Yeah I read about that. Very interesting and thorough debunking in which the Singer APS list was found to contain around 0.4% of the entire APS membership, the list was almost entirely composed of older and retired members (very few signers under the age of 50), and few signers had any research experience in climate science. All in all a pretty pathetic list, but that's what you get for trying to get physicists to sign something utterly stupid.