First freezes ar­rive ever later, data says

Shrink­ing win­ters good for gar­dens, but long-term ef­fects are bad

Houston Chronicle Sunday - - HEALTH | SCIENCE - By Seth Boren­stein

WASHINGTON — Win­ter is com­ing … later. And it’s leav­ing ever ear­lier.

Across the United States, the year’s first freeze has been ar­riv­ing fur­ther and fur­ther into the cal­en­dar, ac­cord­ing to more than a cen­tury of mea­sure­ments from weather sta­tions na­tion­wide.

Sci­en­tists say it is yet an­other sign of the chang­ing cli­mate, and that it has good and bad con­se­quences for the na­tion. There could be more fruits and veg­eta­bles — and also more al­ler­gies and pests.

“I’m happy about it,” said Karen Dun­can of Streator, Ill. Her flow­ers are in bloom be­cause she’s had no frost this year yet, just as she had none last year at this time ei­ther. On the other hand, she said just last week it was too hot and buggy to go out — in late Oc­to­ber, near Chicago.

The trend of ever later first freezes ap­pears to have started around 1980, ac­cord­ing to an anal­y­sis by The Associated Press of data from 700 weather sta­tions across the U.S. go­ing back to 1895 com­piled by Ken Kunkel, a me­te­o­rol­o­gist at the Na­tional Oceanic and At­mo­spheric Ad­min­is­tra­tion’s Na­tional Cen­ters for En­vi­ron­men­tal In­for­ma­tion. ‘Way off the charts’

To look for na­tion­wide trends, Kunkel com­pared the first freeze from each of the 700 sta­tions to the sta­tion’s av­er­age for the 20th Cen­tury. Some parts of the coun­try ex­pe­ri­ence ear­lier or later freezes ev­ery year, but on av­er­age freezes are com­ing later.

The av­er­age first freeze over the last 10 years, from 2007 to 2016, is a week later than the av­er­age from 1971 to 1980, which is be­fore Kunkel said the trend be­came no­tice­able.

This year, about 40 per­cent of the Lower 48 states have had a freeze as of Oct. 23, com­pared to 65 per­cent in a nor­mal year, ac­cord­ing to Jeff Mas­ters, me­te­o­rol­ogy di­rec­tor of the pri­vate ser­vice Weather Un­der­ground.

Dun­can’s flow­ers should be dead by now. Ac­cord­ing to data from the weather sta­tion near her in Ot­tawa, Ill., the av­er­age first freeze for the 20th cen­tury was Oct. 15. The nor­mal from 1981 to 2010 based on NOAA com­puter sim­u­la­tions was Oct. 19. Since 2010, the av­er­age first freeze is on Oct. 26. Last year, the first freeze in Ot­tawa came on Nov. 12.

Last year was “way off the charts” na­tion­wide, Kunkel said. The av­er­age first freeze was two weeks later than the 20th cen­tury av­er­age, and the last frost of spring was nine days ear­lier than nor­mal.

Over­all the United States freeze sea­son of 2016 was more than a month shorter than the freeze sea­son of 1916. It was most ex­treme in the Pa­cific North­west. Ore­gon’s freeze sea­son was 61 days — two months — shorter than nor­mal.

Global warm­ing has helped push the first frosts later, Kunkel and other sci­en­tists said. Also at play, though, are nat­u­ral short­term changes in air cir­cu­la­tion pat­terns — but they too may be in­flu­enced by man­made cli­mate change, they said. ‘Neg­a­tive’ con­se­quences

This shrink­ing freeze sea­son is what cli­mate sci­en­tists have long pre­dicted, said Uni­ver­sity of Ok­la­homa me­te­o­rol­ogy pro­fes­sor Ja­son Fur­tado.

A shorter freeze sea­son means a longer grow­ing sea­son and less money spent on heat. But it also hurts some plants that re­quire a cer­tain amount of chill, such as Ge­or­gia peaches, said Theresa Crim­mins, a Uni­ver­sity of Ari­zona ecol­o­gist. Crim­mins is as­sis­tant di­rec­tor of the Na­tional Phenol­ogy Net­work . Phenol­ogy is the study of the sea­sons and how plants and an­i­mals adapt to tim­ing changes.

Pests that at­tack trees and spread dis­ease aren’t be­ing killed off as early as they nor­mally would be, Crim­mins said.

In New Eng­land, many trees aren’t chang­ing col­ors as vi­brantly as they nor­mally do or used to be­cause some take cues for when to turn from tem­per­a­ture, said Bos­ton Uni­ver­sity bi­ol­ogy pro­fes­sor Richard Pri­mack.

Clus­ters of late-emerg­ing monarch but­ter­flies are be­ing found far fur­ther north than nor­mal for this time of year, and are un­likely to sur­vive their mi­gra­tion to Mex­ico.

Kevin Tren­berth, a cli­mate sci­en­tist at the Na­tional Cen­ter for At­mo­spheric Re­search, said nat­u­ral vari­abil­ity, es­pe­cially an El Nino, made last year ex­cep­tional for an early freeze, but “it rep­re­sents the kind of con­di­tions that will be more rou­tine in a decade or two” be­cause of man-made cli­mate change.

“The long-term con­se­quences are re­ally neg­a­tive,” said Pri­mack, be­cause shorter win­ters and hot­ter tem­per­a­tures are also ex­pected to lead to ris­ing seas that cause worse flood­ing dur­ing heavy storms.

In sub­ur­ban Bos­ton, Pri­mack and his wife are still eat­ing let­tuce, toma­toes and green beans from their gar­den. And they are get­ting fresh figs off their back­yard tree al­most daily.

“These fig trees should be asleep,” Pri­mack said.

David McK­e­own / Repub­li­can-Her­ald via AP

In New Eng­land, many trees aren’t chang­ing col­ors as vi­brantly as they nor­mally do be­cause they take cues for when to turn from the tem­per­a­ture.

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