Aerosols affect climate more than satellite estimates predict

Aug 01, 2011

Aerosol particles, including soot and sulfur dioxide from burning fossil fuels, essentially mask the effects of greenhouse gases and are at the heart of the biggest uncertainty in climate change prediction. New research from the University of Michigan shows that satellite-based projections of aerosols' effect on Earth's climate significantly underestimate their impacts.

The findings will be published online the week of Aug. 1 in the early edition of the .

are at the core of "cloud drops"---water particles suspended in air that coalesce to form precipitation. Increasing the number of causes an increase in the number of cloud drops, which results in brighter clouds that reflect more light and have a greater cooling effect on the planet.

As to the extent of their cooling effect, scientists offer different scenarios that would raise the global average surface temperature during the next century between under 2 to over 3 degrees Celsius. That may not sound like a broad range, but it straddles the 2-degree tipping point beyond which scientists say the planet can expect more catastrophic climate change effects.

The satellite data that these findings poke holes in has been used to argue that all these models overestimate how hot the planet will get.

"The satellite estimates are way too small," said Joyce Penner, the Ralph J. Cicerone Distinguished University Professor of . "There are things about the global model that should fit the satellite data but don't, so I won't argue that the models necessarily are correct. But we've explained why satellite estimates and the models are so different."

Penner and her colleagues found faults in the techniques that satellite estimates use to find the difference between cloud drop concentrations today and before the Industrial Revolution.

"We found that using satellite data to try to infer how much radiation is reflected today compared to the amount reflected in the pollution-free pre-industrial atmosphere is very inaccurate," Penner said. "If one uses the relationship between aerosol optical depth---essentially a measure of the thickness of the aerosols---and droplet number from satellites, then one can get the wrong answer by a factor of three to six."

These findings are a step toward generating better models, and Penner said that will be the next phase of this research.

"If the large uncertainty in this forcing remains, then we will never reduce the range of projected changes in climate below the current range," she said. "Our findings have shown that we need to be smarter. We simply cannot rely on data from satellites to tell us the effects of aerosols. I think we need to devise a strategy to use the models in conjunction with the to get the best answers."

Explore further: Satellites sees a question mark in Tropical Storm Ana

More information: PNAS 2011 ; published ahead of print August 1, 2011, doi:10.1073/pnas.1018526108

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emsquared
2 / 5 (8) Aug 01, 2011
"The satellite data that these findings poke holes in has been used to argue that all these models overestimate how hot the planet will get."

Who would've thought that such a complex system couldn't be accurately represented without a comprehensive knowledge and accounting of all it's constituents? Good to know there are some scientists out there who are still skeptical of what they've been handed and told not to question.
thermodynamics
5 / 5 (4) Aug 02, 2011
emsquared: I was going to use that same quote to point out that the writer of this article (not the writers of the paper) is letting their bias show. The first thing I did was to download the paper (it is free). I then did the thing that the author of this article apparently didn't do (I read it). The paper does not "poke holes" in anything. Aerosols are well known as a weak part of all models. The modelers know that. What this paper does is offer a new way to look at the changes in aerosol loading from pre-industrial to industrial times. An important issue, but one the well written paper points needs a lot more work. I actually like the work they did and I believe it may be on the right track. Now comes replication, statistical analysis, first principle analysis and incorporation into GCMs. This is good falsifiable work and will make a difference but it has not poked a hole in anything. These writers let their bias show on both sides of this scientific discussion.
thermodynamics
5 / 5 (4) Aug 02, 2011
emsquared: One more issue. The modelers know that their models are weak on clouds and aerosols. This has been the subject of whole conferences. Clouds and aerosols are not the only problems. There are conferences on ocean currents, top-water thermal mixing, and periodic oscillations, coupling of water and air, coupling of air and ground,... The list is long. These conferences with tens of thousands of researchers attending each year are made up of the scientists you know as: "Good to know there are some scientists out there who are still skeptical of what they've been handed and told not to question." They are told to get the models right - they are told to falsify and improve the models using science and they are not held to "not questioning." They make their name by being right, not by toeing the standard approach. You have the wrong idea. There are those who are not very good scientists who take other peoples equations and plug them into a computer program and run it.
thermodynamics
5 / 5 (4) Aug 02, 2011
Continued: However, there are smart folks out there who are trying to improve the science on a daily basis. They appear as skeptics in your labeling but they are just doing the job of science. They have a theory and they start out to falsify, verify, and validate. That is the dominant portion of climate scientists. They are the really good scientists who look at what is being done and say they can do it better. However, you will not see them claiming there is a conspiracy and their work is being turned down for political reasons. Instead, when they get peer-reviewed they dig in and show why they were right or why the commenter was right. The process is arduous. That is how we make progress. Papers like these appear at the rates of 10s per day. They are published. They are good scientific work. Some get turned down and they go back and improve their work and get accepted (been there and got the T-shirt). They don't claim political influence.
thermodynamics
5 / 5 (4) Aug 02, 2011
Continued: Only the lawyers, economists, or tea-party supporters go through these scientific papers and make claims about how the "tear holes" or "turn upside down" difficult issues. They then, invariably, make the claim that these modelers just don't know the complexity of what they are trying to model. Give me a break. They, of all people on the planet, understand the problems facing them. What do they do? They do their best to make the programs right. emsquared: you say: "Who would've thought that such a complex system couldn't be accurately represented without a comprehensive knowledge and accounting of all it's constituents?" Why don't you tell me what constituents specific models leave out, why they leave them out, or why they use the algorithms they do? Have you read the paper instead of the article? Do you realize they are not putting in a new factor, they are proposing a method to change the algorithm by which that factor is calculated. (continued)
thermodynamics
5 / 5 (4) Aug 02, 2011
Continued: emsquared: That is the reason I would like to have a list of the components you think are being left out of the models. I see them in but not perfect, and with serious scientists trying to improve them. Please elaborate on what you see.
lengould100
2.3 / 5 (6) Aug 02, 2011
Every current and former scientist should be (and in fact is) deeply insulted by these cowboy highschool dropouts trying to keep their local coal mine operating. Get off the science forums, go back to the beer halls and political rallys.
emsquared
1 / 5 (4) Aug 02, 2011
The list is long.


Despite the litany of things you've listed above as still being "worked on" - which is to say, are not accurately accounted for, AGW is touted as being settled science. As if that's not silly enough, AGW proponents (especially here) trumpet how anything questioning AGW must be some anti-science agenda, despite skepticism and attempts at falsification being a core tenet of scientific method, they choose to ignore that it is their anti-skepticism that is an anti-science mentality. They should welcome attempts at a greater understanding of the system. Even when a stance is as mild as mine (as you know, I believe we have some effect, I just doubt the magnitude claimed by the IPCC), it's met with frothing anger. It's absurd to me, and demonstrates data has little to do with it.

And of course, don't even try and tell people that AGW-theory is only trying to address a symptom of much more dangerous and direct threats to environmental quality. Really I'm over it.
Y8Q412VBZP21010
3.8 / 5 (5) Aug 02, 2011
Emsquared on Spencer's paper, greeted as DOA by the science community:

"What a good article. What good science."

Emsquared on aerosols article:

"Really, I'm over it."

I'm willing to admit climate science has a fuzz factor. But rejecting it on that basis would mean simply dropping out of the discussion. It certainly does not imply accepting or rejecting the argument on the basis of what one wants to hear.

I can certainly say I don't want to hear that climate change is really happening, but even given a fuzzy prediction the centroid of the fuzzball seems to say "warming" to some lesser or greater degree whether I like it or not.

Now if there's some "conspiracy" that's pushing people to say that -- could you please let me know who I can contact to get my payoff? Right now I'm doing it for nothing.
emsquared
1.8 / 5 (5) Aug 02, 2011
Please elaborate on what you see.

While solar variance only results in a .1-.2% variation of total output, how well are the interactions between solar radiation and all layers of our atmosphere understood? It's already known that net solar irradiance has much higher variability via it's interactions with aerosols, cloud formation and those effects on albedo. What other atmospheric mechanisms differ from a weaker or stronger solar wind, i.e. the upper atmosphere?

There are little details like the purported problems with surface weather stations used by the IPCC data sets not meeting criteria for ambient locations.

Not to mention that no matter what we do, humanity will burn every last fossil fuel on earth. That's economics and reality. That anything can be accomplished through focusing on CO2 is highly debatable due to this fact.

Also, it's a falsehood that a warmer earth is a less healthy earth. Enviro quality degradation comes from the other results of consumerism.
emsquared
1.8 / 5 (5) Aug 02, 2011
What I'm over is trying to have meaningful conversations with people on this forum.

I just hope a fraction of those-who-refuse-to-engage carry even just a fraction of the conviction they display on this forum into their every-day lives and actually DO something about their beliefs. My sneaking suspicion though is that the vast majority do not.

That is the nature of the AGW message and the AGW movement: I don't have to change, it's industry that's destroying things and needs to change. Well, guess what? You create industry, you are the problem. You need to fix yourself and your relation with your use of the earths resources. It's tragic and comical at the same time.
defunctdiety
5 / 5 (2) Aug 02, 2011
Now if there's some "conspiracy" that's pushing people to say that...

I'd never claim there's a conspiracy. However it's just as obvious that there is an economic impetus to find evidence for AGW for some, just as there is for others to find against it.
...humanity will burn every last fossil fuel on earth. That's economics and reality.

it's a falsehood that a warmer earth is a less healthy earth. Enviro quality degradation comes from the other results of consumerism.

Care to discuss either of these items, Y8Q412VBZP21010?

Or tell us what you have done in your life, as a result of your belief in AGW, that has bettered environmental quality?
emsquared
1 / 5 (1) Aug 02, 2011
hah, that's funny ^^^ , allow me to wipe the egg from my face.
Y8Q412VBZP21010
2 / 5 (4) Aug 02, 2011
"I'd never claim there's a conspiracy. However it's just as obvious that there is an economic impetus to find evidence for AGW for some, just as there is for others to find against it."

Not for me. I make not a penny either way. Personally, I don't have a dog in the fight. I just want to know the facts.

"Or tell us what you have done in your life, as a result of your belief in AGW, that has bettered environmental quality?"

Nothing that I can think of. What I'm interested in is what is supported by the evidence ... what is done about it is another (uglier) question.

I'm not 100% convinced of the AGW case, but the evidence I've seen tilts towards it. And the arguments against it seem heavily populated, if not absolutely dominated, by "them scientists don't know nuthin!"
thermodynamics
5 / 5 (1) Aug 02, 2011
emsquared: In response to the question of what is not involved in the models, you said: "While solar variance only results in a .1-.2% variation of total output, how well are the interactions between solar radiation and all layers of our atmosphere understood? It's already known that net solar irradiance has much higher variability via it's interactions with aerosols, cloud formation and those effects on albedo. What other atmospheric mechanisms differ from a weaker or stronger solar wind, i.e. the upper atmosphere?"

Fortunately, there are multiple efforts to better define these issues in the models. As you probably know, there are nearly a dozen satellites looking only at the sun to find out what it is doing. At the same time, there are hundreds of ground stations looking up to see how the atmosphere is interacting at multiple wavelengths. Papers are being published every day on these subjects. Watch the SpaceWeather.com site for daily updates on the sun. Continued
thermodynamics
5 / 5 (1) Aug 02, 2011
Continued: I asked what was being left out. emsquared you can see it is not the sun and its interaction. You also mentioned: "There are little details like the purported problems with surface weather stations used by the IPCC data sets not meeting criteria for ambient locations." You should also know that this is the subject of multiple investigations. There are dozens of groups in multiple countries trying to validate and compensate for heat islands and other problems. However, every investigation performed shows that the data set is still of very high quality. This is also part of the constant improvement process. The surface weather system is constantly being looked at, validated, and improved. This is not being ignored or left out (only on Fox News and Watts up).
Continued:
thermodynamics
5 / 5 (1) Aug 02, 2011
You also said: "Not to mention that no matter what we do, humanity will burn every last fossil fuel on earth. That's economics and reality. That anything can be accomplished through focusing on CO2 is highly debatable due to this fact." You are right and it is highly debatable that we can capture and sequester a significant amount of CO2. However, "the science is not settled" about anything. There is strong evidence of some issues (such as the earth is warming and humans have an influence on that). However, it is not settled for anyone and that is the reason that research marches on.

Your main effort at getting people to follow their ecological message is commendable. I am trying to follow your lead on that. It is not easy but it can have the most significant short-term impact on fossil fuel burning. We should also be looking at other sources of pollution from heavy metals to medicines and everything in between. Continued
thermodynamics
5 / 5 (1) Aug 02, 2011
Continued: In most instances when looking at an article on climate we tend to focus on climate when there are other influences (as you point out - such as energy usage as opposed to production). Some keep bringing up the issue of "settled science" when it is misinterpreted. For instance, Gravity (Newtonian and Einsteinian) is considered settled but ongoing research is looking at alternatives and expansions of the view. No one seems to consider that hubris unless you count the creationists. Politicians consider both sides of the climate argument to be settled (depending on which side of the aisle you are on). However, climate scientists refer only to that which has strong evidence and is still a subject of research but with evidence pointing to significant human influence on the climate.

The only point of your issues I draw unbrage with is that you seem to think that climate scientists are satisfied with the models or that they are missing issues. They are not.
emsquared
1 / 5 (1) Aug 03, 2011
The only point of your issues I draw unbrage with is that you seem to think that climate scientists are satisfied with the models or that they are missing issues. They are not.

I realize this. But it's also things like the graphs, say of historical CO2 where they truncate the x-axis, starting at say 250 ppm, it visually overstates the magnitude, it is designed to mislead, and that bothers me, it indicates an agenda. And I realize you are not one of the people in the group I am about to make a gross generalization about, but...

With all of these things that we've talked about that are still being refined, why do people react so hostile to skepticism, especially that as mild as mine or GSwift?

The answer is those people are driven by the religion-like aspect of AGW. It's not a reaction to the science, it's a reaction to what they see as an affront to their singular world view.

And while I've given up trying to get them to acknowledge that, I've never been more certain of it.
emsquared
3 / 5 (2) Aug 03, 2011
I've also decided I need to do some catching up on my literature, I haven't read a single full paper in probably over a year, and the whole Spencer thing put me over the edge. Not that I think his creationism should factor into the validity of his data, as many here seem to, but that I praised it without reading it was a mistake. I read where he posted a retraction for Forbes saying they overstated the impact of his data. Should know better than to trust physorg.
Y8Q412VBZP21010
5 / 5 (2) Aug 03, 2011
Spencer's creationism doesn't affect whether his argument is right or wrong. It simply affects whether I'm going to pay any attention to him. I have known plenty of creationists and have established that none of them are interested in the truth, the actual focus being "willful and unscrupulous misrepresentations of fact". If someone tells me that it is unfair to then not take them seriously in any respect, I would reply that they could sensibly expect any other reaction.

In much the same way, people might argue that a Nigerian email scammer's story might be true, but the betting odds are too low to be considered. If he is telling a true story, one is likely to hear it from more reputable sources and THEN it might be worth taking seriously.
Bob666
1 / 5 (2) Aug 06, 2011
All Models are wrong, some models are useful. Ohms law is a model, it falls apart at extremely high temperatures, and at extremely low temperatures. But for most of us it is a very useful model, provided we know when and where we can apply it.

Climate models need to handled the same way. How many remember the nuclear winter model, and its limits.
Shootist
1 / 5 (2) Aug 07, 2011
I'm not 100% convinced of the AGW case, but the evidence I've seen tilts towards it. And the arguments against it seem heavily populated, if not absolutely dominated, by "them scientists don't know nuthin!"


"The polar bears will be fine." - Freeman Dyson

Who obviously knows a bit more than something, about nothing. But I get your meaning. I would also mention Russell Seitz and Jerry Pournelle as two others who know more about something, than otherwise, yet remain unconvinced. Neither have financial game at stake.
thermodynamics
not rated yet Aug 07, 2011
Shootist: Jerry Pournelle is one of my favorite science fiction writers with a background in statistics and systems engineering. Just how does that make him an expert on climate studies? Just asking because he is one of my favorite writers and I wonder if I have missed something he was involved in that had to do with climate.