Why don't these studies show agreement?

Question

This paper concluded "Atmospheric longwave downward radiation has significantly increased (+5.2(2.2) Wm/2) partly due to increased cloud amount (+1.0(2.8) Wm/2) over eight years of measurements at eight radiation stations distributed over the central Alps. Model calculations show the cloud-free longwave flux increase (+4.2(1.9) Wm/2) to be in due proportion with temperature (+0.82(0.41) °C) and absolute humidity (+0.21(0.10) gm /3) increases, but three times larger than expected from anthropogenic greenhouse gases. However, after subtracting for two thirds of temperature and humidity rises, the increase of cloud-free longwave downward radiation (+1.8(0.8) Wm/2 )"
http://landshape.org/enm/wp-content/uploads/2009/01/philipona2004-radiation.pdf

This study concluded "There is a TOA imbalance of 6.4 W m−2 from CERES data and this is outside of the realm of current estimates of global imbalances (Willis et al. 2004; Hansen et al. 2005; Huang 2006) that are expected from observed increases in carbon dioxide and other greenhouse gases in the atmosphere. The TOA energy imbalance can probably be most accurately determined from climate models and is estimated to be 0.85 ± 0.15 W m−2 by Hansen et al. (2005) and is supported by estimated recent changes in ocean heat content (Willis et al. 2004; Hansen et al. 2005). A comprehensive error analysis of the CERES mean budget (Wielicki et al. 2006) is used in Fasullo and Trenberth (2008a) to guide adjustments of the CERES TOA fluxes so as to match the estimated global imbalance. CERES data are from the SRBAVG (edition 2D rev 1) data product. An upper error bound on the longwave adjustment is 1.5 W m−2, and OLR was therefore increased uni- formly by this amount in constructing a best estimate. We also apply a uniform scaling to albedo such that the global mean increase from 0.286 to 0.298 rather than scaling ASR directly, as per Trenberth (1997), to address the remaining error. Thus, the net TOA imbalance is reduced to an acceptable but imposed 0.9 W m−2 (about 0.5 PW). "
http://journals.ametsoc.org/doi/pdf/10.1175/2008BAMS2634.1

Another paper concluded "After accounting for the measured terms, the residual forcing between 1970 and 2000 due to direct and indirect forcing by aerosols as well as semidirect forcing from greenhouse gases and any unknown mechanism can be estimated as −1.1 ± 0.4 W m−2 (1σ). This is consistent with the Intergovernmental Panel on Climate Change's best estimates but rules out very large negative forcings from aerosol indirect effects."
http://www.agu.org/pubs/crossref/2009/2009JD012105.sht

This study shows that "An ensemble summary of our measurements indicates that an energy flux imbalance of 3.5 W/m2 has been created by anthropogenic emissions of greenhouse gases since 1850."
http://ams.confex.com/ams/Annual2006/techprogram/paper_100737.htm

A final study concluded "Daily L d increased at an average rate of 2.2 W m−2 per decade from 1973 to 2008."
http://www.agu.org/pubs/crossref/2009/2009JD011800.shtml

Which one of these studies is the most accurate?

Answer 1

You've identified the crux: data is open to interpretation. So, whose interpretation do we believe? Raw science gets refined and smoothed with experience. Experienced researchers and inventors will admit that they are on a continual journey of discovery, and that each new discovery brings it's own Eureka! moment as well as a bunch of new questions.



Dependability and integrity are usually accompanied by humility and compassion, which are impossible to hide and difficult to feign. Pride and arrogance indicates shallow character, and usually manifests in poor observations and conclusions about research. A good example is the Evans paper to "...effectively end the argument by skeptics...". Oh, ouch. The paper by Philipona et.al. has the right balance of reality and humility.



Who is most accurate: I'm sure they think they are as accurate as possible, and they are. But human understanding about climate is like the story of the blind men and their individual perspective of the elephant. They were all correct, sort of. It takes a combination of all the points of perspective, and the wider view of experience to bring limited observations into focus. And then, just because some may have a perfect view of the elephant doesn't mean that they know exactly how to put it to good use.

Answer 2

Once upon a time, there lived six blind men in a village. One day the villagers told them, "Hey, there is an elephant in the village today."



They had no idea what an elephant is. They decided, "Even though we would not be able to see it, let us go and feel it anyway." All of them went where the elephant was. Everyone of them touched the elephant.

"Hey, the elephant is a pillar," said the first man who touched his leg.



"Oh, no! it is like a rope," said the second man who touched the tail.



"Oh, no! it is like a thick branch of a tree," said the third man who touched the trunk of the elephant.



"It is like a big hand fan" said the fourth man who touched the ear of the elephant.



"It is like a huge wall," said the fifth man who touched the belly of the elephant.



"It is like a solid pipe," Said the sixth man who touched the tusk of the elephant.



They began to argue about the elephant and everyone of them insisted that he was right. It looked like they were getting agitated. A wise man was passing by and he saw this. He stopped and asked them, "What is the matter?" They said, "We cannot agree to what the elephant is like." Each one of them told what he thought the elephant was like. The wise man calmly explained to them, "All of you are right. The reason every one of you is telling it differently because each one of you touched the different part of the elephant. So, actually the elephant has all those features what you all said."



"Oh!" everyone said. There was no more fight. They felt happy that they were all right.



************

You have five studies, each of which is measuring something different. But taken together, they form a more complete picture.

Answer 3

There's no point in dwelling on what one knows, so keening in on estimates would seem the way to go. When it boils down to aerosol forcing, BVOC's are a undetermined factor considering atmospheric loading, regions, duration and magnitude. Another way of saying; The IPCC is fully aware of these factors in a extremely limited fashion.



This is a old link but does a good job of explaining the concept. There are newer studies but they just show major inconsistencies on aerosol forcing with no new viable knowledge gained.



http://www.co2science.org/articles/V6/N35/EDIT.php

Answer 4

I think the answers to this question are very telling. You gave examples of studies measuring different things. The majority of deniers (Sorry in this instance you are not labeled as skeptics) didn't even read or understand what the journals were about yet happily weighed in with their interpretations.

Answer 5

They're not in disagreement, they're measuring slightly different things.



The first one (Philipona et al. 2004) is measuring the increase in longwave (infrared) radiation at the surface, specifically in the Alps. Basically they're measuring how much the greenhouse effect has increased at the Earth's surface.



The second one (Trenberth et al. 2009) is measuring the Earth's energy imbalance at the top of the atmosphere (TOA). It's measuring how much more energy is going in than coming out - the difference being mainly due to the enhanced greenhouse effect.



The third study (Murphy et al. 2009), the part you quote is trying to determine the radiative forcing from aerosols. The way they do that is to measure the total imbalance (for which they get a value similar to Trenberth) and then subtract all the known forcings like greenhouse gases, solar, etc. From that they estimate that aerosols have a 1.1 Wm-2 negative (cooling) radiative forcing.



Murphy and Trenberth are both discussed here, by the way:

http://www.skepticalscience.com/How-we-know-global-warming-is-happening-Part-2.html



The fourth (Evans et al. 2006) is just calculating the radiative forcing from greenhouse gases and nothing else.



The fifth study (Wang et al. 2009) is similar to the first one (Philipona et al. 2004) in that it's calculating downward longwave (infrared) radiation. Except Wang is measuring it globally, and from 1973 to 2008, whereas Philipona is just in the Alps, and just over an 8 year period.



Wang, Philipona, and Evans are discussed here:

http://www.skepticalscience.com/empirical-evidence-for-co2-enhanced-greenhouse-effect.htm



I find it rather revealing that every denier answer was basically "because we don't understand how the climate works", which is completely wrong. That's the default denier answer - they want us to believe that we don't understand the climate so that they can argue against regulating carbon emissions. 'Before we regulate carbon we need to understand the climate better', they argue. It's why sometimes deniers are also called 'delayers' - they want to delay action. So every time something isn't so simple that it can be immediately understood by the general public, they argue "we just don't understand the climate".



What they're really saying is "I don't understand the climate so I'm not willing to regulate carbon emissions." Which is just like saying "I don't understand why I had a heart attack so I'm not willing to have bypass surgery." The experts understand it, the experts are telling you how to fix it, so you'd really be smart to listen to them. Of course I applaud your (and anyone's) efforts to understand climate science. My point is simply that a layperson's lack of understanding should not lead them to oppose carbon regulation (or heart surgery).



I also don't approve of the denier answers - if you don't know the answer to a question, then don't answer it. Don't say "we don't understand the climate" just because *you* don't understand it. You're not helping the person asking the question to learn anything, you're hindering the learning process by telling her there is no answer, when clearly that's not true.



That's what really bugs me - the deniers aren't here to learn anything or provide accurate answers, they're here to further their agenda of delaying carbon regulation. And if they hinder people's efforts to learn about climate science in the process, they don't care. This is a question and answer site. If you don't know the answer, then don't answer the question.

Answer 6

"Why don't these studies show agreement?"



Because we don't know exactly how the climate system works.



"Which one of these studies is the most accurate?"



That's hard to tell since we don't know exactly how the climate system works.



"This is consistent with the Intergovernmental Panel on Climate Change's best estimates but rules out very large negative forcings from aerosol indirect effects."



I thought the IPCC report was a review of current literature and not a scientific study. That makes that an odd statement.

Answer 7

Because you can spin it any way you like to suit your motive.

Answer 8

They don't agree because we don't really understand the climate, some of us only pretend to.



So the different studies start with different assumptions.... and therefore end up with different conclusions.

Answer 9

Umm...sorry...what was the question again?