Climate change skeptics have often used the great 2000s “global warming slowdown” as evidence that global warming was being blown out of proportion. According to a report from Scientific American, researchers say that global warming actually did slow down over the past 15 years. That still doesn’t prove that the climate isn’t undergoing some massive shifts, however.

The debate was fueled by an observation that the rate of warming was not as fast as some climate models had expected. While the planet continues to warm, it’s doing so at a much slower rate than researchers believed it would.

The debate over whether or not climate change posed a serious threat was centered around whether or not scientists could provide evidence that the planet was actually warming.

The National Oceanic and Atmospheric Administration even recently updated their temperature records to reach the conclusion that the planet was in fact warming. The recent study, published in the journal Nature Climate Change, challenges the NOAA’s new findings and suggests that while it doesn’t disprove climate change, there actually was a slowdown in warming over the past 15 years.

According to lead author John Fyfe, a climate scientist at Environment and Climate Change Canada, “The interpretation the NOAA made was not valid. The slowdown is there, even in this new updated data set.”

The study seeks to address some of the lingering misconceptions in current climate data. Models predicted that temperatures in the early 2000s would be much higher than they actually were. Researchers don’t quite understand why their models overshot the actual average temperature increase during that time period, but they have suggested that it could be due to cooling aerosols from volcanoes or from natural shifts in the currents of the Pacific Ocean.

Whatever the cause, climate skeptics have already jumped in to assert that the new evidence of the hiatus proves that climate change ended in 1998. While the data shows a pretty significant variation from what models predicted, it’s still safe to say that the climate is changing in unpredictable ways.

A press release from Nature describing the details of the study can be found here.