Please turn on javascript in your browser to play chess.
Science Forum

Science Forum

  1. 20 Jul '15 12:01
    I am skeptical about this claim, but even if it is true it only means that "significant" climate change has always been the case. Then again, people probably have very different ideas of what significant is, so polling climate scientists using the word "significant" instead of "primary cause" is stupid and/or deliberately misleading..

    http://www.livescience.com/6675-humans-altered-climate-10-000-years-study-claims.html
  2. 20 Jul '15 13:31
    Certainly in Africa humans have had a significant impact on vegetation and soil carbon content. In Zambia there is a strong tradition of burning the grass each year (for various reasons, including mistaken ones) which results in a lot of carbon loss to the atmosphere. This probably exceeds the carbon produced from burning fossil fuels in that country. In addition, the loss of wildlife also results in poorer soils and loss of soil carbon.

    Europe and the US have seen much more significant changes in vegetation cover, and the use of groundwater to support crop production has a significant impact on local climate.
  3. 20 Jul '15 14:00
    Originally posted by twhitehead
    Certainly in Africa humans have had a significant impact on vegetation and soil carbon content. In Zambia there is a strong tradition of burning the grass each year (for various reasons, including mistaken ones) which results in a lot of carbon loss to the atmosphere. This probably exceeds the carbon produced from burning fossil fuels in that country. In ...[text shortened]... and the use of groundwater to support crop production has a significant impact on local climate.
    But did it cause "significant" climate change?
  4. Standard member sonhouse
    Fast and Curious
    20 Jul '15 15:37 / 1 edit
    Originally posted by Metal Brain
    But did it cause "significant" climate change?
    If you look at the total land area of Earth, Africa is only a small part, consider Eurasia, Australia, N/S America, there was no mass burning in those places so the percentage would have been less than 20% of the total so I would say not a whole lot of impact, compared to modern times. Also, the amount of fuel in grass would have been less than forests, they burn out quickly and go on to the next acre and so forth.
  5. 20 Jul '15 15:56
    Originally posted by sonhouse
    If you look at the total land area of Earth, Africa is only a small part, consider Eurasia, Australia, N/S America, there was no mass burning in those places so the percentage would have been less than 20% of the total so I would say not a whole lot of impact, compared to modern times. Also, the amount of fuel in grass would have been less than forests, they burn out quickly and go on to the next acre and so forth.
    No argument there.

    How would you define significant?
  6. 20 Jul '15 16:32
    In science there are typically two uses of the word significant.

    "Statistically significant" meaning that the effect or observation is large enough to be
    detectable above random background noise with a good enough level of confidence.

    And in the more common use meaning of having a noticeable impact.

    Both [or neither] may be applicable depending on context.
  7. 20 Jul '15 16:42 / 10 edits
    Originally posted by Metal Brain
    No argument there.

    How would you define significant?
    You keep asking flawed questions like that.
    In any natural language, words like "significant", "large", "small", "trivial", "tall", "better", "noticeable" etc have no absolute meaning but rather their meaning, whether unambiguous or not, of each one of those words varies with (within implicit constraints ) and is therefore dependent on the context they were said in.

    Therefore, your question "How would you define significant?" has no answer until if or when either the exact context is obvious or you fully define (preferably unambiguously ) the exact context the word was used in.

    Since the word "significant" has been used several times here in different sentences and in slightly different contexts, its meaning could have varied (and I would guess has ). So you will need to specify exactly which sentence it was used in (and also where this sentence is if that is not immediate obvious ) and only ask what that word means in that particular sentence in its context before you have any hope of getting a valid answer else you are asking an unanswerable question.
  8. 20 Jul '15 16:45
    Originally posted by googlefudge
    In science there are typically two uses of the word significant.

    "Statistically significant" meaning that the effect or observation is large enough to be
    detectable above random background noise with a good enough level of confidence.

    And in the more common use meaning of having a noticeable impact.

    Both [or neither] may be applicable depending on context.
    So now it is "noticeable"? If significant equates to noticeable then neither is necessarily a primary cause, right?
  9. 20 Jul '15 17:54
    Originally posted by Metal Brain
    But did it cause "significant" climate change?
    I don't know. I have seen claims that improving soils by increasing soil carbon could completely eliminate the excess CO2 in the atmosphere. Certainly carbon loss from poor soil management is a significant contributor to atmospheric CO2 and often overlooked in climate discussions.
  10. 20 Jul '15 18:35
    Originally posted by twhitehead
    I don't know. I have seen claims that improving soils by increasing soil carbon could completely eliminate the excess CO2 in the atmosphere. Certainly carbon loss from poor soil management is a significant contributor to atmospheric CO2 and often overlooked in climate discussions.
    How would you define "significant"?
  11. Standard member sonhouse
    Fast and Curious
    20 Jul '15 18:40
    Originally posted by Metal Brain
    How would you define "significant"?
    I would define 'significant' in those terms compared to modern times.
    So some bush people burning a few thousand acres would not be significant to me.

    Even burning a million acres wouldn't mean much on that scale. I'm sure there were major forest fires in the America's 20,000 years ago when there were no humans here so a few million acres of grass burning would not come close to these forest fires that have hundreds of times the fuel per acre.
  12. 20 Jul '15 21:11
    Originally posted by Metal Brain
    How would you define "significant"?
    One report I saw said 9% of CO2 comes from change in land use. I have seen other figures in the past. 'Too large to be ignored' might be another way to say it.
  13. 21 Jul '15 00:27
    Originally posted by twhitehead
    One report I saw said 9% of CO2 comes from change in land use. I have seen other figures in the past. 'Too large to be ignored' might be another way to say it.
    Too large to be ignored could still be not the primary cause. Is that why the only polls asking about anthropogenic warming never say "primary cause"?
  14. Standard member sonhouse
    Fast and Curious
    26 Jul '15 16:26
    Originally posted by Metal Brain
    Too large to be ignored could still be not the primary cause. Is that why the only polls asking about anthropogenic warming never say "primary cause"?
    So, ignoring man made changes, what is causing the increase in CO2 or do you not believe CO2 levels have risen?
  15. 26 Jul '15 17:49
    Originally posted by sonhouse
    So, ignoring man made changes, what is causing the increase in CO2 or do you not believe CO2 levels have risen?
    CO2 levels have risen and the earth is still at a very stable temperature. Vostok ice core samples prove CO2 is not the cause of warming in the historic record, it is the effect of warming. This is a fact, NOT a theory! High CO2 levels do not result in high warming. No cause, no predictable effect. Every time I tell you this you ignore it as if it is not fact, IT IS! You still have your cause and effect backwards! Get you fargin shiit together!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    STOP BELIEVING MYTHS PROMOTED BY PEOPLE LIKE AL GORE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!