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#11
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Second hottest March since records began
There is the weekday day/night cycle and then there is separately the polar day/night cycle and both arising from separate rotations to the Sun, one daily and the other orbital.
Presently it is polar twilight at the South Pole but unfortunately live imaging of this extended twilight isn't up to scratch at the moment - https://www.usap.gov/videoclipsandmaps/spwebcam.cfm Say goodbye to Milankovitch cycles as that notion emerged without recognition of the polar day/night cycle and its rotational cause. The precession of the equinoxes is due to a further refinement of the leap day correction as the proportion of rotations to orbital circuits is not exactly 1461 rotations to 4 circuits hence the slight drift in orbital position when using timekeeping. This drift which is large is terms of the leap day correction where Sirius skips a first annual appearance every 4th 365 day cycle is much smaller after the correction is made but there nonetheless. Remember now, climate is a spectrum between Equatorial and Polar represented by 0 degrees and 90 degrees inclination respectively. |
#12
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Second hottest March since records began
On Sunday, April 23, 2017 at 9:44:48 AM UTC-6, Mike Collins wrote:
Gary Harnagel wrote: On Saturday, April 22, 2017 at 7:50:57 AM UTC-6, Mike Collins wrote: The little ice age was preceded by a substantial drop in atmospheric CO2 possible attributable to the regeneration of the Amazon rain forest after the destruction of its civilisation by disease. Yes, I saw a report that earthen structures were found in cleared Amazon forest areas. But what makes you believe that the forest RE-generated when the natives were decimated by disease? Maybe it just generated. Also, what evidence do you have for a drop in the CO2 levels? The latest entry from the Vostok data is about 2500 years ago: https://en.wikipedia.org/wiki/Milank...insolation.jpg and shows the CO2 level at just over 280 ppm and on the increase. The last 2000 years have shown the following: "The merged, 2000-year record indicates that atmospheric CO2 levels have substantially increased beyond their preindustrial values which fluctuated around 280 parts per million (ppm) for most of the period, with a slight dip from around 1600 to 1800 C.E." Note m a SLIGHT dip. "The Intergovernmental Panel on Climate Change defined preindustrial concentrations as those prior to 1750." How convenient that the Sargasso sea data shows the temperature minimum at that time. "Atmospheric CO2 concentrations rose from around 277 ppm (IPCC, 2007) in 1750 to a global average of around 388 ppm" http://cdiac.ornl.gov/trends/co2/modern_co2.html There is correlation here. The very extensive cultivation of Amazonia ended at the time of the conquistadors and their associated epidemics. The forest regenerated. CO2 fell. http://ir.library.oregonstate.edu/xm...pdf;sequence=1 Actually, the forest is not the largest CO2 sink by far. Irrelevant. The forest regrew. Did it? Or did it just grow? That's a likely CO2 sink in fact it's required or the forest would not grow. Tropical rain forest is a bigger CO2 sink than temperate forest. But forests are a small net change, decaying tress give back most of what they consume during their lives: http://www.livescience.com/44235-ama...-measured.html It's also possible that the medieval warm period was partly due to massive increases in forest clearing and agriculture as the world population, including Amazonia, rose and cleared more forest to grow crops. Hmmm, you're proposing a civilization with a population similar to what exists there now? That's something archaeologists need to find out. But the areas of cleared forest are huge. The civilisation had farms in large forest clearings. Mostly irrelevant since the net CO2 exchange of all Amazon forest is only about 0.3 GT/year. We're adding 7.7 GT/year from fossil fuels: http://cdiac.ornl.gov/carbon_cycle.html |
#13
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Second hottest March since records began
Gary Harnagel wrote:
On Sunday, April 23, 2017 at 9:44:48 AM UTC-6, Mike Collins wrote: Gary Harnagel wrote: On Saturday, April 22, 2017 at 7:50:57 AM UTC-6, Mike Collins wrote: The little ice age was preceded by a substantial drop in atmospheric CO2 possible attributable to the regeneration of the Amazon rain forest after the destruction of its civilisation by disease. Yes, I saw a report that earthen structures were found in cleared Amazon forest areas. But what makes you believe that the forest RE-generated when the natives were decimated by disease? Maybe it just generated. Also, what evidence do you have for a drop in the CO2 levels? The latest entry from the Vostok data is about 2500 years ago: https://en.wikipedia.org/wiki/Milank...insolation.jpg and shows the CO2 level at just over 280 ppm and on the increase. The last 2000 years have shown the following: "The merged, 2000-year record indicates that atmospheric CO2 levels have substantially increased beyond their preindustrial values which fluctuated around 280 parts per million (ppm) for most of the period, with a slight dip from around 1600 to 1800 C.E." Note m a SLIGHT dip. "The Intergovernmental Panel on Climate Change defined preindustrial concentrations as those prior to 1750." How convenient that the Sargasso sea data shows the temperature minimum at that time. "Atmospheric CO2 concentrations rose from around 277 ppm (IPCC, 2007) in 1750 to a global average of around 388 ppm" http://cdiac.ornl.gov/trends/co2/modern_co2.html There is correlation here. The very extensive cultivation of Amazonia ended at the time of the conquistadors and their associated epidemics. The forest regenerated. CO2 fell. http://ir.library.oregonstate.edu/xm...pdf;sequence=1 Actually, the forest is not the largest CO2 sink by far. Irrelevant. The forest regrew. Did it? Or did it just grow? The forst had been cleared. It renew. That's a likely CO2 sink in fact it's required or the forest would not grow. Tropical rain forest is a bigger CO2 sink than temperate forest. But forests are a small net change, decaying tress give back most of what they consume during their lives: It's not a small net change. The forests had been cleared. http://www.livescience.com/44235-ama...-measured.html It's also possible that the medieval warm period was partly due to massive increases in forest clearing and agriculture as the world population, including Amazonia, rose and cleared more forest to grow crops. Hmmm, you're proposing a civilization with a population similar to what exists there now? That's something archaeologists need to find out. But the areas of cleared forest are huge. The civilisation had farms in large forest clearings. Mostly irrelevant since the net CO2 exchange of all Amazon forest is only about 0.3 GT/year. We're adding 7.7 GT/year from fossil fuels: You're missing the point. The forest was not in a normal cycle. It was regrown in general on previously cleared farmland. So the uptake of CO2 was not balanced by decay and liberation of previously fixed carbon. http://cdiac.ornl.gov/carbon_cycle.html |
#14
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Second hottest March since records began
On Monday, April 24, 2017 at 8:45:41 AM UTC-6, Mike Collins wrote:
The forst had been cleared. It renew. .... It's not a small net change. The forests had been cleared. .... You're missing the point. The forest was not in a normal cycle. It was regrown in general on previously cleared farmland. So the uptake of CO2 was not balanced by decay and liberation of previously fixed carbon. Your assertions may or may not be true. There may be evidence, but I haven't seen any. How do we know that the forest wasn't pampas a couple of millennia ago? |
#15
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Second hottest March since records began
Gary Harnagel wrote:
On Monday, April 24, 2017 at 8:45:41 AM UTC-6, Mike Collins wrote: The forst had been cleared. It renew. .... It's not a small net change. The forests had been cleared. .... You're missing the point. The forest was not in a normal cycle. It was regrown in general on previously cleared farmland. So the uptake of CO2 was not balanced by decay and liberation of previously fixed carbon. Your assertions may or may not be true. There may be evidence, but I haven't seen any. How do we know that the forest wasn't pampas a couple of millennia ago? Not just millennia but millions of years. Although severely reduced it probably lasted through the last ice age, unlike the Congo rainforest. The Wikipedia article is good although it quotes old estimates of the poor fertility of the land for crop growing. It fails to mention the "Black Soil"which is the world's most fertile soil and which is produced by adding human and animal faeces, charcoal and bone to the cleared forest soil. This produces soil with long lasting fertility which outperforms modern farming using chemical fertilisers. https://en.wikipedia.org/wiki/Amazon...st?wprov=sfsi1 There are plenty of references in that article Here is another on Black Soil. https://en.wikipedia.org/wiki/Terra_preta?wprov=sfsi1 |
#16
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Second hottest March since records began
On Tuesday, April 25, 2017 at 9:58:43 AM UTC-6, Mike Collins wrote:
.... https://en.wikipedia.org/wiki/Amazon...st?wprov=sfsi1 "One computer model of future climate change caused by greenhouse gas emissions shows that the Amazon rainforest could become unsustainable under conditions of severely reduced rainfall and increased temperatures, leading to an almost complete loss of rainforest cover in the basin by 2100.[54][55] However, simulations of Amazon basin climate change across many different models are not consistent in their estimation of any rainfall response, ranging from weak increases to strong decreases" Interesting how climate models can disagree so much :-| |
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