In the year 2000, esteemed climatologist and geophysicist Michael E. Mann of Pennsylvania State University coined a term he would come to loath. “Atlantic Multidecadal Oscillation”, or AMO for short, was used to describe an oscillation pattern between the North Atlantic ocean currents and the wind patterns above. Similar to the El Nino/Southern Oscillation (ENSO), however the AMO lasting over the course of decades rather than a year or two like ENSO.

In an article recently published by Mann, he explains “back in the 1980s and 1990s, a number of articles pointed to a pattern of North Atlantic warming during the 1930s-1950s, subsequent cooling in the 1960s and 1970s, and warming thereafter, which seemed to resemble a natural oscillation in the climate system”.

At the time, Mann and his colleagues had mountains of data collected from the analysis of a long-term ocean-atmosphere model from the Princeton Geophysical Fluid Dynamics Laboratory. This state-of-the-art (at the time) model processed data that expanded over a thousand years in the past and presented the conclusion that over time, the North Atlantic went through several internal warming and cooling periods. Basically, it was something that simply just happens. However, there was one major (unbeknownst) caveat to the model. It ran as a “control” model, meaning it did not factor in external “forcing” such as no greenhouse gas changes, no variations in solar output, no volcanic eruptions, etc.

In Mann’s article, he states “at times I feel like I created a monster when I gave a name to this putative climate oscillation in 2000. The concept of the AMO has since been misapplied and misrepresented to explain away just about every climate trend under the sun, often based on flawed statistical methods that don’t properly distinguish a true climate oscillation from a time-varying trend.”

Essentially, this was the fuel climate change deniers needed to fund a 20-year long campaign that involved a respected climatologist conducting a study that proves that climate change is not caused by humans (anthropologic forces), but rather a natural warming/cooling phenomenon that occurs every few decades.

But Dr. Mann and his colleagues recently came to realize that their initial climate simulations that “discovered” the AMO failed to take into account volcanic activity, the massive amount of aerosols that injects into the atmosphere, and the climate impacts that can have.

New climate simulations Dr. Mann recently ran, taking into account historic volcanic activity and also the current human-induced emissions of heat-trapping gases, found a different conclusion.

His simulations now prove that spikes in temperatures that lasted for decades thousands of years ago were actually a result of explosive volcanic forcing, and not internal temperature fluctuations caused by the AMO. This evidence also now concludes that the AMO is not the reason for our current warming trend over the past few decades, but is actually highly attributed to a combination of anthropogenic forcing such as greenhouse warming and sulphate aerosol cooling.

In his latest scientific findings, Mann and his colleagues now discovered that they were in fact wrong when coining the AMO in 2000, and that the AMO is “an artifact” and “doesn’t actually exist”. This comes as evidence from runs of “last millennium” climate models that take into account such forcing that his models from the late 1990s did not, in particular volcanic and solar radiation.

The current warming trend has been attributed to the recent hyper-activity in tropical systems over the past 20+ years. Leading many to think that this is a cycle that will eventually come to an end. Now that it is found that the AMO is non-existent, the question of how long extreme activity in the Atlantic Basin will last weighs heavy on many scientists and bureaucrats.

In conclusion, Mann and his team were not wrong about the warming trend currently taking place across the globe. But he was wrong in that it is not a result of the existence of the AMO.