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Post by aj1983 on Jan 11, 2010 12:29:14 GMT
Indeed, Sigurdur, the long term forecasters with the best record predict continuing cooling with shorter growing seasons. Of course, the firm of Jones and Mann disputes that. However, let me put forth a slight quibble. Timberline and "treeline" need the disambiguation treatment, lest the discussion turn into a comparison of watermelons and grapes. "Timberline" should be reserved for how far up a mountain - at what altitude - even the most cold hardy trees can no longer survive. When you see a mountain top naturally devoid of timber, the highest trees are at the timber line. Within known limits the Earth's precession does not affect timberline below 60 degrees north or south latitude. At this moment, timberline is generally "coming down the mountain," indicating a cooler climate at present. In the context of climate, "Treeline" properly refers to the latitude the most hardy trees can no longer survive. This depends on many factors, including atmospheric and oceanic currents and the Earth's precession. Since precessional changes have been infinitesimal for as far back as we can measure it with any accuracy, and timberline has changed appreciably in places it would be best to examine the evidence without conjecture. From personal conversation with Arctic dwellers it appears the tree line is edging south as well. Also indicating a cooling trend. Whether that trend is short or long term remains to be seen. But it would be a delicious irony if the most prominent exponent of "ice age now" gave up on his thesis just 22 years too early. Stranger In Europe, from the Pyrenees to the Alps and the mountains in Norway, there has been a strong increase of the height of the timberline. So strong, that especially in the Alps, I would call it dramatic. You should go and visit there sometime, it's very beautiful .
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Post by poitsplace on Jan 11, 2010 13:22:00 GMT
The North Atlantic Oscillation and Arctic Oscillation are air masses...and therefore very fickle. The unusually powerful NAO fluctuation may be an indication it (and/or the AO) switched into a cooling mode...or it could just be a fluke. It is reasonable to assume it may have changed. commons.wikimedia.org/wiki/File:Winter-NAO-Index.pngThe Atlantic Multidecadal Oscillation is a little more coherent since it's an ocean current but still hard to tell. It is most likely going to be in a warming mode for another 10-20 years. None of the cycles are true oscillations...and their periods can vary quite a bit. We're about 15 years into its warm phase. Its period appears to be probably 25-40 years as of late. www.aoml.noaa.gov/phod/faq/amo_flarain.phpThe Pacific Decadal Oscillation is also more coherent, being an ocean cycle. The rough period and values of the PDO indicate it's probably gone into cooling mode. jisao.washington.edu/pdo/And finally the solar cycle. The solar cycle appears to have gone into a phase of very low activity. Livingston and Penn observed that if current rates continue the sun won't even be able to support sunspots (although the magnetic spots will remain) by 2015. LOL, so if you think THIS minimum was bad...imagine how bad the next could be if things don't pick back up by then The currents were LIKELY responsible for most (if not all) of the warming of the 20th century. If they all go into cooling mode, the solar activity doesn't pick up and there's not something else warming us...we could theoretically undershoot the previous cold period's temperatures. My more reasonable prediction would be for something between flat temperatures and a drop of .4C
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Post by aj1983 on Jan 11, 2010 14:17:17 GMT
that does not sound very dramatic to me, compared to many AGW skeptic stories predicting a Dalton/Maunder minimum, little ice age, a grand ice age etc, especially because they usually state that it was around 2 C colder during the little ice age, and warmer than today during the MWP.
If temperatures remained at the current high level (due to high solar activity, and some positive variations which have been proposed to explain the recent warming, wouldn't this be strange considering decreasing solar activity, the prospect of an even stronger decrease in solar activity (several "low cycles"), and internal variability going from their positive phases into their negative phase? If the current warming can be explained by natural variation only (solar/space+internal), then I can understand why people are afraid of a new LIA in the near future.. it would seem that we are going to have a substantial drop in temperatures (~ 1 C or so on the long run). However, you could also note of course that while everything was in positive phase, the rate of temperature rise has never recently been above 0.2 C/decade, so that it would be unlikely to have a stronger drop than 0.2 C/decade. During the 1940-1960 period we've already seen something like a 0.1 to 0.2 C temperature drop, on top of a rising trend, so this suggests that temperatures might fall more rapidly (without AGW), if we are entering a phase of significantly lower solar activity.
Any other forecasts?
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Post by hairball on Jan 11, 2010 14:37:02 GMT
"Any other forecasts?" Irrespective of CO2, sooner are later everyone will be living close to the equator.
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Post by nautonnier on Jan 11, 2010 14:38:45 GMT
If I understand it correctly, nearly? all natural variations are in a cooling phase, that's why many AGW skeptics and even some AGW proponents forecasts global cooling which will peak in 2030. Is it true that ALL major variations (will) show cooling? I'm wondering which variations are in a negative phase? I've heard: solar activity NAO/AO (NH only) PDO ... ~maybe ENSO tending toward more La Nina. Any others I've forgot? What is the average period for these oscillations to stay negative, and is anything known on how large the temperature anomaly is for these phases? What will be the temperature drop around 2030? I think if you don't consider AGW (but even if you do), this very important to know for the coming decades. Maybe we should start a topic "what will the global average temperature (anomaly) be around 2030?" You should not disregard things outside Earth - Millennium-Scale Sunspot Number Reconstruction: Evidence for an Unusually Active Sun since the 1940s "The extension of the sunspot number series backward in time is of considerable interest for dynamo theory, solar, stellar, and climate research. We have used records of the 10Be concentration in polar ice to reconstruct the average sunspot activity level for the period between the year 850 to the present. Our method uses physical models for processes connecting the 10Be concentration with the sunspot number. The reconstruction shows reliably that the period of high solar activity during the last 60 years is unique throughout the past 1150 years. This nearly triples the time interval for which such a statement could be made previously."prl.aps.org/abstract/PRL/v91/i21/e211101This fits with Svensmark
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Post by nautonnier on Jan 11, 2010 15:07:05 GMT
that does not sound very dramatic to me, compared to many AGW skeptic stories predicting a Dalton/Maunder minimum, little ice age, a grand ice age etc, especially because they usually state that it was around 2 C colder during the little ice age, and warmer than today during the MWP. If temperatures remained at the current high level (due to high solar activity, and some positive variations which have been proposed to explain the recent warming, wouldn't this be strange considering decreasing solar activity, the prospect of an even stronger decrease in solar activity (several "low cycles"), and internal variability going from their positive phases into their negative phase? If the current warming can be explained by natural variation only (solar/space+internal), then I can understand why people are afraid of a new LIA in the near future.. it would seem that we are going to have a substantial drop in temperatures (~ 1 C or so on the long run). However, you could also note of course that while everything was in positive phase, the rate of temperature rise has never recently been above 0.2 C/decade, so that it would be unlikely to have a stronger drop than 0.2 C/decade. During the 1940-1960 period we've already seen something like a 0.1 to 0.2 C temperature drop, on top of a rising trend, so this suggests that temperatures might fall more rapidly (without AGW), if we are entering a phase of significantly lower solar activity. Any other forecasts? AJ I think you should start thinking in terms of global heat content rather than some reservoir of heat somewhere that natural cycles can dip into if they want. IF the quiet sun results somehow in less energy input into the Earth weather system, then the natural cycles cannot create that energy. What is more likely is that the natural cycles are in response to the energy input and the imbalance of the input between the tropics and the poles and between the hemispheres and convection and the Coriolis effects. These together with tides cause the complex turbulent flows that we call weather and ocean currents. Some of the ocean cycles such as the thermohaline currents have a lot of inertia and may take decades to respond damping out brief alterations in energy but reinforcing longer lasting changes. Atmospheric changes may be relatively fleeting and lead to some of the more fleeting ocean surface effects like El Nino / La Nina being caused by trade-winds. The point is that the cycles are just moving the energy around - if there is less energy input then it will get colder regardless of these cycles.
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Post by poitsplace on Jan 11, 2010 15:17:04 GMT
that does not sound very dramatic to me, compared to many AGW skeptic stories predicting a Dalton/Maunder minimum, little ice age, a grand ice age etc, especially because they usually state that it was around 2 C colder during the little ice age, and warmer than today during the MWP. If temperatures remained at the current high level (due to high solar activity, and some positive variations which have been proposed to explain the recent warming, wouldn't this be strange considering decreasing solar activity, the prospect of an even stronger decrease in solar activity (several "low cycles"), and internal variability going from their positive phases into their negative phase? Would it? The minimum of the early 1900's was quite pronounced and temperatures were still warmer than the LIA. Why was THAT warmer? Almost all of the increase in CO2 was after the 1940's...why was THAT warmer??? The main thing is, I don't fear warming...but a degree or two of cooling would really screw mankind over.
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Post by northsphinx on Jan 11, 2010 15:31:45 GMT
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Post by trbixler on Jan 11, 2010 15:53:35 GMT
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Post by steve on Jan 11, 2010 18:18:28 GMT
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Post by icefisher on Jan 11, 2010 18:52:57 GMT
I thought it was warm in Europe this winter too Steve. Today's weather at Iqualuit is -29degC feels like -43degC.
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Post by aj1983 on Jan 11, 2010 20:28:49 GMT
that does not sound very dramatic to me, compared to many AGW skeptic stories predicting a Dalton/Maunder minimum, little ice age, a grand ice age etc, especially because they usually state that it was around 2 C colder during the little ice age, and warmer than today during the MWP. If temperatures remained at the current high level (due to high solar activity, and some positive variations which have been proposed to explain the recent warming, wouldn't this be strange considering decreasing solar activity, the prospect of an even stronger decrease in solar activity (several "low cycles"), and internal variability going from their positive phases into their negative phase? If the current warming can be explained by natural variation only (solar/space+internal), then I can understand why people are afraid of a new LIA in the near future.. it would seem that we are going to have a substantial drop in temperatures (~ 1 C or so on the long run). However, you could also note of course that while everything was in positive phase, the rate of temperature rise has never recently been above 0.2 C/decade, so that it would be unlikely to have a stronger drop than 0.2 C/decade. During the 1940-1960 period we've already seen something like a 0.1 to 0.2 C temperature drop, on top of a rising trend, so this suggests that temperatures might fall more rapidly (without AGW), if we are entering a phase of significantly lower solar activity. Any other forecasts? AJ I think you should start thinking in terms of global heat content rather than some reservoir of heat somewhere that natural cycles can dip into if they want. IF the quiet sun results somehow in less energy input into the Earth weather system, then the natural cycles cannot create that energy. What is more likely is that the natural cycles are in response to the energy input and the imbalance of the input between the tropics and the poles and between the hemispheres and convection and the Coriolis effects. These together with tides cause the complex turbulent flows that we call weather and ocean currents. Some of the ocean cycles such as the thermohaline currents have a lot of inertia and may take decades to respond damping out brief alterations in energy but reinforcing longer lasting changes. Atmospheric changes may be relatively fleeting and lead to some of the more fleeting ocean surface effects like El Nino / La Nina being caused by trade-winds. The point is that the cycles are just moving the energy around - if there is less energy input then it will get colder regardless of these cycles. I agree, but that does not change my point. I assume you are not saying that internal variability can't lead to an increase/decrease in global temperatures (as observed currently)? What's the difference between the global heat content, and the reservoir you are talking about? I agree that, simply put, if the net heat input becomes smaller, it will cool. That's why it will warm with CO2.
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Post by aj1983 on Jan 11, 2010 20:37:37 GMT
Amsterdam -6 coldest since when? That's plain bullshit. The lowest temperature here (30 km from Amsterdam) is -24.4 C. Hamburg -22 a record? -37 in Siberia, that also sounds rather warm. That's hardly imaginable, but might be close. This figure is plain misleading, is it in F or C? I think there is confusion about that!
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Post by aj1983 on Jan 11, 2010 20:50:21 GMT
But do we agree that from natural variation and the current (and forecasted) trend in solar activity there will likely be global cooling?
(which is forecasted by very many AGW skeptics, who do their utmost best to try and show that it has already begun)
So what happens if the temperatures have risen in 2030 compared to the current average?
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Post by icefisher on Jan 11, 2010 21:56:42 GMT
that does not sound very dramatic to me, compared to many AGW skeptic stories predicting a Dalton/Maunder minimum, little ice age, a grand ice age etc, especially because they usually state that it was around 2 C colder during the little ice age, and warmer than today during the MWP. If temperatures remained at the current high level (due to high solar activity, and some positive variations which have been proposed to explain the recent warming, wouldn't this be strange considering decreasing solar activity, the prospect of an even stronger decrease in solar activity (several "low cycles"), and internal variability going from their positive phases into their negative phase? If the current warming can be explained by natural variation only (solar/space+internal), then I can understand why people are afraid of a new LIA in the near future.. it would seem that we are going to have a substantial drop in temperatures (~ 1 C or so on the long run). However, you could also note of course that while everything was in positive phase, the rate of temperature rise has never recently been above 0.2 C/decade, so that it would be unlikely to have a stronger drop than 0.2 C/decade. During the 1940-1960 period we've already seen something like a 0.1 to 0.2 C temperature drop, on top of a rising trend, so this suggests that temperatures might fall more rapidly (without AGW), if we are entering a phase of significantly lower solar activity. Any other forecasts? I don't think it would be surprising to see a lack of cooling with low solar activity. We have the CO2 forcing folks pooh poohing 11 years of no warming as a mere expected diversion. Solar activity proponents have to only explain away 2 years of unusually low solar activity. It isn't even a contest on this score. One of those 2 years did see substantial cooling and the warming spike the following year is well precedented throughout the instrument record. What needs to happen to start settling the score is for the Met prediction to come through, or for the solar guys another full cycle with very low activity without any cooling at all. Anything in between can be labeled a mystery. In other words you need to cut the solar guys about 9 more years slack than you cut for the AGW folks.
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