Comments 1 to 16:

1. nigelj at 06:20 AM on 26 February, 2023

   Regarding the engineered solutions to humanities various problems. I acknowledge the downsides of this and I oppose geoengineering the climate, but I get tired of listening to academics (and the general public) potificate on the dangers of engineered solutions, while they fly around the world and live in their homes packed full of technology and drive their sophisticated cars. If its really a huge problem, wouldn't they set an example and live simply?

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2. John Hartz at 14:12 PM on 26 February, 2023

   nigelj: At this moment in time, the human race seems to be caught between a rock and a hard place with respect to mitigating man-made climate change. Sooner or later, something has to give. As someone who turns 80 years old this coming summer, I don't know if I'll live long enought to see which path is chosen.  For my childrens' and grandchildrens' sake, I sure hope its the right one.

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3. Evan at 23:38 PM on 26 February, 2023

   Saturn and Jupiter do a dance with the Earth which, over the course of 100,000 years, causes sea level to rise and fall by 120m (400 ft). This demonstrates how delicately balanced our planetary systems are.

   Do humans have any chance of artificially controlling such a delicately-balanced system (i.e., through geo-engineering), short of ceasing to poke a prod the system the way we do?

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4. ubrew12 at 04:34 AM on 27 February, 2023

   Re Evans@3.  The gravitational pull of all solar system objects, on Earths surface, relative to the moon is: Moon 1, Sun 0.4, Venus 6E-5, Jupiter 3E-6, Mercury 4E-7, Saturn 2E-7, Mars 5E-8, Uranus 3E-9, and Neptune 8E-10.  

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5. Philippe Chantreau at 04:43 AM on 27 February, 2023

   Evan at 3: Do you have a source, link, published paper for this very bold assertion?

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6. Bob Loblaw at 05:35 AM on 27 February, 2023

   ubrew12, Phillippe:

   At a guess, I expect that Evan may be claiming that the variations in the Milankovitch cycles are due to the gravitational effects of Saturn and Jupiter, such that we have glacial/intergalcial periods at 100,000-year intervals. And that causes sea level changes of 120m.

   Just a hunch. Evan can confirm.

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7. Evan at 06:35 AM on 27 February, 2023

   Bob@6, correct. These are not tidal forces due to Jupiter and Saturn, but rather complex feedback processes triggered by varying orbital cycles due to the tug and pull of Jupiter and Saturn on the Earth, ala the Milankovitch cycles.

   I did not give a reference because I am simply framing the effects of the Milankovitch cycles in a way that people may not normally think of them.

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8. Bob Loblaw at 10:36 AM on 27 February, 2023

   Indeed, Evan. That's what I figured. A subtlety in mentioning, without naming, the gravitational effects that might see minor - and are, in a direct sense, based on ubrew12's numbers.

   But those minor direct effects lead to indirect effects, with a well-known and plausible physical mechanism, that make for major shifts in climate.

   A delicate balance for sure. People argue that we don't know enough about climate to be confident that CO2 is having a warming effect - all those pesky unknown unknowns - but we know enough to be confident that geoengineering will be entirely predictable and problem free? Surely a place to be skeptical.

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9. scaddenp at 10:58 AM on 27 February, 2023

   The milkankovich cycles are only able to force ice ages (and sea level) when GHGs levels are so low that summer insolation at high latitudes doesnt not melt snow. (The milankovich cycles operated long before the Pleistocene ice ages). The simple geoengineering to prevent an ice age is to increase GHG to such a level (around 400ppm) that they dont have an effect. Whoops! we have just done that.

   We definitely agree with Wally Broecker that climate is an angry beast and that we shouldnt be poking it with a stick.

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10. Evan at 11:14 AM on 27 February, 2023

    scaddenp@9, good points. Isn't it remarkable that the Earth ever so slowly changed over millions of years until we arrived at this delicate position where ice-age cycles took us up and down, cycling between 180m and 60m equivalent sea level rise worth of ice on land. The incredible sensitivity of Earth to the tugs and pulls of Jupiter and Saturn are a true indication of the delicate balance that Earth has functioned in for so long.

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11. One Planet Only Forever at 13:03 PM on 27 February, 2023

    Evan,

    Humans certainly would have difficulty being reasonably certain of the results of the collective accumulating impacts of their actions. A January 13, 2016 Carbon Brief article "Human emissions will delay next ice age by 50,000 years, study says" covered a study published in Nature. It explains how climate impacts have significantly delayed the onset of the next ice age. A key point is not 'the positive' of delaying the ice age. The key point is that the climate impacts will last 10s of thousands of years unless some generations of humans 'unprofitably' drawdown CO2.

    Even if CO2 is drawndown there will be many harmful results of the short term excessive CO2 levels that are irreversible. And many of those permanent harms will be surprises because humans don't really understand the complexity of life on this amazing planet.

    Humans have proven they can have massive impacts. And have proven to resist learning about how harmful their developed beliefs and actions actually are.

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12. ubrew12 at 14:02 PM on 27 February, 2023

    Evan@7 said "I am simply framing the effects of the Milankovitch cycles in a way that people may not normally think of them."  Yes, you certainly fooled me.  It makes sense that they would be a 'forcer' for those cycles, but I thought you were refering to some kind of direct gravitational effect.

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13. Evan at 14:20 PM on 27 February, 2023

    ubrew12@12, glad we cleared that up. I simply like to remind people how delicately balanced Earth's systems are. The current effect of the Milankovitch cycles on our planetary systems fascinate me.

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14. nigelj at 17:12 PM on 27 February, 2023

    Jon Hartz @2.

    Agreed. 

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15. Bob Loblaw at 05:27 AM on 28 February, 2023

    ubrew12 @12:

    I don't think Evan was trying to fool anyone, but he was trying to make people think. Seeing his original comment @3, and the responses @4 and 5, the path my brain went into was:

    • 100,000 years sounds an awful lot like glacial cycles.
    • 120m sounds an awful lot like sea level changes between glacials and interglacials.
    • Effects of Saturn and Jupiter sound an awful lot like the kinds of gravitational forces that cause wobbles and slight shifts in earth's orbital patterns...
    • ...which leads to Milankovitch theory.

    Rather than jumping into a mode of "this seems absurd..", I went into a mode of "maybe Evan is thinking about something other than the obvious..."

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16. Evan at 06:37 AM on 28 February, 2023

    Bob@15, I've been found out. :-)

    You are correct that I am simply trying to get people to appreciate the unbelievably delicate balance that defines many of our natural systems.

    That planets 100's of millions of miles away can cause sea-level change (by whatever mechanism) on the order of 120m (400') is astounding!

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