Sep 7, 2016

Early springs could occur more frequently

Warm springs in the Great Lakes and Northeast regions – which create havoc for agriculture – may start earlier by mid-century if greenhouse gas emissions are not reduced, according to a new Cornell study published in Climate Dynamics.

Very warm springs have been anomalies, but this new analysis of climate model data shows an increased frequency to nearly one in every three years by the end of this century.

“The spring of 2012, with its summerlike warmth, brought plants out of dormancy and then had a lengthy freeze. This was a nightmare scenario for many growers, and it showed us a snapshot of what global warming might look like in this region,” said Toby Ault, assistant professor in earth and atmospheric sciences, an author on the study.

Unusually warm temperatures early in spring 2012 led to the warmest March, breaking records in more than 15,000 U.S. sites.

Modeling shows that frequency and magnitude of early springs could occur more than a month earlier, for example, throughout the Great Lakes region by 2080.

“The time to act on curbing greenhouse gas emissions is now. If we don’t, years like 2012 – ruinous to farmers and producers – in the U.S. could become normal by 30 to 40 years from now in addition to a host of other impacts,” said Ault.

The researchers sought to understand seasonal-transition timing to offer strategies as climate change unfolds. To ensure their models are accurate, Ault said researchers distinguished and separated normal climatic variability from long-term atmospheric alterations, by using a new ensemble of climate change simulations.

Meteorologists said March 2012, the earliest spring since 1900, prematurely interrupted winter plant dormancy. After a warm winter 2011-12, some orchards blossomed earlier than usual that spring. Temperatures tumbled in April, and crops were destroyed. Economic losses mounted.

In Ithaca, for example, temperatures March 12-25, 2012, averaged 15- to 30-degrees above normal. On March 18, 19 and 21, the thermometer struck 77 degrees – all new records. The high temperature March 20 was 74 degrees. March’s normal average is 32.6 degrees. Like many Northeastern locations, Ithaca recorded its average warmest March on record at 45.2 degrees, according the Northeast Regional Climate Center.

This warming set up the perfect scenario to ruin tree crops: On April 6 and 7 the temperature plummeted to 20 degrees. Temperatures below 24 degrees for several hours can damage blossoming crops. The April 6 low temperature went below 24 degrees for six hours, while on April 7, the low temperature dropped below the threshold for seven hours.

That spring, U.S. tart cherry production plummeted 68 percent, according to the U.S. Department of Agriculture. Michigan – with 135 million pounds of tart cherry production in 2010 – saw only 5.5 million pounds of that crop, while New York, which saw 7.8 million pounds in 2010, harvested only 1.1 million pounds. Michigan reported about $500 million in agricultural damage.

In addition to Ault, the authors of “Identifying anomalously early spring onsets in the CESM large ensemble project,” include Zachary Labe, University of California, Irvine, and Raul Zurita-Milla, University of Twente, Netherlands. The research was supported by the United States Geological Survey, the National Science Foundation and the National Phenology Database at the USA National Phenology Network.

— Blaine Friedlander, Cornell University

Source: Cornell Chronicle