Here's a question I get asked fairly often.

“How much warming do I think will happen this century”?

This is a critical question and one that generates a LOT of discussion.

Because we are likely going to hit 560ppmCO2 by around 2065 at THE LATEST.

In Mainstream Climate Science that means +3°C of warming.

In the paleoclimate record it means about +6°C of warming.

SO.

Could the Earth really warm +6°C in just 40 years. Is that even possible?

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The short answer is that it's an UNKNOWN.

Imagine two scenarios A and B.

In "A" the CO2 level is 180ppm, the GMST is around +8°C, and CO2 levels increase SLOWLY. Like +100ppm over 6,000 years slowly.

In "B" the CO2 level is 180ppm, the GMST is around +8°C, and CO2 levels JUMP SUDDENLY by +100ppm. Like in less than 100 years suddenly.

Now, we KNOW from scenario A that the GMST increases by +6°C at a rate of about +1°C per 1,000 years. That's actually what's happened multiple times over the last 800,000 years and we can see and measure it in the ice core record.

Scenario B is the one that there is NO geologic analog for in the entire 485my history of life on Earth. The ONLY thing that comes close is the Chicxulub Impact Event (dino killer 65mya).

We do know that the minimum answer in case B has to +6°C.

The same amount of CO2 should generate the same Equilibrium Climate Response. However, there is no guideline for "how fast" the Climate System is capable of processing a "bump" in CO2 levels on that scale.

Which means.

Case B is different than Case A. The SPEED at which it happens makes the response to the increase in CO2 MUCH WORSE.

In my papers looking at Mass Extinction Events, I point out that there are periods when the GMST got to the same level as the End Triassic Extinction. However, in these other "hot periods" there was no mass extinction event. The level of extinctions was barely above the normal background rate.

The difference is the SPEED of the warming.

If there isn't time for life to adapt, and I am specifically thinking of trees, they die and burn. Mass death of the world's forests is a commonality in mass extinctions. Because they happen so fast that trees don't have time to adjust.

The death/burning of the global forests then acts as an amplifier and accelerant of the CO2 warming.

Case B could see Equilibrium Temperature levels that are MUCH higher than Case A. Because of the cascade of environmental die off caused by the speed of the warming.

The paleoclimate record suggests that's the "most likely" outcome.

NOW

We just lived through temperatures going from +1.1°C over baseline in 2021 to +1.6°C by 2024. A Rate of Warming of +0.125°C PER YEAR.

At that Rate of Warming, that's +1.25°C per decade and +6°C happens within 50 years.

We just lived through 3 years of warming at that rate, clearly the Earth "is capable" of it. To say it's"impossible" is too ignore reality AND it could be WORSE than that. We DO NOT know how fast the Earth is capable of responding to a jolt of CO2 of that magnitude.

SO.

Theoretically, +6°C of warming can happen in just 50 years.

If you want to argue for a longer timeframe that's fine. It could be much longer. Maybe it takes 100 years or even 1,000.

We DO NOT know the answer to this question.

What we do KNOW, because we measure it now with the ARGO float network, is how much ENERGY is going into the oceans each year.

In 2023 AND 2024 it was 15 zettajoules, each year.

15Zj works out to about 3.4 Hiroshima bombs worth of ENERGY into every square mile of open ocean on Earth.

About 500 million bombs.

When the Chicxulub Asteroid hit, it released an estimated 10 billion HIROS worth of ENERGY in a single day.

We were at 12.5 Billion HIROS going into the oceans since 1955 in 2021.

At the current rate of yearly increase, we will hit TWO asteroids worth of ENERGY going into the ocean by 2040.

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Mainstream Climate Science is saying that at 560ppmCO2 there will be +3°C of warming. That’s our “best case”.

The paleoclimate data indicates that 560ppmCO2 means +6°C of warming. It is “possible”.

The SAD thing is that we will KNOW for certain which one it’s going to be in about 10 years. By 2035 we will be at +2°C over baseline and then it will be CLEAR who was right.