NOAA/WDS Paleoclimatology - Pederson - Middleburgh - QUPR - ITRDB NY039

Six water emergencies have occurred since 1981 for the New York City region (NYC) despite: 1) its perhumid climate, 2) substantial conservation of water since 1979 and 3) meteorological data showing little severe or extreme drought since 1970. We reconstruct 472 years of moisture availability for the NYC watershed to place these emergencies in long-term hydroclimatic context. Using nested reconstruction techniques, 32 tree-ring chronologies comprised of 12 species account for up to 66.2% of the average May-August Palmer Drought Severity Index. Verification statistics indicate good statistical skill from 1531-2003. The use of multiple tree species, including rarely-used species that can sometimes occur on mesic sites like Liriodendron tulipifera, Betula lenta and Carya spp., seems to aid reconstruction skill. Importantly, the reconstruction captures pluvial events in the instrumental record nearly as well as drought events and is significantly correlated to precipitation over much of the northeastern US. While the mid-1960s drought is a severe drought in the context of the new reconstruction, the region experienced repeated droughts of similar intensity, but greater duration during the 16th and 17th centuries. The full record reveals a trend towards more pluvial conditions since ca 1800 that is accentuated by an unprecedented, 43-year pluvial event that continues through 2011. In the context of the current pluvial, decreasing water usage, but increasing extra-urban pressures, it appears that the water supply system for the greater NYC region could be severely stressed if the current water boom shifts towards hydroclimatic regimes like the 16th and 17th centuries.