Geological

 The temperature is about to return to livable, where I live. We are expected

to go back to temperatures above freezing next week. Hourah!

Checked for how to explain ice Ages to children, only to realize I was all wrong myelf.

We did not leave an Ice Age for the warmer Holocene, we left a Glacial. An actual

Ice Age is whenever there is considerable permanent ice on the ground, and we are

in one... Below, asking Copilot:

Stricly speaking, are we still in a long ice Age, only in an interglacial. There is after all  qjuite a bit of ice on the planet...

Absolutely — and this is one of those delightful cases where the strict scientific definition and the popular mental image diverge.

🌍 Yes: strictly speaking, we are still in an Ice Age

In geology, an Ice Age is defined as any period in which permanent ice exists on Earth’s surface — meaning long‑lasting ice sheets at either pole or on continents.

By that definition:

Earth currently has large, permanent ice sheets in Greenland and Antarctica

Therefore, we are still in an Ice Age

This ongoing Ice Age began about 2.6 million years ago, at the start of the Quaternary Period.

🌤️ We are living in an interglacial — a warm pulse inside an Ice Age

Within an Ice Age, climate oscillates between:

                                                                              

Right now, we are in the Holocene interglacial, which began about 11,700 years ago.

So the structure looks like this:

Ice Age (Quaternary)

Glacial

Glacial

Glacial

Interglacial (Holocene — now)

Future glacial (if natural cycles continued)

                                                                               

❄️ How much ice is “enough” to count as an Ice Age?

Geologists use a simple criterion:

If there is permanent ice at both poles or large continental ice sheets, Earth is in an Ice Age.

We currently have:

Antarctica: ~14 million km² of ice

Greenland: ~1.7 million km²

Mountain glaciers worldwide

That’s plenty.

🔄 Why the confusion?

People often use “Ice Age” to mean “glacial period with mammoths and giant ice sheets.”

But geologists use it to mean “any time Earth has permanent ice.”

By the strict definition, the last time Earth was not in an Ice Age was over 34 million years ago, before Antarctica froze over.

🔮 Would we naturally enter another glacial?

If humans weren’t altering the climate, orbital cycles (Milankovitch cycles) suggest:

Northern Hemisphere glaciation would return in ~50,000 years

Human-driven warming has likely delayed or disrupted that cycle

That’s a whole other fascinating discussion if you want to go there.

If you want, we can dig into:

How interglacials normally behave

Whether the Holocene is unusually long

How human activity interacts with glacial cycles

What Quebec would look like in a natural future glacial

Just say the word.

How many distinct per definition  Ice Ages have there been?

Geologists have a very specific, almost minimalist definition of an Ice Age:

If Earth has permanent ice on land at either pole, it is in an Ice Age.

Using that strict criterion, Earth has only been in an Ice Age a handful of times — far fewer than people imagine.

Here’s the clean, consensus list.

❄️ The 5 major Ice Ages in Earth’s history (strict definition)

These are the big, long‑lasting episodes when Earth had persistent polar or continental ice.

                                                                                   

So the strict answer is:

👉 Five. Earth has had five distinct Ice Ages.

🌡️ Why not more?

Because most of Earth’s history has been ice‑free, even at the poles.

For roughly 80–90% of the last 4.5 billion years, Earth had:

No permanent polar ice

Sea levels much higher

Tropical conditions extending far poleward

Ice Ages are the exception, not the rule.

🧊 And within each Ice Age?

Each major Ice Age contains many glacial–interglacial cycles.

For example, in the current Quaternary Ice Age, there have been dozens of glacials and interglacials. But those are sub‑cycles, not separate Ice Ages.

If you want, we can go deeper into:

Why Ice Ages start and end

How rare “Snowball Earth” events really were

Whether the Quaternary is unusually long

What ends an Ice Age in geological terms

Just tell me where you want to take it next.

Do we know when we might hope to 'naturally' get rid of all ice in the future?

This is a wonderfully sharp question, because it forces us to separate natural climate dynamics from the anthropogenic override we’re currently applying.

Let’s take it step by step and keep it grounded in what paleoclimate physics actually allows.

🌍 Short answer: Naturally, Earth would NOT lose all ice again for a very, very long time — millions of years at least.

And even that is uncertain. The default trajectory of Earth’s climate system is to stay in an Ice Age (with glacial–interglacial cycling) for millions of years into the future.

The only times Earth has been ice‑free were during:

Greenhouse climates (e.g., Cretaceous, Eocene)

Super‑greenhouse events (e.g., PETM)

Periods with radically different continental configurations

Those conditions are not naturally returning anytime soon.

❄️ 1. Orbital cycles alone would keep ice on Earth for millions of years

Milankovitch cycles (eccentricity, obliquity, precession) control the pacing of glacials and interglacials. Under purely natural forcing:

The Holocene interglacial would normally end in ~50,000 years

Glacial cycles would continue for at least another 1–2 million years

There is no natural mechanism in the next few million years that would melt Antarctica or Greenland entirely.

🧊 2. Antarctica is extremely stable — it only melts in super‑greenhouse worlds

Antarctica froze over ~34 million years ago when CO₂ dropped below ~600–800 ppm.

To melt it naturally, Earth would need:

CO₂ sustained above ~1,000–1,200 ppm

A very different continental layout

A long period of high solar input

None of these are on the natural schedule.

Even with the Sun slowly brightening, the timescale for that to matter is hundreds of millions of years, not thousands.

🌞 3. Solar evolution will eventually melt all ice — but not for ~1 billion years

The Sun brightens by about 1% every 100 million years.

In ~500 million years: Earth becomes too warm for large ice sheets

In ~1 billion years: Earth likely loses all surface water entirely

This is the ultimate end of Ice Ages — but it’s far outside human timescales.

🔥 4. The only realistic way to melt all ice “soon” is anthropogenic, not natural

If humans push CO₂ high enough (800–1200+ ppm), models show:

Greenland melts over thousands of years

West Antarctica collapses

East Antarctica partially melts over tens of thousands of years

Sea level rises 50–70 meters or more

But that is not a natural outcome — it’s a human‑driven one.

📌 So the strict scientific answer:

**Naturally, Earth will keep permanent ice for millions of years.

We are nowhere near the next ice‑free world.**

The only things that can melt all ice:

Anthropogenic greenhouse forcing (centuries to millennia)

Solar brightening (hundreds of millions of years)

Radical tectonic rearrangements (tens of millions of years)

None of these are part of the “normal” near‑future natural climate cycle.

If you want, we can explore:

Whether the Quaternary Ice Age is unusually long

How stable Antarctica really is

What CO₂ threshold melts Greenland vs. Antarctica

What Quebec would look like in a natural future glacial

Whether humans have already prevented the next glaciation

Just tell me where you want to take the model next.

                                                    *     *     *

From Wikipedia:

                                                                   

Indeed, one can disinguish between an ice Age, a Glaciation, and a Glacial:

Timeline of glaciation - Wikipedia