Two things stood out above the other findings: an examination of the so-called “pause” in global warming, so much talked about in recent years; and estimates of the world’s “carbon budget,” or the amount of greenhouse gas that can safely be released into the atmosphere if the limit of 2 °C (3.6 °F) over preindustrial levels — beyond which scientists estimate that aspects of climate change are likely to become catastrophic and irreversible — is not to be exceeded.