Global Warming

[10Seven]

Gene, I think you are guilty of tending toward convenient interpretation - your railing against 'cooking data' is hypocritical.

 

[Gothmog]

You're basically saying that we have do a lot of weird things (cooking, processing) the data before we can test GW. That's not what I like to hear when evaluating a hypothesis. It is a bad sign, and worthy of raising suspicion.

No, I am saying that compiling and evaluating this massive a data set is more than a full time job. The quality of the data needs to be checked and rechecked. There are spatial and temporal issues to be addressed. Even the satellite data is very hard to interpret, no single (solar looking) satellite has been up for more than ten years, there are calibration issues and intercalibration issues.

I have looked at the pnas article, and it is a good one. Of course it doesn’t say anything like the outrageous claim I called you on earlier. I’ve punished you enough on that one, I’ll stop harping on it now.

PNAS is not peer reviewed in the traditional sense, the articles are called for by the editor. But it is well respected, and the editors are top scientists in their respective fields. So it is archived, I fully accept it, and it would have a decent ISI rating.

It is a very long timescale modeling exercise and fully agrees with the forcings I posted from the Hansen article earlier. Everyone agrees that the sun is important, Milankovitch cycles are at the heart of climate research. A good climate model must include solar forcing, along with all the rest.

I even posted a number of other articles that talk about a solar link beyond the direct forcing (secondary effects through solar proton events). Good articles like the one you link to above. I am far from believing that human understanding of climate is complete.

You tone of debate has improved, I appreciate that. If you go back through the posts you will notice that I tend to respond in kind. I have read your papers, when I could access them. I didn’t get to the pnas article because I was busy. It is a good article.

I totally agree that observations take precedent. I’ve tried to bring them into this debate (my forcings stuff, and my continued appeal to start debating individual process models).

The thing is that CO2 isn’t the only thing affecting climate, a large part of the correlation in the graph I posted above is due to other factors. Remember that correlation does not imply causation, one needs to posit a mechanism and then test that mechanisms independent variables in a controlled way. That is what is done with process models.

I would be interested to see the AAPG article, can’t you find a PDF to post?

Edit: My favorite example of correlation and causation is that crime rates are strongly correlated with the density of churches.

Of course this is because there are lots of churches in inner cities where crime rates are also high, but it shows that you need to look at mechanisms and not data in isolation.

Lies, danm lies, and statistics...

 

[gene90]

I have looked at the pnas article, and it is a good one. Of course it doesn’t say anything like the outrageous claim I called you on earlier. I’ve punished you enough on that one, I’ll stop harping on it now.

That's appreciated. In return, I admit that it was an outrageous claim, and one I no longer hold. Though it may seem hard to believe, your efforts have somewhat altered my views on global warming.

You tone of debate has improved, I appreciate that. If you go back through the posts you will notice that I tend to respond in kind.

Yeah, and again I take a lot of responsibility for the general quality of debate. Sorry about that, I have an unfortunate habit of being impatient in prolonged exchanges. I can also get too enthusiastic sometimes.

Remember that correlation does not imply causation, one needs to posit a mechanism

Yes, this is one of my profs favorite talking points. Every male between 18 and 25 who drank milk in 1825 is now dead. And umbrellas do not cause rain, though they appear on rainy days.

But, the correlation between CO2 and temperature, while not a final proof, is definately an important test. And your charts speak for themselves on that.

I would be interested to see the AAPG article, can’t you find a PDF to post?

I don't think I can scan it in the current journals room. Maybe I could run off a copy of that figure that I've been harping on and scan it? Yeah, I am forced to recognize there's no way you can get to that one.

EDIT: This is an interesting thing I came across. It tends to illustrate my concerns about how science can be politicized:
http://www.globalwarming.org/article.php?uid=901

(I do realize that the site above has a stated agenda)

Dear colleagues,



After some prolonged deliberation, I have decided to withdraw from participating in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). I am withdrawing because I have come to view the part of the IPCC to which my expertise is relevant as having become politicized. In addition, when I have raised my concerns to the IPCC leadership, their response was simply to dismiss my concerns.



With this open letter to the community, I wish to explain the basis for my decision and bring awareness to what I view as a problem in the IPCC process. The IPCC is a group of climate researchers from around the world that every few years summarize how climate is changing and how it may be altered in the future due to manmade global warming. I had served both as an author for the Observations chapter and a Reviewer for the 2nd Assessment Report in 1995 and the 3rd Assessment Report in 2001, primarily on the topic of tropical cyclones (hurricanes and typhoons). My work on hurricanes, and tropical cyclones more generally, has been widely cited by the IPCC. For the upcoming AR4, I was asked several weeks ago by the Observations chapter Lead Author — Dr. Kevin Trenberth — to provide the writeup for Atlantic hurricanes. As I had in the past, I agreed to assist the IPCC in what I thought was to be an important and politically-neutral determination of what is happening with our climate.



Shortly after Dr. Trenberth requested that I draft the Atlantic hurricane section for the AR4's Observations chapter, Dr. Trenberth participated in a press conference organized by scientists at Harvard on the topic "Experts to warn global warming likely to continue spurring more outbreaks of intense hurricane activity" along with other media interviews on the topic. The result of this media interaction was widespread coverage that directly connected the very busy 2004 Atlantic hurricane season as being caused by anthropogenic greenhouse gas warming occurring today. Listening to and reading transcripts of this press conference and other media interviews, it is apparent that Dr. Trenberth was being accurately quoted and summarized in such statements and was not being misrepresented in the media. These media sessions have the potential to result in a widespread perception that global warming has made recent hurricane activity much more severe.



I found it a bit perplexing that the participants in the Harvard press conference had come to the conclusion that global warming was impacting hurricane activity today. To my knowledge, none of the participants in that press conference had performed any research on hurricane variability, nor were they reporting on any new work in the field. All previous and current research in the area of hurricane variability has shown no reliable, long-term trend up in the frequency or intensity of tropical cyclones, either in the Atlantic or any other basin. The IPCC assessments in 1995 and 2001 also concluded that there was no global warming signal found in the hurricane record.



Moreover, the evidence is quite strong and supported by the most recent credible studies that any impact in the future from global warming upon hurricanes will likely be quite small. The latest results from the Geophysical Fluid Dynamics Laboratory (Knutson and Tuleya, Journal of Climate, 2004) suggest that by around 2080, hurricanes may have winds and rainfall about 5% more intense than today. It has been proposed that even this tiny change may be an exaggeration as to what may happen by the end of the 21st Century (Michaels, Knappenberger, and Landsea, Journal of Climate, 2005, submitted).



It is beyond me why my colleagues would utilize the media to push an unsupported agenda that recent hurricane activity has been due to global warming. Given Dr. Trenberth’s role as the IPCC’s Lead Author responsible for preparing the text on hurricanes, his public statements so far outside of current scientific understanding led me to concern that it would be very difficult for the IPCC process to proceed objectively with regards to the assessment on hurricane activity. My view is that when people identify themselves as being associated with the IPCC and then make pronouncements far outside current scientific understandings thatthis will harm the credibility of climate change science and will in the longer term diminish our role in public policy.



My concerns go beyond the actions of Dr. Trenberth and his colleagues to how he and other IPCC officials responded to my concerns. I did caution Dr. Trenberth before the media event and provided him a summary of the current understanding within the hurricane research community. I was disappointed when the IPCC leadership dismissed my concerns when I brought up the misrepresentation of climate science while invoking the authority of the IPCC. Specifically, the IPCC leadershipsaid that Dr. Trenberth was speaking as an individual, even though he was introduced in the press conference as an IPCC lead author. I was told that that the media was exaggerating or misrepresenting his words, even though the audio from the press conference and interview tells a different story (available on the web directly); and that Dr. Trenberth was accurately reflecting conclusions from the TAR, even though it is quite clear that the TAR stated that there was no connection between global warming and hurricane activity at this time. The IPCC leadership saw nothing to be concerned with in Dr. Trenberth's unfounded pronouncements to the media, despite his supposedly impartial important role that he must undertake as a Lead Author on the upcoming AR4.



It is certainly true that "individual scientists can do what they wish in their own rights," as one of the folks in the IPCC leadership suggested. Differing conclusions and robust debates are certainly crucial to progress in climate science. However, this case is not an honest scientific discussion conducted at a meeting of climate researchers. Instead, a scientist with an important role in the IPCC represented himself as a Lead Author for the IPCC and has used that position to promulgate to the media and general public his own opinion that the busy 2004 hurricane season was caused by global warming, which is in direct opposition to research written in the field and is counter to conclusions in the TAR. This becomes problematic when I am then asked to provide the draft about observed hurricane activity variations for the AR4 with, ironically, Dr. Trenberth as the Lead Author for this chapter. Because of Dr. Trenberth's pronouncements, the IPCC process on our assessment of these crucial extreme events in our climate system has been subverted and compromised, its neutrality lost. While no one can "tell" scientists what to say or not say (nor am I suggesting that), the IPCC did select Dr. Trenberth as a Lead Author and entrusted to him to carry out this duty in a non-biased, neutral point of view. When scientists hold press conferences and speak with the media, much care is needed not to reflect poorly upon the IPCC. It is of more than passing interest to note that Dr. Trenberth, while eager to share his views on global warming and hurricanes with the media, declined to do so at the Climate Variability and Change Conference in January where he made several presentations. Perhaps he was concerned that such speculation — though worthy in his mind of public pronouncements — would not stand up to the scrutiny of fellow climate scientists.



I personally cannot in good faith continue to contribute to a process that I view as both being motivated by pre-conceived agendas and being scientifically unsound. As the IPCC leadership has seen no wrong in Dr. Trenberth's actions and have retained him as a Lead Author for the AR4, I have decided to no longer participate in the IPCC AR4.



Sincerely,



Chris Landsea



This is not a minor point. I was in Florida in early January. They had a billboard up that said: Global Warming Causes More Hurricanes. George W. Bush Just Doesn't Get It. This looks to me like political groups profiting off a commonly-held (apparent) misconception. And in Florida, a 2004 swing state that was hit hard by hurricanes before the election, that kind of claim could be considered serious business.

 

[Gothmog]

And umbrellas do not cause rain, though they appear on rainy days.

I'll have to remember that one.

See, we can find common ground.

I agree with Dr. Landsea 100% and respect his letter. I would be very suprized if the final IPCC report supports any connection between global warming and hurricane activity. I don't know of any work suggesting such a link, and the IPCC always reviews actual work done. Not just speculation by an individual scientist.

It’s funny you bring this up because my first post in this thread relates exactly to this issue: http://forums.civfanatics.com/showpost.php?p=2481881&postcount=30

One of the only non-politicized web sites I've ever seen on the global warming issue is: http://www.realclimate.org/

I just recently became aware of it, but what I have seen of it has all been good.

I do respect the IPCC and the work they have done. I know a good number of contributors. Again, I will be very surprised if they compromise themselves that way. They will lose much respect from the scientific community if they go the way of a lobby group.

 

[gene90]

Have you ever heard about anoxia in ocean basins due to the burning of carbon? The alleged effect is not from global warming, but from use of fossil fuels. I was reading the GW section of Our Angry Earth (Pohl and Asimov, 1988, I think) to try to see if/how changes in what to expect from GW have changed. They mentioned that Freeman Dyson has suggested that the reduced O2 levels could cause anoxia in the Pacific. I'd never heard that before. Anyone have comments?

 

[Pikachu]

paradoxically, you believe that aerosols will destroy the correlation in the short term, while at the same time, you insist that natural variants like aerosols will not protect us from anthropogenic global warming!

Aerosols do evidently reduce the global temperature right now. The increased aerosol load is however not natural. It is a direct product of industrial pollution. Aerosols only stay in the atmosphere for some days or weeks though while CO2 stays there for centuries, so CO2 get time to accumulate up there while aerosols don’t. As long as we spew more and more sooth, smog and nasty chemicals into the atmosphere, it can more or less cancel out the effect from the greenhouse gas emissions, but in the long run I am afraid that our aerosol pollution cannot keep up with the CO2. I don’t see why this analysis should be paradoxical?

And I am not insisting on that natural variants in anything will not protect us from global warming, but I think such coincidences are somewhat unlikely to save us. I think we have to accept that we most probably will not be that lucky.

Or in other words, if global warming is real, then more CO2 should cause temperatures to go up. And we are pumping more CO2 into the environment right now...therefore there should be an observed increase in surface temperature. This would not "prove" global warming because there is a possibility of coincidence, though unlikely. However, for global warming to be true, as long as CO2 concentrations increase temperature must increase.

Not if something that should cause the temperature to decrease happens at the same time.

Anyway, the surface temperature is indeed increasing right now, just like expected. You already knew that, didn’t you?

 

[gene90]

And I am not insisting on that natural variants in anything will not protect us from global warming, but I think such coincidences are somewhat unlikely to save us. I think we have to accept that we most probably will not be that lucky.

This is a valid concern.

Anyway, the surface temperature is indeed increasing right now, just like expected. You already knew that, didn’t you?

Yes, I pretty much accepted that temps were going up to begin with, though you can't always be sure about it. What the causes are is the issue. [begin speculation] CO2 may be one of the causes, it certainly varies closely with temperature even on shorter timescales. It could be an effect but that seems less probable on decadal timescales, because it seems as though you would need more time to effectively change the ocean load, or to thaw out that much permafrost *and* offgas a meaningful quantity of carbon dioxide. On the long-term (paleoclimatic) scale, there are still those papers that appear to show a lag between temp and CO2. It still seems to me that on, say, 10,000 year or greater scale temperature may be driving CO2 and CH4...it doesn't make sense to me that CH4 would vary with CO2 unless they are each responding to the same cause. I bet that aerosols are asimportant over 10,000-100,000 year scales as they are over ...changing temps drive forests back, and glaciers generate lots of windblown loess. Apparently there is a solar component as well, which seems to be proving difficult to constrain.

 

[betazed]

Much to my surprise, it seems that we are heading towards a convergence of views. This gotta be a very rare occassion indeed in CFC.

 

[polymath]

The article in The Guardian, which I linked to, tried to pin it on GW.

You would know this had you actually read the link.

You mean this bit?:

"I don't think that aerosols by themselves would be able to produce this amount of global dimming," says Farquhar. Global warming itself might also be playing a role, he suggests, by perhaps forcing more water to be evaporated from the oceans and then blown onshore (although the evidence on land suggests otherwise). "If the greenhouse effect causes global dimming then that really changes the perspective," he says. In other words, while it keeps getting warmer it might keep getting darker. "I'm not saying it definitely is that, I'm just raising the question."

Where they are saying that it's most likely aerosols, but they might not be enough on their own? I don't really call that "trying to pin it on GW". I call it a bunch of 'might's and 'perhaps's. As you would know if you had read the article.

 

[gene90]

Where they are saying that it's most likely aerosols, but they might not be enough on their own? I don't really call that "trying to pin it on GW". I call it a bunch of 'might's and 'perhaps's. As you would know if you had read the article.

Yeah, you caught me there.

The point doesn't really seem as important since the context was whether or not CO2 showed a correlation with temperature. That issue has been settled to my satisfaction.

 

[polymath]

The point doesn't really seem as important since the context was whether or not CO2 showed a correlation with temperature. That issue has been settled to my satisfaction.

Nonetheless, since we know global dimming is taking place, why isn't the earth getting cooler? The answer is because of global warming. That issue has been settled to my satisfaction.

 

[Gothmog]

I brought this up before but this is the original Gaia hypothesis as put forward by Lovelock.

The greenhouse effect warms the atmosphere

the atmosphere warms the ocean

the warmer ocean causes oceanic bugs to emit more sulfur compounds like DMS

more emitted sulfur compounds become more sulfate aerosols in the upper troposphere and stratosphere

sulfate aerosols increase the earth's albedo, reducing the amount of sunlight reaching the surface.

That is equivalent to the statement in a magazine saying 'global warming causes global dimming' as far as I can see.

When Lovelock put forth that hypothesis (the mid 1960's) there was no good data about the efficacy of sulfate aerosols, Keeling was just starting to measure CO2 in a systematic way, and Lovelock himself was just beginning to establish that oceanic bugs were the biggest player in the natural atmosphereic reduced sulfur cycle.

I think the most widely accepted hypothesis currently is that increased atmospheric temperature decreases the average particle size of clouds in general, thus increasing their reflectivity. I don't know of any solid verification of this idea though.

 

[polymath]

A bigger cause of global dimming is atmospheric pollution. Burning oil, wood, or from cars, power stations, the usual suspects. So this causes global warming through CO2 and global dimming through particle pollution. But we are reducing pollutant emissions drastically in the west through cleaner fuels, etc etc, so the balance will be lost. In other words, there will be a lot less particle pollutants to cause global dimming (the visible problem as opposed to the invisible CO2 problem). Then we'll see the real problems...

 

[Gothmog]

That is exactly the indirect aerosol effect (changing the size distribution of cloud droplets thus increasing their reflectivity), then there is the effect I mention above (sulfate directly increases the reflectivity of any given droplet).

Both of these forcings were included in the plot I posted earlier (representing current state of the art)

and were also included in the 2001 IPCC report (though with large error bars). It just takes time for these things to get to the popular press.

Notice that soot has a warming and cooling effect.

It also indicates another problem that climate modelers have, they must assume what the sulfur cycle will look like in ten (or however many) years, and what the aerosol distribution will be. These are both controlled by human politics (because humans currently dominate the atmospheric sulfur and aerosol cycles), which is very hard to predict.

So the modelers have to run a 'suite' of simulations, representing a number of best guesses as to how things will be in the future. Hard at a time scale of ten years, difficult at 25 years, nearly impossible at 50 years, pie in the sky at 150 years.