Conservative billionaire brothers Charles and David Koch are turning down an invitation extended in a full-page ad in their hometown newspaper asking them to join a public debate on climate change.

The Wichita Eagle reports  that Friday’s advertisement was placed by NextGen Climate Change, a group supporting the views of retired billionaire investor Tom Steyer.

Koch corporate spokeswoman Melissa Cohlmia says they are not experts on climate change.

NextGen spokeswoman Heather Wong says they are glad Koch Industries has acknowledged they are not experts on climate change.

The political advertisement labeled itself as “An invitation to the Koch brothers,” and juxtaposed photographs of David Koch vs. Steyer side by side.