Global warming not just a blanket: In the long run, it's more like tanning oil

Earth
A composite image of the Western hemisphere of the Earth. Credit: NASA

While computer models churn out bleak forecasts for the planet's future, we also have a more conceptual understanding of what is happening as humans pump carbon dioxide into the air. But the conceptual understanding of carbon dioxide wrapping the planet in a blanket that traps more heat is not quite right.

A new study from the University of Washington and the Massachusetts Institute of Technology hopes to complete the understanding of what happens to the planet under . Instead of , or CO2, creating a blanket to slowly warm the planet, a paper this week in the Proceedings of the National Academy of Sciences shows the story is a little more complicated - though the ending is, unfortunately, the same.

"This is a neat study in that it changes the way we think about the climate system," said lead author Aaron Donohoe, a postdoctoral researcher at MIT who is now beginning as a research associate at the UW's Applied Physics Laboratory. "We looked at processes that are well captured in the models, but the conceptual understanding of how they work hasn't been fleshed out before."

When CO2 is first added, it does act as a blanket, trapping long-wave infrared energy coming off the Earth. The atmosphere then emits less of this long-wave radiation to space because the upper atmosphere is cooler than the Earth's surface, just as the top of your blanket is cooler than your body. But the Earth gradually heats up under this blanket, and hotter objects emit more long-wave radiation, so within about a decade the effect of adding the thicker blanket has been canceled by the warmer body emitting more energy.

So what keeps the planet warming after the first decade? In the longer term, the study shows that the Earth begins to absorb more shortwave radiation - the high-energy rays coming directly from the sun.

Global warming not just a blanket: In the long run, it's more like tanning oil
Outgoing longwave radiation from CERES Instrument on NASA Aqua Satellite for March 18, 2011, near Vernal Equinox of 2011 Credit: Courtesy of NASA

Previously people had shied away from talking about shortwave radiation because clouds can reflect this visible light back to space, and clouds remain one of the big unknowns under climate change.

Regardless of what happens to clouds, these researchers say, the planet is likely to have less ice and the air will become more humid under climate change, both of which will act to absorb more shortwave radiation from the sun. Those effects will be like putting tanning oil on the planet, letting it absorb more of the sun's incoming rays.

Melting ice creates darker surfaces that can absorb more heat, and the more melting the more heat it can absorb. Likewise, warmer air holds more water vapor, causing it to absorb solar radiation that might otherwise bounce back off clouds, ice or snow.

"While greenhouse gases trap one type of radiation, it's the other type - visible, shortwave radiation - that is really sustaining global warming over the long term," said co-author Kyle Armour, a at MIT who will join the UW faculty this fall with a joint appointment in oceanography and atmospheric sciences.

Global warming not just a blanket: In the long run, it's more like tanning oil
The image shows longwave radiation emitted to space from Earth's surface and atmosphere (left sphere) and shortwave solar radiation reflected back to space by the ocean, land, aerosols, and clouds (right sphere). Credit: Courtesy of NASA

The result could help people better conceptualize . It could also help better detect climate change in satellite data, which can measure both shortwave radiation reflected by the Earth and long-wave radiation emitted by the Earth.

Most of the study's simulations involved a one-time addition of carbon dioxide into the atmosphere. One scenario simulated continuously increasing CO2, as is happening now - in that case, the long-wave radiation effect lasted about 20 years before the shortwave effect took over.

"Our results do not change our overall expectation that the planet will continue to warm due to the burning of fossil fuels, but they do change our fundamental understanding of how that warming comes about," said co-author David Battisti, a UW professor of atmospheric sciences.

The study supports what scientists are seeing in models and observations, Battisti added.


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More information: Shortwave and longwave radiative contributions to global warming under increasing CO2, www.pnas.org/cgi/doi/10.1073/pnas.1412190111
Citation: Global warming not just a blanket: In the long run, it's more like tanning oil (2014, November 10) retrieved 14 October 2019 from https://phys.org/news/2014-11-global-blanket-tanning-oil.html
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Nov 10, 2014
Hmmmm, melting ice is causing trouble and is the primary result of climate change?

Where have I heard that before?

Now they have to discover it's the heat, not the blanket...

Nov 10, 2014
"these researchers say, the planet is likely to have less ice and the air will become more humid under climate change" It shouldn't be necessary to speculate about ice cover and humidity. We have measurements for the total snow and ice cover and we should have estimates for the humidity over the last 50 years when CO2 has increased markedly. Has the total ice cover increased or decreased? Has the humidity increased or decreased?


Nov 10, 2014
Oh, no, . .

You folk told us it is all a trick by hippies and scientists to make all of you homosexual, and take your guns.

Nov 10, 2014
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Nov 10, 2014
This comment has been removed by a moderator.

Nov 10, 2014
You gotta love the "settled" AGW Cult "science", long on stupidity, short on reality.

Nov 10, 2014
" . . . in the recent decade this argument was simply dismissed"
------------------------

Like the flat Earth.

Nov 10, 2014
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Nov 11, 2014
Jim4321 asked
.. Has the total ice cover increased or decreased? Has the humidity increased or decreased?
There is this 'thing' called google (& other search engines) on the "internet" which are easy for most to use when u are motivated to find out instead of being lazy and asking others:-

Website re global ice coverage, with useful animations
http://www.skepti...-ice.htm

Humidity: Here is a start
http://tamino.fil...umid.jpg

Perhaps you would like to do the opposite to the effort of your last post & locate a global humidity distribution graph ?

Nov 11, 2014
the air will become more humid under climate change, both of which will act to absorb more shortwave radiation from the sun
The humid air contains white clouds, which reflect the heat quite well (which is why the weather gets cold under clouds, as everyone of us experienced already).

It's called physics my friend and your comprehension of this part of it is an epic fail.
Humidity as two aspects - absolute and relative humidity. It let you toddle off and study the difference. And why more WV in the air does NOT result in more in more white reflecting clouds (overall).
FFS

Nov 11, 2014
imido claimed
..humid air contains white clouds, which reflect the heat quite well (which is why the weather gets cold under clouds, as everyone of us experienced already).
By far most of the atmospheric volume has no clouds of any kind, Clouds are NOT water vapour, they are suspended droplets of water small enough to stay aloft. Therefore water vapour distributed over the whole atmosphere has much greater mass than mere clouds.

imido claimed
..so within about a decade the effect of adding the thicker blanket has been canceled by the warmer body emitting more energy
You must look at the maths, partial reflection vs overall increase in water vapour over whole atmosphere for comparative assessment.

imido claimed
Why such an insight is used with mainstream just after twenty years of climatic research?
Its been known a long time before you were born.

For media/public not everything in climate science & meteorology is given as free education !

Nov 11, 2014
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Nov 11, 2014
So @imido, I am curious, are there any
proponents of
who are not blind?

Nov 11, 2014
Another hypothesis, but no proof.

Nov 11, 2014
Another hypothesis, but no proof.
@joeblooper
a lesson in reality
the following is called conjecture based upon stupidity
Another hypothesis, but no proof
why? because you can see the linked study above: http://www.pnas.o...12190111
the study uses evidence to generate it's conclusions
Observational constraints of radiative feedbacks—from satellite radiation and surface temperature data—suggest an OLR recovery timescale of decades or less, consistent with the majority of GCMs. Altogether, these results suggest that, although greenhouse gas forcing predominantly acts to reduce OLR, the resulting global warming is likely caused by enhanced ASR
it also uses other types of proven empirical data like this: http://www.scienc...abstract
(although that one is not cited that i saw)

conjecture is meaningless as you have no evidence supporting it and make false ASSumptions


Nov 11, 2014
the blind proponents of anthropogenic global warming will fight & downvote angrily every opposite opinion like the proponents of nowadays religion. Whereas in fact they just don't understand their own model well.
@ZEPHIR/imido
no
you are downvoted because you do not provide evidence of your conjecture and you continually support falsified failed debunked philosophies (NOT theories, philosophies... when something is debunked with empirical evidence and proven that it cannot exist, like so: http://exphy.uni-...2009.pdf
it is not a theory, it is a philosophy)

perhaps you can show your scientific acumen and refute the following with equivalent studies?
http://www.scienc...abstract
http://marine.rut..._pub.pdf

Nov 12, 2014
imido doesnt understand
What the mass has to do with reflectivity of clouds?
Sorry thought it was obvious to those that write as if they have some education :-(

Any increase in cloud cover regarding partial reflectivity is more than offset by greater greenhouse gas effect from higher water vapour concentration BECAUSE the increased mass of water vapour is the factor in its property as a greenhouse gas, can you NOW understand what I said in my post
You must look at the maths, partial reflection vs overall increase in water vapour over whole atmosphere for comparative assessment.
imido went on
I know, I linked the source from 1901.
No, U missed the point, these 'insights' were known long ago.

imido
Why no mention of warming saturation/blanket effect exists in mainstream press?
Depends where..

imido claimed
Actually this is the first article, where we could read about it and it's also presented here as a very new insight.
Its only popular press.

Nov 12, 2014
Captain Stumpy offered a very interesting link
http://www.pnas.org/content/early/2014/11/05/1412190111
Thanks, fascinating, adds complexity to changes of issues of SW absorption, I wonder how much effect of reduced albedo with tremendous changes in major oceans re floating rubbish plastic particulates absorbing & scattering more SW causes in respect of local heating & thus effect on LW radiation.

Given fact oceans >70% of surface AND ocean ice mass/extent declining AND knowing some algae & other water based plants increase mass then it only needs one other aspect to be summed in respect the Physical Chemical interface of atmosphere to ocean's surface.

Clearly best investigated by a competent Physical Chemist who has integrity & independence to properly undertake literature review & assess that with the benefit of their 3-4 yrs of university training to arrive at some quantitative judgement.

Where could one find a good mature & competent Physical Chemist ?

Nov 15, 2014
You gotta love the "settled" AGW Cult "science", long on stupidity, short on reality.


Excellent rebuttal jack ass.

Nov 15, 2014
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Nov 15, 2014
only trolling below them, do you?
@ZEPHIR/imido
1- you've ignored a century of science with your belief in daw/aw while it is directly falsified with the following: http://exphy.uni-...2009.pdf

2- Mike is multilingual
3- how do you know it wasn't a satirical comment or meant as hyperbole?
a troll (/ˈtro�Šl/, /ˈtrÉ�l/) is a person who sows discord on the Internet by starting arguments or upsetting people,[1] by posting inflammatory,[2] extraneous, or off-topic messages in an online community (such as a newsgroup, forum, chat room, or blog) with the deliberate intent of provoking readers into an emotional response[3] or of otherwise disrupting normal on-topic discussion.[4]
https://en.wikipe...ernet%29

so by definition, YOU are trolling with your comments
not Mike

Nov 15, 2014
The above article's SIMPLISTIC conclusion are just as erroneous and misleading as some of the denialist 'arguments/conclusions'.

I explained all this some years back. It's not as simple as everyone tries to make out!

So I'll specifically address some obviously-missed 'relevant variable factors' to Water_Prophet, imido et al for their considerations of what the W vapours/clouds actually do...and...when in the DAILY, as well as longer period, movements/distributions/phase-changes etc.

Cloud/vapour coverage at any one moment globally is like a 'patchwork quilt' with great big 'localised holes' in it being dragged over your bed.

There are arid climatic regions where vapour/precipitation phases are 'scarce/rare' in extent over time and geography. So any extra heat being shuffled around by the atmosphere will eventually reach these 'holes' and escape upwards to upper atmosphere where, IF more CO2, that heat does not further escape as easily/much to space.

[continued...]

Nov 15, 2014
[...continued]

Then there's 'tropical regions pattern' of cloud formation/precipitation that occurs in the late afternoon, when the sun is slanting in UNDER the forming clouds!

That radiation is NOT reflected up, but ALONG (horizontally/downwards) the atmosphere between the base of the cloud cover and the ground! So not as much 'upward reflection by cloud TOPS' as is being 'calculated/assumed'.

Moreover, formation of clouds in many of warmest regions occurs in late afternoon/evening, and precipitation and overnight. So again there is no 'cloud TOPS' up-reflection of SUNLIGHT in may times/places!

Hence, transient effects of more/less vapour/clouds is NOT 'the' significant factor if heat can be transported via atmospheric turbulence to arid/nighttime regions.

So short AND long term problem IS the CO2 in upper atmosphere!...which traps heat OTHERWISE normally lost to space via the 'patchwork quilt holes' in the usual water vapour/cloud distribution/dynamics mentioned. :)

Nov 15, 2014
"What I'm convinced of is that we don't understand climate." - Freeman Dyson

As a general rule, if Freeman Dyson doesn't understand something, you don't, either.

Nov 16, 2014
imido claimed
You apparently don't read articles at PO, only trolling below them, do you?
No.

I am on ~50+ forums, bulk with various nicknames, often speed read well over a dozen articles each day, many lengthy. Article in question popped up later on another forum & thus attributed compliment to the Captain, if at least as reminder to me, when I came back again.

I'm semi retired with serious commercial interest in several projects from electronics through to mechanics, food science, microbiology etc. I'm also in the (accepted) later years & on several unusual food supplements, so occasional reminder is indeed helpful, we all have feet of clay/

Your ignorance & presumptions on this forum do U no credit as U appear to act on it with petty negative intent.

C'est la vie

imido muttered
This is the link to article, which we are supposed to discuss about... ;-)
Be additive then re intellectual input, arbitrarily denying AGW proves ignorance, get educated !

Nov 16, 2014
so where are the soil temp data GST] ? there is none , does frost take longer to form? Whats the GST when it does ?
they may have a point with warmer oceans

Nov 16, 2014
""What I'm convinced of is that we don't understand climate." - Freeman Dyson

As a general rule, if Freeman Dyson doesn't understand something, you don't, either."

Ah, the Appeal to Authority logical fallacy. Of course, Dr. Dyson has said that he hasn't bothered to learn any of the science associated with the climate, he just objects to it because he doesn't like the people involved. So it's not so much an Appeal to Authority fallacy so much as an Appeal to Non-Authority fallacy. Such, regrettably, are the qualifications of the pseudo-skeptics out there.

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