Arguments
Global cooling: the new kid on the block
Posted on 4 March 2008 by John Cook
A new argument is hurtling up the Skeptic Leaderboard, leaving old stalwarts like mid-century cooling and water vapor in its wake. The argument is that global warming has reversed and we're now undergoing global cooling. No, it's not the old chestnut global warming stopped in 1998. The new contention is that global warming stopped in January 2007.
The argument originated from Anthony Watts who plotted data from 4 sources (HadCRUT, GISS, RSS and UAH), all of which show sharp cooling of around 0.6°C from January 2007 to January 2008. The most common interpretation around the blogosphere is that the long term global warming trend has reversed. Daily Tech goes so far as to say 2007 "wipes out a century of warming".
Figure 1: global temperature anomaly from HadCRUT (graph courtesy Anthony Watts).
The flaw in this interpretation is in drawing conclusions about long term climate change over a relatively short period of 13 months. Particularly when a large portion of that cooling occured over one month (January 2008). Only over a period of years to decades can you confidently discern climate trends. Otherwise, you run the danger of mistaking weather for climate.
Nevertheless, several important questions remain - what's causing this sudden cooling and is it the start of a long term trend?
Is the sun driving global cooling?
The general consensus among skeptic blogs is that diminished solar activity is the cause. The sun is currently at solar minimum - cycle 23 just ended and cycle 24 is having trouble kicking along. It's as cool as it gets in the solar cycle.
However, a temperature drop of 0.6°C would require a dramatic reduction in Total Solar Irradiance (TSI). According to theoretical calculations at Atmoz, TSI would need to fall to 1347.65 W/m2 to produce a global cooling of 0.6°C. In other words, 13 W/m2 less than current levels. This is ludicrously large considering the solar cycle varies only around 1.3 W/m2.
Alternatively, Camp 2007 adopts an empirical approach to calculate solar influence on global temperature. He determines the solar cycle contributes 0.18°C cooling to global temperatures as the sun moves from maximum to minimum. Note - this includes any influence due to cosmic rays as TSI closely correlates with the solar magnetic field which modulates cosmic radiation. Employing back of a napkin calculations, TSI would need to fall roughly 4.3 W/m2 to provide 0.6°C of cooling.
Either way, TSI needs to drop considerably to be considered the driver of 2007 cooling. So what has the sun been doing over the last few years?
Figure 2: TSI Composite and Sunspot Numbers (graph courtesy Greg Kopp).
Satellite measurements show no dramatic drop in TSI over the past several years. Instead, the solar cycle is following its usual 11 year cycle, flattening out as it reaches solar minimum. So if not the sun, what's causing the cooling?
La Niña - the likely culprit
Currently, the Pacific Ocean is in a La Niña phase. During La Niña, cold waters upwell to cool large areas of the equatorial Pacific Ocean. This has the effect of cooling the atmosphere. During the La Niña episode of 1999, global temperatures dropped around 0.5°C.
The Southern Oscillation Index (SOI) is a measure of La Niña. Positive SOI corresponds to a La Niña phase. In 2006, the Pacific Ocean was in El Niño phase (negative SOI). However, in late 2006, El Niño subsided and in mid 2007, crossed into La Niña phase. La Niña peaked around January 2008 and is the strongest La Niña since 1999. In the Eastern Pacific, sea-surface temperatures are about two degrees colder than normal over an area the size of the United States.
Figure 3: Southern Oscillation Index (graph courtesy bom.giv.au).
Future predictions for global cooling
The UK Met Office predict the cooling effect of La Niña will be slightly greater in 2008 than it was during 2007. According to NOAA’s Climate Prediction Center, the current La Niña episode is expected to start weakening in February 2008. The moral of the story - don't use short term weather patterns to draw conclusions about long term climate trends. My prediction is the current global cooling trend will reverse around mid-2008 when La Niña subsides. That's a bit vague though - feel free to go out on a limb and post a comment with your own prediction of the following months.
Meanwhile, solar cycle 24 is expected to crank up later this year so over the next 5 years, the global warming trend will accelerate as increasing solar activity adds to CO2 warming. So enjoy the cold while it lasts. Personally, I'm strongly considering a skiing holiday.
Update 13 March 2008: NASA GISS have updated the Land Ocean Temperature Index. February 2008 shows a global temperature increase of 0.14°C from January 2008. Not as much as John Cross predicted but more than I expected - I thought La Nina cooling might continue for at least a few more months. Probably a bit early to say La Nina cooling has reversed though - will be interesting to see March's figures.
UPDATE 9 April 2008: I've updated the monthly temperature with March's data at La Nina watch: March update (also busied up the graph with Southern Oscillation Index data).
First. The effect from the sun controlling the temperature according to the number of sunspots is cooling when many sunspots. That's the effect which for example IPCC AR4 gives a few tenth of a degree cooling when there is many sunspots in the 11 years cycle. This is only the TSI effect, not involving a cosmic ray connection. (This description I guess also quite well fits in to the "reversed" covariance that Locwood/Frohlish noticed, but I think they missed a delay factor.) According to this TSI effect only we shall have a warmer world now, not a cooler.
A bigger problem with this post is however that you try to debunk those who believe the sun's controlling climate through the cosmic ray link, but you not even involve that controlling function in your text. You can't debunk the strong cosmic ray and cloud force with another weak TSI effect (which I'm not even sure you're use the right way around).
Also the La Nina argument. In a post late 2007, you refused that El Nino didn't forced heat through an increased amount of water vapor in the air, thus increasing the greenhouse. Instead you claimed that this was not at all the case. How can you claim the opposite about La Nina and still think you that will be taken seriously?
Of course there are redistribution of heat as well as implications of increase or decrease in water vapor on a global scale in both phenomenon!
http://www.skepticalscience.com/ocean-and-global-warming.htm
So Camp 2007 empirically compares the solar cycle to global temperatures. The cosmic radiation cycle is the same as the solar cycle. He doesn't do any modelling on solar warming or cloud albedo - it's purely a statistical analysis to see whether there's a statistically significant pattern in global temperature that matches the solar cycle. And he finds a strong solar signal in global temperature - 0.18 degrees worth.
So basically, when Camp calculates the solar influence on global temperature, he includes the whole kit and kaboodle - TSI, UV, cosmic rays - it's all bundled in one big solar package. Note - I've never said cosmic rays don't affect climate but that the cosmic ray trend doesn't correlate with global temperatures.
Re my post on ocean warming, I wasn't denying the El Nino warming influence. Of course El Nino warms the atmosphere as the spike in 1998 shows. In fact, I say the opposite - that phenomena like El Nino demonstrate how oceans transfer heat into the atmosphere.
I would disagree that Watts claimed anything else, as I read the post when it was originally posted. He does not draw the conclusion you suggest but he does poke fun at the over reaction of the warmers to every bump and wiggle in the record like the 2005 hurricane season. I haven't read Daily Tech but I expect if I go there I will find the same thing.
Wasn't the reason for the post by Watts that the GISS record was finally showing what the other 3 main records, like the HadCRUT you show here, had been showing for a year already, a dramatic cooling related to La Nina.
I also disagree on your idea that this is seperate from the claim that warming stopped in 1998. It is clearly part of the same argument. The world is cooler than 1998. Quite a bit in fact. This fact is also irrelevent to the entire argument about long term trends and is them making fun of people who pretend 1998 was some dramatic human caused thing. Natural variability is clearly a big factor and the warming signal over a short term is relatively small next to it. Overly dramatic statements on either side are likely wrong and are certainly not science.
I am not sure if I understand what the first commentor is saying about the solar effect, but I believe the idea is low sunspots are a proxy for high amounts of cosmic rays reaching the earth. High cosmic ray incidence means more cloudiness and reflective cooling. So the idea is even though TSI change is small temperature effect can be relatively large... like say a degree or so.
Denialism is about hemming and hawing isn't it...
Any other brave climate watchers out there?
John
John, I predict February was cold and March will be cold and April will be cold, and if you lived where I do you would too. Around here if the groundhog predicts 6 more weeks of winter on Feb 2, we celebrate an early spring. We are all somewhat products of our environment.
Wasn't the last La Nina a double dip kind of a pattern with a weakening in the middle? If so than either Feb or March could show a recovery followed in a few months by another nasty dip. At the end of which, global averages will be farther down... and it still won't mean temperatures are really falling long term. I think that is the way I'm guessing for 2008. But a guess is all it is, based on the last La Nina.
Regards,
John
I do wonder how much is regional, how much is land use, and how much is GHG or some natural variation we don't understand yet. That's why I keep questioning and reading.
My best Canada story was running my car into a snowbank near Orangeville. I managed to bury my car to the firewall without ever leaving my lane. I would think you would want warming almost as much as I do.
Seriously, I guess my prediction is out there too. I think we'll know a lot more one way or another in about 4 years especially if the solar cycle is weak, but the waiting is tough and while I don't believe we'll see significant cooling I do fear it a bit.
http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf
When incoming energy is larger than outgoing energy, the energy / temperature rises, i.e., First Law of Thermodynamics.
Due to increasing Greenhouse gasses like water vapor, CO2, CH4, etc, the temperature of the Earth *as a whole* is rising.
So, why do we see such jiggles in the Earth’s surface temperature, which is what NASA GISS, Hadley, etc report? Why doesn’t the energy difference just show up as a smooth rise in temperature?
A: most of the energy goes into the oceans, which have 1000X the heat capacity of the atmosphere. The ocean-atmosphere system has all sorts of jiggles that *move heat around*, but do not create or destroy energy.
We care about surface temperature because we live here, and we have the longest temperature series, but the surface is a miniscule slice of the whole thing, and surface temperatures in any one place jiggle daily (day and night, far more than any long-term trend), yearly, and from decadal-scale oscillations. Likewise, the surface temperature as whole jiggles, from things like El Ninos that move energy from ocean to atmosphere, and La Ninas that do the reverse.
Analogy:
A bathtub is being filled [sun], slightly faster than it is being drained [heat radiation]. You have a few floats, measuring the depth of the water. The depth would go up smoothly, except there’s a kid splashing around in the bath.
Sometimes the kid lies back in the water, in which case the overall water level goes up [El Nino], but with waves, so that some floats go down.
Sometimes the kid sits up, in which case the overall water level temporarily goes down [La Nina], but with waves, so a few of the floats go up.
The kid splashes around the whole time, jiggling all floats second by second.
At any point in time, there is a certain amount of water, but the average as measured by 1% of the floats is subject to lots of jiggles.
Still, the water *is* going up, as long as more as coming in than draining out, and the physics of GHGs say that we’re slowly plugging the drain.
The Earth as a whole is gaining energy, and all that some cold spell means is that some oscillation transfers energy from atmosphere/sea surface deeper into the ocean … but that energy doesn’t magically disappear, and the next time it comes back to the surface.
Also a good post there by John Cristy on the subject.
http://tamino.wordpress.com/2008/03/02/whats-up-with-that/
IMHO, Watts has got much more attention than he deserves.
That way, if the sunspots do not come, and, we get past La Nina, and other "weather" effects, and, the earth's temperature continues to drop, then, we need to refine GCMs to account for some as of yet undiscovered mechanism linking solar output to the earth's climate. On the other hand, if the temperature does go up, then, well, obviously, that would argue in favor of existing GCM models, so long as the temperature increases were as predicted.
What better to depress a humanity that so pathologically feels like it needs to matter than to have to shake its fist in futility at the sun as the earth freezes and billions of people go hungry. The best is that, we know the sun is a big ball of hydrogen and helium, and therefor, even praying to it is utterly pointless. May as well stand in front of the tide and try it hold it back with your hand.
There is nothing simple about the physics involved here, indeed physics and astronomy are where a lot of very credible disagreement is coming from. It seems the better I understand a specific portion of the issue the less convincing it becomes.
Hmm... it said that paper was ppv I'll have to try again. However if vulcanism is the big driver here how about the driver of the ice ages? Unless vulcanism has a 100,000 year cycle I think this is going to be a hard sell. Because now we are talking about two different mechanisms between IA and LIA. Not impossible but ...
http://www.scienceonline.org/cgi/content/abstract/317/5839/796
In my recollection they suggested a short term stabilization or slight cooling until 2009 and more warming afterwards. Who knows? They may be right.
The really interesting thing is that there is almost no difference in the amount of energy that the earth receives from the sun during these cycles but how it is distributed is important. Thus there are feedback mechanisms required to explain ice ages.
In fact, the idea of a constant sun but different earth processes changing climate seems to be a common theme that I have seen in paleoclimate. Another way to say it is that internal processes of the earth are more variable than solar output. There is speculation that the development of the isthmus of Panama - which took place about 2 million years ago - was the trigger that caused the current cycle of ice ages. I don't know how it fits into the idea of skeptical science, but there may be a very interesting post in there John.
On the other hand you may not want my advice right now. The preliminary numbers are looking like February will be about the same as January (temperature anomaly wise). Thus my prediction is looking high! I am game for making a prediction for next month if anyone wishes to join me!
John
1} volcanic activity under the melting ice sheets in both Greenland and Antarctica that "may be contributing to their melting".
2) El Nino and La Nina are a part of one cycle driven by vulcanism at the South American subduction zone off the coast of Peru.
3) The atmosphere has had less particulates in the past 100 years due to decreased volcanic ejecta (not reduced vulcanism however).
4) The planetary alignment of 1976, while not having any immediate catastrophic effects, did intensify vulcanism all over the Earth.
5) The sudden increase in temperature slope begins in 1976. Please tell me that this is all coincidental.
Since he passed away 2 years ago his hypothesis never saw a lot of attention. I think he may have been onto something, only time will tell.
And don't forget what William Ruddiman says in "Plows, Plagues, and Petroleum" about temperature dips possibly being contributed to by major pandemics (Chapter 13), i.e., with the causal mechanism being:
- humans die
- previously-forested farmland goes back to forest, sequestering CO2
That's still a hypothesis, but I have seen at least one paper somewhere that seemed to support it:
Abandonment of farmland and vegetation succession following the Eurasian plague pandemic of ad 1347–52.
In particular, the later LIA coincided with the biggest die-off in human history, the deaths of native Americans from smallpox, etc. See 2007 conversation.
One part I can verify personally: I grew up on a small farm in Pennyslvania farmed for 140 years. I have a drawing from the 1840s that shows a big pasture in front of the barn, and it was there when I grew up. My parents sold the place for development, they built nothing on the pasture, and 15-20 years' later, there was a forest there indistinguishable from that on the next property.
The January figure was 12, I predicted February to be between 35 and 45 and it actually came in at 26!
Let the unseemly gloating begin!!
John
In the paper by Richard Mackey (2007) he states: "The IPCC dismissed any significant link between solar variability and climate on the grounds that changes in irradiance were too small." ... "Short wavelength radiation (UV and Xrays) ionises the upper atmosphere and heats the middle atmosphere. As a result, atmospheric temperature varies in a nonlinear manner with the amount and type of solar radiation. The sun ejects enormous quantities of matter continuously in the form of the solar wind, or periodically as either a mix of high energy protons and electrons (Coronal Mass Ejections, (CMEs)), or as mostly high energy protons (Solar Proton Events (SPEs)). The earth’s atmosphere is more sensitive, and more reactive, to the CMEs and SPEs than to the sun’s short wavelength radiation, to which it is, in any case, highly reactive. The effect of the solar wind, CMEs and SPEs is to reduce the amount of ozone and as a result, warm the middle atmosphere. The overall effect on climate is more turbulence: stronger winds, more storms and greater precipitation." Your blog on solar cycles did not mention this.
But more importantly, the long term, decadal trend of solar activity does not correlate with global temperatures. This applies to Total Solar Irradiance, Cosmic Radiation, UV and X-Rays. However, I haven't looked at data on CMEs and SPEs - I imagine as they correlate with other indices of solar activity, they would show a similar lack of correlation with climate.
The most striking feature is that sun has correlated so closely with temperature over the past 1,500 years and yet just in the last 3 decades has diverged so sharply (Usoskin 2005).
Where is this from? Is it proxy data Be10 they mention? If so why would we use proxy data for a time interval where direct measurement is available and cited on other threads? Would you expect there to be no time lag? This graph doesnt support TSI temp link even starting in 1900. It has a dandy cause effect reversal dominating the middle of the graph.
Even if you imagine a 30-35 years lag, to explain the 1975 upward trending temp by the 1940's TSI peak, then you're out of an explanation for the 1940 temp spike. All in all, the TSI to temp idea is a really difficult case to make with this data.
Perhaps this link woulod be a nice contrast.
http://icecap.us/images/uploads/Solar_Changes_and_the_Climate.pdf
Even worse is their use of Lassen's 1991 solar cycle length graph. In 1999, Lassen updated his data concluding "since around 1990 the type of Solar forcing that is described by the solar cycle length model no longer dominates the long-term variation of the Northern hemisphere land air temperature". The 1991 data is erroneous and to use it when even the author has debunked his earlier work is misleading or at best, ignorant.
The Hoyt and Schatten's data used by icecap was part of the topic of a thread at Tamino's, in which Joe D'Aleo did not have much to say that was convincing. Dr. Svalgaard mentioned there that the authors themselves have acknowledged the weakness of their reconstruction, which is not used anymore since much better ones have been done (including Solanki's).
http://tamino.wordpress.com/2008/02/03/exclamation-points/#comments
The dubious mathematical methods used by D'Aleo in the paper that is the subject of the thread are very nicely dissected by Tamino and provide an interesting insight into the reliability of Icecap, in which I believe D'Aleo to be a major contributor.
"Earth’s Orbit Creates More Than A Leap Year: Orbital
Behaviors Also Drive Climate Changes, Ice Ages"
ScienceDaily (Feb. 18, 2008)
The Earth’s orbital behaviors are responsible for more than just presenting us with a leap year every four years. According to Michael E. Wysession, Ph.D., associate professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis, parameters such as planetary gravitational attractions, the Earth’s elliptical orbit around the sun and the degree of tilt of our planet’s axis with respect to its path around the sun, have implications for climate
change and the advent of ice ages.
Are you aware that your own citation linked Krivova 2007 clearly disagrees with your entire premise of some big drop in solar activity in 1975 and since!
So Icecap is debunked? Maybe,I haven't checked that out. It does appear that your own reference completely destroys the graph and claim you made in your response in 28. Either Krivova is totally wrong or this graph is. Krivova does not show declines in either magnetic activity or the less important TSI that started somehow in 1975 or apparetnly at all.
http://en.wikipedia.org/wiki/Solar_variation
It's a pretty good match (which isn't surprising, Krivova 2007 does make a point of checking their reconstruction against the satellite data). Last year, I did ask Solanki if he could upload their TSI data to his website (so I could provide a link to it). He said he'd run the idea by Krivova but I'm guessing they never got around to it. I'd be happy to email you the Solanki data if you're interested.
This could suggest warming throughout the last century was solar related. dram a trend line on this graph and you'll see it. Add a reasonable time lag and you could have the sun inducing warming out to about 2030 based on this data alone.
Now just to be naughty I'll admit I think this is a coincidence
Just for fun assume the timelag for a solar affect on the Earth is about 35-40 years, probably not true but you see the result would fit interestingly. It also seems to fit somewhat with the PDO.
I believe that the half cycle average is 11.1 and full cycle average is 22.3, but I can't remember where I read that.
Disagreed, as I pointed in post #31.
"The dip your talking about around 1920 (in post 31)would than be part of the cause of the mid century cooling."
But then you would have no temp response to the increase of the 1890's. And the 1965 dip does not have a response either. No matter how you cut and slice it, it's hard to fit, to the point of being impossible. Especially when considering how small these variations actually are when you translate them in terms of energy received per square meter and what's reflected by albedo (roughly divide by 4, the multiply by 0.49).
Sorry, but I don't find it convincing at all. Imagine you're applying your skeptical outlook to that hypothesis. How well is it truly defended? Being a real skeptic means you're equally skeptic of all hypotheses and HOLD THEM ALL TO THE SAME STANDARD OF SCUTINY (that which you're aplying to CO2). You can't cut slacks to the solar idea just because it's not CO2.
I find that true skeptic attitutde profoundly lacking with all skeptics but very few (counted on one hand's fingers) whose writings I have read on blogs. Ironically, those show much greater intellectual integrity than "skeptic scientists" like Baliunas, Pielke Sr. and others.
It is a derived graph of a "corrected" value rather than a raw data graph and as a result tends to magnify trends, if any, near the end of the time line. It is very easy in that case to get suckered into seeing trends even if they aren't there.
I don't have any idea what the time lag for any of this stuff is. I am trying to suggest that the instant response idea is wrong and unlikely because of the heat capacity of the system. There are a lot more than one or two interactiong variables here and how much of a factor the ocean plays and how long it takes to respond to a change are big factors.
For example the 1890s increase could play a roll in the 1930s being warming. The correlation isn't that great. It just happens to be a bit better than CO2 temp one or the TSI temp one.
I am just playing with the numbers, it seems obvious to me that simple answers to complicated questions are usually wrong. Which is why current cooling does not disprove AGW, however the warming of the late 20th century doesn't prove it either.
Being a skeptic is usually what science is all about.
Just because I posed another unllikely hypothesis doesn't meen I suddenly believe it's right. The way science works is the correct hypothesis has to take on and defeat all competing hypothesis. If it ever fails it's done. What you may not see is that people cut the CO2-warming idea a lot of slack, as you say, while holding all other ideas to tight scrutiny.
Perhaps you are also dealing with people who have been around for the last 50 or more years and have been bitten by the distortion, dishonesty and alarmism that has been characteristic of every big environmental crusade I can think of. This has in the past led to policy that is in fact harmful to the environment.
If you want a dandy example take a look at the story of DDT. Every thing used to replace it was more environmentally harmful more expensive less effective. Here we are 35 years since the ban, National Geographic still telling us it was killing the eagles, all long ago disproven and millions still paying for the lie with their lives. Or would you like to think about acid rain, logging, the new ice age, nuclear power dangers, alar, asbestos or how about compact florescent bulbs ?... the list goes on and on. Here is my question on this rant, how many times does it take for the same people to lie to you before being a skeptic becomes your knee jerk reaction? Maybe you should cut the skeptics a little slack, they are doing their job.
The fact that anyone is even willing to listen to claims of global warming, or any impending environmental disaster, is a miracle. We better not be wrong this time, especially not for inciting another overblown panic, or we may never regain the influence to get anyone to believe us if we have a real warning.
Before regurgitating propaganda, why don't you look at how much DDT was used per square meter of beach for instance, vs. what was necessary to achieve the desired result. DDT did kill birds because it ended up in the doses needed to kill birds' eggs, instead of the much lower doses needed to kill mosquito eggs and larvae. Of course, once something is legislated, it's hard to track back. The DDT backlash was not created by environmentalists but by businessmen.
Since we're talking about lies, why don't we examine the lies of the lead industry about the neurological effects of lead containing paints on children. Or we could also examine the lies of the tobacco industry. There are plenty of lies to go around, really. Acid rain is real, I've seen the effects of it. Take a trip to China, yuo'll see plenty for yourself. While you're there, reflect on how you would like to live in such a place. The new ice age is media created bunk. Asbestos does cause lung disease, I have not met a pulmonologist who'd deny that. It's easy to see where your list comes from. For each and any of those items, how closely have you looked at the "alternate" side of the story that you were presented?
"Being a skeptic is usually what science is all about." This claim is often heard, along with the suggestion that all the climate scientists doing research full time are not exercising the proper amount of skepticism. What's funny is that most of the time, that half veiled accusation comes from people who are not scientists and would be hard pressed to distinguish between what warrants great skepticism and what's more likely to be truly interesting. Quietman's recent interest in the miserable Gerlich "paper" is a case in point.
I'm not going to cut skeptics any slack if they are not aware of the all story and rely on sources that are worthless. GRL is a good source. Energy and Environment is not. Heartland is a miserable source. NOAA and NASA are good ones. There are objective criteria for this. If you decide to ignore them, your skepticism is nothing more than well dressed bias. Skepticism cuts both ways. How much skepticism did you direct toward the version of the DDT story that you were told?
Go ahead and find research that shows that DDT harmed Raptor birds. I can save you time it doesn't exist. Audobon and hawk mountain bird counts clearly showed increased populations at the height of DDT use. Something I experienced first hand.
The bird egg thing had already been disproven 30 years ago. Tests with real birds at even wildlly elevated levels ranged from inconclusive to downright favorable. Long term persistence in the environment was exaggerated. In fact the test they were using to detect it at the time required that it break down readily in the environment. I went to a professional conference 25 years ago where this precise issue was used as an example of bad scientific ethics.
Not to be argued? You are aware of the huge residue levels of DDT found in elephants? Yes Siberian elephants found in permafrost and the resulting discovery that the supposed marker for DDT building up in living tissue was in fact not a marker for DDT at all.
Then you hit me with that old saw about the manufacturers wanting to sell too much when in fact since it was long out of patent and they made the patented replacements they were quiet supporters of the ban.
It was used foolishly and broadly and had an effect of messing up local food chains from misuse; but you'll have a tough time finding a replacement that wasn't worse on every particular.
Or perhaps a quote from Ruckelshaus at the time of the ban "We admit there is no scientific evidence to support the ban of DDT never the less we are banning it."
Sorry, I tried very hard my first year in grad school environmental chemistry to try to prove the DDT issue wasn't a politically motivated fraud, I failed completely. It is the only project in hundreds of grad hours I never managed to complete, and the professors involved admitted at the end that they couldn't do it either. It is probably why I switched to surface chemistry and later into physics.
The one "Real" and "not to be argued" thing in the DDT issue is the bodies of the innocent children who have died as a result of the ban.
On acid rain, being "real" doesn't make it a crisis, which I suspect you well know. As in Canada blaming emissions from Sudbury on Gary Indiana. The perpose of that scare was to reduce fossil fuel use. When it faded in the mid to late 1980s it was replaced by another scare.
As I recall the lead paint thing was basically "they'd have to actually eat the paint for it to be a problem." Which is exactly the issue.
Which part of NASA is such a good source? or NOAA for that matter as there are public figures on both extremes in both agencies. Several of AGW's best known skeptics are NASA scientists or retired NASA scientists.
Sorry for my immoderate tone there phillippe it isn't your fault. But when ones youthful idealism is squashed he tends to remember it. Especially when the entire chemistry department in a major university system considers the issue an open joke.