The article is suggesting that the current climate models have failed to take into account the natural heating of the Arctic Ocean caused by the expansion of warmer Atlantic waters into the region before the Industrial Revolution.

This actually means, contrary to your interpretation, that the climate models need to add this heating force in addition to the heating caused by greenhouse gas emissions. This means that the current climate models may be under-reporting the rate of global heating, especially in the Arctic.

You forgot to add this crucial quote by one of the authors of the study,

It is possible that the Arctic Ocean is more sensitive to greenhouse gases than previously thought.

In light of this, I still accept the current evidence for human induced climate change.

• edited: I change "are" to "may" as science is never 100% no matter what Pfizer says ;)