On June 23, 1988, a sultry day in Washington, James Hansen told Congress and the world that global warming wasn’t approaching — it had already arrived. The testimony of the top NASA scientist, said Rice University historian Douglas Brinkley, was “the opening salvo of the age of climate change.” Thirty years later, it’s clear that Hansen and other doomsayers were right. But the change has been so sweeping that it is easy to lose sight of effects large and small — some obvious, others less conspicuous.