture of the wetlands' capacity for carbon storage.

"This data shows us how we can maximise carbon storage in wetlands globally," Trevathan-Tackett said.

The findings

The team studied the effect of temperature in two ways: using local weather station data for each site and comparing differences in climate regions.

"Generally, warmer temperatures led to increased decay of organic matter, which translates to reduced carbon preservation in soil," Trevathan-Tackett said.

The two tea types acted differently with increasing temperature.

"For the harder to degrade rooibos tea, it didn't matter where it was -- higher temperature always led to more decay, which indicates that types of carbon we'd typically expect to see last longer in the soil were vulnerable to higher temperatures," Trevathan-Tackett said.

"With increasing temperatures, the green tea bags decayed at different rates depending on the type of wetland -- it was faster in freshwater wetlands but slower in mangrove and seagrass wetlands.

"Increasing temperatures may also help boost carbon production and storage in plants, which could help offset carbon losses in wetlands due to warmer weather, but this warrants further investigation with future studies."

Freshwater wetlands and tidal marshes had the highest tea mass remaining, indicating a greater potential for carbon storage in these ecosystems.

The study's findings are helping piece together the puzzle of wetland carbon sequestration on a global scale. Within the terrestrial TeaComposition initiative led by Djukic, information on litter decomposition has been collected at about 500 sites worldwide resulting in several peer-review publications.

"Applying the common metric across aquatic, wetland, marine and terrestrial ecosystems allows for a conceptual comparison and understanding of key drivers involved in the control of global litter carbon turnover," Djukic said.

"Now that we are starting to get a better understanding of which environments are storing more carbon than others, we can use this information to ensure we protect these areas from environmental or land-use change."

...

https://www.sciencedaily.com/releases/2024/12/241202124231.htm

So we finally found an actual use for rooibos...
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vox_mundi

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Re: Carbon Cycle
« Reply #768 on: January 21, 2025, 04:56:20 PM »
After Millennia as CO₂ Sink, More Than One-Third of Arctic-Boreal Region Is Now a Source
https://phys.org/news/2025-01-millennia-arctic-boreal-region-source.html



After millennia as a carbon deep-freezer for the planet, regional hotspots and increasingly frequent wildfires in the northern latitudes have nearly canceled out that critical storage capacity in the permafrost region, according to a study published in Nature Climate Change.

An international team led by Woodwell Climate Research Center found that a third (34%) of the Arctic-boreal zone (ABZ)—the treeless tundra, boreal forests, and wetlands that make up Earth's northern latitudes—is now a source of carbon to the atmosphere. That balance sheet is made up of carbon dioxide (CO2) uptake from plant photosynthesis and CO2 released to the atmosphere through microbial and plant respiration.

When emissions from fire were added, the percentage grew to 40%.


"While we found many northern ecosystems are still acting as carbon dioxide sinks, source regions and fires are now canceling out much of that net uptake and reversing long-standing trends."

... For example, the study found that while 49% of the ABZ region experienced "greening"—in which longer growing seasons and more vegetation means that more carbon can be photosynthesized and stored—only 12% of those greening pixels on the map showed an annual increasing net uptake of CO2.

Wildfires offset the increasing but spatially heterogeneous Arctic–boreal CO2 uptake, Nature Climate Change (2025)
https://dx.doi.org/10.1038/s41558-024-02234-5

------------------------------------------------------



------------------------------------------------------

Map Reveals Alaskan 'Hotspots' of Extreme Warming
https://www.woodwellclimate.org/arctic-hotspots-climate-stress-in-northern-alaska-siberia/

http://dx.doi.org/10.1029/2023GL108081

------------------------------------------------------

Meanwhile ...

Trump Leaves Paris Climate Agreement, Doubles Down On Fossil Fuels
https://phys.org/news/2025-01-trump-paris-climate-agreement-fossil.html

President Donald Trump on Monday announced the United States' withdrawal from the Paris climate accord for a second time, a defiant rejection of global efforts to combat planetary warming as catastrophic weather events intensify worldwide.

The Republican leader also declared a "national energy emergency" to expand drilling in the world's top oil and gas producer, said he would scrap vehicle emissions standards that amount to an "electric vehicle mandate," and vowed to halt offshore wind farms, a frequent target of his scorn.

He also signed an order instructing federal agencies to reject international climate finance commitments made under the previous administration, and issued a formal letter to the United Nations notifying it of Washington's intent to leave the agreement.

.... Manish Bapna, president of the Natural Resources Defense Council, pushed back: "There is no energy emergency. There is a climate emergency."
« Last Edit: January 21, 2025, 05:19:58 PM by vox_mundi »
There are 3 classes of people: those who see. Those who see when they are shown. Those who do not see

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

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