To the editor:

It was gratifying to see Mark Larson’s letter in response to my climate change article of Dec. 16, asking pertinent questions and searching for more information, so in contrast to the ad hominem attacks so frequently appearing in this international debate. I invite Mark and any others who have a sincere interest in the science to contact me. My e-mail address is in the KU directory.

The decrease in effectiveness of carbon dioxide as a greenhouse gas was first documented over 100 years ago, and most climate scientists are familiar with the thermodynamics. Carbon dioxide is interpreted to have been 17-18 times present levels 500 million years ago, a time when glaciers covered at least part of proto-North America. Their deposits can be seen in Utah. Levels gradually declined into the Cretaceous Period, when they dramatically increased, and have dropped since then. There are numerous chemical measurements of carbon dioxide concentration in the 19th century that were greater than those of the present. I would be pleased to share the references to all of these statements and more if contacted.

Science is advanced by the continual testing of hypotheses. As tests discover discrepancies, hypotheses change. Belief is not part of the scientific method.