whitebark pine going down

Discussion in 'Earth Science' started by iceaura, Jul 21, 2011.

  1. Trippy ALEA IACTA EST Staff Member

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    I apologize in advance for the mess, however:

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    The shallow blue solid line represents the first scenario - based on the error bars.

    The steep blue line that looks solid at the start, and becomes broken further along its length is the second scenario I mentioned.

    The numbers match what you've cited closely because its very close to a least squares fit for the data for the last decade. A good least squares fit would probably be a little shallower, and .05-0.1 degree lower at its starting point.

    The blue dotted line (as I have already indicated) is the scenario that I was describing.

    The yellow lines are just me getting a feel for how much cooling that would represent.
     
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  3. adoucette Caca Occurs Valued Senior Member

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    I think we agree on this and it's also why I deal in a minimum of a decade when looking at the climate, and preferably longer.
    In this particular case I've only used this last decade of data to show that the current evidence doesn't support the claim that warming is accelerating.
    I think one of the misconceptions is that people are assuming more than I've asserted.
    I'm not using this short period of data to claim that climate change has stopped or that the trend is likely to continue or that it is now cooling etc.
    The ONLY assertion I've made is that the trend in the Global Temperature record over the last decade has been flat and thus the global temperature data doesn't support the claim that climate change is accelerating

    See what I mean?

    That is not my position at all. Indeed I started out by saying that the last decade remained abnormally warm. That sustained level of warmth alone would continue to cause the Climate to change over time.
    My point was quite a bit narrower than that (see above).

    Well I think my views coincide with the views of the IPCC.

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    As every cause of Climate Change is viewed as a level of Forcing and stated in relation to it's heating/cooling effect on the climate.

    Clearly they believe it is these forcings that are driving Climate Change and they use the modeled future Global Surface temperature as the direct measure of the rate of change. Indeed, their forecasts outputs are presented in two key metrics: Rise of Surface Temperature over the next century and rise in sea level over the next century (with the rise in sea level directly attributed to the rise surface temperature and ocean heat content)

    It has never been called the International Panel on Global Warming.
    And true, while temperature is just one facet of climate, according to the IPCC it is what is driving Climate Change.

    There are no new heat sinks or significant changes in the existing ones and by far the largest one that does exist does not show any signs of acceleration.

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    Indeed, two recent reports based on tidal guages (US and Australia) suggest a slight deceleration in the rate of rise (with the peak rate in the 90s, which coincides with the recent peak rate of warming in the last century).

    http://www.jcronline.org/doi/full/10.2112/JCOASTRES-D-10-00141.1

    Arthur
     
    Last edited: Aug 5, 2011
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  5. Trippy ALEA IACTA EST Staff Member

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    And my point is that the data do not neccessarily exclude/preclude the possibility. And that the current trends would have to continue for some time before they could be considered significant, or even slowing down. I have tried to illustrate this by demonstrating how far above the lower boundaries defined by the predictions we are (you'll note, of course, that I've only assumed a linear rate.

    W = J/s
    The chart shows the amount of additional long wave energy absorbed by the atmosphere, from that we compute a number for warming, assuming that a proportion of that energy is retained as thermal energy, however there are other heat sinks available.

    Well then, it seems I may be in disagreement with the IPCC on something then, because I view warming as a symptom, rather than a cause. I think I have already explained it, but the way I see things is this:
    CO[sub]2[/sub] absorbs long wave IR energy.
    This energy is stored in the atmosphere as heat energy.
    That heat energy is available to do work (through things like melting ice-caps).
    QED a period of time where there is no growth in the temperature anomaly curve could reflect a genuine period of cooling, or it could be that some process has kicked in that is taking additional thermal energy out of the atmosphere at a rate equal to, or greter than it is being put in. You seem to be asserting the first, I'm merely pointing out the possibility of the second.

    Meanwhile, the rate at which the greenland icesheet has been melting at above average rates since the '90s, and the rate at which it has been doing so has been generally increasing.
    http://www.sciencedaily.com/releases/2011/01/110121144011.htm
    I'd need to take a closer look at the arctic dataset before I commented on it, and yes, I know you posted a graph, however it lacked the data that I am interested in.
     
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  7. iceaura Valued Senior Member

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    No. The heat trapping by CO2 is the claimed driver. Temperature rise is an effect - which of course has effects of its own.
     
  8. adoucette Caca Occurs Valued Senior Member

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    Gee and I wonder how we measure this trapped heat?

    Oh, right that would be by a rise in temperature.
     
  9. iceaura Valued Senior Member

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    Not necessarily. Quantity of melted ice would do. Increased water vapor pressure. Faster winds and ocean currents (or slower). and so forth

    A deep ocean layer a small fraction of a degree warmer would replace many degrees of air temperature, in estimations of trapped heat - and climate change.

    And of course you have to compare apples to apples - the atmosphere temps should be compared with those in the same phases of the ongoing natural cycles (ENSO, etc). They could fall for ten years, and still be registering a rapidly warming planet.

    That's why indications of change in naturally cumulative effects - such as the ranges of insects, the volume of the Arctic ice pack and Greenland ice cover, the extent and volume of glaciers, etc, - are significant.

    Climate change is a delayed effect of heat trapping. It hits us years down the road.
     
    Last edited: Aug 5, 2011
  10. adoucette Caca Occurs Valued Senior Member

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    The global surface temperature includes the sea surface temperature and as shown that is not accelerataing.

    The amount of melting and the growth in ocean heat content can be measured indirectly by tracking sea level, which as pointed out previously, the rise in sea level is not accelerating.

    http://www.jcronline.org/doi/full/10.2112/JCOASTRES-D-10-00141.1

    You still have not provided any examples of Acceleration in the rate of climate change.

    Arthur
     
    Last edited: Aug 8, 2011
  11. iceaura Valued Senior Member

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    And as noted that is not the only symptom or effect of CO2 heat trapping, or the only measure of climate change.
    Better to measure directly (at least in part) by measuring ice pack and glacier volume, which shows accelerating change - such as the Arctic ice pack hitting a second record low less than ten years from the more than century mark of 2007, progress which would graph on semilog paper as a straight (regression) line with downward slope over the past 100 years.
     
    Last edited: Aug 8, 2011
  12. Trippy ALEA IACTA EST Staff Member

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    Not neccessarily - an ice shelf, or an ice pack does not raise the sea level when it melts, any more than an ice cube melting in a glass of water does.
     
  13. adoucette Caca Occurs Valued Senior Member

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    Agree, that ONE form of ice does not influence the sea level, but that does not invalidate the statement I made either.
     
  14. adoucette Caca Occurs Valued Senior Member

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    We don't have long enough Arctic Ice records to claim any such 100 year records. We have no comparable ice records that go back before 1979.

    However it doesn't matter.
    Ice volume is simply an indirect measurement of global temperature and global temperature it is not accelerating.

    But since Ice has a very specific melting point > 0C, the point at which it exists or doesn't exist. The amount of ice is primarily a geographical issue and NOT a valid way of determining that the rate of global warming is accelerating.

    Arthur
     
    Last edited: Aug 8, 2011
  15. Trippy ALEA IACTA EST Staff Member

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    I would argue that that's not neccessarily the case - my recollection is that the majority of the sea level rise is due to the thermal expansion of the oceans rather than neccessarily melting ice caps tp begin with, but at the same time (for example) the arctic ice sheet is poised at the interface between the ocean and the atmosphere, and its melting should be expected to draw thermal energy from both (because melting ice is endothermic).

    Seemingly supporting this possibility is the fact that of the decade in question, the year with the lowest temperature anomaly (2007 - I think) was also the year with the highest loss of arctic sea ice.
     
  16. Trippy ALEA IACTA EST Staff Member

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  17. adoucette Caca Occurs Valued Senior Member

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    No, that would be 2008.

    2005 0.474
    2006 0.427
    2007 0.402
    2008 0.312
    2009 0.439

    The IPCC AR4 WG1 said: Mass loss of glaciers and ice caps is estimated to be 0.77 ± 0.22 mm yr–1 between 1991 and 2004.

    Arthur
     
  18. adoucette Caca Occurs Valued Senior Member

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    No it is true.

    While as your source says, scientists studying Arctic sea ice trends can rely on a fairly comprehensive record dating back to 1953, using a combination of satellite records, shipping records, and ice charts from several countries.

    The data for the actual amount of ice remaining at that small interval at the end of the season is too sparce to say the 2007 record was a record for the last 100 years, because the last Arctic warm period was in the 40s.

    Arthur
     
  19. iceaura Valued Senior Member

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    We enough evidence of pack ice cover to estimate its size since the early 1700s, from climate records and shipping records to eyewitness accounts of local residents, in addition to various indicative physical and biological traces (such as the age of the ice in pack ice and fast ice cores).

    The NW Passage opened on the Canadian side for the first time in recorded history a few years ago, on the Russian side shortly afterwards, and on both sides simuiltaneously just recently.
    No. Other factors intrude: for one, ice has a specific heat of melting and the meltwater can absorb heat faster than the solid ice - which means ice melting from trapped heat can accelerate considerably despite constant temperature regimes or even, in the case of meltwater spread and flow, cooling of the air and water in the general area.

    One of the standard explanations for some of the cold snaps in the North Atlantic, times of lowered atmospheric temps, is an influx of meltwater from suddenly released inland ice melting, for example - cold snaps symptomatic of warming trends.
     
  20. Trippy ALEA IACTA EST Staff Member

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    No, it's only somewhat true.
    It's true that we currently have the most complete record, and that record is only very young.

    However it's untrue that we don't have any record beyond that. We have records dating back to 1870, which the links I provided included, and refered to, from which some useful comparisons can be made.

    EG:

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    Source

    Which suggests that while sea ice set record lows in 1940-1941, that those lows were exceeded some time in the '70s and '80s, and have been exceeded every year since 1980 - which is what one might come to expect examining the temperature anomaly chart.
     
  21. adoucette Caca Occurs Valued Senior Member

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    Blue shading indicates the pre-satellite era; data then is less reliable.

    In any case, the presense of ice, because of it's here at temp 0 and gone above 0, is not a reliable climatic indicator of rate of climate change which is what it is being presented as, and for that it doesn't hold up.

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    OOPS
     
  22. iceaura Valued Senior Member

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    When it's here yesterday and gone today, the weather has changed.

    If a lot of it disappeared quickly, the weather changed rapidly.
     
  23. Trippy ALEA IACTA EST Staff Member

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    Yes Arthur, I am aware of that.
    I do read my own sources.
    I made no comment on the reliability of the data, other than
    I indicated that with the comments (or thought I did) that I made, and even included a verbatim quote of that exact phrase, taken from page that I linked to as the original source of the data.
    I even went as far as using conservative language like 'suggests', rather than proves.

    I suspect the only error here is yours.
    First off, my recollection is that modelling generally predicts that in East Antarctica at least, that rising global average temperatures will lead to increased precipitation (in the form of snow) - to the point where IPCC predictions attribute a reduction in the rate of sea level rise of as much as 0.12mm/yr to it - which will logically lead a generally increasing extent anomaly, as your graph shows. So your graph, it seems argues in favour, rather than against Iceaura's suggestion.

    One might also be tempted to assess the total ice extent anomaly, which is still, on the whole decreasing.
     

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