The Mann, Bradley and Hughes reconstruction covering 1,000 years (MBH99) was published by "Geophysical Research Letters" in March 1999 with the cautious title "Northern Hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations". Mann said that "As you go back farther in time, the data becomes sketchier. One can't quite pin things down as well, but, our results do reveal that significant changes have occurred, and temperatures in the latter 20th century have been exceptionally warm compared to the preceding 900 years. Though substantial uncertainties exist in the estimates, these are nonetheless startling revelations." When Mann gave a talk about the study to the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory, climatologist Jerry D. Mahlman nicknamed the graph the "hockey stick".