In the climatologists at work file, here's Dorothy Peteet exploring a marsh about twenty miles north of New York City, taking core samples from the past to extract pollen records, and discovering that during the Medieval Warm Period, what eventually become NYC endured a 500-year drought.
Peteet is on the hunt for pollen. She dredges up mud from as deep as 45 feet underground and hauls it back to her lab at the nearby Lamont-Doherty Earth Observatory. There she boils, bakes, and filters it to sift out pollen, not much thicker than a human hair, from plants several thousand years old. The relative abundance and variety of different species indicate climate conditions at the time the pollen was dropped: An uptick of dry-weather species like hickory and pine points to drought.
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In 2005, Peteet unearthed evidence of a 500-year-long drought that baked the New York City region from 800 to 1300 A.D., a time known as the Medieval Warming Period (because this ancient warming happened in an age before human greenhouse gas emissions, it’s become a favorite reference of climate skeptics; however, today’s temperatures are even warmer than then, and recent science indicates that the Medieval warming was driven by higher-than-normal solar radiation and lower-than-normal volcanic activity. It was also concentrated in the Northern Hemisphere, unlike contemporary global warming, which is worldwide).
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“What is it going to be like if we have a 500 year drought?” Peteet says. Piecing together the pollen record, she says, can help establish patterns that policymakers and the public could draw on to better anticipate what the future will hold. As it stands, climate scientists think New York is in for hotter and wetter conditions, which, meteorologist Kevin Trenberth of the National Center for Atmospheric Research explains, can, somewhat counterintuitively, lead to more droughts. Precipitation is expected to increase, but it will happen in a series of severe downpours interspersed with dry spells; warmer temperatures in these dry spells can prolong them and increase the risk of drought.
Fracking in NYC has been controversial in large part because Manhattanites are nervous about their water supply: perhaps they should be asking how well they are equipped for a long-term drought.
From the ever-industrious Climate Desk.
Kit Stolz 