Continuing with our fact check of Al Gore’s rant in Davos we come to his claim that you-know-what is “creating these atmospheric rivers”. And “atmospheric rivers” is, admittedly, a very impressive piece of rhetorical imagery, but they are as normal as the regular kind of river and have been around at least as long. The specific term was coined in 1998 to describe a pattern observed in the water cycle, in which about 90 percent of the water vapor moving poleward in the atmosphere out of the tropics gathered itself up into relatively narrow channels that only took up about 10 percent of the available space. Because of the concentration of moisture, they do play an important role in determining where rainfall will land. But they didn’t appear in 1998. Rather, they seem to be normal, permanent elements of the Earth’s climate system though the IPCC didn’t discuss them until its most recent Sixth Assessment Report, where they said they might be a bit more common now than in the past but maybe not, and even if they are there is no evidence tying the change to greenhouse gases. But what would they know? Al Gore hath spoken.
Specifically the AR6 said:
“In summary, it is likely that there was an increasing trend in the AR activity in the eastern North Pacific since the mid-20th century. However, there is low confidence in the magnitude of this trend and no formal attribution, although such an increase in activity is consistent with the expected and observed increase in precipitable water associated with human-induced global warming.”
They also said that climate models project Atmospheric Rivers will become more common in the future along the North American west coast (aha!), but another study says they will become a bit less common globally (rats.) Make of it what you wish. For Al Gore, the rhetorical flood is impossible to resist.