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Carbon Dioxide - Everyone's Favorite Pollutant

Posted on 5 October 2010 by dana1981

Before assessing whether or not CO2 is a pollutant, we must first define the term.

What is an Air Pollutant?

The US Clean Air Act was incorporated into the United States Code of Federal Regulations, Title 42, Chapter 85.  Its Title III, Section 7602(g) defines an air pollutant:

"The term “air pollutant” means any air pollution agent or combination of such agents, including any physical, chemical, biological, radioactive (including source material, special nuclear material, and byproduct material) substance or matter which is emitted into or otherwise enters the ambient air."

Clearly this is a very broad definition.  More importantly, its Title 1, Part A, Section 7408 states that the US Environmental Protection Agency (EPA) Administrator must publish a list of certain air pollutants:

"emissions of which, in his judgment, cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare"

In Massachusetts v. Environmental Protection Agency (in 2007), the US Supreme Court held that the Clean Air Act gives the EPA the authority to regulate tailpipe emissions of greenhouse gases. Two years after the Supreme Court ruling, in 2009 the EPA issued an endangerment finding concluding that

"greenhouse gases in the atmosphere may reasonably be anticipated both to endanger public health and to endanger public welfare....The major assessments by the U.S. Global Climate Research Program (USGCRP), the Intergovernmental Panel on Climate Change (IPCC), and the National Research Council (NRC) serve as the primary scientific basis supporting the Administrator’s endangerment finding."
Greenhouse gases including CO2 unquestionably fit the Clean Air Act's broad definition of "air pollutants," and must be listed and regulated by the EPA if it can be determined that they endanger public heath and/or welfare.
Alternatively, the definition of "pollution" from Encyclopedia Brittanica is:
"the addition of any substance (solid, liquid, or gas) or any form of energy (such as heat, sound, or radioactivity) to the environment at a rate faster than it can be dispersed, diluted, decomposed, recycled, or stored in some harmless form."
Thus legally in the USA, CO2 is an air pollutant which must be regulated if it may endanger publich health or welfare.  And according to the encyclopedic definition, CO2 is a pollutant unless our emissions can be stored "harmlessly."

Is Increasing CO2 Dangerous or Harmless?

Humans are Increasing Atmospheric CO2 Concentrations

Humans have increased the amount of CO2 in the atmosphere by 40% over the past 150 years, primarily through the combustion of fossil fuels.


Figure 1: CO2 levels (parts per million) over the past 10,000 years. Blue line from Taylor Dome ice cores (NOAA). Green line from Law Dome ice core (CDIAC). Red line from direct measurements at Mauna Loa, Hawaii (NOAA).

We know that the increase in atmospheric CO2 is anthropogenic from a number of lines of evidence.  Atmospheric oxygen is decreasing at approximately the same rate as the atmospheric CO2 increase, which tells us that the source of the change is from a release of carbon combining with atmospheric oxygen rather than a natural release of CO2.  We also know that the 30 billion tonnes of CO2 released by human activity must go somewhere, and in fact atmospheric CO2 is only increasing by about 16 billion tonnes per year (the rest is going into the oceans).  CO2 produced from burning fossil fuels or burning forests also has quite a different isotopic composition from CO2 in the atmosphere, because plants have a preference for the lighter isotopes (12C vs. 13C); thus they have lower 13C/12C ratios.  And indeed we've observed this ratio decline in the atmosphere.


Figure 2: Atmospheric 13C ratio as measured at Mauna Loa (CDIAC)

The Increasing CO2 is Causing Global Warming

Thus we know that human emissions are increasing the amount of CO2 in the atmosphere, which as a greenhouse gas, in turn increases the greenhouse effect.  This increases the amount of energy (in the form of longwave infrared radiation) reaching the Earth's surface.  We've observed this increase through spectroscopy, which measures changes in the electromagnetic spectrum.  Climate scientists have also quantified the amount of warming we expect to see from the energy imbalance caused by this increased downward radiation, and it matches well with observations.  Given the amount of CO2 humans have added to the atmosphere already, once the planet reaches a new equilibrium state, it will have warmed approximately 1.4°C from pre-industrial levels.  Additionally, we have observed numerous key 'fingerprints' of anthropogenic global warming which confirm that the warming we've experienced is due to an increased greenhouse effect.

How Much Warming is Dangerous?

There are some positive effects of global warming from increased CO2 emissions.  For example, improved agriculture at high latitudes and increased vegetation growth in some circumstances. However, the negatives will far outweigh the positives.  Coast-bound communities are threatened by rising sea levels. Melting glaciers threaten the water supplies of hundreds of millions.  Species are  already becoming extinct at a rate 100 to 1000 times higher than the “background” rate of long spans of geological time, partially due to the effects of global warming and climate change.  

Quantifying exactly at what point global warming will become dangerous is a difficult task.  However, based on the research and recommendations of climate scientists, more than 100 countries have adopted a global warming limit of 2°C or below (relative to pre-industrial levels) as a guiding principle for mitigation efforts to reduce climate change risks, impacts, and damages.  This 2°C warming level is considered the "danger limit". During the last interglacial period when the average global temperature was approximately 2°C hotter than today, sea levels were 6.6 to 9.4 meters higher than current sea levels. Large parts of the Antarctic and Greenland ice sheets melted, with the southern part of Greenland having little or no ice.

As discussed above, the CO2 we've already emitted has committed us to about 1.4°C warming above pre-industrial levels.  Given a climate sensitivity to a doubling of atmospheric CO2 of 2-4.5°C and the fact that on our current path we're headed for a CO2 doubling by mid-to-late 21st century, we're fast-approaching the danger limit.

How Soon Will we Reach Dangerous Warming?

Meinshausen et al. (2009) found that if we limit cumulative CO2 emissions from 2000-2050 to 1,000 Gt (approximately an 80% cut in global emissions), there is a 25% probability of warming exceeding the 2°C limit, and 1,440 Gt CO2 over that period (an 80% cut in developed country emissions) yields a 50% chance of 2°C warming by the year 2100.  If we maintain current emissions levels, there is an approximately 67% chance that we will exceed 2°C warming by 2100.

Figure 3: Probability of exceeding 2°C warming by 2100 in various emissions scenarios in gigatonnes of carbon (RealClimate)

In short, to avoid the amount of global warming which is considered dangerous based on our understanding of the climate and empirical evidence, we need to achieve major reductions in global CO2 emissions in the next 40 years.   Thus it becomes quite clear that not only is CO2 a pollutant, but it also poses a risk to public health and welfare.

Ocean Acidification

Another impact of increasing atmospheric CO2 emissions is ocean acidification.  When CO2 dissolves in seawater, it increases the hydrogen ion concentration though the chemical reaction CO2 + CO32- + H2O ? 2HCO3-, thus decreasing the pH of the oceans (NOAA 2008).  Among other impacts, this decreasing oceanic pH has a damaging effect on corals, which form the habitat of approximately 25% of marine species (Karleskint et al. 2009).  A seminal study co-authored by 17 marine scientists (Hoegh-Guldberg et al. 2007) found:

"Many experimental studies have shown that a doubling of pre-industrial [CO2]atm to 560 ppm decreases coral calcification and growth by up to 40% through the inhibition of aragonite formation (the principal crystalline form of calcium carbonate deposited in coral skeletons) as carbonate-ion concentrations decrease"

Thus not only does anthropogenic CO2 act as a dangerous pollutant due to its impacts on global warming and climate change, but it also has a major effect on marine ecosystems through ocean acidification.

CO2 is a Pollutant

When considering the legal definition of "air pollutants" and body of scientific evidence, it becomes clear that CO2 meets the definition and poses a significant threat to public health and welfare.

This post is the Advanced version (written by Dana Nuccitelli [dana1981]) of the skeptic argument "CO2 is not a pollutant".

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Comments 1 to 50 out of 120:

  1. Nicely comprehensive. I suppose it goes without saying that almost anything is a pollutant if it's found in the wrong place and/or at the wrong concentration. Skeptics are fond of referring to the naturalness of C02. C0 is also found in the atmosphere as a natural constituent, so I guess by the same logic as that applied to C02, sitting in one's garage with the engine running and the doors closed is perfectly ok.
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  2. I quote from above "This 2°C warming level is considered the "danger limit". During the last interglacial period when the average global temperature was approximately 2°C hotter than today, sea levels were 6.6 to 9.4 meters higher than current sea levels." If a 2°C in the past caused a 6.6 to 9.4 rise in sea levels, doesn't it intuitively seem that 2°C is past the danger limit?
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  3. Thanks doug. Yes it's really a silly argument to begin with. Just because something has beneficial effects doesn't mean it can't be bad in excessive quantities. Bob - true, but it will take several centuries for sea level rise to reach that level. We're looking at probably less than 1 meter by 2100 if we keep temperatures less than 2°C higher. Thus it's a reasonable limit for the short-term.
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  4. Hi Dana, This means that the human race needs a long term plan to reverse the warming trend because this still seems to be too much of a rise of sea level in several centuries. And of course, we could be in for some rude surprises! I know that reversal of the warming trend is asking too much since we can't even get the ball rolling for stabilizing the temperature at 2°C
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  5. Just another thought. Even though we may not be past the danger level, I'm sure that a 2°C is still going to put us on a roller coaster. Therefore, I'm guessing that more than a 2°C rise will put us past a tipping point. Some say we may have already passed a tipping point but reversibility may still be an option. Sounds bad to me!
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  6. I agree that CO2 is increasing in the atmosphere as a result of human activity. After that we disagree. The science behind CO2 as a problem with warming is absurd. If the basis that it causes warming is the only reason for it being a pollutant then you have nothing. My article on the original theory based on Arrhenius is here: http://theinconvenientskeptic.com/2010/09/the-extremely-flawed-foundation-of-global-warming/ You can argue all you want about the water vapor feedback, but the simple fact is that no model has ever been able to predict the impact of CO2. Even Judith Curry is not convinced the models can show anything useful. The only empirical evidence you have ever posted is based on differences in brightness temperature which is independent of infra-red energy transmission. If the atmosphere is not absorbing more energy as a result of higher CO2 concentrations, then there is no such thing as global warming. My article tomorrow will be about pollution and CO2 emissions. You should read it because it focuses on what matters. I will gladly discuss science on any topic. Should be fun. :-) John Kehr The Inconvenient Skeptic
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  7. "We know that the increase in atmospheric CO2 is anthropogenic from a number of lines of evidence." Here's another bit of evidence, from Cerveny and Coakley 2002: The Mauna Loa MSR [a statistic developed by the authors] curve (figure 1a) strongly suggests a prominent seven-day cycle in CO2 concentrations. Friday through Sunday experience the lowest values of CO2 while Monday through Wednesday has highest values. ... Such a weekly cycle would be due to either local causes or hemispheric causes. Such weekly cycles were also reported for NO2, which is clearly a pollutant, by Beirle et al. 2003: In the cycles of the industrialized regions and cities in the US, Europe and Japan a clear Sunday minimum of tropospheric NO2 VCD can be seen. Sunday NO2 VCDs are about 25–50% lower than working day levels. Metropolitan areas with other religious and cultural backgrounds (Jerusalem, Mecca) show different weekly patterns corresponding to different days of rest. In China, no weekly pattern can be found. Since the former work was based on surface measurements and the latter based on satellite measurements, with VCD='vertical column density', it would seem that 'measurement error' or 'sample bias' is not an issue with these conclusions.
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  8. Excellent post Dana (once again!). Just a small point: is it worth pointing out that the extinction rate is currently primarily due to habitat destruction/land use change, plus widespread agricultural practices? Climate change will increasingly contribute to this and exacerbate the problem, but as it currently stands it is not the top driver, let alone the only driver, as is possibly implied by your current wording. Keep up the great work!
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  9. John Kehr - I suggest you click some of the links in this article. You might learn something. Your claim "The only empirical evidence you have ever posted is based on differences in brightness temperature" is false and refuted by those links. As for the accuracy of climate models, in addition to the 'fingerprints' article linked in this rebuttal, I also suggest you read the Advanced rebuttal to 'Hansen's 1988 predictions were wrong'. I'm not sure why you seem to consider Judith Curry the world's foremost authority on climate models, since unlike James Hanse, she's not even a climate modeler. As Senator Pat Moynihan once said, "Everyone is entitled to his own opinion, but not his own facts."
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  10. Byron - thanks, and fair point. I didn't intend to imply that the increased extinction rate was solely due to climate change. I'll modify the wording.
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  11. The Inconvenient Skeptic, 'debunking' Aarhenius is all very well but his work has been superceded by others many times over. I would recomend Ramanathan and Coakley as a good place to start getting up to speed on the modern (i.e post 1905) science.
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  12. Incidently The Inconvenient Skeptic, is your post not merely link baiting?
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  13. Dana, The problem with modeling the future is that those same models cannot be used to explain the past. For instance. The warming at the end of the last glacial is a serious problem for computer models that depend on CO2 levels. If the feedback of the global climate is so sensitive to CO2 levels then the any change in CO2 would cause unbounded feedback and thermal runaway. Since the Earth is stable (within a temperature range, +/- 7C over the past 1 million years) there has never been a thermal runaway. The reason is that the Earth is a stable system. Your chart showing CO2 levels for the past 10,000 years shows a gradual increase in CO2 levels for basically the whole period until anthropogenic CO2 changed the path. The problem is that the steady increase in CO2 has not caused a steady increase in global temperatures. Temperature has been widely variable in the past 10,000 years. The Earth was at it's warmest period from about 5,000-9,000 years ago when CO2 was in the 260-270ppm range. The Earth has cooled over the past 5,000 years while CO2 has gone up. It is that disconnect between temperature and CO2 that I am referring to. While it is fun to focus on short term (our lifetime is very short scale climate wise) changes, it is the long term that matters. If the climate is so sensitive to CO2 that it was responsible for the end of the last glacial, then the increases in the past 5,000 should have caused warming. The increases CO2 for the past 5,000 years did not. Any model that tries to deal with that disconnect fails. That is why models have not been able to deal with the past. Since they cannot do that, they cannot be trusted for the future. I should have stated that the brightness temp post was the most convincing argument showing CO2 matters. Again, I don't argue the anthropogenic impact on CO2 levels, but what impact that CO2 will have on the temperature. John Kehr The Inconvenient Skeptic
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    Moderator Response: See the Argument CO2 is not the only driver of climate.
  14. "The Earth was at it's warmest period from about 5,000-9,000 years ago when CO2 was in the 260-270ppm range. The Earth has cooled over the past 5,000 years while CO2 has gone up." When it was physically closer to the sun during the nothern hemisphere summer.
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  15. TIS #6: "My article on the original theory based on Arrhenius is here:" What is with the 'skeptic' tendency to focus on disputing 100+ year old science? Are they stuck in the wrong century or something? From the article; "Unfortunately it was 80 years before it could fully be proven as incorrect and as a result the flawed idea had plenty of time to become well entrenched in the scientific community." So this is to be a work of fiction? In reality Arrhenius's idea of human CO2 emissions increasing global temperatures was completely rejected based on reasonable but ultimately incorrect objections; At the time instrument quality was not sufficient to show the IR bands absorbed by CO2 but not water vapor, scientists hadn't considered that CO2 occurs at higher altitudes than water vapor and thus would have a warming impact even if they DID overlap totally, and it was believed that the oceans would be able to absorb all human CO2 emissions because they didn't consider the surface saturation rate. Et cetera. Arrhenius's theory was consequently all but forgotten for decades until the accumulating evidence proved him right. The exact opposite of the scenario presented in the story. I see below that Agnstrom is cited. It was Angstrom who made the aforementioned incorrect assumptions about the IR absorption of CO2, so apparently TIS is aware of some of this but chose to present a false narrative anyway... even claiming Angstrom's findings as correct when they've been proven to be completely wrong for many decades now.
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  16. CO2 cannot "enter" the air, since "air" takes its definition from its constituents, CO2 being one of them. The Clean Air Act targeted CO emmissions as these are toxic. The idea that CO2 is pollutant is absurd since according to AGW if it were completely removed from the atmosphere we would all perish. First, from a lack of food and second from temperatures dropping (according to AGW).
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  17. The classification of CO2 as a pollutant is a very serious subject that will have a profound impact in the United States. I have spent a significant period of time studying all aspects of this from original sources. I have a pretty good grasp on what drives the Earth's climate from the view of an engineer. Modeling is not science until the results match the observations. Using them as proof until that is achieved is not science.
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    Moderator Response: See Models are unreliable. And post any comments about that topic on that page, not this one. Off topic comments will be deleted from this page.
  18. CB Dunk, CO2 does in fact have a limited absorption bank limited to 14-16 micron (for purposes of the GH effect). That it exists at high altitudes is irrelevant as it has absorbed those bands long before the higher altitudes is reached. I only point out Arrhenius because he is often cited as the originator of the idea behind global warming. It is worth noting that no "theory" was provable until the 1970's. That is when time series temperature data became readily available. Arrhenius's idea that doubling CO2 levels would increase warming 5-6C is still used by many. Only the explanation of why it happens has changed over the years.
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    Moderator Response: See CO2 effect is saturated. And post any comments about that topic there, not here.
  19. Inconvenient Skeptic (#6), Thank you for pointing out the absurdity of the idea that rising CO2 levels significantly impacted climate over the last 80 years. Even though the idea does not fly at any time scale the faithful on this site are hard to persuade! Getting back to the idea that CO2 is somehow a "pollutant", it seems that the EPA is running this flag up the pole to see if anyone salutes. Thus far they have have dismally failed with all the scientists I work with. For those of you who see CO2 as a pollutant, can you explain how life flourished during tens of millions of years when the atmospheric concentration of CO2 exceeded 6,000 ppm (15 times higher than today)?
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  20. gallopingcamel... There is a section on SkS for that here.
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  21. Pardon me for making free with advice but this conversation is rapidly heading in an extremely boring direction, promising all sorts of pointless repetition of shopworn canards. "TIS" (The Inconvenient Skeptic) if you're going to make any serious inroads into thinking around here, you're first going to want to revise the inconvenient embarrassment of the article you wrote and have advertised here, taking into account the corrections already on offer. Blunders like your essay are a solid impediment to your credibility and you'll never be allowed to forget it; getting fundamentals so wrong is an important clue as to how seriously any remarks you make here should be taken. You're using your real name, you should respect its worth because it's the only one you have. Also, your alacrity in citing Judith Curry is a unhelpful clue about your perspective and further saps your credibility. Dr. Curry is of course a handy rhetorical prop these days for self-professed skeptics; among skeptics Curry's seen as some sort of evangelized convert to climate skepticism. While it's true that pickings in that department are precious thin, leaving only one example from which to choose, invoking Dr. Curry immediately casts a political tone over anything else you say, meaning people are made aware you're not really concerned with science but instead political theatrics. Problems with dully redundant regurgitation of tired misdirection can be avoided by circumspection, looking at the complete picture as best we know it today, which of course implies such easily accomplished behaviors as not referring to anachronistic narratives of science as it stood over 100 years ago, politically expedient personalities, etc.
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  22. RSVP #16: You need to read the definitions of 'pollution' in the article again. MANY pollutants are naturally occurring and/or beneficial in smaller quantities. Ergo, the fact that a certain level of CO2 is needed does not change the fact that CO2 far in excess of that level is pollution. Without light there would be no life on this planet at all... yet "light pollution" is a real problem for cave ecosystems and some cities. TIS #18: "That it exists at high altitudes is irrelevant as it has absorbed those bands long before the higher altitudes is reached." That statement is false. I suggest reading Is the CO2 effect saturated?
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    Response: Not only reading that post, but commenting there, not here. That includes people responding to those comments mis-posted on this page. You are free to post a comment pointing to your response on the appropriate page, though. Reminder to everyone: You can see all recent comments regardless of which page they appear on, by clicking the Recent Comments link in the blue horizontal bar at the top of this page.
  23. Oh boy, this comment thread seems to be de-evolving into a repetition of every long-debunked skeptic myth, from 'models are useless' to 'CO2 is saturated'. I suggest that those making these arguments spend some time perusing Skeptical Science, where these myths are refuted. gallopingcamel - believe it or not, life on Earth hundreds of millions of years ago was slightly different than life on Earth today.
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    Moderator Response: Indeed, we are going to start deleting comments (and even responses to comments, to be fair) that are off the topic of this page.
  24. gallopingcamel... There is a section on SkS for thathere.
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    Moderator Response: And galloping camel and everyone who wants to reply to him, please comment on that page, not this one.
  25. Inconvenient Skeptic Oh, no... another "skeptic" throwing out claims in a faster rate than he can deal with. "Models are not confirmed by observations", "Arrhenius got it wrong and everyone else just followed it", "period x had low CO2 and high temperatures"... Come on, pick any source you think is reliable for atmospheric physics. Maybe a university's website, some large research institute or just a plain textbook. I'm sure your background as an engineer will be enough to understand it. If you don't have any source in mind, don't hesitate to ask.
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  26. Expect a lot of squealing as the rubber of regulation meets the road. "C02 is a pollutant" goes straight to the gut of the fossil fuels industry, so of course there's been a lot of attention paid to sowing confusion on the issue.
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  27. Speaking of which, whoever is acting as moderator is doing a commendable job referring to the appropriate rebuttals. Nicely done.
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  28. #16 CO2 cannot "enter" the air, since "air" takes its definition from its constituents, CO2 being one of them. Air is a mixture of gases by definition. It's not at all clear why this definition should prevent us from speaking of a constituent gas "entering" the air. I'd love to see the logical steps here laid out in a little more detail. The idea that CO2 is pollutant is absurd since according to AGW if it were completely removed from the atmosphere we would all perish. The definition of "pollutant" is not "something that's inherently bad in all concentrations and at all times and places." And the fact that CO2 is necessary for life doesn't mean that industries should be allowed to emit as much as they want. "A little is necessary, so a lot is beneficial or harmless" doesn't make any kind of logical sense in the real world. These really are not difficult concepts. #17 I have a pretty good grasp on what drives the Earth's climate from the view of an engineer. Oddly enough, a lot of us prefer to get our information from climatologists, whose expertise and training tend to be a lot more relevant. Full disclosure: I also take my cat to the veterinarian for check-ups, rather than the mechanic.
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  29. Good point doug - seeing as how the EPA cannot regulate CO2 if it's not a "pollutant" which endangers public welfare, it's not surprising that this is such a sore subject for those who are 'skeptical' of AGW because they oppose government regulation of CO2. But as I think the article clearly shows, there's really no question that CO2 is a pollutant by whatever definition you want to choose, whether it be legal or encyclopedic. It's certainly not harmless.
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  30. BTW, given that the whole 'skeptic' argument here is that something cannot be a pollutant if it is naturally occurring and/or has some beneficial effect(s) I might suggest the 'Basic' version of this article just list various examples of other substances which meet the same criteria but, like CO2, become pollutants at higher concentrations.
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  31. Arrhenius in his recent paper no more than a century old, with all of the massive parallel computing power he used, milions of lines of codes, tens of super-specialists working for him, an integrated network of land, ocean and satellite instruments, huge fundings from what we now know as IPCC, got his numbers wrong by a factor of two ... what a shame! John Cook, you should consider a new skeptic argument: Arrhenius was off by a factor of two so AGW is disproved. It's easy, you don't even need a formal rebuttal.
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    Moderator Response: Let's take this conversation to a more appropriate page, please.
  32. Sorry Dana, I now a switch to serious mode. I strongly agree with your beginning with the legal part of the problem. Indeed, I often see a lot of confusion on this respect. People think that a pollutant is something dirty or something that directly and immediately hurts our health. They tend to see it more like a poison than a pollutant. Clarify on this was a great move.
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  33. Is someone trying to make a mountain out of a CO2 molehill? I was visiting Dr. Roy Spencer's website the other day, and this is what he had to say about CO2: "It is interesting to note that, even though carbon dioxide is necessary for life on Earth to exist, there is precious little of it in Earth’s atmosphere. As of 2008, only 39 out of every 100,000 molecules of air were CO2, and it will take mankind’s CO2 emissions 5 more years to increase that number by 1, to 40." See that? The famous Dr. Roy Spencer says that there is "precious little of it [carbon dioxide] in Earth's atmosphere" and that "carbon dioxide is necessary for life on Earth to exist." And now we are declaring that that life-giving elixir, so precious little of it in the atmosphere, is an air pollutant? OK.
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  34. Cruise the web and you'll see a plethora of slick, obviously well-funded sites dedicated to conveying the virtuous nature of C02, Dana. Sunlight! All natural! No way to hurt yourself with a suntan... More charitably, the problem here is that C02 is not acutely toxic at 800ppm, as opposed to C0 with its swiftly acting 25ppm threshold, nor is it like lead in usually being toxic via chronic exposure. At the levels we're speaking of,it's not even a toxicity problem at all. The gulf of understanding here may arise because as it's a chemical, the established regulatory framework offers an existing way of approaching C02 as a pollutant loosely akin in some ways to a chronic exposure problem. In fact we could also think of excess C02 as being more akin to building a faulty dam above a community but since we're paralyzed in terms of creating a policy framework to handle "dangerously defective" on such a huge scale we're stuck w/the EPA et al.
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  35. Roger #33: The precious "life-giving elixir" of CO2 is a deadly poison to humans which our bodies have evolved to get rid of as quickly as possible. If the atmosphere somehow increased to ~10% CO2 (not going to happen any time soon) every human being on the planet would immediately fall over and die. CO2 is a lethal poison that kills human beings all the time. Try asking some coal miners about how wonderful and life-giving it is. Again, things become pollutants when their concentration in a given area is harmful to the environment of that area. CO2 has now risen high enough that it is actually becoming harmful to the environment of the entire planet... it's a pollutant.
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  36. Roger, Raising from 39 in 100,000 to 40 in 100,000 is a 2.5% increase. Humanity has already increased the CO2 atmospheric content by 40% over the past 150 years. 2.5% in 5 years 40% in 150 years Playing on the innumeracy of the crowd doesn't change the facts. Phila said it best above
    The definition of "pollutant" is not "something that's inherently bad in all concentrations and at all times and places." And the fact that CO2 is necessary for life doesn't mean that industries should be allowed to emit as much as they want. "A little is necessary, so a lot is beneficial or harmless" doesn't make any kind of logical sense in the real world.
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  37. #33 See that? The famous Dr. Roy Spencer says that there is "precious little of it [carbon dioxide] in Earth's atmosphere" and that "carbon dioxide is necessary for life on Earth to exist." And now we are declaring that that life-giving elixir, so precious little of it in the atmosphere, is an air pollutant? OK. I hope you're being ironic. But it's hard to tell sometimes, so let me say again that "a little is good" doesn't mean "a lot is better." Copper is essential to life, but the fact that there's "precious little" of it in our bodies is not actually a bad thing. Spencer's reputation doesn't make his argument more credible. His argument makes him less credible. Also, saying that there's "precious little" CO2, and calling it a "life-giving elixir" is a bit maudlin. We're not in any danger of running out of CO2. Quite the opposite.
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  38. @Phila: excellent points. Let me briefly go off-topic to suggest the site should eventually improve its comment system. I'd love to be able to upvote comments such as #28 and 37. Threaded comments and the ability to flag off-topic posts would also greatly enhance the level of discussion. SkS 2.0, if you will! ;-)
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  39. The Inconvenient Skeptic @#6 & #13, etc.: Thanks (but not really) for providing the summary of unsubstantiated postulates that so-called "skeptics" believe to be true, even in the absence of scientific evidence. You might consider expanding it into a movie script, to be entitled, "The Attack of the Zombie Straw Men" (Tag line: "You can try to destroy them, but they will not die!"). If it weren't for "skeptics" such as yourself, this web site would have no reason to exist... so at some absurd and ironic level, we owe you a debt of gratitude. Your recitative also reminds me of the very first lecture on climate change I ever attended, presented by a "skeptical" geologist colleague who provided a rundown of all the many reasons why he believed AGW to be false. I didn't know enough about climate science at the time to know what specifically was incorrect about his talk.... but I did know that one (and only one) of the following statements was true: a) The entire population of climate scientist (internationally) are utterly incompetent, OR b) This guy was wrong about essentially everything he said. The difference between him and me... and between you and me as well, I would presume, is that the very next day I set about with an open mind to investigate the science behind his claims. Suffice it to say, it was NOT my ultimate conclusion that the entire population of climate scientists are incompetent. If you aspire to skepticism (and it's an admirable pursuit), I recommend you start over from scratch, with no biases this time. And just as a little "heads up", try to bear in mind at all times that there are many factors that influence climate; not just CO2
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    Moderator Response: And comments on that particular topic should be posted in CO2 is not the only driver of climate.
  40. GC - I am very disappointed that you could be cheering for TIS when you must know from many discussions that his/her points are utterly uninformed and bogus, as many have been discussed with you at length. Are you still having issue with role of CO2 in ice ages? Feel free to take conversation to email.
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  41. Sigh... So will it be in bad taste to point out that the labeling on the CO2 chart is mis-labeled. The Taylor Dome is the 11 kYear source and the Law dome data is the 1,000 year source. I agree that this is not a big deal, but that is part of what peer review.
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  42. CoalGeologist @39... I have to say, that was very well put.
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  43. svettypoo - generally for a concern to merit a response, it must be substantiated. If TIS says that global warming is caused by unicorn farts, he's probably not going to receive a response for that either.
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  44. svettypoo, the problem is when claims are not supported by any known science. For example, your claim "Temperature records of the past are in conflict with what climate models predict" does not seems to have strong bases. And if one such claim is used to disprove one century of science (as TIS did), well, what should one say?
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  45. svettypoo - Discussions of climate models should take place on How reliable are climate models, where this is addressed, or perhaps in this case the CO2 was higher in the past thread, where it's clear that solar and CO2 forcings together with other inputs match previous climate behavior (see CO2 is not the only driver of climate). Your claim about model inconsistency is not supportable - and I note that you have presented no evidence in that regard.
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  46. Thanks for the speedy response dana1981. Before I make a rebuttal, I want to make sure I have this right. Do you claim that TIS's concern is unwarranted because climate models are NOT in conflict with temperature measurements of the past?
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    Moderator Response: Please see KR's list of suggested appropriate locations for detailed discussion on model performance.

    Note, this not to suggest svettypoo intended to continue here but instead is a general request.

    As was mentioned earlier, the "Latest Posts" list at left is a convenient way of discovering where the crowd has gone.
  47. TIS #41 is correct about the labeling. The two samples are correctly described in the comments under the picture (i.e. Blue = Taylor, Green = Law), but incorrectly in the legend on the chart itself (i.e. Blue = Law, Green = Taylor).
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  48. The Blue Moderator wrote: As was mentioned earlier, the "Latest Posts" list at left is a convenient way of discovering where the crowd has gone. The "Latest Posts" list will tell you what the latest posts are, but the "Recent Comments" link at the top will tell you where the crowd has gone.
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  49. The Inconvenient Skeptic writes: The warming at the end of the last glacial is a serious problem for computer models that depend on CO2 levels. If the feedback of the global climate is so sensitive to CO2 levels then the any change in CO2 would cause unbounded feedback and thermal runaway. Since the Earth is stable (within a temperature range, +/- 7C over the past 1 million years) there has never been a thermal runaway. The reason is that the Earth is a stable system. The idea that positive feedback implies an "unbounded" increase in temperature (or "thermal runaway") is both common and completely mistaken. See the article on Does positive feedback necessarily mean runaway warming? for an explanation. Positive feedback will not lead to a "runaway" increase if the feedback factor f is less than 1. And, in fact, modest (f < 1) positive feedbacks are a necessary feature of the climate regime as seen in the glacial/interglacial cycles. So ... I'm sorry, but your ideas expressed in the quote I've excerpted above are pretty much completely wrong. I hope you'll continue reading this site. John Cook and the rest of the community here have developed an exceptionally high-value resource for exploring many of the common questions and misconceptions that persist around climate change issues.
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    Moderator Response: And put comments about that topic on that page, not this one.
  50. The nature of "pollution" and what it means is where alot of greens go wrong in science. The question is not whether something does 'bad' to the environment, the question from a human nd ecological perspective is whether the bad outweighs the good. Using the argument that everything that is 'bad' for the envrionment is no good would mean no houses (cuts down habitat), no roads, no mines, no anything. The question is one of balance, and that mean looking at things from a broader perpsective. This is general government policy in Australia, weighing up the environmental, social and economic costs and benefits of various policy decisions. With regard to 'pollution', the issues are the same. A pollutant can also be 'good', it depends on the degree of the relative effects. Eg DDT saves lives, and causes cancer at the same time. Mines damage an area and create jobs. Radiactivity creates energy and causes cancer. etc etc. This is also the general argument of the Skeptical Environmentalist by Lomborg. C02 obviously is necessay for life, but too much might not be good. But there is a danger in giving bureacratic agencies legislation which classifies something as a 'pollutant' which is also necassary for society to function. Have a look at the first definition, it is completely circular and doesn't define what a pollutant actually is: "The term “air pollutant” means any air pollution agent..." .......ie 'a pollutant is a pollutant'. the 2nd definition, doesnt weigh up the costs and benefits: "....anticipated to endanger public health or welfare". So do cars. This is not the issue, it is "whether the danger to public health or welfare" outweighs the benefits. Again, it is only half a definition. The third: "in some harmless form", which again fails to mention the cost/benefit issue. It only refers to whether somethng is harmless or not. By this defintion cars would have to stay in garages, otherwise they would be harmless. It is not about whther or not something is harmless, but whether the 'harm' outweighs the benefits, in other words, is a certain amount of harm acceptable, or can the hamr be reduced to an acceptable level? The argument over c02 as a pollutant depends on whether the IPCC worst-case scenarios turns out to be correct, and whether there is any practical way of mitigating greenhouse gas warming by other methods (eg large scale c02 extraction from the atmosphere and suitable capture). I tend to agree with Lonborg that money would be better spent on alternative energies and mitigation effects, than various other policies such as Kyoto nad issues relating to eg 'pollutants'. etc
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