1) The second half of the 20th century warmed more rapidly than any previous time in the last 2000 years, putting the extraordinary rate of current climate change into a long-term context.
2) Before the industrial revolution, volcanic eruptions were the most important forcing of multi-decadal climate variations during this time period.
3) Climate models capture the magnitude of volcanic-forced cooling and natural variability well.
This study was an international collaboration which used a global collection of well-vetted proxy records (such as tree rings, corals, and ice cores) to reconstruct Common Era climate, led by Raphael Neukom at the University of Bern. Coauthors of this study at Northern Arizona University include Darrell Kaufman, Nicholas McKay, and myself.
An NAU press release about the paper can be read here: https://news.nau.edu/pages-2k/