evidence: Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that Earth’s climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly 10 times faster than the average rate of warming after an ice age. Carbon dioxide from human activities is increasing about 250 times faster than it did from natural sources after the last Ice Age.3 [...] Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30%.13, 14 This increase is due to humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the ocean. The ocean has absorbed between 20% and 30% of total anthropogenic carbon dioxide emissions in recent decades (7.2 to 10.8 billion metric tons per year).15, 16 [...] 15. C.L. Sabine, et al., "The Oceanic Sink for Anthropogenic CO2." Science 305 (16 July 2004): 367-371. https://doi.org/10.1126/science.1097403.