A new study published recently comes to the incredible conclusion that ocean temperatures are now about where they were more than 100,000 years ago, when sea levels were 20 or even 30 feet higher than they are now. It’s a head-scratching finding that causes scientists to question why we are not seeing those sea levels today, and if our understanding of sea levels from ages ago are even accurate given what we now know about climate change.

The Earth has fluctuated between warming and cooling trends over the billions of years it has been around. Scientists have been able to identify these trends and when they happened by examining ancient rock and ice. But there’s a problem: based on what we now know about climate change, its effects aren’t spread out over the globe equally, as some areas get hotter than others, meaning that perhaps we are often getting an inaccurate snapshot of one area when we look into the past.

That’s why a lot more work will need to be done to understand this latest, study, which claims that the last interglacial period that happened between 129,000 and 116,000 years ago had similar temperatures to our current planet, but with a global sea level that was much, much higher.