Climate and Weather

Bernie Sanders said:
If you were to throw out a guess, given what information we can all pretty much agree on, where would we be within a natural cycle today?
Would we be at or near the top of a warming peak, cooling, or static?
Just looking at the most reliable temp records we have over the last 800,000 years, what pattern emerges, and where would we be without any AGW?
I know its a guess.
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To my understanding, the main predictable drivers on that time scale are the Milanovich cycles. See attached for where we are regarding those cycles. There's a news/views part and then the paper from earlier this year. Mideval warm period appears to have been a road bump on a longer Milankovich-associated cooling trend that would normally lead to the close of the latest interglacial period. But it now appears the sufficiently high GHG concentrations (above ~240 ppm) can interfere with stabilizing the cooling trend. So we've given the next Ice Age the slip. Given the slow rate of CO2 removal from the atmosphere (absorption into oceans, photosynthesis, and rock weathering), the calculations suggest we may well miss the next one in ~100,000 years as well. During the mid-cretaceous warming period shown earlier, it appears the planet skipped hundreds of them.
 

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Bernie Sanders said:
Here's the last 800,000 years. (allegedly)
Is there a pattern?
I see one, and I also see the peaks are steeper, and higher over the last 400,000 years or so.
Were c02 levels higher or lower during the last 400,000, or the preceding 400,000?
If the amazingly consistent pattern over the last 400,000 years continues, what should we expect?
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The peaks you're referring to I interpret as the normal oscillation between interglacial periods due to the Milankovich cycles. The peaks come at ~100,000 intervals which is what is expected for the eccentricity periodicity and the wiggle and wobble tweak the interglacials and interact with other climatic processes so that each interglacial is not exactly the same. Regarding CO2 during the last 400,000, the green line on the graph (GHG forcing) is in essence showing that [CO2] normally tracks with these cycles but is now continuing at high. What they are normally linked is something I don't understand. My reading suggests that what we should expect is that the temp and CO2 components of these larger cycles are now being overridden by the anthropogenic components-hence continuing the current interglacial. Other than that depends on how warm its going to get and for how long. The changing of geologic epochs is frequently associated with major climatic periods that disrupt climate patterns tied to Earth's orbit. If we do start skipping oscillations, it's been suggested that we bring the Holocene to a close and start the Anthropocene.
 
Wez said:
Is it possible we are changing Climate?
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For me the answer is clearly yes. The questions are to what extent, how accurately can we anticipate outcomes, and what policies make the most sense. The medieval warming period, which increasingly appears to have been a mostly Northern hemisphere event is not well understood and there are lots of theories. One of the older ones actually is that large scale deforestation in Europe at that time was a trigger. I've read that there were areas of Europe that were actually more densely inhabited in the middle ages than they are now, which is something I would not have guessed. Anyway, once the Black Death arrived all the building came to a stop and nature resumed it's course towards a cooling climate.
 
EvilGoalie 21 said:
For me the answer is clearly yes. The questions are to what extent, how accurately can we anticipate outcomes, and what policies make the most sense. The medieval warming period, which increasingly appears to have been a mostly Northern hemisphere event is not well understood and there are lots of theories. One of the older ones actually is that large scale deforestation in Europe at that time was a trigger. I've read that there were areas of Europe that were actually more densely inhabited in the middle ages than they are now, which is something I would not have guessed. Anyway, once the Black Death arrived all the building came to a stop and nature resumed it's course towards a cooling climate.
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Exactly, why deniers spend so much energy railing against the possibility of AGW/ACC is a total mystery. Their politics have hijacked their ability to reason...
 
Lion Eyes said:
Hmmmm.......Deniers or skeptics?
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Call it what you want, the real question is why be either? Other than a false impression that AGW is a left wing conspiracy, what do you gain by being a skeptic? Skepticism is politically motivated, not science driven.
 
Wez said:
Call it what you want, the real question is why be either? Other than a false impression that AGW is a left wing conspiracy, what do you gain by being a skeptic? Skepticism is politically motivated, not science driven.
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Skepticism is a healthy personality quality. However, the word has been hijacked and redefined for political purposes, kind of like what happened to "conservative".
 
Wez said:
Call it what you want, the real question is why be either?
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Go 90 days without the use of any fossil fuels or petroleum products and let us know what the difference is. Donʻt let your politically driven science hijack your ability to reason Wezdumb.
 
Wez said:
Call it what you want, the real question is why be either? Other than a false impression that AGW is a left wing conspiracy, what do you gain by being a skeptic? Skepticism is politically motivated, not science driven.
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Alarmism is politically motivated, not science driven. See Al Gore.
 
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