Before global warming, was the Earth cooling down or heating up?

A review article published today in Nature addresses this conflict between models and evidence, known as the Holocene global temperature conundrum. Lead author Darrell Kaufman, a Regents’ professor in the School of Earth and Sustainability, and University of Arizona postdoctoral researcher Ellie Broadman, a co-author who worked on this study while earning her Ph.D. at NAU, analyzed a broad swath of available data from the last 12,000 years to break down the conundrum.