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Global Climate Change and Scientific Proof

  1. Andrew Mason

    Andrew Mason 6,850
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    The global warming skeptics advance arguments against the conclusions of the IPCC. They argue that anthropogenic global warming has not been "proven".

    But there is no such thing as scientific proof. There are merely falsifiable theories. The 'proof' of a positive theory is simply the result of disproving all alternative theories.

    We observe that the earth is getting warmer (there may be some controversy over correctness of methods to determine that, but even the skeptics seem to agree with that observation). Scientist offer plausible explanations. Some suggest it is caused by non-anthropogenic factors such as natural solar cycle increasing solar radiation, volcanos belching green-house gases, the tilt of the earth's axis, reduced cloud cover due to natural factors. Some suggest it is caused by green-house gases resulting from burning of fossil fuels and the loss of forests and other CO2 sinks due to human activity.

    One by one, scientists uncover evidence that falsifies the proposed explanations. They succeed in falsifying all theories but one: the increase in greenhouse gases, principally CO2, due to human activity.

    Now, maybe the conclusion is wrong because there is some other, as yet unproposed theory, to explain the increase in global temperature. That is always a possibility in ANY scientific theory and that is why science can never prove anything. But until someone proposes another theory, or is able to show that the evidence which destroys an alternative theory is wrong, we are left with the anthropogenic model. And that is as close to 'proof' as anyone can get.

  2. jcsd
    Earth sciences news on Phys.org
  3. Bystander

    Bystander 3,441
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    The temperature field has a range of 120-125K; the daily variation at a single point is 15-20K (might reach 40-50K in desert areas); annual variation at a point is 60-70K in temperate zones, less at equator and poles (70-80K in a few extreme locations); the meteorological record is comprised of observations made with a half dozen or more different instrument types and methods over the past hundred years, "nominal" specification of uncertainties for the instruments is plus or minus 1K, global means are calculated from station medians, and the locations of the observation network have been constantly changing over the past century.

    "We" observe that a lot of data has been collected using methods that "we" would have been flunked out of freshman chemistry, physics, and even biology labs for using.
  4. Ivan Seeking

    Ivan Seeking 12,521
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    I think he meant the consensus among real climate scientists who feel that the data is reliable.
  5. "We" note that glaciers that are known to have existed for millennia in a stable form are now melting. "We" note that the Inuit are giving up hunting traditions that have been developed over countless generations, because sea ice is no longer as stable as necessary to sustain the methods used.

    The greenhouse effect is a theory. Global warming is an observation.
  6. I agree that climate change is not a theory: is an observation, a fact.
    And, honestly, my opinion is that we, our activities , are the cause.
    But take care: when you talk about glaciers that have been there for millenia you are completely wrong. Last summer, I've been on a retreating glacier in the Alps (terminal morraine retreating not less than 500m in last years at 2000m) that uncovered big trees (what remain of them). OK, not giant red firs, but having a diameter not less than 40cm. And at that altitude there are no trees at all nowdays.
    So search a little bit on Little Ice Age and you will discover that climate is not as stable as we think. And, of course, this should not be interpreted as we can do anything, but the opposite: how fragile the climate is, what a risk for our global economy just to play with greenhouse gasses.
  7. Andrew Mason

    Andrew Mason 6,850
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    You make a good point. All the other factors that could drive climate change seem to be in favour of cooling: solar activity has been declining since the mid-80's; the angle of the earth's axis to the sun is decreasing so the poles should be getting colder; volcanic activity (which contributes on average 200 megatonnes of CO2 per year) has been declining, sulphate concentrations have been declining;. One the other hand ghg concentrations are increasing as emissions are up and carbon sinks are declining.

  8. In fact, I've read about a theory that states exactly this: without human activities, the earth would still be in the middle of an ice age. It is just a theory, but as most theories, it is based on some observations like those you point.
  9. Global climate change is a scientific theory. A scientific theory is a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses.


    Scientific Theory =/= 'Theory' in everyday usage.

    Even though global climate change due to human activity is factual, it is not a fact. It is a theoretical construction to explain the observed facts (or data points).

    The facts that have been observed supports this theory. I agree that there are no such thing as 'proof' in science, only evidence.
  10. In my opinion, climate change is a fact. Then, there are theories to explain why climate is changing. And, it might be that we should rethink the whole thing to discover that climate is not changing now, it has been changing forever.
  11. Global temperature is mathematically impossible.

    Averages are rarely of any value in real science. Scientists prefer to examine the range of data or whether the distribution of data resembles something like a bell curve.

    Averages can hide what is happening. For example, temperature changes with significant environmental impact could occur with no impact on the average temperature. Higher temperatures in summer and lower temperatures in winter would adversely affect plant life, but would not change the average temperature. An increase in temperature in one part of the globe and a decrease elsewhere could impact climate without affecting the average temperature.
  12. Andrew Mason

    Andrew Mason 6,850
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    If I take a volume of air in a column 30 m. high, say, above a m^2 of earth and measure its temperature at various points, there will be a slight temperature variation but essentially it will have the same temperature throughout. If I do that at every point on the earth and average those temperatures, I will get an average temperature of the earth's lower atmosphere. Assuming that the heat capacity of air is the same throughout the range of temperatures that exist on the earth (this is not exactly correct, largely because water vapour does not fit the ideal gas approximation), then the average of those temperatures can be reasonably considered as the average temperature of the earth's low atmosphere.

    Now if I take the temperature of each column of air each hour of each day for a year and average them, I can determine the average temperature for the year for each column. If I average that for all columns, I can determine the average temperature of the earth's low atmosphere for a year. If I compare that over many years, one may see trends.

    The concentration of ghgs is virtually uniform at all points in the atmosphere. So whatever the effect of ghgs is, it should be the same at all points on the earth. If its effect is to trap heat, this will have the effect of increasing the long-term yearly average temperature of the earth's low atmosphere. That is a very meaningful, and useful, thing to know.

  13. Insurance companies are already considering how to respond to global warming, but many politicians don't like to associate with global warming because the leftist are using the issue to justify industry regulation.
  14. Of course that's a serious political issue. The political right doesn't want to see regulation. But covering your ears and saying "Is not, is not, I can't hear you!!"' isn't a very bright response.
    Personally, I don't see any alternative to regulation, because I can't see how business can choose to produce less, or how consumers can choose to consume less, or how a corporation can choose to spend millions on mitigation when their competitors don't. I just don't see how that would happen. If the political right doesn't think the situation warrants regulation, they need to show us an alternative.
  15. The numbers tell nothing about what actual conditions worldwide because the set of possibilities the average temperature represents is too large. Consider the following for example,

    Let's examine what an increase in average temperature might mean. Clmatologists who claim they can predict the future seem to believe that any global temperature change would be the same throughout the globe with high and low temperatures both going up.

    That is only one possiblity and the least probable. Other possibilities include:

    High (daily) temperatures increase, but low tempertures remain unchanged.

    Low temperatures increase, but low temperatures remain unchanged
    High temperatures increase by more than low temperatures decrease - in other words temperatures would move toward both extremes.

    Low temperatures increase by more than high temperatures decrease - that is temperatures become more moderate

    Temperatures increase uniformly during the year.

    Temperatures increase during one season with temperaturres in other seasons remaining unchanged.

    Summer temperatures increase by more than winter temperatures decrease - the seasons become more extreme.

    Winter temperatures increase by more than summer temperatures decrease - the seasons become less extreme.

    Temperatures during spring or fall might also increase with seasons during other seasons falling by a lower amount.

    Temperatures could increase uniformly throughout the world.

    Temperatures in some areas could increase with temperatures in other areas remaining unchanged.

    Temperatures in some area could increase by more than temperatures in other areas decrease.

    These are just the simple possibilities. Some areas might experience warming in one season with other areas experiencing cooling in other seasons. Temperatures in some areas might increase during the day with temperatures in other areas increasing at night.

    Temperatures near ground level may even be increasing because heated air is not able to rise as far in the atmosphere. Last year was one of the coldest years on record for the stratosphere.
  16. First a couple of questions.

    1) What do you mean by "predict the future" and
    2) What climatologists do you know of who "seem to believe that any global temperature change would be the same throughout the globe with high and low temperatures both going up"?

    BTW the cooling of the stratosphere is in line with expectations. I don't know what you think would prevent hot air from rising, or why you think no one would have noticed by now.

    In general, your post reads as though you've been trying to figure things out without bothering to learn about it first.
  17. Nature's past experiment


    An experiment of nature on the effect of intense global warming has already occurred in the Eocene 38-55 million yrs. ago; the so-called Paleocene-Eocene Thermal Maximum (PETM).(1,4) There were no massive extinctions comparative to that of the Cretaceous-Tertiary (K-T) period defining the Mezozoic/Cenazocic eras at 65Myrs. At the Paleocene-Eocene divide, paleo-stratigraphic results show that there was deep water benthic foraminifera mass extinction associated with the increased temperature and hence dysoxic (less oxygenated) waters.(1) But most marine and terrestrial extinctions occurred with cooling at the end of the Eocene, and into the Oligocene epoch.(1) The conseqences of the present warming are unknown in regards to extinctions. However nature already has conducted one experiment in regards to intense global warming, with seemingly not overwhelming catastrophic results.
    An alternative question for the future and for our cognition/imagination might be as follows: From current habit destruction and hence species extinction, for say 100k years duration; would this be significant enough to leave a paleo-stratigraphic signature say 3 million years hence? The PETM might be considered herein as maximizing for over approximately 3 Myrs. So for shallow geological time, might the current extinction times we are inducing be more likely to leave a signature (if any?) due more to habit destruction (and ocean degrading environment?) than to any long term geological stratigraphic consequences from global warming?

    1. Hallam Tony, Catastrophes and Lesser Calamities Oxford Univ Press, 2004, and references therein.

    Other sources consulted.

    2. Raup David M., Extinction: Bad Genes or bad Luck?, W.W. Norton, 1991, and references therein.

    3. Stanley Steven M., Extinction, Scientific American Books, 1987, and references therein.

    4.Paleocene-Eocene Thermal Maximum. Wikipedia.

    some look at things and ask why,
    while others dream of things that never were,
    and ask why not.
    George Barnard Shaw
  18. You apparently aren't paying attention to the Rev. Gore of the Church of Global Warming. HIs followers regularly forecast disastrous weather that will result from "global warming". You know more and more hurricanes each year except of course for the last two years.



    The second study is particularly absurd because temperatures would still range from below freezing in winter and above 100 F in summer with normal transitions in spring and fall. Severe storms might occur earlier in spring with warmer temperatures, but the temperatures wouldn't be different from now.

    Note on the temperature change I used the word "seem". I'm not really sure what some of them believe by "global warming", particularly considering the above study. There is too much vagueness to what they are talking about.

    Climate change could occur without any "global" warming. The use of global averages could mask evidence of regional change if regions had cooler temperatures.

    Something interesting happened after 9/11. High flying jets were grounded over the U.S. for a time which allowed scientists to examine the potential impact of jet contrails on air temperature. They found that the difference between high and low temperatures increased with higher day time temperatures (possibly because contrails reflect some sunlight) and lower night time temperatures because the contrails didn't block warmed air from rising into the stratosphere.

    Last edited: Oct 19, 2007
  19. Greg Bernhardt

    Staff: Admin

    Closing this necro'd thread
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