Prescient about mankind’s negative impact on nature, the multidisciplinary artist Carl Cheng has focused his work on this subject since the early 1960s, when he came of age during the counterculture decade. In his sculpture, photography, and public art, Cheng juggles the severity of our many environmental crises with a biting sense of irony. For example, his “Erosion Machines,” a series of sculptures in which water erodes “human rocks,” is a commentary on the man-made landscapes destroying our natural surroundings. An exhibition highlight is the hundreds of sculptures, gathered in a greenhouse, that Cheng carved in avocado pits. This show in Austin is his first in-depth institutional survey. —Lucy Horowitz