Scientist responds to climate criticism

To the editor:

In a letter to the editor published in your newspaper paper on Feb. 21, you allowed an individual named John Loew to do a grave disservice to your readers by making false and defamatory statements about me and my climate scientist colleagues.

Mr. Loew’s most egregious false claim is that I had “manipulated data” to “hide the decline” in global temperatures. The stolen private e-mail correspondence he cites, firstly, does not refer to me, but to UK scientist Phil Jones. Secondly, it does not even pertain to a discussion of “global temperatures.” The e-mail was written by Jones in 1999, just after the warmest year ever recorded (1998) to that date. It could not possibly have referred to the claim made by climate change deniers like Mr. Loew that global temperatures have declined over this past decade — a claim that is false anyway (the current decade, as recently reported, was the warmest on record).

Jones used the phrase “hide the decline” in reference to work by tree-ring expert Keith Briffa. Because tree-ring information has been found to correlate well with temperature readings, it is used to plot temperatures going back hundreds of years. Briffa described a phenomenon wherein a certain type of tree-ring data (the density of wood) showed an enigmatic decline in response to temperature after about 1960. This decline was the focus of Briffa’s original article, which clearly indicated that these data should not be used to represent temperatures after 1960. Jones simply meant that he was not showing Briffa’s data during the unreliable post-1960 tree-ring data in a diagram he was producing.

Both the U.S. National Academy of Sciences and Penn State University have exonerated me of the false claims by climate change deniers like Mr. Loew that I have engaged in any “manipulation” of data.

Readers interested in the truth behind the science of climate change, rather than the falsehoods and smears perpetuated by people like Mr. Loew, should consult the scientist-run website www.realclimate.org, or scientifically based books on the topic like my “Dire Predictions: Understanding Global Warming.”

If find it ironic that Mr. Loew accuses scientists (including myself) of being “dishonest.” It is those like Mr. Loew who spread false information about science and scientists — whether knowingly or by simply uncritically parroting the disinformation of others — who do the greatest harm to the public discourse on vital issues such as climate change.

Michael E. Mann,Professor

Dept. of Meteorology, Penn State University

Director, Penn State Earth System Science Center