Native Tree Society BBS

I didn’t see this coming. Yes, winter 2011-2012 has been quite unusual and it is becoming more obvious that almost anything can happen with our weather these days (see October snowstorm followed by days in winter 2012 when my house windows were opened). But, a moderate to severe drought just seven months after many of us were wondering if the rainstorms were going to stop? With the insight that my co-authors and I had looking over the past 500 years of drought history for the Greater NYC region, I didn’t expect this.



In a paper currently in revision with the Journal of Climate, we reconstructed drought history using tree rings back to the year 1531. We were wrapping up the manuscript in Summer 2011 when the march of the tropical storms was beginning. To talk about the drought reconstruction for a hike I was leading on Columbia’s Lamont-Doherty campus, I put together a record of the Palmer Drought Severity Index derived from meteorological measurements. When I first calculated annual and summer drought for the past 110 years, I thought I or the web source used to gather the data made a mistake because it looked odd, unnatural even. It looked like The Hockey Stick, but for moisture, not temperature.