Future projections of extreme precipitation intensity-duration-frequency curves for climate adaptation planning in New York State

Abstract

Listen

Translate article

A set of future extreme precipitation probabilities are developed for New York State based on different downscaling approaches and climate model projections. Based on nearly 50 downscaling method-climate model combinations, percent differences are computed between simulated extreme precipitation amounts for one historical (1970–1999) and three future (2010–2039, 2040–2069, and 2070–2099) time periods. These percent change factors are then applied to the observed extremes to estimate future precipitation extremes. The results are presented to users via an interactive website (http://ny-idf-projections.nrcc.cornell.edu). As the engineering community is the primary user, the website displays intensity-duration-frequency (IDF) graphs depicting the: 1) mean projected extreme precipitation intensity, 2) range of future model projections, 3) distribution of observed extreme precipitation intensities, 4) confidence intervals about the observed values.One-hundred-year recurrence interval precipitation amounts exhibit a median increase of between 5 and 10% across the state in the 2010–2039 period regardless of greenhouse gas concentration. By the 2040–2069 period, the median increase is on the order of 10–20% for the high concentration case (RCP 8.5), but remains below 10% if concentrations are lower (RCP 4.5). At the end of the century, all downscaling method climate model combinations indicate increases, with a median change of between 20 and 30% in the case of high concentrations.