August 15, 2016 4:13PM

You Ought to Have a Look: Natural Climate Variability

You Ought to Have a Look is a feature from the Center for the Study of Science posted by Patrick J. Michaels and Paul C. (“Chip”) Knappenberger. While this section will feature all of the areas of interest that we are emphasizing, the prominence of the climate issue is driving a tremendous amount of web traffic. Here we post a few of the best in recent days, along with our color commentary.


We’ve got a lot cover this week, so let’s get right to it.

On the science front, we want to highlight two new papers that both suggest that attributing heavy precipitation events in the United States to human-caused climate change is a fool’s errand (not that there aren’t plenty of fools running around out there). This is a timely topic to explore with the big rains in Louisiana over the weekend leading the news coverage.

One paper by a research team from the University of Iowa found that “the stronger storms are not getting stronger” and that there has not been any change in the seasonality of heavy rainfall events by examining trends in the magnitude, frequency, and seasonality of heavy rainfall events in the United States. They did report that the frequency of heavy rain events was increasing across much of the United States, with the exception of the Northwest. As to the reason behind the observed patterns, the authors write “[o]ur findings indicate that the climate variability of both the Atlantic and Pacific Oceans can exert a large control on the precipitation frequency and magnitude over the contiguous USA.”

The other paper, from a research team led by NOAA/GFDL’s Karin van der Wiel, examined climate model projections and observed trends in heavy precipitation events across the United States and concludes:

Finally, the observed record and historical model experiments were used to investigate changes in the recent past. In part because of large intrinsic variability, no evidence was found for changes in extreme precipitation attributable to climate change in the available observed record.

Pretty emphatic and straightforward summary.

So, the next time you read that such and such extreme precipitation event was made worse by global warming, you’ll know that there is precious little actual science to back that up.

We’ll note that the more astute science writers are actually familiar with findings like these but rather than fess-up about them, they prefer to further the climate change narrative through the use of weasel words like “is consistent with” expectations from climate change. This particularly useful phrase encompasses virtually all possibilities and allows every weather event to be linked to the nefarious burning of fossil fuels. And we do mean every—bad or good. But in practice, it is reserved by the media to be applied only to bad events or trends. For good-seeming goings-on, “dumb luck” is the preferred descriptor, despite plenty of science that could be used to show that good things, too, “are consistent with climate change expectations.” Go figure.

This unseemly situation is well-summed up in a recently uploaded video by PragerU featuring Bjorn Lomberg titled “Climate Change: What’s So Alarming?” The video is short, roughly 5 minutes, but Lomborg hits on many alarmist talking points and why they are unhelpful in the discussion of how to best approach the climate change issue. 

And if you liked that video from PragerU, the next video in the series (that autoplays in some browsers) is by our Alex Epstein looking into that whole “97% of Scientists Agree” thing.  It too is worth a watch.  

And if you still haven’t gotten your fill of the role of natural viability in the climate system, check out the just-dropped report from the National Academy of Sciences (NAS) on its role in decadal scale climate change.  Judith Curry has her thoughts about the report here, including:

It is certainly gratifying to see this topic being addressed by the NAS, since decadal variability is too often dismissed by the ‘establishment’ as climate ‘noise.’ The questions asked in the report, and the knowledge gaps, raise the important unresolved issues….

What is missing from the report is the longer term context of multidecadal to millennial variability, and the importance of paleoclimate observations. Without this context, we are not going to make much progress on understanding and predicting the decadal variability in the Atlantic, Pacific, Indian Oceans….

Until these issues and knowledge gaps are sorted out, we don’t have the basis for making the above statements with high confidence.

Here’s to hoping that the climate community is ready to take more seriously the natural climate variability on time scales from decades to millennia.

And we found this quote in the report from Geophysical Fluid Dynamics Laboratory’s Dr. Tom Knutson on the global warming slowdown (a.k.a. hiatus) and the interplay between natural variability and climate sensitivity in producing it (and determining how long it will last) particularly interesting:

With a lower [transient climate sensitivity], models can produce slowdown periods that match observations to date and can extend to about 2030.

It seems that the global temperature evolution over the next few years may produce some pretty important insights for coming near-term (this century) greenhouse-gas-induced temperature change and a test of climate model utility and formulation.

We’ll be watching!

You can check out whole NRC report “Frontiers in Decadal Climate Variability: Proceedings of a Workshop (2016),” here.



Mallakpour, I., and G. Villarini, 2016. Analysis of changes in the magnitude, frequency, and seasonality of heavy precipitation over the contiguous USA. Theoretical and Applied Climatology, doi 10.1007/s00704-016-1881-z.

van der Wiel, et al., 2016. The resolution dependence of contiguous US precipitation extremes in response to CO forcing. Journal of Climate, doi:10.1175/JCLI-D-16-0307.1, in press.