It's the Ocean not the Atmosphere, dummy!

[ding]

And your own argument implicitly requires thresholds and feedbacks too.

ocean circulation changes

freshwater pulses

salinity shifts

ice extent

thermal gradients

delayed equilibration

Those are nonlinear feedback dynamics.

Not really. I just need the ocean to warm up and the ice in the Arctic to melt. Once the AMOC switches off, everyone agrees what will happen. Which makes the reverse true as well.

 

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Your model does not adequately explain the timing, direction, and modern acceleration of the global energy increase.

Sure it does. It's very conventional. No one disputes what happens when the northern hemisphere begins to glaciate or deglaciate.

 

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On the 41k-to-100k transition...

Nobody claims eccentricity alone directly supplies the warming energy. The current understanding is that ice-sheet dynamics, regolith removal, nonlinear feedbacks, and internal climate responses altered how the system responded to orbital forcing after the Mid-Pleistocene Transition. That's an active research area.

You say there is no synchronization, but the pacing relationship is far stronger than random coincidence. Deglaciations repeatedly align with northern summer insolation maxima in ways difficult to explain with purely internal stochastic ocean variability.

Your present-day argument still has a major unresolved problem...

Current orbital forcing trends are weakly toward cooling while greenhouse forcing trends strongly positive. Yet global ocean heat content continues increasing. If this is merely delayed deglacial recovery, why did the warming accelerate sharply alongside industrial CO2 rise instead of following a smoother multi-millennial trajectory?

I'll wait for you to stumble through explaining a full cycle to respond to this.

 

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The disagreement is that you are elevating a major internal climate mechanism into the sole root cause while dismissing the forcing framework that appears to pace it over geological timescales.

You don't think ocean currents existed through geologic timescales?

 

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The facts you mentioned alone do not establish that ocean circulation is the primary independent driver of glacial pacing.

You mean it wasn't clear to you that for the last 3 million years it's temperature dependent?

 

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You're stating the mechanism of heat transport while skipping the pacing question. Why do these large-scale transitions repeatedly align with orbital configurations over hundreds of thousands of years?

My explanation explains the timescales. For any given landmass configuration, ocean currents are temperature dependent. So I don't have the problem you do with inconsistent and changing timescales. Let alone explaining why orbital forcing wasn't a thing before 3 million years ago.

 

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Saying "the ocean naturally cycles" is not a full explanatory model.

Good thing I never said that, huh? And if you couldn't understand my model, that's on you. It's quite simple. I've even explained it to you a half dozen times.

 

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If the AMOC strengthens, the North Atlantic can warm dramatically through redistribution while other regions cool or lose heat. That is different from increasing total planetary heat content.

Albedo of a glaciating northern hemisphere or a deglaciating northern hemisphere. It's quite conventional. I don't understand how you aren't getting it.

 

[ding]

The modern climate signal includes a substantial increase in total ocean heat content globally, not merely North Atlantic redistribution. That's a major reason greenhouse forcing remains central in current attribution studies.

So the issue is not whether ocean circulation matters. It obviously does.

The issue is whether it alone adequately explains the pacing of glacial cycles, the phase relationships in paleoclimate data, and the modern global energy imbalance.

Right now your argument explains an important part of the system, but it does not fully close those gaps.

When it switches off it will be fully understood. Trust me. That's when the real science will begin and the hunt for the guilty will start. They will all be pointing fingers at each other saying they knew all along AGW was wrong but they were too afraid to speak out.

 

[Anomalism]

Let's just call it temperature dependent for now. I think we can agree on that. I've walked you through how I see it happening. I asked you in the last post for you to walk me through how you believe orbital forcing causes abrupt climate changes from an interglacial period to a glacial period. Without of course using AMOC switch off.

Orbital forcing doesn’t need to inject large amounts of global heat. It changes where and when sunlight hits hardest, especially summer insolation in the high northern latitudes. That matters because ice sheets are governed by a threshold: if summer melt exceeds winter accumulation, ice retreats; if not, it grows. Over thousands of years, small but persistent orbital shifts push that balance point.

Once ice sheets start expanding or shrinking, internal feedbacks amplify the response into large global climate shifts. That’s what produces the glacial–interglacial transitions. Ocean circulation is part of that internal response system, but orbital forcing is what repeatedly nudges the climate into and out of those unstable states in a paced, predictable way over geological time.

 

[Anomalism]

It's based on the empirical climate evidence of the geologic record. Which is where every good analysis should begin.

We know for a fact that the planet's unique configuration makes the northern hemisphere a critical region for impacting planet wide climate. Or at least you should know that. And we know why that is. Or at least you should know that.

Do you understand this? Or do I need to explain this in more detail?

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No need for the condescension.

That still doesn’t remove the energy-constraint issue. The climate system doesn’t keep warming because it was cold. What’s actually happening in the standard framework is orbital forcing gradually changes summer insolation at high northern latitudes, which creates a small persistent imbalance in ice sheet mass. Once that imbalance favors retreat, feedbacks amplify it into a full deglaciation. The energy source is still solar radiation; the system is responding to a slowly shifting boundary condition, not self-propelled warming from past cold states.

 

[Anomalism]

We shall soon find out as you walk me through the science and your evidence for how orbital cycles trigger abrupt climate changes like glacial and interglacial periods.

Orbital cycles change summer sunlight at high northern latitudes, not total global energy. Ice sheets are controlled by whether summer melt fully removes winter snow.

When summer insolation drops below a threshold, ice accumulates over thousands of years. Ice growth then triggers feedbacks that amplify cooling into a glacial state.

When summer insolation rises above that threshold, ice sheets become unstable and retreat. Feedbacks amplify the warming, producing rapid deglaciation.

 

[Anomalism]

Not really. I just need the ocean to warm up and the ice in the Arctic to melt. Once the AMOC switches off, everyone agrees what will happen. Which makes the reverse true as well.

That still doesn’t explain the repeating, orbitally timed glacial cycles on its own. You’re describing internal amplification mechanisms, not what sets the long-term pacing.

In the standard framework, ocean circulation, ice extent, salinity shifts, and thermal gradients are responses and amplifiers within the system. The slow, repeating driver that nudges the system toward those thresholds is orbital variation in high-latitude summer insolation. Without that external pacing, the feedbacks you listed don’t naturally produce a 100k/41k-year global rhythm.

 

[Anomalism]

Sure it does. It's very conventional. No one disputes what happens when the northern hemisphere begins to glaciate or deglaciate.

That doesn’t actually answer the objection.

Saying “we know what happens during glaciation/deglaciation” is describing the response of the system, not what is currently driving the net global energy increase today.

 

[Anomalism]

I'll wait for you to stumble through explaining a full cycle to respond to this.

The Mid-Pleistocene shift is understood as a change in how the climate system responds to the same orbital forcing, mainly due to larger ice sheets and stronger internal feedbacks. Orbital cycles still provide the timing signal, with deglaciations clustering around peaks in northern summer insolation, while ice-albedo, CO2, and ocean feedbacks amplify those triggers into full climate transitions. That’s why the pacing looks orbitally structured even though the response is nonlinear.

The modern warming is a different regime. Orbital forcing today is slightly cooling, yet we observe a global increase in ocean heat content and surface temperature. That mismatch in timing and direction is why attribution studies point to greenhouse gases as the dominant current forcing.

 

[Anomalism]

You don't think ocean currents existed through geologic timescales?

Ocean currents absolutely existed throughout geologic timescales.

The point is that having a persistent internal mechanism does not automatically mean it is the primary pacemaker of glacial cycles.

The disagreement isn’t “do ocean currents matter?” It’s “do they alone generate the long-term, orbitally structured pacing of ice age cycles, or are they responding to that pacing while amplifying it?”

 

[Anomalism]

You mean it wasn't clear to you that for the last 3 million years it's temperature dependent?

Temperature dependence is not disputed. The issue is what sets the boundary conditions that make those temperature shifts repeat with orbital timing.

The disagreement is whether temperature driven circulation alone can generate the repeating, orbitally timed global glacial cycles, or whether it is amplifying a slower external pacing signal.

 

[Anomalism]

My explanation explains the timescales. For any given landmass configuration, ocean currents are temperature dependent. So I don't have the problem you do with inconsistent and changing timescales. Let alone explaining why orbital forcing wasn't a thing before 3 million years ago.

Ocean circulation being temperature dependent doesn’t by itself generate a repeating 100k/41k/23k year rhythm. It explains how the climate responds once it is pushed, not what repeatedly provides the push at those intervals.

The orbital framework uses the same geography, but explains the timing via slow, predictable changes in high-latitude summer insolation that affect ice-sheet stability. Before ~2.7 million years ago, the climate system was in a different state, so the same orbital variations didn’t produce the same glacial cycles.

 

[ding]

Orbital forcing doesn’t need to inject large amounts of global heat. It changes where and when sunlight hits hardest, especially summer insolation in the high northern latitudes. That matters because ice sheets are governed by a threshold: if summer melt exceeds winter accumulation, ice retreats; if not, it grows. Over thousands of years, small but persistent orbital shifts push that balance point.

Once ice sheets start expanding or shrinking, internal feedbacks amplify the response into large global climate shifts. That’s what produces the glacial–interglacial transitions. Ocean circulation is part of that internal response system, but orbital forcing is what repeatedly nudges the climate into and out of those unstable states in a paced, predictable way over geological time.

What were the orbital parameters at the end of the last interglacial period that made this happen?

 

[Anomalism]

Good thing I never said that, huh? And if you couldn't understand my model, that's on you. It's quite simple. I've even explained it to you a half dozen times.

The issue isn’t whether that mechanism exists. The issue is whether it can by itself reproduce the observed regular orbital pacing over ~2.7 million years, including the shift in dominant periodicity and the consistent alignment of deglaciations with northern summer insolation peaks.