Water’s unclear origins, shaky solutions to climate change and more reader feedback

Water’s origin story

New evidence suggests that comets may not have delivered water to Earth. Water detected in comet 67P/Churyumov–Gerasimenko’s hazy atmosphere isn’t a chemical match for Earth’s oceans, as Ashley Yeager reported in “Ocean water may not be from comets” (SN: 1/10/15, p.