Large Precipitation Events in Northern Vermont Compared to Global Temperature Anomalies and Carbon Dioxide Concentrations

Large precipitation events are a likely outcome of climate change as stated in the Intergovernmental Panel on Climate Change (IPCC) fifth assessment report. The goal of our study was to develop a large precipitation database for Northern Vermont. In a collaborative examination of northern tier weather data that included the stations in Burlington (1864-2014), Johnson (2000-2014), Morrisville (1962-2014), and St. Johnsbury (1894-2014), we analyzed data trends and correlations within the context of larger scale climate change. Large precipitation events, per calendar day, were classified by a baseline of 0.8 inches of precipitation or greater. The number of events per month, year, decade, and the entire dataset were recorded, averaged, and normalized. Positive correlations between global temperature anomalies and the number of events at St. Johnsbury for the years 1894-2014 (0.34), 1900-1949 (0.25), 1950-2014 (0.39) 1984-2014 (0.48) were calculated. Decadal frequencies of event numbering ≥ 1 more than average (1894-2014) reveal twofold increases from 1900-1909 to 2000-2009, indicating a positive trend. Large precipitation events at St. Johnsbury were compared to mean concentrations of atmospheric carbon dioxide (CO2). A correlation of 0.51 between CO2 concentrations and event number from 2000-2010 indicated a close relationship between anthropogenic warming and large precipitation events. Our results suggest that a more in depth analysis of the other Vermont stations is needed to corroborate these findings and confirm trends.