Climate change

[Al_U_Card]

Yet more warmist "consensus"...

 

An additional source or irritation are all those claims of consensus and unanimity amongst specialists about the effects of CAGW viz:

 

6:31 AM, MARCH 25, 2012

DennisA said...

I notice Ed Maibach is mentioned. Find out more about him here:

http://sppiblog.org/news/propaganda-from-the-public-purse

 

"In fall 2007, after joining Mason’s Department of Communication, Maibach founded the Center for Climate Change Communication and became its director.

 

The center is the first behavioral science research center in the United States dedicated solely to improving climate change public engagement methods.

 

Starting with the community he knew best, Maibach planned his first study, which was conducted in partnership with the Environmental Defense Fund, to be a national survey of public health department directors.

 

"The research team was surprised to find that nearly 60 percent of local public health department directors nationwide reported that they were already seeing harmful health effects of climate change in their jurisdictions, yet few felt they had the capacity to respond."

 

So what happened?

 

Out of 2,296 members of the National Association of County & City Health Officials, they produced a sample size of 217, who were contacted. The responses were:

 

Take a running jump = 38

 

Refused to answer calls or e-mails = 46

 

This left 133, of whom 81, (61%), believed their jurisdiction had seen the effects of climate change in the last 20 years.

 

So the actual figure of 3.5% of 2,296 local public health department directors becomes “nearly sixty percent of local public health department directors nationwide.”

 

Funding from the National Science Foundation, your money.

 

"Numerous organizations — from the local to the global — have sought their guidance, including Virginia state and local governments, environmental organizations, nongovernmental organizations, federal agencies and even foreign embassies."

[PassedOut]

Scientists Race to Save World's Rice Bowl From Climate Change

 

Climate change is predicted to cause more intense and frequent floods and droughts in Southeast Asia, threatening the world's rice bowl and millions of people who live there unless preventive actions are taken soon, scientists warn.

 

At the Climate Smart Agriculture in Asia workshop held in Bangkok, Thailand, last month, climatologists and agricultural researchers discussed farming practices and technologies that could help the region cope with global warming's effects, including rising temperatures, increased salinity, and sporadic rainfall.

 

The conference was about "bringing all these players together to look at how the research agenda needs to change in the agricultural research world in relation to climate change," said Bruce Campbell of the Consultative Group on International Agricultural Research (CGIAR), which helped organize the two-day workshop.

 

In addition, scientists at the meeting discussed potential ways to use agriculture to mitigate the effects of climate change by reducing greenhouse gas emissions such as methane. Agriculture, forestry, and changes in land use account for a third of greenhouse gas emissions, said Campbell, who is the program director of CGIAR's Research Program on Climate Change, Agriculture and Food Security (CCAFS).

 

"That's a significant portion," Campbell said, "but we can reduce it."

Sure, let the industrial nations keep warming the earth by pouring billions of tons of heat-trapping gas into the atmosphere -- but let poor farmers bear the brunt of it. For the time being...

[Al_U_Card]

Scientists Race to Save World's Rice Bowl From Climate Change

 

 

Sure, let the industrial nations keep warming the earth by pouring billions of tons of heat-trapping gas into the atmosphere -- but let poor farmers bear the brunt of it. For the time being...

 

Well, if it's a race, how soon will it be too late? As CO2 increases, it helps to increase crop yields. Sporadic rainfall? Rice paddies depend on monsoons and I would be interested to see the studies indicating how monsoons have been affected over the last, say, 75 years of increasing CO2.

Or even temperatures. Warmer and wetter, it seems. But then, that too will be a race. Just a race about getting those temperature values before the warmists get to them and adjust them to show even greater catastrophies on the way.

 

There is an interesting analysis of the most recent CRUTEM4 database and its "adjustments" relative to CRUTEM3 to be found at WUWT. Don't shoot the messenger or his host but look instead at the types and manner of adjustments made.

 

http://wattsupwiththat.com/2012/05/03/has-the-crutem4-data-been-fiddled-with/#more-62667

 

Curiouser and curiouser...

 

http://wattsupwiththat.files.wordpress.com/2012/05/clip_image004_thumb1.gif?w=588&h=445

 

 

yet another thing that the CRU has in common with GISS (see above for those pesky adjustments...)

[Al_U_Card]

Nothing yet on those monsoons, but the US seems to demonstrate a terrifying trend as the warming continues unabated (except for the cooling periods, of course)

 

http://stevengoddard.files.wordpress.com/2012/05/screenhunter_898-may-04-07-04.jpg?w=640

[Al_U_Card]

FOIA commissioner has ruled in favor of Steve McIntyre, and the released data not only refutes the hockey-stick warming proffered by the Climategate gang, it puts the lie to the various "Inquiries" that exonerated the UEA CRU of wrong-doing...

 

Why they left out the "other" trees that were available for study.

 

http://climateaudit.files.wordpress.com/2012/05/regional_chron.png

 

so, instead of a hockey stick, it makes their version look more like a hokey-shtick. :P

 

http://climateaudit.files.wordpress.com/2012/05/chron_siteadj2.png?w=420&h=300

 

 

 

 

The synopsis of this sad story is to be found at:

[Al_U_Card]

The "source" of the Yamal chronologies has provided live tree data as part of the dendroclimatology for the region where the UEA CRU (sounds more like a rap group name but hopefully they will soon be taking the rap...)cherry-picked "convenient data from Yamal to show the hockey stick in a dozen "appropriate" trees. (In a published paper, when you don't include reasons and examples of why certain data are excluded, that is not just cherry-picking, it is the whole pie.)

 

More to come...

 

providing this comparison.

 

http://climateaudit.files.wordpress.com/2012/05/hantemirov_compare2.png

[hrothgar]

The "source" of the Yamal chronologies has provided live tree data as part of the dendroclimatology for the region where the UEA CRU (sounds more like a rap group name but hopefully they will soon be taking the rap...)cherry-picked "convenient data from Yamal to show the hockey stick in a dozen "appropriate" trees. (In a published paper, when you don't include reasons and examples of why certain data are excluded, that is not just cherry-picking, it is the whole pie.)

 

 

FWIW, Real Climate has a useful post providing a more balanced description of the Yamal chronologies

 

http://www.realclimate.org/index.php/archives/2012/05/yamalian-yawns/#more-11699

[kenberg]

FWIW, Real Climate has a useful post providing a more balanced description of the Yamal chronologies

 

http://www.realclima...wns/#more-11699

 

I took a (brief) look at this and while I gather that it is informed I would not use the word balanced to describe it.

 

 

Here is a practical problem: You link to this report. He, the author, links to McIntyre and many other places. McIntyre refers back to various interchanges with other people. Al seems to have devoted his life to this, I don't plan to follow suit.

 

A suggestion: You, Richard, or maybe someone else, could briefly, repeat briefly, summarize the three strongest arguments for the proposition that global warming is sufficiently established that strong action is needed. Al, or someone, could briefly, repeat briefly, summarize the three strongest arguments against this proposition. We could all read these arguments, look into them, and perhaps come away wiser. Preferably these arguments would be presented withou the use of words such as "charlatan", "nut" "evil", etc.

 

This is an important issue. There are many important issues.. My approach here is to find go with what the National Academey of Science says. It's not that I am under the impression the NAS is infallible, you have to go to the Pope for infallibility, but on any scientific subject where I lack expertise and lack time/interest to develop expertise, I certainly think that the NAS is the place to start.

[Al_U_Card]

Well, I have certainly devoted my attention to this subject.

 

When you consider that it involves taxing us into the stone age with concommitant policies, it is worth the effort.

 

The jig has been up for the IPCC et al since Nov. 2009 when the climategate e-mails confirmed pretty much everything that the CAGW skeptics were saying. Since then, it has been one revelation after another. You just have to look.

 

1) Alarmism is based solely on model-generated projections that need water-vapour in a warmer climate to triple the effect of [CO2] on global temperature.

 

2) The alarmists hide their work and obfuscate all efforts at transparency of analysis and data.

 

3) The observational data refutes "unprecedented" warming as well as dangerous anthropogenic contributions to it by way of [CO2] additions since the industrial age.

 

We are seeing and will continue to see this play out as reality overcomes rhetoric. Those who would benefit from continued alarmism will continue to plead for us to panic and trust them.

 

Science will triumph over consensus, as it eventually does, every time.

[kenberg]

Well, I have certainly devoted my attention to this subject.

 

When you consider that it involves taxing us into the stone age with concommitant policies, it is worth the effort.

 

The jig has been up for the IPCC et al since Nov. 2009 when the climategate e-mails confirmed pretty much everything that the CAGW skeptics were saying. Since then, it has been one revelation after another. You just have to look.

 

1) Alarmism is based solely on model-generated projections that need water-vapour in a warmer climate to triple the effect of [CO2] on global temperature.

 

2) The alarmists hide and obfuscate all efforts at transparency of analysis and data.

 

3) The actual data refutes "unprecedented" warming as well as dangerous anthropogenic contributions to it by way of [CO2] additions since the industrial age.

 

We are seeing and will continue to see this play out as reality overcomes rhetoric. Those who would benefit from continued alarmism will continue to plead for us to panic and trust them.

 

Science will triumph over consensus, as it eventually does, every time.

 

I was hoping we could move the argument away from the name calling. But let me take the arguments. I wish to encourage a rewrite.

 

1. Led me check: You are saying that if I look through the literature on global warming I will find that all papers on the subject which argue that global warming is occurring will be using a computer model, that every one of these computer models will have the same assumption about water vapour, and that this assumption is false. Is that right? There are no opther arguments, just this one, and if we can see that this compuational model fails then there have been no other arguments put forth so we are done? I am guessing that not all eggs are in this one basket and there are further arguments as well. But if this is the really the only argument that has ever been presented it will greatly simplify the discussion. It seems to easy. I doubt that the debate would last three weeks if that's all there is.

 

2. This seems to go nowhere. "You hide and obfuscate". "No, you hide and obfuscate" "You do" "No, you do" "What you say is what you are" "Your mama..."

 

 

3. This seems promising, although I imagine even precedented warming, or whatever the negation of unprecedented warming is, could still be a problem.

 

 

I more had in mind three arguments that would go along the lines of "The following scientific investigation, reported at ...., is strong evidence that ....". We coould look it up, read the critiques, decide who we believe.

[Al_U_Card]

Knock yourself out.

 

The skeptical position has always been for alarmists to "show their work" such that it might be analyzed and criticized objectively and rationally instead of being accepted "on faith" of good intentions. The inner workings of "pal review" are presented in several good works on the subject.

 

"The delinquent teenager who was mistaken for the world's top climate expert" by Donna Laframboise is an interesting exposé on the methods used by the IPCC to further their agenda.

 

Take a look through the above posts to see where data is adjusted to increase warming trends. Quality control is all about removing errors that, generally, result in no net change to the overall data....except in recent climate science.

 

All of the FOIA requests and their refusals are a litany of Phil Jones' classic "Why should we give you the data when you will only use it to find something wrong with our work?...."

 

Finally, just use google to find references to just how expensive climate "control" would be, EVEN USING THE IPCC's own INFLATED-EFFECT NUMBERS. Can we control the climate? Just that proposition is absurd enough in and of itself. Mitigation against heat and/or cold where and as needed would be much more sensible, less expensive and less invasive.

 

Either way, the massive use of media to instill guilt is gradually subsiding as both the science and the actual climate put the lie to the anthropogenic climate alarmism. I guess we just luck out this time, for a change. :P

[hrothgar]

Here are the three key points that I would cite to try to convince people that anthropogenic climate change is taking place.

 

1. The relationship between carbon dioxide and heat retention by the atmosphere is a well understood phenomena. Carbon dioxide is relatively transparent to visible light. It is relatively opaque to infrared radiation. This relationship has been well understood for since the 19th century. Scientists have been predicting that burning large amounts of fossil fuels would heat the atmosphere since Arrhenius.

 

2. Observed data is consistent with this theory. The National Oceanic and Atmospheric Administration published a nice summary report describing why it accepts athropogenic climate change. http://www1.ncdc.noaa.gov/pub/data/cmb/bams-sotc/2009/bams-sotc-2009-brochure-lo-rez.pdf

At a more basic level, take a look at changes in plant hardiness zones in the Northern hemisphere. http://www.arborday.org/media/mapchanges.cfm or just look at changes in growing seasons, distributions of bird ranges, etc.

 

3. There is “scientific consensus” regarding the existence of anthropogenic climate change. Quoting wikipedia “No scientific body of national or international standing has maintained a dissenting opinion; the last was the American Association of Petroleum Geologists, which in 2007 updated its 1999 statement rejecting the likelihood of human influence on recent climate with its current non-committal position.”

[Daniel1960]

Ken,

 

You may which to check on the recent RC thread concerning climate models.

http://www.realclimate.org/index.php/archives/2012/05/plugging-the-leaks/#more-11491

There seems to be quite a wide range of results when it somes to modelling the ocean-atmosphere water cycle. Also presented is this recent paper dealing with the difficults models had just hindcasting temperatures.

http://curryja.files.wordpress.com/2012/05/kim-et-al-2012_grl.pdf

[phil_20686]

This is an important issue. There are many important issues.

 

Ok, so three arguments for global warming: I like this challenge.

 

(1) The earth's Energy Eco-System

Essentially, the only way that energy can reach or leave the earth is via electromagnetic energy. The energy that reaches the earth from the sun is primarily in the visible spectrum. This is absorbed by the earth, which warms it, and it emits infra red radiation. The atmosphere is fairly opaque to infra red radiation, and the temperature of the earth is essentially determined by how long, on average, it takes this infra red radiation to leave the earth and radiate into space. Suppose that on average, it takes a photon from the sun one minute to reach the earth, be absorbed, re-emitted, scattered multiple times in the earth's atmosphere, and leave. In that case the energy content of the earth's atmosphere is exactly one minute*sun's energy input. (one minute is completely made up btw).

 

In practice, the only thing that matters for this estimate is the albedo, and the so called "scattering length" for a photon of a given wavelength in the atmosphere. The albedo is important, because some of the sun's light is reflected, and because of the transparency of the atmosphere to visible light, reflected energy leaves the earth immediately. This is pretty easily measured by satellite surveys: we are essentially just measuring how "bright" the earth is.

 

The scattering length is where all the fun is. Essentially, if we know the composition of the atmosphere, we can measure their scattering cross-sections in the infra red in the lab, and then calculate from this the scattering length. Once we know the scattering length, the light does a random walk in steps of the scattering length. You can work out how long it takes to leave the atmosphere, and hey presto, you now have your answer. Carbon dioxide, among others, has a large scattering crossection for IR light, so adding more shortens the step length, and increases the insulation effect. This is all very well understood physics, and there is essentially no room for debate on any of these effects.

 

However, the problem arises mainly because the composition of the atmosphere is not fixed. We have pretty good information of the atmospheric composition since about 1960. Before that it is fairly sketchy, but what we do no, about the composition of CO2 H2O CO SO2 CH4 etc, makes it essentially incontrovertible that the earth is warmer now than in 1960. Whatever errors and difficulties exist in the temperature record, are largely irrelevant. If this argument can be summed up in one sentence it is this: If you know the composition of the atmosphere and the global albedo, you know the global temperature.

Sadly, this is not the end of the story. There are large uncertainties in forecasting the future composition of the atmosphere. Mainly to do with feed back in its various forms. Does melting ice caps release significant effects of methane? How will increased demand for meat affect the amount of methane in the atmosphere (cattle are the largest generators of atmospheric methane). How rapidly will deforestation release CO2 into the atmosphere? How much extra water will end up in the atmosphere as a consequence of higher temperatures? This is a particularly non trivial question, as a lot of this depends on the water cycle, which is highly dependent on the quantity of vegetation. Thus if rainfall moves such that more rain falls on land and there is more vegetation, this will both decrease the albedo, and increase the amount of water in the atmosphere. It is these kind of model uncertainties that make climate forecasting hard.

 

(2) Ensemble Modelling

The purpose of ensemble modelling is to make predictions despite large uncertainties. Essentially, you take every parameter that has some variation, randomly select a configuration, and run your model. Then take another random selection of parameters, and run it again. Take each model and run it against the historical record for the last 40 odd years, and exclude every configuration that diverges wildly from the historical record as an unphysical choice of parameters. Take all those that remain, and run them for 40 odd years into the future, and then you get some predictions. You then to some statistics and end up with some comes, and you say well 80% of the models end up with warming of 2-4 degrees. So that is our most likely scenario. In fact, comparing with the historical record gives us a configuration space that has pretty good clustering for the models. Of course, there is always the danger that the future is wildly different from the past, but this is really the best you can do. Clustering indicates that there are good "rules" about how these parameters relate to each other. The primary danger with ensemble modelling is that the relations between say, temperature and water vapour, that were true in the past, are not true in the future. This is a model risk that you cannot really deal with, the further that the model moves away from the temperatures of the historical record, the greater the chance that there will be a large deviation. Nevertheless, the statement that, if the future is pretty much like the past, then the addition of x amounts of CO2 will lead to y amounts of warming, is already very strong.

 

Here is a particular plot from an ensemble model. Just off wikipedia, I don't knwo anything abotu the details, so don't boether asking, but it seems representative:

http://upload.wikimedia.org/wikipedia/commons/a/a2/Climate_Change_Attribution.png

 

 

So the model tracks five major components, over the last 100 years of data, and predicts the temperature based on them. The bottom is the individual components to the warming from each individual factor.

 

 

(3) Data

 

So in the public imagination, the most important thing is the relationship between CO2 and temperature in the past. I hope this post has made it clear that that relationship is not that important. There are vast uncertainties about the composition of the atmosphere in the past. There are almost no uncertainties about the relationship between atmospheric composition and temperature. CO2 estimates from the past are not enough. You also need to know about all the other trace gases if you want to have a robust correlation. Some of these gases, particularly the organic ones like Methane, are very difficult to get accurate data on.

Further, all data has to be interpreted through a model. We cannot directly measure past temperatures, or past atmospheric composition. We always have to measure some proxy, and then use some model to interpret the proxy in terms of the original variables. Each of these models is subject to its own flaws and biases. This makes historical Data a living nightmare. All of this argument about `adjustments' is really arguments about models. To give you a taste of the kind of problems inherent in this, suppose that I take an ice core and look at the composition of the gases, now in order to say that this is the composition of the atmosphere I need to ask: Is the atmosphere at the arctic representative of the whole globe? Particularly when it comes to the amount of water vapour in it, you know that it is not. Some gases can permeate frozen ice. Some can permeate it at some temperatures but not others, and some basically cannot, so there is some kind of relationship between the original composition, the date of that original composition, and the final, measure composition. Was there originally any bacteria in the air? If there was, even a few cells per cubic centimetre could, upon decay, vastly change the amount of organic gases in a sample. Finally, I need to draw a relationship between the depth and the age. Each of these sources of error needs a model, each of these models is based on assumptions about how the world worked in the past, and every such assumption is a possible source of error.

 

Now, the data does show a decent enough correlation between the CO2 level and the temperature, but it is not nearly as good as the models suggest that it should be. My take is that this tells us that in the past, the world was different in a way not fully accounted for by our models. Maybe it had much more SO2 in the atmosphere than we thought. Maybe the Earths orbit was significantly different. Maybe the measurements of the past are not so accurate as we believe. To me, it is not a great surprise that ensemble models based on forty years of good data do not accurately forecast conditions 5000 thousand years in the past. There are lot of assumptions that could go wrong.

 

 

To me, then, historical data is not a good way to investigate this type of forecasting. Its just too messy. I find the arguments that I sketched in parts one and two basically completely convincing, as they are based wholly on things that we understand really very well. It does not make it 100% true, but we should plan based on our most likely forecasts, with some precautions against particularly devastating consequences that are outside the main channel of forecasts, and that means 2-4 degrees of warming in the next forty odd years

[Daniel1960]

hrothgar,

Commenting on your three points:

 

1) The opaqueness of CO2 to IR also results in its absorption of incoming solar radiation. There is also a significant overlap in the absorption bands between CO2 and water vapor, with the latter being both more absorbant and abundant. There is the added relationship that when ocean temperatures rise, CO2 is outgassed to the atmosphere, so there is a two-fold relationship here. While the warming ability of CO2 has been known for years, it has only been recently that some have tried to amplify its warming capabilities through various feedbacks, which are much less understood.

 

2) Do not confuse with correlation with causation. All the effects mentioned will occur regardless of the cause of the warming. Few scientists are disputing the warming of the plant over the past three centuries. While many acknowledge that CO2 has contributed to the warming, its contribution to the observed warming has been widely debated. Several other sources have been cited as contributors to the observed temperature increase, which are now being mentioned as causes of the observed cooling (or lack of warming as referred to be some climatologists).

 

3) This is false. The "scientific consenses" to which you are referring is simply that the planet has warmed and mankind has contributed. There is no consensus as to the warming attributed to the rise in atmospheric CO2 (see #2). Some people refer to the "IPCC consensus," which was published by the UN in 2007, but this has been challenged repeatedly by other scientists. While many scientists acknowledge that the increased CO2 could lead to large warming, this is generally considered the high end of the probability curve. On the low end of the curve, with equal probability of occurrance, is that warming due to CO2 is insignificant, and the planet will compensate to maintain constant heat flow. Most scientists reside somewhere in between, or simple acknowledge that we do not know enough yet about the interactions of the planet to make a sound scientific guess. Wikipedia is not a good scientific source here, especially with its acknowledged bias towards AGW.

[phil_20686]

hrothgar,

Commenting on your three points:

 

1) The opaqueness of CO2 to IR also results in its absorption of incoming solar radiation.

 

This is false. As I laid out in more detail, most of the sun's energy is in the visible spectrum. Look up Wien's law for the maximum energy out put of a black body per unit frequency. The higher the temperature, the shorter the wavelength where it peaks. The earth is cooler than the sun, and emits in the IR wavelengths.

[Zelandakh]

McIntyre's work in this area has specifically not been aimed at suggesting that there is no global warming occurring. His stance has, to my knowledge, always been that the world is warming but that there is little evidence that this warming is exceptional, in particular in relation to the Little Ice Age (LIA). He has been extremely successful in pointing out various statistical failings used in the modelling that produces the "hockey stick" graphs. As a mathematician, the most fundamental thing wrong with these models is that they fail the statistical test usually used for models of this type. In fact the climate models have a correlation on this statistic of close to zero. On the other hand the modellers use a different statistic which has a confidence level of over 90%. It is still unclear what these differing statistics mean but the whole process has not been without criticism from some statisticians.

 

What is clear is that the process used is extremely sensitive to a single dataset becoming dominant in the final numbers. The reason for this is that the whole methiod depends on weightings for different datasets representing regions. Some datasets have only a small number of data points which means that each data point has a very high weighting. If such a dataset is used in combination with other datasets with a comparatively weak signal the result is that the final graph will look very much like the "dominant" dataset. This is the reason why Yamals, and bristlecone pines before that, are so important. Without these datasets containing such a dominant signal the hockey-stick shape of the graph disappears. This is the major problem with these graphs - they are not really very resilient to different data sets being used. This may well be a remnant of the zero correlation I mentioned in the first paragraph.

 

Meanwhile, there are continuing fears about the ice sheets. The good news here is that the Antarctic may be gaining ice. It is certainly gaining ice in some places and losing it in others. On the other hand the Arctic has certainly lost a significant area of ice. I say area because the ice sheet covers less land but is thicker. Overall there is less ice though and (afaik) noone is disputing this. This is where we come back to the LIA. During this period the records indicate that there was less ice in, for example, Greenland than there is now. The models do not show a LIA because the modellers say the Southern Hemisphere was cold enough to offset the LIA effect, which their records indicate was localised to Northern Europe (despite some records suggesting there were abnormally warm years during this period in many other countries). If this is the case then it might well be that the world was (much) cooler during the LIA despite having less Arctic ice. It does not suggest that the lack of ice alone should be taken as an indicator of catastrophic warming though.

 

There are several other aspects which have been effectively debunked despite newspaper claims that like to suggest them from time to time. One obvious one refers to "serious wether events". When this was first mentioned a (pro-AGW) Norwegian group investigated the numbers of SWEs and found that there had been no change over time. There was a slight increase in the Northern hemisphere and a slight decrease in the Southern. This came as a surprise. You can, of course, change the criteria and create statistics on both sides of this. Nonetheless I believe this original study is still valid.

 

Now to the computer models. The most compelling evidence for AGW comes from these. It surprises a lot of people that the amount of warming that greenhouse gases, especially CO2, cause directly is tiny. You can measure this in the lab and the effect is that beyond a certain point the increased warming would not increase temperatures to anything like dangerous levels, pretty much ever. However, this does not tell the whole story because increasing greenhouse gases does a lot more than the direct effect would suggest. There are a number of feedbacks that occur which amplify the effects. These feedbacks are complicated and every computer model has different values for them. The most controvercial feedback is currently clouds. Clouds are just incredibly complicated; it depends on what type of cloud you get as to whether clouds are a positive feedback (warmer) or a negative feedback (colder). There are several scientists who believe clouds will turn out to be an overall negative feedback. However, all of the major models currently have clouds with a positive feedback.

 

Finally, there is the temperature record itself. You might think it is simple to measure the temperature and for the numbers to be comparable acorss centuries. Unfortunately almost all of the older temperature records are taken in urban areas of wealthy countries. That leaves a huge hole for less welathy countries. Worse than that, these urban areas have generally become major cities which are automatically warmer due to the heat island effect. This is not a trivial problem. There are also some records of the temperature record in less wealthy countries being highly inaccurate due to poor procedure being used. It should not happen but it does.

 

A more consistent and objective record is available using satellites. This has the disadvantage of being compartaively new but ought to be comparable acorss the entire timeframe. The problem with the satellite records is that the instruments have changed over time, both in terms of their sensitivity (age) and because new instruments needed to be fitted as replacements. This means that the satellite records are continually adjusted. These adjustments are often derided by those opposed to AGW since they are almost always positive (except for the earliest years where they are negative). I am not ebtirely sure why this is so. However, we can be fairly sure that the satellite temperature record showing an increase is true since a prominent scientist on the anti-AGW side also keeps a satellite record and this also shows warming (or did last time I looked). Therefore the main argument is not whether there is warming but rather by how much (and for some from what cause).

 

A few years back I got interested in this subject quite a lot and did a fair amount of research on it. I came in as a sceptic, open to the evidence. What I found is that it is clear that there is AGW. What is less clear is how much and whether our models have the feedbacks set to the right levels. Equally clear is that the maths behind the hockey-stick graph should come with a warning and are not 100% reliable. It is also obvious (to me) that we have the technology now to fix the problem, however serious it really is. We can extract the CO2 directly and store it in containers, artifical trees as some call them although I prefer the term aeroforming. Naturally noone wants to be the one paying.

 

The most important thing here at the end of the day is to understand "tipping points". Tipping points are where the levels change in a sudden, usually catastrophic, way. These are what produce the doomsday scenarios the papers are so fond of printing. They sound perhaps impossible and yet the world has gone through this before. So it is important to make sure that we take out insurance against these points. The good news is that they are some way off so we have a bit of time yet. The bad news is that we do not know exactly how long.

 

Overall, I personally do not think either side is right. The world will warm somewhat through AGW but I doubt we will ever see the levels predicted in the more extreme IPCC scenarios. The answers are available through technology. I will not be changing my lifestyle to "make a difference" and neither will the Chinese. I just hope that when we finally get around to implementing the technology that Europe gets its share of the pie too and it is not just shared out between America and China.

[Daniel1960]

phil,

 

I am not sure where got the impression that the sun does not emit radiation in the IR spectrum. Here is a graph for your information:

 

http://www.physics.otago.ac.nz/nx/eman/about-solar-energy.html

 

While solar radiation certainly peaks in the visible region, there is considerable incoming IR (otherwise, we would be darn cold). Integration would yield more totla energy in the IR region than visible. The cooler Earth emits radiation at much higher IR wavelengths.

[Daniel1960]

Zelandakh,

 

Nice summary. Let me add that the assumed reason that there was less ice in Greenland during the LIA, was the large melting attributed to the MWP. Eventually, the glacial ice expanded to reach the maximum extent in the 19th century, and started receding again in the 20th century.

 

I agree that much of the AGW evidence comes from computer models. Most modelers will tell you that clouds constitute a positive temperature feedback, but some incorporate a positive feedback associated with increased cloud coverage, others a positive feedback associated with a decrease in cloud coverage. None have a negative feedback attributed to clouds, even though there is much speculation that increased clouds will act to decrease temperatures due to blockage of incoming radiation.

 

I definitely agree with your last paragraph, and find it heartening that at least one person shares a similar view to my own.

[phil_20686]

I am not sure where got the impression that the sun does not emit radiation in the IR spectrum.

 

I am sure that I have never been under that impression. My assertion was that your argument that CO2 in the atmosphere would lead to a cooling effect by reflecting/absorbing solar radiation. This is completely wrong. For lots of reasons:

 

(1) when we say "CO2 absorbs in the infrar red" it does not mean that all of the infrared spectrum, equally. CO2's primary absorption band is at about 1500nm from memory, and then a bunch more at higher wavelengths. This is almost off the end of the spectrum for solar energy you linked to. The atmosphere is almost totally transparent in the near infrared.

 

 

(2) Here are some graphs of atmospheric transmission:

http://www.astro.virginia.edu/~mfs4n/ir/transh2o1.gif

 

This includes CO2 and all other atmospheric gases. So you can see that I was correct. I used `visible light' as short hand for wavelengths greater than 1350nm. I am not going to attempt to provide publishable-level rigour on an internet board. Compare this to your graph of solar energy and you will see that there is virtually no solar emission in the bands of significant absorption.

 

(3) You realise I am a physicist yes? :)

[phil_20686]

I agree that much of the AGW evidence comes from computer models. Most modelers will tell you that clouds constitute a positive temperature feedback, but some incorporate a positive feedback associated with increased cloud coverage, others a positive feedback associated with a decrease in cloud coverage. None have a negative feedback attributed to clouds, even though there is much speculation that increased clouds will act to decrease temperatures due to blockage of incoming radiation.

 

I feel that there is a disconnect between how science is actually done, and how the public thinks science works. For one thing, the more science one does the more skeptical one becomes about data. There is always a reason why the data is wrong. If you can't think about at least three ways in which a data set may be completely wrong you probably are not trying hard enough. Most scientists don't care too much about actual data for this reason, because we appreciate just how poor lots of it can be. Especially if you use some kind of selection procedure. Narratives based on sound theories actually carry a lot more weight. Normally for every new piece of data there are lots of different interpretations, but there tend to be relatively few theories that are consistent across broad ranges of different types of data.

 

 

Ensemble models can generally work around uncertainties in the modelling, the only thing they require to be true is that the relationships between the variables in the past also hold in the future.

 

So you have two models of cloud formation, and their relationships to temperature: f(T) and g(T), and you don't know which, if any, are dominant, no problem, you put into your model af(T) +bg(T) and choose a, and b randomly as part of your mix of parameters. It might be the case that it doesn't matter too much what you choose for a and b, in which case your sucessful model runs on past history will look like a scatter plot in a and b, which means that your could formation doesnt matter at all. Ideally you might get a really strong condition like a=0.2 b=0.6 or something, which all the models need to be accurate, in which case you are pretty sure that the real atmosphere is a mix. More likely you get some range of conditions which are strongly correlated, with other variables. E.g. you can fit the past either with more cloud formation but less albedo change due to vegetation, or vice versa.

 

This type of uncertainty is only a problem if it causes your models to become uncorrelated. E.g., suppose g(T) is basically constant, but f(T) grows exponentially, then in the past in the flat part of the exponential it is possible for albedo to off set it, but in the future on the steeper part these two models may diverge wildly in their future estimates. If this happens you need to make theoretical choices about which are more likely, or use more past data to calibrate it.

 

Essentially you can see where this goes, as long as the ensemble models are reasonably strongly correlated, you are pretty sure that your parameter choices are ok, and that the range of uncertainty does not effect the model too much. The danger of ensemble modelling is that it never has new physics. It might be the case that one of your cloud formation functions changes dramatically in an unpredictable way if you warm the world two degrees, and that no quality of correlation with past data will help predict the future as the new physics is just not there in the old models.

 

However, I don't think many people believe that is plausible in the next fifty years or so. Most things in science are (or can be reasonably approximated as) power laws (over small changes in parameters). You can get pretty good correlation with the AGW results if you just assume that every physical law is a polynomial and fit every parameter off past data. Even if you restrict yourself to the past 50 years when data is pretty good, you get a strongly correlated set of models that predict warming.

 

So for cloud feedback, its very unlikely that they had to choose a specific model. More likely they have tried multiple models to see what best fit the past. They are not generally putting their models together based purely on scientific theory. They are a combination of theory and ensemble models. I suspect could formation ensemble modelling has come up with a range of parameters for the feedback, which are mostly positive, so people put the mid point of the ensemble cloud models in as theory when they want to use their models for something else.

[phil_20686]

On selection procedures:

 

Came across an interesting thought experient on selection procedures.

 

Suppose that beauty and acting are uncorrelated, but that hollywood looks for actors who have beauty+acting skill>c

 

Then when you look at hollywood actors you get a strong negative correlation between acting and beauty. This can also completely negate a positive correlation. This type of selection effect is prevalent in data sets, in fact its close to impossible to avoid. You look for a data set to measure A, and then someone else uses your data set to measure B instead. Suddenly they find a correlation that may be nothing more than the way in which you selected it in order to best measure A.

[Al_U_Card]

 

Essentially you can see where this goes, as long as the ensemble models are reasonably strongly correlated, you are pretty sure that your parameter choices are ok, and that the range of uncertainty does not effect the model too much. The danger of ensemble modelling is that it never has new physics. It might be the case that one of your cloud formation functions changes dramatically in an unpredictable way if you warm the world two degrees, and that no quality of correlation with past data will help predict the future as the new physics is just not there in the old models.

 

However, I don't think many people believe that is plausible in the next fifty years or so. Most things in science are (or can be reasonably approximated as) power laws (over small changes in parameters). You can get pretty good correlation with the AGW results if you just assume that every physical law is a polynomial and fit every parameter off past data. Even if you restrict yourself to the past 50 years when data is pretty good, you get a strongly correlated set of models that predict warming.

 

 

The GCMs all have issues with fitting past data, they ignore ENSO cycles (for the most part) and they certainly haven't been able to predict squat since they came into existence in the last several decades. Might it be possible that their correlation amongst themselves, as good as the theoretical science they use may be, is also a result of parameterization and the matching of their variable "effects"?

[Daniel1960]

Phil,

 

I am a chemist, so I can relate. Having worked considerably with FTIR, I find your 1350 cutoff rather interesting, but I see you are including some of the near infra-red in the visible spectrum. Still, the sun's radiation tails off slowly, so that significant incoming radiation still exists at wavelenths past 2000 nm, out to the edge of the near IR (2500). While CO2 does absorb a greater percentage of the terrestrial IR, than solar, the solar radiation is significantly higher, such that the absorption by CO2 is non-negligible.

[phil_20686]

Phil,

 

I am a chemist, so I can relate. Having worked considerably with FTIR, I find your 1350 cutoff rather interesting, but I see you are including some of the near infra-red in the visible spectrum. Still, the sun's radiation tails off slowly, so that significant incoming radiation still exists at wavelenths past 2000 nm, out to the edge of the near IR (2500). While CO2 does absorb a greater percentage of the terrestrial IR, than solar, the solar radiation is significantly higher, such that the absorption by CO2 is non-negligible.

 

SUre but its just not significant. The earth emits nearly all in the deep infra red, and if you look at the absorption for that you can see it is is really much much more opaque in the deep infrared.

 

http://www.astro.virginia.edu/~mfs4n/ir/transh2o4.gif

 

http://www.astro.virginia.edu/~mfs4n/ir/transh2o8.gif

 

 

you can look at the whole spectrum in bits here