You don’t want them walking away saying, ‘I paid to get in, I bought my kid a hot dog, I just want to show my kid a fish -- and you are making me feel bad about climate change,’

Paul Boyle, the senior vice president for conservation and education at the Association of Zoos and Aquariums, on why some zoos' and aquariums' are reluctant to dwell on climate change during tours or on instructional signs.