From NASA Goddard: Tiny particles suspended in the air, known as aerosols, can darken snow and ice causing it to absorb more of the sun’s energy. But until recently, scientists rarely considered the effect of all three major types of light-absorbing aerosols together in climate models.
In a new study, NASA scientists used a climate model to examine the impact of this snow-darkening phenomenon on Northern Hemisphere snowpacks, including how it affects snow amount and heating on the ground in spring.
The study looked at three types of light-absorbing aerosols – dust, black carbon and organic carbon. Black carbon and organic carbon are produced from the burning of fossil fuels, like coal and oil, as well as biofuels and biomass, such as forests.
With their snow darkening effect added to NASA’s GEOS-5 climate model, scientists analyzed results from 2002 to 2011, and compared them to model runs done without the aerosols on snow. They found that the aerosols indeed played a role in absorbing more of the sun’s energy. Over broad places in the Northern Hemisphere, the darkened snow caused some surface temperatures to be up to 10 degrees Fahrenheit warmer than it would be if the snow were pristine. As a result, warmer, snow-darkened areas had less snow in spring than they would have had under pristine snow conditions.
According to the study, dust’s snow darkening effect significantly contributed to surface warming in Central Asia and the western Himalayas. Black carbon’s snow darkening effect had a larger impact primarily in Europe, the eastern Himalayas and East Asia. It had a smaller impact in North America. Organic carbon’s snow darkening effect was relatively lower but present in regions such as southeastern Siberia, northeastern East Asia and western Canada.
“As we add more of these aerosols to the mix, we are potentially increasing our overall impact on Earth’s climate,” said research scientist Teppei Yasunari at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.Impact of snow darkening via dust, black carbon, and organic carbon on boreal spring climate in the Earth system, Journal: Geophysical Research: Atmospheres.
http://onlinelibrary.wiley.com/doi/10.1002/2014JD022977/full
Abstract
Dust, black carbon (BC), and organic carbon (OC) aerosols, when deposited onto snow, are known to reduce the albedo of the snow (i.e., snow darkening effect (SDE)). Here using the NASA Goddard Earth Observing System Model, Version 5 (GEOS-5) with aerosol tracers and a state-of-the-art snow darkening module (GOddard SnoW Impurity Module: GOSWIM) for the land surface, we examine the role of SDE on climate in the boreal spring snowmelt season. SDE is found to produce significant surface warming (over 15 W m−2) over broad areas in midlatitudes, with dust being the most important contributor to the warming in central Asia and the western Himalayas and with BC having larger impact in the Europe, eastern Himalayas, East Asia, and North America. The contribution of OC to the warming is generally low but still significant mainly over southeastern Siberia, northeastern East Asia, and western Canada (~19% of the total solar visible absorption by these snow impurities). The simulations suggest that SDE strengthens the boreal spring water cycle in East Asia through water recycling and moisture advection from the ocean and contributes to the maintenance of dry conditions in parts of a region spanning Europe to central Asia, partially through feedback on the model’s background climatology. Overall, our study suggests that the existence of SDE in the Earth system associated with dust, BC, and OC contributes significantly to enhanced surface warming over continents in northern hemisphere midlatitudes during boreal spring, raising the surface skin temperature by approximately 3–6 K near the snowline.
h/t to WUWT reader “Parakoch”
So, something other than a warming atmosphere is causing ice loss?
Y’know, if China actually cleaned up its coal plants — not removing CO_2, only scrubbing out the soot — it might actually have a major impact on the sea ice situation in the Arctic. It would be enormously interesting to measure and plot the downstream distribution of this soot as it gets caught up in the jet stream. At a guess, a substantial fraction of it is getting pulled into the polar circulation because a lot of China’s industry and power consumption are pretty far north. If one measured the downwind path and compared it to the pattern of sea ice melt, one wonders what one would find?
Note that I said measure, not simulate. Surely it cannot be that difficult to sample arctic snow pack during the summer melt and work out where the carbon particulates and sulphates (probably) came from? It also wouldn’t be that difficult to add tracers to the coal deliberately to determine their downwind path — it might even be sufficiently in China’s interest to do so domestically that one could convince them to do this.
But even the simulation suggests that these “aerosols” (I would have called them particulates) have a net warming effect, not the net cooling effect that they are given in ever so many of the GCMs. Yet another flat out error in the GCM physics.
rgb
And the same would likely be true of volcanic ejecta?
If soot levels are causing the ice loss, why wasn’t it there from the higher levels in the 1860’s.
“C”ing Arctic Climate with Black Ice Richard B. Alley
They obtained highly accurate, well-dated chemical histories—including black carbon concentrations—from 1788 to 2002, with a time resolution of less than a year. For the first 60 years of the record, black carbon concentrations remained relatively stable, but the period from 1850 to 1951 showed highly elevated soot concentrations, especially during winter, when peak values were 10 times higher than the baseline. Lower values (although still higher than before 1850) mark the last 50 years of the record. Comparison to selected sections of a second core, collected 350 km to the south, shows close agreement, demonstrating the regional coherence of the signal.
Why didn’t they also look at photosynthesising microalgae and cyanobacteria?
Abstract
Darkening of parts of the Greenland ice sheet surface during the summer months leads to reduced albedo and increased melting. Here we show that heavily pigmented, actively photosynthesising microalgae and cyanobacteria are present on the bare ice. We demonstrate the widespread abundance of green algae in the Zygnematophyceae on the ice sheet surface in Southwest Greenland. Photophysiological measurements (variable chlorophyll fluorescence) indicate that the ice algae likely use screening mechanisms to downregulate photosynthesis when exposed to high intensities of visible and ultraviolet radiation, rather than non-photochemical quenching or cell movement. Using imaging microspectrophotometry, we demonstrate that intact cells and filaments absorb light with characteristic spectral profiles across ultraviolet and visible wavelengths, whereas inorganic dust particles typical for these areas display little absorption. Our results indicate that the phototrophic community growing directly on the bare ice, through their photophysiology, most likely have an important role in changing albedo, and subsequently may impact melt rates on the ice sheet.
http://www.ncbi.nlm.nih.gov/pubmed/23018772
Okay, I see now, why measure something when you can computer model and get the answer your paid for. By the way, soot levels in the ice cores are measured in pica grams per ml with values like 612 pgmL−1. Not a lot there.
http://www.clim-past.net/10/1905/2014/cp-10-1905-2014.pdf
And the 1860’s soot was traced to NE USA
Agreed. A combination of chemical analysis and elastic (optical) scattering measurements would be very interesting.
– TGBatRochester
Particulate ejecta, certainly, if it were pulled into the jet stream along a path that made it likely to come back to earth in the Arctic or Antarctic. I’m very skeptical about the sulphates playing any major role. They are supposed to globally cool (as opposed to perhaps locally melt sea ice) but I see very little evidence to that effect in the temperature record. But sure, it could be that Iceland’s recent volcanic eruptions have contributed to the melting of Arctic sea ice along with Chinese coal soot. It is at least plausible, but again I’d believe it a lot more readily if somebody simply went and looked at five to ten year surface cores of Arctic Sea Ice. Even in places where it wasn’t sufficient to cause complete melting, one ought to find dirty snow where layers melt together and aggregate the soot.
I grew up (in part) in upstate New York, living in back of a big grocery store parking lot. The would shovel up fifteen to twenty foot snow mountains just outside my back yard every winter. All winter long that snow would look pretty clean and white most of the time — there would be a new snow every week or two, so still more snow would be piled up — until March-ish it would start to warm at least some days and the land snow would get all soggy and slowly disappear. The snow mountains, of course, took weeks longer to go away, and as they shrunk all of the dirt, and gravel, and soot that had fallen on them or gotten scraped up into them would gradually reappear and blacken the snow until the last two feet or so of the ice was crusted almost completely black, and would live a 1-2 inch deep pile of tiny gravel and sand where the snowpile used to be.
I imagine that this is all nicely preserved in Arctic ice, and that IF soot is a factor, the marginal ice that is melting should be manifestly dark grey with measurably less albedo by this time in the summer. It might be as little as a single winter’s worth of accumulation, but on the edges of this where the ice survives multiple winters it should be packed down to much darker layers with a bit of snow in between. There could even be a cumulative acceleration as melt works through multiyear ice and several years of soot builds up on the surface that could help explain the “burstiness” of Arctic sea ice melt and recovery.
rgb
Many of us whose job it was to take cold ashes from a coal or wood burning fire and tip them onto icy paths know the effects of soot. It melts snow and ice. Many of us have pointed to the sometimes extraordinary amount of soot that can be seen in many pictures of the arctic snow, even as far down as the ice lakes at the bottom of crevasses.
However , this was first noticed during a Royal Society exhibition to the arctic in the 1820’s to examine the melting arctic. They attributed the melting of the snow they could observe to soot that was assumed to have blown from the industrialising US.
tonyb
I seem to recall that in the “coming ice age” scare of the 1970’s one of the geo-engineering solutions suggested was to spread massive amounts of soot, ash & other black carbon on glaciers to retard their advance.
What I’ve noticed about cinders and soot on snow is that it doesn’t take much new snow on top to retard the melting process. Given the increase in cloud cover that appears to be accompanying the decline of solar cycle 24 and the history of temperature drop following similar cycles, there may be a much shorter period in the arctic summer where fresh snow does not cover the particulates in the future. We will see as the el nino subsides and the AMO continues it’s negative trend.
See second photo:
The fact is, much of this dark material is from cyanobacteria and blue-green algae.
http://meltfactor.org/south-greenland-dark-ice-maintaining-promice-climate-stations/
The ‘industrialising US’ in the 1800’s was emitting wood smoke as land was cleared and charcoal made in large quantities. Both produce prodigious amounts of PM1.0. Is that what is deposited on Greenlandic snow? That should be easy to demonstrate as RGBatDuke suggests.
“As a result, warmer, snow-darkened areas had less snow in spring than they would have had under pristine snow conditions.”
Well, if we eliminated all bacterial and combustion particles maybe we could have pristine white snow all year round! Wouldn’t that be great? We would have cleaned up Nature and put it back into its aboriginal condition! The supreme achievement: putting Gaia through the car wash.
Meanwhile back at the ranch the hog-washing continues.
Data is coming
Alan
That stirred a memory. You are correct that it was seriously considered that it was wise to coat the arctic in soot to melt it.
http://www.washingtonsblog.com/2009/12/scientists-considered-pouring-soot-over-the-arctic-in-the-1970s-to-help-melt-the-ice-in-order-to-prevent-another-ice-age.html
tonyb
If nations stopped sending icebreakers to the North Pole to see whether it’s melting it would have a major impact on the sea ice situation. Which is easier to test? China aerosols or icebreakers?
However to the extent (which isn’t much) that icebreakers expose more open water to the atmosphere, the more heat is liberated.
agreed. i would much rather see taxpayer dollars/pounds/euros spent on addressing real time physical problems that have a realistic chance of success in the short to mid term than chasing some mythical effect from a gas that may or may not cause problems 100 years in the future.
If correct, humans can control albedo to the extent necessary to prevent another ice age.
I would be reluctant to use the word “can”, & use the term “could possibly”, instead, it’s somewhat less exact”
The authors are saying that unintentional dispersion of particulates raises the temperature by 3-6 K at the snowline. Think of what targeted dispersion could do.
Guys, how many days will a coating of soot stay uncovered by fresh snow during the onset of an ice age? When would we have good enough weather to apply it?
Less than one day. It works only during a melting season.
You don’t necessarily have more snow during an ice age, just cooler summers to the extent that you don’t melt all the last winter’s snow, so it accumulates. Soot and dirt don’t require melting temperatures to work. They speed sublimation, too.
When I was a kid walking barefoot seven miles to school through snowdrifts up to my chin, the city spread coal ash on the streets for traction. Even with temperatures continually below freezing, it was common to see the darker ash eroding itself down into the drifts piled up by the snow plows.
“When I was a kid walking barefoot seven miles to school through snowdrifts up to my chin…”
I think my dad was from that town? It wasn’t uphill, both ways, was it?
This is just another retarded attempt at conflating the real issue of air pollution with the fake issue of manmade climate due to use of fossil fuels.
I don’t think so. The fake issue is CO2-controlled climate. The authors do shake the fossil-fuel voodoo doll, but the message is that warming is caused by something other than CO2.
They’re defo doing the conflation boogie, with the usual trailing mighta, mebbe, possibly, probably conclusions. It’s funny how all those probabilistic qualifiers disappear on the press release – almost like an SPM on an IPCC report.
https://thepointman.wordpress.com/2014/05/08/conflation-confusion-and-conditioning/
Pointman
““As we add more of these aerosols to the mix, we are potentially increasing our overall impact on Earth’s climate,” said research scientist Teppei Yasunari at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.” Says it all, really. Their contention is that our use of fossil fuels is bad, in this case because it might be “impacting our climate”. The CO2 argument is really just a means to an end.
Exactly. That’s another reason why Antartica has not seen any ice loss (actually the opposite). The southern hemisphere is fairly absent of soot producing industries.
I thought it was because 99% of Antarctica is far below freezing, even in Summer.
+10F means a lot at a 25F air temperature.. but not so much at 0F temperature. Plus there also has to be some insulating effect on cloudy days and temperatures below freezing.
As with all things, it probably isn’t as simple as one might think.
This argument will not stand the test of time.
hmmmm. This is not new information. Layered deposits on ice fields is how they pinpoint annual seasons. Natural fires that added loads of carbon soot into the upper troposphere allowed at least some of it to ride the upper atmospheric train to arctic ice fields. Without these aerosols, there would be precious little information in ice cores that allows a fairly fine-tuned time line. Because of our current fire suppression efforts starting in the early 20th century, carbon soot has been reduced by substantial amounts. What models can do is only point BACK to a time when carbon soot was an annual large event.
Lord almighty, isn’t anything safe? That’s it, no more beehive hairdos for me.
Pointman
For many years I’ve speculated that dark soot on Northern Hemisphere snow and ice, probably from burning coal and other fuels, could explain why the weather satellites measure so much more warming in the northern half of the Northern Hemisphere, than in the southern half of the Southern Hemisphere.
While there are other possible explanations, one of them is not: ‘That’s exactly what we’d expect from CO2 greenhouse warming!’
I think it’s safe to say the post-1976 warming has been uneven around the globe, and intermittent, so it doesn’t match the theory of constant “global” warming from constant year-after-year CO2 increases, with the largest warming effect on both poles … not to mention the lack of the “CO2 footprint” of warming peaking about six miles up in the air over the tropics.
It is amazing to me that so-called “environmentalists” can bellow every day about a valuable plant food called CO2 … as they completely ignore gross air, water, and land pollution in China.
Perhaps a new focus on dark soot in the air could increase the attention paid to Chinese pollution … but then that would require “environmentalists” to be logical people, working on a real environmental issue, rather than continuing to be scaremongers looking for attention and money, using false scares, as they have been doing since the false DDT scare in the 1960s.
Climate blog for the average guy:
http://www.elOnionBloggle.blogspot.com
It is amazing to me that so-called “environmentalists” can bellow every day about a valuable plant food called CO2 … as they completely ignore gross air, water, and land pollution in China.
Why, it’s almost as if the whole thing is not really about the environment at all, isn’t it?
Of course it is not about the environment. It is about the sin defined in the Western eco-religion.
Most anyone who lives near a major snow field in France, Switzerland, or Austria, can tell you that the depth and reach of the fields has improved as clean diesel technology has become the norm. Back in the 70’s and 80’s there were a lot trucks sending up black plumes in the Western Alps.
What is the all green rectangular patch in western China that turns to dark blue in the snow cover shot? If aerosols are that effective I presume the CO2 sensivity will be further reduced.
Correct me if I’m wrong but while the soot is suspended in the air it is blocking the sun’s warming effect from reaching the surface level. Isn’t that the rational for “nuclear winter”
further once the landed soot is covered by the next snowstorm isn’t that the very definition of “carbon sequestration”
I agree .
I think the oil fires back during the first Gulf War stomped on the Nuclear Winter theory, but hard.
How is it that they left volcanism out of the contributing factors? Banners of the anthropogenic agenda are being used to hide the signs nature provides.
There is a certain arrogance in assuming the aerosols that man produces are enigmatically potent at affecting air quality in comparison to natural emissions. Animals of all kinds have developed filtration methods in their respiratory systems, because the normality of earth is that there are particulates in the atmosphere.
If the pristine planet that existed before industrial society had been free of air pollution, that natural selection would not have chosen the individuals with filtered respiration to carry on the evolution.
+1
Just urban myth. The “science” behind the myth is all wrong. Were it true then nuclear winter would have been called nuclear summer.
Ha ha
I believe particulates explain more of the delta between northern and Southern Hemisphere ice changes…
Steve
No. The arctic sea ice melts from above as small “melt ponds” form across wide areas of the Arctic, with about half of each year’s sea ice able to survive to form thicker ice the next year.
Almost all of the Antarctic sea melts completely away every year, with only a little bit surviving in small clusters right up against the Antarctic coast where they are sheltered by the circulating currents. Antarctic sea ice melts from the “warmer” ocean waters continually passing under the sea ice. A firm upper surface also means that any snow that does fall around Antarctica falls on this sea ice, and reflects extra sunlight as “new” snow instead of immediately melting when it hits the open water of a melt pond. Thus, over the same part of the winter-spring-summer season, the Antarctic sea ice has a measurably higher albedo than its Arctic opposite in the same part of its freeze-melt-refreeze season.
Again – Note the possible difference of what this papers modeled: “Arctic (land-based ?)” snow and ice compared to Arctic and Antarctic sea ice .
I’m going to try to get the jump on Max photon and post this warning of darkened snow…
Yeah, you’ve got to “watch the pee”.
The SHEBA sea ice experiment 1997-1998 (winter-summer melt season-fall freezeup) that Dr’s Curry, Perovich, Pegau, Sereze (and many others) participated in actually measured the Arctic sea ice alebdo every two days around a frozen-in Canadian icebreaker over the year.
They reported very little “soot” or “dust” on the Arctic sea ice itself, but instead, found that local surface sea ice albedo was controlled by the presense (or absence!) of small melt ponds scattered over the surface of the sea ice. As each day’s weather changed (snow, rain, sunshine, high or low clouds, or surface skim ice (after late July ) the measured albedo would change significantly.
If frozen ice with new snow, average area sea ice albedo was 0.8 to 0.9 ( 0.83) from 1 January through 1 April
1 April to mid-September, it varied day-by-day to a nominal 0.46,but as going down to as low as 0.38 on July 20-25.
After July 25, sea ice albedo increased as skim ice increased each night, and snow covered such sea ice. Open melt ponds froze over completely 12 August, and kept freezing over each night until the sea ice minimum was reached in mid-September.
http://files.engineering.com/getfile.aspx?folder=f407264b-1ce6-4859-bd22-38c247bbf52d&file=Perovich_2002_Fig_8_Integrated_Arctic_Sea_Ice_Albedo_vs_Day_of_Year.jpg
This the “cleanest” plot of the SHEBA results, from one of several different papers by Perovich summarizing albedos. See also:
http://polar.erdc.dren.mil/people/personnel_sid/perovichweb/SHEBAice/shebapdf/albedo.pdf
Not quite as “pretty” of graphics, but see also Dr Curry’s information at
http://www.ral.ucar.edu/projects/GCSS/WG5/sheba_albedo/
Also: Note that the specific “paper” this thread is discussing writes about “arctic” albedo iin general (land-based snow and ice albedo is implied, though NOT specifically stated. Land-based “Arctic” snow and ice is much – being limited by geography to 60 north up to 70 north latitudes, much further south than the arctic sea ice. Sea ice has only two little areas south of 70-71 north latitudes: The Bering Sea and its neighbor the Chuckio Sea to the west, and the Hudson Bay.
Also, note that the ENTIRE “data set” for this study consists of “model” results. There is NO actual measured on-site Arctic albedo data cited anywhere in the paper.
Well you answered my question before I had the chance to ask it! Reading the article my first question was “why model this without data?” It seems pretty straight forward to go sample chunks of ice and snow and measure its albedo, but these folks chose to go to the computer without collecting data from the actual ice that is out there for the taking. Surely one could get a grant to actually go measure this stuff directly. It would at least make for a real-world data comparison to model output to attempt to certify your model. Models are worthless if their outputs are never checked against real world data.
I was going to ask if anyone had ever actually gone out and measured this and I saw your post showing that indeed it had been done and came to a different conclusion.
An interesting question. How do satellites count this area of study? It looks like it is maybe 50% covered with meltwater ponds at various stages late in the summer, but as you can see from the people walking around in it, those are ponds on top of unmelted ice!
Is that counted as “sea ice melt” by a satellite that is only sensitive to albedo and that cannot see the ice underneath? Or is it still counted as “frozen”?
rgb
IIRC, the satellites at first could not distinguish meltwater ponds from seawater, but their handlers now claim that they can.
“But until recently, scientists rarely considered the effect of all three major types of light-absorbing aerosols together in climate models.”
Does that mean that previous climate models were wrong?
Say it ain’t so!
Actual observations of undisturbed ice? They must be daft they might be able to actually formulate a hypothesis that could be further confirmed by more actual observations…It would be the end of science in the modern age where wherein we posit as plausible story and run a computer model to balance all the incomplete observations to a statistical likely hood to support our story.
All we get is hypotheses about climate and no one can accurately model all the known or unknown variables that might affect the possible changes. We are basically dealing with a chaotic sun and an earth affected by earthquakes, volcanoes, etc., that may or may not be associated with the sun or even galactic phenomena. We take ice cores and make assumptions based on present day physical concepts as being constant such as planetary orbital periods and gravity. It appears that the more we think we know because of available exponential increases in information plus the added spice of political science we really have a stew of ignorance! However, the main endeavor should be to thwart those political hacks that want to control all human activities thus making us political slaves to a science that has never been settled.
Aerosols wrt climate is both a giant red herring, as well as dishonest attempt to conflate the mythical issue of manmade CO2 warming with the real, but in no way alarming issue of air pollution. They do the same thing with the issues of things like asthma attacks. The end goal is to paint our use of fossil fuels as “bad”, and the methods used are various and sundry forms of lying, including issue conflation, meant to confuse the public.
“GO SWIM” — sometimes the names of government projects are unintentionally (or maybe intentionally) amusing. I wonder if it was deliberately chosen to mirror “go fish”:
http://www.bicyclecards.ca/game-rules/go-fish/76.php?page_id=32
Sometimes, I am amazed at the naivety of NASA scientists. They’ve only just discovered that windblown dust causes snow to melt in the summer? They need to get out more. If you ski in the winter/spring and find your skis suddenly coming to a violent stop then you have likely encountered some finely divided dust in a layer on the surface. In the European Alps, most winds from the south will bring a layer of dust that plays havoc with your stylish skiing.
Similarly, go up to a glacier in the European Alps in August and in the areas below the freezing level it is likely they will look pink from the Saharan dust that has accumulated over the winter and stays on the surface as the snow melts beneath it. It all gets covered up again in the fall.
Dark matters.
As rgbatduke, Owen and others have pointed out, but rephrased in my own words.
Those brainless gits needed models to show that soot melts snow!?
How far can NASA – NOAA descend!?
Obviously, stopping at moronic wasn’t possible.
“From NASA Goddard: Tiny particles suspended in the air, known as aerosols, can darken snow and ice causing it to absorb more of the sun’s energy. ”
1) Then does that [mean] soot and not global warming has been melting the glaciers?
2) My bet is that soot partially cooled the globe prior to 1970’s Clean Air Act, and that is why the N Hemi temperature has a rapid increase after 1970, and then temperatures plateau with China’s growth starting in about 1995.
Can somebody explain why a pile of snow removed from a parking lot and dumped in a heap does not disappear until way after snow has gone ( as in weeks). i realize there is a density thing involved but the article talks about sea ice and soot The snow pile seems to smaller but has a thick layer of dirt etc on it as it melts but contrary to what is being said it lasts a lot longer than the regular snow layers witch also has a layer of soot on it btw.
It has to do with the thickness of the soot and dirt layer. It can also form a protective shell, protecting the snow and ice from the heat. It acts like an insulator.
But hey, if Australia deindustrialises that should make a huge difference.
Yes, snow and ice can melt when the ambient temperature is below freezing. I have been spreading the ash from my pellet stoves over the snow and it melts like July, except in February.
Except for the fact that your trick doesn’t work after 9:00 pm and before 4:00 am
More like from 5PM to 7AM…
I tried to make a “safe” guess, not knowing exactly what latitude you reside at.
From NASA Goddard: Tiny particles suspended in the air, known as aerosols, can darken snow and ice causing it to absorb more of the sun’s energy. But until recently, scientists rarely considered the effect of all three major types of light-absorbing aerosols together in climate models.
Is this a joke?
Leading up to the 2009 Copenhagen Climate Conference, we were told the IPCC’s 2007 4th Assessment Report was the “gold standard in climate science”. Global warming alarmists, from Al Gore to UK Prime Minister Gordon Brown, proclaimed “the science is settled”.
What say those global warming alarmists, today, who declared “the science is settled”? All the scientific revelations since 2009 have demonstrated the science was never settled, and the IPCC Chairman, Dr Pachouri, really got it so very wrong.
Presumably during the epoch of snowball earth when most incoming radiation was reflected,, the cycle was broken by volcanic action, blackening the surface thereby increasing the absorptivity/emissivity
chemengrls “Presumably during the epoch of snowball earth when most incoming radiation was reflected,, the cycle was broken by volcanic action, blackening the surface thereby increasing the absorptivity/emissivity”
Ice has a near unity emissivity. At long infrared wavelengths, ice is “black”. It is reflective to visible wavelengths.
What seems to be believed about the Earth’s escape from snowball state was an enormous concentration of carbon dioxide, about 100,000 ppm accumulating over several million years since no plant life-cycle existed to take up the carbon dioxide. That produced a greenhouse effect powerful enough to overcome the reflectivity of the ice. What happened next I do not know but I suspect that much carbon in the atmosphere produced an incredible surge in carbon-loving plant life and subsequent oxygenation of the atmosphere along with huge beds of carbonate rock being laid down in the seas.
Increasing the emissivity raising the temp and thereby melting the ice.