More evidence that CO2 is clearly the most powerful temperature driver? CO2 forced the high in Waterloo, Iowa all the way up to 54 degrees F. yesterday, while on the same date in 1934, back when CO2 levels were safe, the high only reached 108 F.

Waterloo sets apparent record after chilly day

WATERLOO, Iowa --- Thursday proved cool across much of Iowa and may have set a record for the date.

The temperature topped out at 54 degrees, according to the National Weather Service, an apparent record low maximum temperature for May 31 in Waterloo.

...May also has the potential for extremes in the other direction. The record high for the month in Waterloo is 108 degrees set on May 31, 1934.