Meteorologists’ Statement Reflects ‘Vast Weight’ of Evidence

Meteorologists’ new statement reaffirms scientific ‘consensus,’ runs counter to widespread views of meteorologists as disproportionately ‘skeptical.’


The nation’s leading association of meteorologists August 27 announced its new seven-page statement on climate change, reaffirming its commitment to “peer reviewed-scientific literature” and what it called “the vast weight of current scientific understanding.”

The statement comes at a time of continued anxieties among some that broadcast meteorologists in particular are disproportionately skeptical of what many have come to characterize as the “consensus” scientific- and evidence-based view on a warmer climate and principal causes for the warming over the past half-century.

Observed Warming ‘Unequivocal,’ CO2 ‘Most Important’

The new American Meteorological Society statement points to “observed” and “unequivocal” warming of the climate system going “beyond what can be explained by natural variability of the climate.”

“It is clear from extensive scientific evidence that the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases, including carbon dioxide (CO2),” the AMS statement says. It stipulates that CO2 is “the most important” of the greenhouse gases, pointing, for instance, to its long life time in the atmosphere.

Noting that warming effects are “especially evident in the planet’s polar regions,” the AMS statement says that human and natural factors “will continue to alter climate in the future” and calls further warming “inevitable for many years” because of the accumulation of greenhouse gases in the atmosphere and oceans. While largely avoiding policy issues, the AMS statement says “amelioration might be possible through devising and implementing environmentally responsible geoengineering approaches, such as capture and storage measures” for reducing atmospheric CO2 loadings, but it also cautions that “potential risks of geoengineering may be quite large.”

“Were future technologies and policies able to achieve a rapid reduction of greenhouse gas emissions — an approach termed ‘mitigation’ — this would greatly lessen future global warming and its impacts,” the group’s new statement says.

Forecast for Strong Hurricanes, Heat Waves

Addressing potential weather impacts in a warmer world, the AMS statement points to modeling simulations projecting “an increased proportion of global hurricanes that are in the strongest categories … although the total counts of hurricanes may not change or may even decrease. It points to continuing heat waves and cold snaps but says “proportionately more extreme warm periods and fewer cold periods are expected. Indeed, what many people traditionally consider a cold wave is already changing toward less severe conditions. Frost days (those with minimum temperature below freezing) will be fewer and growing seasons longer.” Look for “more severe episodes of extreme heat,” the statement cautions.

It points to “already thawing” regions of Alaskan and other northern polar area permafrost, “with the potential to release massive amounts of carbon into the atmosphere beyond those being directly added by human activity.” It also points to increased acidification of the planet’s oceans, with risks in particular for shell fish and other organisms and for ocean ecosystems more broadly.

The AMS climate change statement concludes that “there is unequivocal evidence that Earth’s lower atmosphere, ocean, and land surface are warming; sea level is rising; and snow cover, mountain glaciers, and Arctic sea ice are shrinking” and that the “dominant cause” since the 1950s is “human activities.”

“Avoiding this future warming will require a large and rapid reduction in global greenhouse gas emissions,” it says, and “technological, economic, and policy choices in the near future” will determine the extent of future impacts.

Uncertainty … and Weather/Climate Distinction

“Science–based decisions are seldom made in a context of absolute certainty,” it says, but mitigation and adaptation efforts can help reduce risks and impacts “that are potentially large and dangerous.”

In discussing climate and related weather issues, the AMS statement says “climate is potentially predictable for much longer time scales than weather …. climate can be meaningfully characterized by seasonal-to-decadal averages and other statistical measures, and the average weather is more predictable than individual weather events.”

The statement introduces a useful metaphor or analogy in this regard: “Population averages of human mortality are predictable while life spans of individuals are not.”

The statement also points to long time scales in climate physical systems and processes in contrast to short time scales in weather and related atmospheric phenomena, such as thunderstorms and intense snow storms.

The statement was approved unanimously by the AMS’s 21-person Council, according to AMS Executive Director Keith Seiter, a member of that council. He said the “guiding issue” in writing the statement was that it be supported by peer-reviewed literature.

“Quite a number of people contributed in various ways along the line, helping to shape the language in specific parts of the document.  Many AMS members submitted comments on the draft posted for member comment — with some questioning statements that needed to be refined to be more precise and others suggesting additions,” Seiter said.

“All of those comments were reviewed and helped shape the final form.   The number of people involved and the range of checking and rechecking that was done by Council members and outside experts who provided input to the Council is why this statement took so long to complete.”

Seiter said he personally accepts that some dismissive of the underlying climate science “may still not like what they read, and they may still feel that the peer-reviewed literature is not presenting the correct answers on some aspects of all this, but I think everything in this can be traced directly back to the literature in clear ways.”

AMS is among a relatively small group of key scientific organizations and “fraternities” whose climate change policy statements are closely watched in climate policy circles eager to detect and softening or hardening of their positions based, for instance, on ongoing scientific reports or on political and scientific arguments advanced by climate “skeptic” interests. The new statement is unlikely to provoke howls of protest from those generally in sync with the Intergovernmental Panel on Climate Change (IPCC), the National Academy of Sciences, or the U.S. Global Change Research Program. Those determined to deny the climate science positions of such interests, on the other hand, are likely to find little, if anything, in the AMS statement to their liking.

The new AMS statement is expected to be in force until August 2017 unless superseded by a new one issued by AMS prior to then.

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26 Responses to Meteorologists’ Statement Reflects ‘Vast Weight’ of Evidence

  1. Dan Rogers says:

    How can carbon dioxide be the “most important” greenhouse gas? Water vapor is a powerful greenhouse gas — much more powerful than CO2 — and it exists in the atmosphere at a very high concentration compared to the concentration of CO2. Al Gore and his disciples simply ignore water vapor as an inconvenient truth.

  2. Peter Capen says:

    It is clear from Dan Rogers’ statement to the above article that he did not bother to read the comment on water vapor (page 2, paragraph 4) by the American Meteorological Society. Had he done so, he would have realized that, as the AMS statement clearly points out “…the concentration of water vapor depends on atmospheric temperature and is controlled by the global climate system through its hydrological cycle of evaporation-condensation-precipitation.” The more CO2 is pumped into the atmosphere, the greater the average temperature of the planet, which leads to greater evaporation from soil, plants, and water bodies, hence more water vapor held in the atmosphere the warmer it becomes. Yes, water vapor also plays a “greenhouse” role, but it is a complement to the release of other greenhouse gases, especially CO2. While it may be ideologically conforting for Mr. Rogers to bash “Al Gore and his disciples,” it ignores the climate science about the reasons why water vapor in the atmosphere is increasing. As the AMS statement goes on to say, “Observations indicate an increase in globally averaged water vapor in the atmosphere in recent decades, at a rate consistent with the response by climate models that simulate human-induced increases in greenhouse gases.” Unfortunately, continued denial of the scientific basis for why the planet is heating leads to the adoption of no policy solutions of the problem. Focusing on increased water vapor in the atmosphere, exclusive the role of increased CO2 releases from the continued burning of fossil fuels, only serves to “muddy the water” and confuse the public, thereby further delaying any action being taken at the national level. And in the end, we will all pay the price of climate change inaction.

    • Dan Rogers says:

      Is water vapor a greenhouse gas? I think the answer is “yes.” Is there much more of it in the atmosphere than carbon dioxide? Again the answer is “yes.” Is it much more powerful a greenhouse gas than carbon dioxide on a molecule for molecule basis? Yes.

      I think Mr. Capen agrees that these are facts. Do these facts constitute “bashing” of Al Gore? I don’t think so. I am not “ideologically comforted” by bringing these facts to the fore. They are, once again, “inconvenient truths” that call into question the virtues of the entire global warming crusade, and ignoring them is folly.

      Climate change has always occurred and is still occurring. The climate has been warming up fairly steadily for about ten or twelve thousand years as we continue to emerge from what we refer to as “the last ice age.” Can we humans stop the process or slow it down? I believe we cannot, and I believe that attempts to do so detract very seriously from our ability to make sensible preparations for it.

      • Charles says:

        Well, Dan, you may not believe humans can have an influence on climate, but the vast weight of scientific, empirical evidence does not support your claim.

        • John says:

          Charles, good point. To think that humans cannot impact on the atmosphere means to deny that chloro-fluorocarbons have caused the ozone hole.

          • Dan Rogers says:

            The “ozone hole” over the Antarctic appears each southern winter when the Sun disappears from the sky down there. Ozone (O3) is created by the interaction of ultraviolet light in sunlight with normal oxygen molecules which consist of two oxygen atoms. The UV radiation breaks normal O2 molecules apart, (some of them, not all of them), and they continually reformulate themselves into O2 and O3 molecules.

            When winter comes and sunlight goes away over the Antarctic continent, that battle of oxygen and UV radiation comes to a halt, and the creation there of O3 molecules pretty much comes to a halt. In the absence of UV radiation, the atmosphere above the continent becomes devoid of ozone. The ozone is not really “destroyed” by chloro-fluorocarbons or by anything else for that matter. Ozone is simply unstable and quickly reverts to normal oxygen. For there to be any ozone at all in the upper atmosphere there must be constant sunlight interacting with normal oxygen molecules. The ozone must be constantl replenished.

            We don’t see as much ozone depletion over the north pole each northern winter because the air over the north pole mixes year round with air from the rest of the northern hemisphere. In the Antarctic, however, during each southern winter, an atmospheric circumpolar gyre forms which isolates the air above that continent and very much restricts that air from mixing with air from the rest of the planet.

            The demonization of chloro-fluorocarbons was essentially the work of DuPont. When the company’s Freon patents were about to expire, DuPont didn’t want to allow other companies to start manufacturing it, so in order to preveent such competition, the company worked with environmental groups to have Freon outlawed by treaty. DuPont then patented Freon substitutes. Clever, eh? The substitutes are not as good as Freon, but what the heck. Profit comes first.

          • John K says:

            So UV light generates ozone, that is true. UV light will also break ozone to generate oxygen radicals from ozone. This means that so long as you keep an ozone/oxygen balance, then the UV light will be absorbed.

            What you are kind of missing is the fact that this whole processes stops in the presence of a radical trap, like a halogen radical (chlorine, fluorine). Halogen radicals are produce when a CFC is hit with UV radiation. They are long lived radicals, unlike ozone, and stop the cycle of oxygen -> oxygen radicals -> ozone -> oxygen + oxygen radicals -> ozone (where each arrow involved the absorption of UV). Instead what you get is oxygen -> oxygen radicals -> ozone -> oxygen (there the last step is catalyzed by halogen radicals).

            If DuPont was really responsible for the phasing out of CFCs, why did they do everything possible to try and stop them from phasing out? They testified before congress… Killing your own product invites more competition to replace it, which causes you to lose market share and profit…? Even if their patent was going to run out, they had a monopoly on the market and other people breaking into it isn’t going to be easy.

            Look at Tylenol. They still have a huge hold on the acetaminophen market, even though the patent has expired. If they outlawed acetaminophen, that would allow other startups to enter the market with a new product. These new products could have been less effective analgesics, but are now marketable due to acetaminophen being illegal, which results in a net loss of market share for Tylenol.

            I thought conspiracy theorists were supposed to be conservative? I thought conservatives were good at business…? If you have a monopoly, the absolute last thing you want to do is introduce competition. Outlawing your own product does just that.

  3. Peter Capen says:

    It is unfortunate that Dan Rogers has apparently still not read the AMS statement, or if he has, he has clearly not understood what the scientists are saying. What he seems to be essentially arguing is that climate change is natural, that the current rapid warming of the planet is not caused by the burning of fossil fuels, and that there is nothing that humans can do to at least slow down the changes and stabilize the climate. That is nothing short of a recipe for disaster. Modern civilization has arisen precisely because the earth’s climate since the last ice age has been so stable. The longer we wait to seriously address the issue of global warming, the harder it will be to find viable solutions to the challenge it presents modern civilization, the fewer our viable options will be, and the more costly they will be for everyone. And for some, the costs of mitigation will simply be out of reach, which portends massive human suffering and growing ranks of environmental refugees. Continued denial of reality (and science) will not lessen the prolonged drought in the Southwest, the greater intensity of storms, the record melting of glaciers and sea ice, steady and accelerating sea level rise, which is on course to submerge may lowlying islands and coastal areas in the coming years, including in the U.S., and increasing acidification of the ocean, which threatens to destroy many of the world’s coral reefs by mid-century, as well as seriously disrupt the entire marine food chain. Neither denial nor prayer will solve the challenges of climate change that now confront us.

    • Hakon says:

      What “rapid warming” are you pretending to observe? What “stable climate” on which planet are you speaking of?

      What is the average temperature of this planet?

      Does the temperature remain constant on a daily, monthly, yearly, decadal, millennial average?

    • Hakon says:

      “Modern civilization has arisen precisely because the earth’s climate since the last ice age has been so stable.”

      A major issue with this statement arises when one pretends that we have had a stable climate since the last glaciation. If we had a stable climate since the last glaciation, there would still be glaciers over all of North America and Northern Europe. The fact that the climate indeed has not been stable at the peak of the last glaciation is why those glaciers are, for the most part, gone.

  4. Dan Rogers says:

    I have read the AMS statement and disagree with the conclusion that increasing CO2 in the atmosphere is causing increased global temperatures. I think it is much more likely that the cause and effect is the other way around. Increased global temperatures cause increased metabolism in the biosphere with increased CO2 as a byproduct.

    “Neither denial nor prayer will solve the challenges of climate change that now confront us.”

    I cannot say much for prayer, but vigorous demands for proof that humans are causing climate change — and that humans can stop it —can go a long way towards getting us moving in sensible, constructive ways to deal with that climate change challenge.

    For instance, the middle of North America is in desperate need of new sources of water. Meanwhile, as warming continues, there is more and more fresh water running off the north slopes into the Arctic Ocean causing the salinity of the water to decline and threatening the Atlantic Conveyor. We need to intercept a good portion of that runoff and move it south to where fresh water is needed. Is that possible? Of course it is, but it will never be done as long as our decision-makers continue to be assailed by “scientists” assuring them that global warming is something we can prevent or delay by closing down fossil fuel power plants.

    • Gws says:

      Dan: ever wondered why your clever explanation has not been explored before and found to be incorrect? It has …
      Is it so hard to believe that all these brilliant ideas people have to explain why CO2 is not a problem, something else is the culprit of warming, or (fill in favorite opinion here) … are not considered any more because they have long found to be inadequate to explain what is going on?
      Been there, done that. If there were indeed an alternative explanation for current rapid global warming, you can bet scientists would pursue it …

      • Dan Rogers says:

        My “explanation” of increasing CO2 in the atmosphere — increasing from one minuscule level to another, higher minuscule level — isn’t clever at all, and it isn’t really an explanation. I am not “explaining” that increased global temperatures cause increased CO2. I am only suggesting that it might true.

        The current warming trend is not particularly rapid compared to other warming periods our planet has been through in the past. When the “little ice age” went away back in the 1800′s, the changeover to warmer weather was quite abrupt and dramatic. The onset of the medieval warm period was also fairly rapid, although temperature records from that time period are not very extensive or reliable.

        GWS, I don’t imagine that you have ever done any research yourself into the physics of greenhouse gas warming of the atmosphere. I expect that you are just taking the word of Al Gore and others that the greenhouse gas effect plays a major role in the warming phenomenon, and that CO2 is the principal greenhouse gas in the atmosphere. You should be aware, however, (1) that warming of the atmosphere is not solely a phenomenon caused by the greenhouse gas effect; (2) that water vapor is a much more powerful greenhouse gas than CO2; and (3) that there is much, much more water vapor in the atmosphere than CO2.

        The existence of water vapor in the atmosphere simply gives Al Gore and his people the fantods.

        • Gws says:

          Actually Dan, I teach this stuff. Sad to say, your reply shows you have no point but seem to be troll.

          • Dan Rogers says:

            Since you “teach this stuff,” I suppose you feel I should just recant and retreat. That is a typical “appeal to authority” argument.

            I used to “teach this stuff” as well. Shall we compare institutions of learning?

            I am sorry that you fail to see my point, Gws, but I do indeed have one. My point is that carbon dioxide in the atmosphere exists there in too minute a quantity to have the outsized effect on atmospheric temperature that is claimed by Albert Gore and his disciples.

            Furthermore, I do not think that they are innocently mistaken about this. I think that Mr. Gore and many or most of his elite followers know very well that what they are preaching is false. They believe that the vast majority of people are simpletons who can be taken in by them, and that there is much to be gained by continuing on course with this deception.

            Do you get my point?

    • Charles says:

      “I think it is much more likely that the cause and effect is the other way around. Increased global temperatures cause increased metabolism in the biosphere with increased CO2 as a byproduct.”

      Okay, that is a testable hypothesis. Now, show us the evidence to support it.

      • Dan Rogers says:

        I can only cite common experience. We all know that:

        The trees moving do not make the wind blow.

        Cold weather is not caused by snow.

        Thunder is not the cause of lightning.

        Bears coming out of hibernation do not cause Spring.

        A thing that happens at or about the same time as another thing is not necessarily caused by, nor is it necessarily the cause of, the other thing.

        I have no real evidence that rising temperatures cause an increase of CO2 in the atmosphere. Conversely, I have seen no evidence that increasing levels of CO2 in the atmosphere comprise a primary cause of atmospheric warming. I do think, however, that the first scenario is more likely true than the second.

        If this question were to be presented in a court of law, Charles, who would have the burden of proof? Under our Anglo-American justice system, a party asserting that something has happened or is currently happening has the burden of proving that his assertion is in fact true. He will not prevail simply by saying to the court that his assertion has long been known to be true by many, many people and that “the debate is over.” Such an “appeal to authority” is a classic logical fallacy.

  5. Peter Capen says:

    Those who cannot see the future are condemned to live it.

    • Dan Rogers says:

      Does that mean that people who can see the future — visionaries — are NOT destined to live it?

      Like Steven Wright, I am a peripheral visionary. I can tell what’s going to happen, but only things that are going to happen off to the side.

      • LP says:

        Who are you? Why do we care what you “think?” Why are you dominating this board with your scathing lack of knowledge?

  6. Nullius in Verba says:

    Could somebody find out for me – journalists reporting this story presumably have the relevant contacts? – exactly what percentage of the AMS membership voted in favour of this statement. Thanks.

    Given how these things usually work, I suspect the answer is ’0%’. But I’d be interested to see if a definitive answer can be produced.

  7. Nullius in Verba says:

    Some people have asked concerning the state of the science on this question of “observed” and “unequivocal” warming of the climate system going “beyond what can be explained by natural variability of the climate.” Here’s what the IPCC has to say on the question:

    “Detection does not imply attribution of the detected change to the assumed cause. ‘Attribution’ of causes of climate change is the process of establishing the most likely causes for the detected change with some defined level of confidence (see Glossary). As noted in the SAR (IPCC, 1996) and the TAR (IPCC, 2001), unequivocal attribution would require controlled experimentation with the climate system. Since that is not possible, in practice attribution of anthropogenic climate change is understood to mean demonstration that a detected change is ‘consistent with the estimated responses to the given combination of anthropogenic and natural forcing’ and ‘not consistent with alternative, physically plausible explanations of recent climate change that exclude important elements of the given combination of forcings’ (IPCC, 2001).”

    “Detection of anthropogenic influence is not yet possible for all climate variables for a variety of reasons.”

    “The approaches used in detection and attribution research described above cannot fully account for all uncertainties, and thus ultimately expert judgement is required to give a calibrated assessment of whether a specific cause is responsible for a given climate change.”

    From AR4 WGI Ch9.

    So, the truth is that unequivocal attribution is not possible, and so the definition is changed to mean ‘consistent with’ current models, and not consistent with current models of plausible alternatives. This is a very different proposition.

    Existing work cannot fully quantify the errors and uncertainties, and thus cannot demonstrate causation in a rigorous scientific sense. Therefore, the opinions of experts have been substituted, their numbers and consistency weighed, and this is the ultimate basis of the IPCC’s attribution statement – that at least 50% of the 0.6 C post-1950 warming is anthropogenic with more than 90% confidence, given the current understanding of the climate system.

    That’s what climate science says.

  8. Steve Reed says:

    I can think of 3 possibilities why the AMA statement has potential value:

    1. it leads to greater meterological coverage in mass media to influence public attitudes
    2. it’s propagandistic value
    3. it’s encouragement of further outreach efforts

    It is not clear that the AMS statement will result in 1. Have to watch that metric.

  9. Dan Rogers says:

    Computer models of the Earth’s climate are based upon the assumption that there are relatively few greenhouse gases in the atmosphere, the most important ones being carbon dioxide and methane. Water vapor is ignored entirely, based upon the assumptions that water vapor’s greenhouse gas warming effects are difficult or impossible to quantify and that it is likely that its effects are cancelled out by countervailing cooling effects attributable to water evaporation and cloud cover reflectivity. No one can say with any certainty that these two assumptions are true. The models are, for that reason, unreliable.

    • Dags says:

      @Dan, that is simply not true. Even the IPCC AR4 says, “Water vapour is the most important greenhouse gas in the atmosphere.” To say that, “increased global temperatures cause increased CO2″ in no way negates the fact that increased CO2 causes increased global temperatures. They both can be true, and most likely are to some extent. As to the (very important) relationship between CO2 and water vapor generally, Googling ‘water vapor feedback’ provides a multitude of responses to that tired old question.