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Causes of global warming

  1. Nov 16, 2016 #1

    hagar

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    I would imagine that most here believe in global warming. My question is what effect does the sun have on global warming because the heat increases as it's fuel is consumed.
     
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  3. Nov 17, 2016 #2

    Simon Bridge

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    A typical answer would look like this:
    "...the Sun's output changes so slowly and solar variability is so slight (less than 0.00425% of the total energy per year on time scales of days), that continuous monitoring by state-of-the-art instrumentation is necessary to detect changes with climate significance. Scientists theorize that as much as 25% of the 20th century anticipated global warming of the Earth may be due to changes in the Sun's energy output. Systematic changes in irradiance as little as 0.25% per century can cause the complete range of climate variations that have occurred in the past, ranging from ice ages to global tropical conditions. For example, scientists believe the "Little Ice Age" that occurred in Europe in the late 17th century could have been related to the minimum in sunspot activity (and a correlated minimum in total solar irradiance) that occurred during the same period."
    NASA Cosmicopia citing ACRIMSAT website (2000)​
    Note that this is not due to "heat increases as its fuel is consumed" - the output of the Sun varies anyway.

    Have you seen:
    https://xkcd.com/1732/
     
    Last edited: Nov 17, 2016
  4. Nov 17, 2016 #3

    hagar

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    I thank you for the quick response. You show what I expected to see. It was something that I thought of to farther the discussion on this subject.
     
  5. Nov 30, 2016 #4
    Temperatures and Solar Cycles follow each other very closely. More importantly you will see that it is not exact. You will have times of higher sunspots and lower temperatures and you will also have the opposite. Why is this so important? Because weather is not based on one element. You could double the sunspots but if one major volcano erupted it would counter every sunspot for years. You could increase sunspots, co2, and have no volcanoes erupting but if the earth's orbit around the sun is at a further distance it could cancel out everything else.
     
  6. Nov 30, 2016 #5
    Ha ha that's excellent! Thanks Simon!
     
  7. Nov 30, 2016 #6

    1oldman2

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    Very nice, I assume from the chart that Randall is a fan of Ten years after.
     
  8. Nov 30, 2016 #7
    I had intended to stay away from this thread, but there are a couple things that I think should be addressed. One is that scientists "believe" in global warming. I've been involved in the larger aspect of that--global environmental change, of which global warming is an aspect-- for pretty much all of my years in science. Because of the way I was educated, I came to "accept" things in science, so long as they worked and set them aside when they didn't. I don't know of any scientists in the Global Environmental Focus Group of the American Geophysical Union who uses "believe" as part of the language of science, even if we might know what that person actually meant. It's hard enough to relate to the public on science issues without interjecting what they might see as a misguided belief. This is particularly true with climate science/global warming/global environmental change. On a broader platform, I suggest reading this piece by Helen Quinn, that appeared in Physics Today:
    https://ned.ipac.caltech.edu/level5/March07/Quinn/Quinn.html
    Belief and knowledge - a plea about language

    That being said, there are some interesting developments regarding the Little Ice Age and the Maunder Minimum and a controversy that developed about relating a possible coming ice age and a Maunder Minimum.
    http://onlinelibrary.wiley.com/doi/10.1029/2011GL050168/full

    Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks
    "Here we present precisely dated records of ice-cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430–1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium...Our results suggest that the onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea-ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required."

    http://www.livescience.com/51597-maunder-minimum-mini-ice-age.html
    Is a Mini Ice Age Coming? 'Maunder Minimum' Spurs Controversy
    "At the National Astronomy meeting in Llanduno, north Wales last week, Zharkova said that a series of solar phenomena will lead to a "Maunder Minimum," which refers to the seven decades, from 1645 to 1715." [That meeting was in July. 2015]

    http://phys.org/news/2015-07-mini-ice-age-hoopla-giant.html
    The 'mini ice age' hoopla is a giant failure of science communication
    We followed the story from the beginning--from her original talk to subsequent spinning by Zharkova--and saw that there was a rising "belief" in the popular press that sun activity and a cooling or possible ice age was looming. No one ever mentioned that in 1610, Momotomba in Nicaragua erupted and its cooling effects on the Northern hemisphere, well before the solar influences.
    This is not to say that solar activity is not significant, just that cooling was already happening.









     
  9. Nov 30, 2016 #8

    1oldman2

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  10. Nov 30, 2016 #9

    hagar

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    Last edited by a moderator: May 8, 2017
  11. Dec 1, 2016 #10

    Simon Bridge

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    My 2c.
    Language stuff keeps coming up...
    There is a language issue with different uses for words commonly getting mixed up - just look at the meaning of "force" and "work" in common vs scientific use. Similarly - I've seen chemists get annoyed at ads for "organic salt" (but but salt is a mineral... splutter). I'm more sanguine about that - there will always be this issue with language.

    I think the word (believe) is useful in a scientific context... that may change: a belief is a form of conviction.
    In general - we are convinced of things according to the evidence. When we say we believe things, in the scientific sense, we are convinced of their truth.
    The strength of the conviction should be in proportion to the number and cleverness of the attempts to undermine that conviction. The truth in question has the unspoken qualification "to the extent that it has been demonstrated".
    Knowledge is a subset of belief. We can only know things in the sense that we are very very confident that they are true... so confident that it would be World-shattering to discover they are not.

    Example:
    I know the World is not an exact sphere ... I would not be surprised to find that the coefficient of the some-teenth spherical harmonic in some model of the earth needed to be tweaked but it would be world shattering to discover that the Earth was, in fact, a cube. In that sense I know the Earth is ball-shaped, and I believe that is the simplest shape that accounts for the observed facts.

    I still cannot absolutely rule out that the ball shape so far observed is some kind of elaborate illusion... but that is not my job. It is up to the people who want to propose some other shape to demonstrate that.

    However - this is not how the words are commonly used.
    We do need to bear that in mind as we take part in science communication... but bear in mind also that there are vested interests in making non-science sound like science: whatever language we choose will end up used also by those people (advertisers, charlatans, etc.). The trick is the way you use the words, not the words themselves - and always have the explaination ready.

    Also need to take care not to lapse into philosophy... just my take.
     
  12. Dec 2, 2016 #11
    I think this video by Dr. Powell explains global warming very well. Beginning around 3:00 he answers the question does an increase in the sun's output cause global warming.

     
    Last edited: Dec 2, 2016
  13. Dec 3, 2016 #12

    rbelli1

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    I agree completely.

    Belief for many people is acceptance of statements as fact based on absolutely no objective evidence. That is a good reason for simply not using that word in a scientific context. There are plenty of words and phrases that can be used as an alternative.

    Now theory has a problem. For many it means "Some s**t i just made up!" We should probably come up with an alternate word to use in a scientific context for theory as well.

    BoB
     
  14. Dec 6, 2016 #13

    Simon Bridge

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    ... for example?
    Give us the best one you got.
     
  15. Dec 6, 2016 #14
    With regard to the use of "belief" in language with the public, its worse case scenario popped up at Thanksgiving Day dinner. I have been avoiding contact with a couple who are both rabid believers that climate change is a hoax. The dinner was uneventful, but we retired to the den and the "discussion" began. As it turns out even "accept" is a dangerous word to use in an unscientific public. "So, you accept climate change? Like we accept Jesus into our hearts?......." The conversation ended up with, from their perspective, as my acceptance being a manifestation of scientism and thereby holding, albeit misguided, a Belief equal to theirs.

    I still stand by my notion that the words we use do matter. There is a flexibility in usage in the scientific community that is often lacking in other venues. Elsewhere, there is far too often a rigidity that makes communication tedious. Whereas we don't have to carry the weight of what we mean by a word or expression and qualify that meaning every time, it doesn't work that easily in public. It may be hard to choose the best words before writing or speaking, but better in the long run.
     
    Last edited by a moderator: Dec 8, 2016
  16. Dec 6, 2016 #15

    DrClaude

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    When the public misunderstands/misuses even the word "theory", there is no point in being so careful with language. Any choice of word will be used by ideologues for their own purpose.
     
  17. Dec 6, 2016 #16
    How about "I have been convinced by the evidence that XXX."

    Cumbersome, yes...
     
  18. Dec 6, 2016 #17

    phinds

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    And it appears to me that you are misunderstanding what happened in the thread and focusing on a specific word. Basically, the OP in that thread was asking for support against non-scientific arguments. That's not the purpose of PF, as you should have noted in the rules when you joined. We are not here to debunk nonsense.
     
  19. Dec 6, 2016 #18

    Drakkith

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    Thread locked for moderation.
     
  20. Dec 8, 2016 #19

    DrClaude

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    This thread has veered off far away from the causes of global warming and will remain closed.
     
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