What the ocean is telling us

Ocean heat content hit another record. I want to explain why this metric matters more than air temperature for understanding where the climate is heading.

Wait, more than surface temperature? That's what everyone focuses on.

The ocean absorbs 90% of excess heat. Air temperature is noisy — El Niño, La Niña, volcanic eruptions all create variability. Ocean heat content is the smooth signal underneath. It only goes up.

And it drives everything downstream. Sea level rise is primarily from thermal expansion — water getting warmer and literally expanding. Hurricane intensity is fueled by ocean heat. Coral bleaching is triggered by it.

So the ocean is like a savings account for heat. We keep making deposits and the balance keeps growing. Even if we stopped all emissions today, the ocean would keep warming for decades from the heat already stored.

That's a perfect analogy. And it's why the Arctic is changing so fast — the ocean heat is reaching polar waters and accelerating ice loss in ways our models underestimated even five years ago.