Posted: Mar 30, 2018 3:10 am
by OlivierK
Two other possible lines of response are to note the page you linked is all about US climate, not global climate, and also to direct him to the work of skeptic Richard Muller's BEST study, which sought to establish whether such adjustments were valid, and whether handling them the way skeptics suggest they should be handled would lead to different conclusions about whether warming was occurring and whether it was anthropogenic (spoiler: it actually convinced Muller that those doubting mainstream climate science on these grounds were wrong.)