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vox_mundi

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Cloud feedback to global warming
« on: July 19, 2021, 10:21:48 PM »
Global Satellite Data Shows Clouds Will Amplify Global Heating
https://phys.org/news/2021-07-global-satellite-clouds-amplify.html

Research, by scientists at Imperial College London and the University of East Anglia, is the strongest evidence yet that clouds will amplify global heating over the long term, further exacerbating climate change.

The results, published today in Proceedings of the National Academy of Sciences, also suggest that at double atmospheric carbon dioxide (CO2) concentrations above pre-industrial levels, the climate is unlikely to warm below 2°C, and is more likely on average to warm more than 3°C.

Inspired by ideas from the artificial intelligence community, the researchers developed a new method to quantify relationships between state-of-the-art global satellite observations of clouds, and the associated temperature, humidity and wind conditions. From these observed relationships, they were then able to better constrain how clouds will change as the Earth warms.

They found it was very likely (more than 97.5% probability) that clouds will amplify global heating, by both reflecting less solar radiation and enhancing the greenhouse effect. These results also suggest that a doubling of CO2 concentrations will lead to around 3.2°C of warming. This is the highest confidence of any study so far, and is based on data from global observations, rather than local regions or specific cloud types.

Paulo Ceppi el al., "Observational evidence that cloud feedback amplifies global warming," PNAS (2021).
https://www.pnas.org/content/118/30/e2026290118
« Last Edit: July 21, 2021, 12:13:22 PM by kassy »
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The Walrus

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Cloud feedback to global warming
« Reply #1 on: July 20, 2021, 03:43:39 PM »
I find their reasoning rather dubious.  While the do show strong evidence that clouds will enhance the greenhouse effect, evidence supporting their conclusion that clouds will reduce the reflection of solar radiation is severely lacking.
« Last Edit: July 21, 2021, 12:13:31 PM by kassy »

kassy

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Cloud feedback to global warming
« Reply #2 on: July 21, 2021, 11:05:15 AM »
Some details via Eurekalert:

Global satellite data shows clouds will amplify global heating

...

The largest uncertainty in climate sensitivity predictions is the influence of clouds, and how they may change in the future. This is because clouds, depending on properties such as their density and height in the atmosphere, can either enhance or dampen warming.

Co-author Dr Paulo Ceppi, from the Grantham Institute - Climate Change and the Environment at Imperial, said: "The value of the climate sensitivity is highly uncertain, and this translates into uncertainty in future global warming projections and in the remaining 'carbon budget' - how much we can emit before we reach common targets of 1.5°C or 2°C of global warming.

"There is therefore a critical need to more accurately quantify how clouds will affect future global warming. Our results will mean we are more confident in climate projections and we can get a clearer picture of the severity of future climate change. This should help us know our limits - and take action to stay within them."

Low clouds tend to have a cooling effect, as they block the sun from reaching the ground. High clouds, however, have a warming effect, as while they let solar energy reach the ground, the energy emitted back from the Earth is different. This energy can be trapped by the clouds, enhancing the greenhouse effect. Therefore, the type and amount of cloud a warming world will produce impacts further warming potential.

...

Co-author Dr Peer Nowack, from the School of Environmental Sciences and Climatic Research Unit at the University of East Anglia and Imperial's Grantham Institute and Data Science Institute, said: "Over the last few years, there's been a growing amount of evidence that clouds probably have an amplifying effect on global warming. However, our new approach allowed us for the first time to derive a global value for this feedback effect using only the highest quality satellite data as our preferred line of evidence.

https://www.eurekalert.org/pub_releases/2021-07/icl-gsd071521.php

So they have sat data which shows which type of clouds are where not in space but also in height.

In general as the atmosphere warms it holds more vapor which means that low clouds will form later if you keep all else the same.
« Last Edit: July 21, 2021, 12:13:43 PM by kassy »
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kassy

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Cloud feedback to global warming
« Reply #3 on: July 21, 2021, 11:14:30 AM »
This thread is for science about the cloud feedback to global warming in general.

Discussion of aerosols and their direct influence has it´s own thread:
https://forum.arctic-sea-ice.net/index.php/topic,1384.0.html

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oren

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Cloud feedback to global warming
« Reply #4 on: July 21, 2021, 12:10:14 PM »
You need to edit the subject of the top post.
« Last Edit: July 21, 2021, 12:13:59 PM by kassy »

kassy

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Re: Cloud feedback to global warming
« Reply #5 on: July 21, 2021, 12:15:52 PM »
You need to edit the subject of the top post.

Oops. Modified them all now.
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kassy

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Re: Cloud feedback to global warming
« Reply #6 on: July 22, 2021, 07:37:38 PM »
Since the cloud effect has been uncertain, its accurate measurement also helps affirm other recent projections that a doubling of carbon dioxide in the atmosphere will warm the planet’s surface by about 5.8 degrees Fahrenheit, said said co-author Paulo Ceppi, a climate scientist with the Grantham Research Institute on Climate Change at Imperial College London.

“Most previous cloud studies focused only on certain regions or regimes, so say they look at places where there are low clouds and they look at low clouds only,” he said. “We did this analysis everywhere, at every point regardless of what type of cloud was there, and that allowed us to get a global picture.”

The new research is an important update to the scientific understanding of clouds in the climate system, said Piers Forster, director of the Priestley Centre at Leeds University.

“It is a really good step forward,” said Forster, who was not involved in the new study, but has worked on other recent research assessing the climate system’s response to building greenhouse gas levels.

“It really tells us how clouds respond to changes in local surface temperature, especially the reflectance of low clouds,” he said. “This is then used to make an accurate estimate of the total cloud feedback: the amplifying effect that clouds have on global warming.”

To get a sense of how important clouds are in the global warming equation, Ceppi said their effects can be compared to the warming effect of carbon dioxide.

“We calculate that, on average globally, clouds reflect something like 50 watts per square meter of solar radiation,” he said. “You can compare that to the forcing from a doubling of CO2, which would be about 4 watts per square meter, much smaller than the average effect of clouds on sunlight. So even a very small change in how much sunlight is reflected by clouds would be comparable to the effect of a CO2 doubling.”

In general, the new research confirms what some of those other studies have suggested, he said.

“People have argued that clouds will amplify global warming because of solar impacts, so less reflected sunlight from low clouds, but also because of the greenhouse effect of clouds, where high clouds rise, which makes them have a larger warming effect,” he said. “Our study finds evidence of both. I’m not aware of any other studies that have been able to show that, especially the greenhouse part.”

One recent study, led by University of Oslo researchers, shows global warming will reduce the amount of ice particles in widespread low clouds around Antarctica that currently reflect a huge amount of solar radiation back into space. That would make the clouds less reflective and amplify global warming, said cloud researcher Trude Storelvmo.

https://insideclimatenews.org/news/19072021/climate-driven-changes-in-clouds-are-likely-to-amplify-global-warming/

Even more detailed info on how clouds work/what they detected in general.

The last paragraph is a bonus mention of another troubling feed back.
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jai mitchell

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Re: Cloud feedback to global warming
« Reply #7 on: July 22, 2021, 08:35:27 PM »
This thread is for science about the cloud feedback to global warming in general.

Discussion of aerosols and their direct influence has it´s own thread:
https://forum.arctic-sea-ice.net/index.php/topic,1384.0.html

The problem here is that the two are causally linked but this causation has not been proven conclusively through scientific analysis, either through lack of information and understanding or simply due to the lack of effort and focus on it.

For instance, scientific study in 2012 at UK Leeds showed that the Atlantic Multi-decadal Oscillation was driven by regional aerosol loading, this was called into question and now this result is still uncertain.

Similarly, Michael Mann led a paper recently that declared that the Pacific Decadal Oscillation was driving primarily by Volcanic activity.

However, if you look at the Pacific Decadal Oscillation series, you see quite clearly that high global aerosol loading is linked with a long and persistent negative phase of the PDO and that subsequent to short term Aerosol reduction activities the PDO swings positive. 

This happened during the swing in 1978, our most recent period of warming acceleration prior to 2014, when China successfully reduced their aerosol emissions enough to swing the PDO positive (who would have thought that SE Asian aerosols would have a stronger effect on the Pacific???)

--------------
and now the point
--------------

The pattern effect cloud studies have shown that the pattern effect from warming is only really extracted from the data after 2014 when the PDO went positive.

If I am correct, then we will see a strong positive PDO prevalence and that this will increase with forcing into a permanent positive PDO.  This will show that the pattern effect is a significant percentage of the total GHG forcing as a short-term feedback, adding to the lapse rate and water vapor feedbacks. 

And that ECS is greater than 4.5K
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kassy

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Re: Cloud feedback to global warming
« Reply #8 on: July 22, 2021, 10:07:41 PM »
Clouds That Can No Longer Cool

The other recent cloud study, led by University of Oslo scientists, showed that global warming will eventually cut the volume of ice particles in massive cloud banks over the Southern Ocean, around Antarctica.

“The ice in those clouds makes them brighter and more reflective, but if we allow enough warming, there won’t be any more ice,” said University of Oslo climate researcher Trude Storelvmo, co-author of the study, published Oct. 26 in the journal Nature Geoscience.

The findings suggest that, if the average global temperature increases by 5 to 7 degrees Fahrenheit, the clouds over the Southern Ocean would lose their cooling effect and further raise the global temperature by an additional 2 to 3 degrees.

Figuring out exactly how sensitive the climate is to rising greenhouse gas concentrations depends in large part on knowing what happens to clouds, and the computer models have to use correct information to end up with accurate projections.

“We have to start at the right point to be able to simulate how it will change over time, and we haven’t had good measurements on this particular cloud property,” Storelvmo said. “But now we have these wonderful new measurements that have really changed things,” she continued, describing the lidar and radar readings that can show the ratio of water to ice inside the clouds much more accurately than just 10 years ago.

In this model, we saw that, when we had warming of 3 to 4 degrees Celsius (5.4 to 7.2 degrees Fahrenheit), we had no more ice,” she said. At that point, the clouds lose their cooling effect.

https://insideclimatenews.org/news/10112020/clouds-cooling-climate-effects/

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kassy

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Re: Cloud feedback to global warming
« Reply #9 on: December 13, 2022, 01:25:58 PM »
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
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jai mitchell

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Re: Cloud feedback to global warming
« Reply #10 on: September 01, 2023, 04:31:19 PM »
Paper just came out that shows the total climate feedback (including cloud and pattern effect) is enough forcing to be responsible for ALL of the observed warming from 1980-2014

This means that there is still a lot of warming left

https://journals.ametsoc.org/view/journals/clim/36/18/JCLI-D-22-0862.1.xml
Observational Constraints on the Cloud Feedback Pattern Effect
Timothy A. Myers, Mark D. Zelinka , and Stephen A. Klein
Online Publication: 28 Aug 2023

Abstract
Model evidence for the “pattern effect” assumes that global climate models (GCMs) faithfully simulate how clouds respond to varying sea surface temperature (SST) patterns and associated meteorological perturbations. We exploit time-invariant satellite-based estimates of the sensitivity of marine low clouds to meteorological perturbations to estimate how these clouds responded to time-varying SST patterns and meteorology between 1870 and 2014. GCMs and reanalyses provide estimates of the historical meteorological changes. Observations suggest that increasing estimated inversion strength (EIS) between 1980 and 2014 produced a negative low cloud feedback, opposite to the positive feedback expected from increasing CO2. This indicates that the processes responsible for marine cloud changes from 1980 to the near present are distinct from those associated with an increase in CO2. We also observationally constrain the difference between the historical near-global marine low cloud feedback, λhistcloudand that arising from increasing CO2. We find that this cloud feedback pattern effect depends strongly on time period and reanalysis dataset, and that varying changes in EIS and SST with warming explain much of its variability. Between 1980 and 2014, we estimate that 0.78 (90% confidence) assuming meteorological changes from the Multiple Reanalysis Ensemble, implying a total pattern effect (that arising from all climate feedbacks) of 1.86 ± 0.45 W m−2 K−1. This observational evidence corroborates previous quantitative estimates of the pattern effect, which heretofore relied largely upon GCM-based cloud changes. However, disparate historical meteorological changes across individual reanalyses contribute to considerable uncertainty in its magnitude.
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kassy

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Re: Cloud feedback to global warming
« Reply #11 on: September 26, 2023, 08:26:17 PM »
Rise In Global Thunderstorm Activity Might Increase The Quantity Of Wispy Cirrus Clouds – Accelerating Global Warming


A new study has found a significant statistical correlation between thunderstorms occurring around the world and the formation of wispy cirrus clouds – which might increase global warming. The researchers: “We know that cirrus clouds can contribute to global warming. However, it is very difficult to track these clouds and obtain accurate data about them. Our findings indicate that a rise in the number of thunderstorms occurring globally might significantly increase the quantity of cirrus clouds, thereby exacerbating the climate crisis.”

...

Prof. Price explains: “Cirrus clouds, those feathery clouds we see in the sky, significantly impact the earth’s climate. An increase of these clouds will act as a blanket that increases warming, while a decrease will allow the heat of the Earth to rise and escape from the atmosphere. This is why climate researchers are highly interested in cirrus clouds, trying to predict potential changes due to the rise in greenhouse gases and global warming. But here we encounter a significant problem: it is very hard to obtain accurate, comprehensive data about cirrus clouds. Being so wispy, they can be invisible to the human eye and even to satellites, plus they form in the upper atmosphere, far from the monitoring stations operating on the ground.”

To address this challenge the researchers explored the possibility of predicting the quantity of cirrus clouds on the basis of readily available data about thunderstorms and lightning activity. They explain that the brilliant flash of lightning is formed when a huge electric field is discharged instantaneously, generating a very high temperature of up to 30,000 degrees Centigrade in the lightning channel. The light waves and radio waves emitted by the lightning discharge can be detected even thousands of kilometers away, enabling long-term monitoring and mapping of thunderstorms.

The present study is based on thunderstorm data collected worldwide over a period of 6 years by the NASA satellite ISS-LIS that detects the light emitted by lightning. The researchers compared these data with data on cirrus clouds (the partial information available combined with supplementary models), looking for a correlation between lightning activity on a specific day, month, or year, and the amount of cirrus clouds formed in the upper atmosphere. Findings indicate a statistically significant correlation, with the quantity of cirrus clouds increasing with the number of thunderstorms. According to the researchers, this means that thunderstorms, which are easy to detect and measure, can in fact be used as a reliable indicator for the amount of cirrus clouds in the atmosphere, today and in the future.

Prof. Price: “We discovered that thunderstorms are a major mechanism in the formation of cirrus clouds, and that lightning activity can account for over 70% of the changes in the quantity of cirrus clouds in the world. Thunderstorms act as an enormous ”vacuum cleaner”, lifting moisture from the surface of the planet, especially above oceans and forests, to higher levels of the atmosphere. There, at an altitude of about 10km, this moisture turns into ice crystals that form the cirrus clouds.”

...

https://scienceblog.com/539613/rise-in-global-thunderstorm-activity-might-increase-the-quantity-of-wispy-cirrus-clouds-accelerating-global-warming/
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