Wash.
Me.
Mont.
N.D.
Minn.
Vt.
Ore.
N.H.
Idaho
Wis.
N.Y.
S.D.
Mich.
Wyo.
Pa.
N.J.
Iowa
Neb.
Nev.
Ohio
Ind.
Ill.
Utah
W.Va.
Colo.
Calif.
Va.
Kan.
Mo.
Ky.
N.C.
Tenn.
Okla.
Ariz.
Ark.
N.M.
S.C.
Ga.
Ala.
Miss.
Tex.
La.
SPRING FOLIAGE
Fla.
Days early, against 30-year average
5
15
25
By the 2017 calendar, the first day of spring is
March 20. But spring leaves arrived in mid-January in some parts of the
South, and spread northward like a wave. The map above plots the date
of “first leaf,” a temperature-based calculation of when vegetation that
has been dormant starts to show signs of life. This year, with the
exception of a few small areas, the wave has arrived much earlier than
the 30-year average.
An early spring means more than just earlier
blooms of fruit trees and decorative shrubs like azaleas. It can wreak
havoc on schedules that farmers follow for planting and that tourism
officials follow for events that are tied to a natural activity like
trees blooming. Some plant species that bud early may be susceptible to a
snap frost later, and early growth of grasses and other vegetation can
disrupt some animals’ usual cycles of spring feeding and growth.
First leaf can vary greatly from year to year
and location to location, but the general long-term trend is toward
earlier springs.
End of January
End of February
Wash.
Wash.
Me.
Me.
Mont.
Mont.
N.D.
N.D.
Minn.
Minn.
Ore.
Ore.
Idaho
Idaho
Wis.
Wis.
N.Y.
N.Y.
S.D.
S.D.
Mich.
Mich.
Wyo.
Wyo.
Pa.
Pa.
Iowa
Iowa
Neb.
Neb.
Nev.
Nev.
Ohio
Ohio
Ill.
Ill.
Utah
Utah
Colo.
Colo.
Calif.
Calif.
Va.
Va.
Kan.
Kan.
Mo.
This year
Ky.
N.C.
N.C.
Okla.
Okla.
Ariz.
Ariz.
Ark.
Ark.
N.M.
N.M.
S.C.
S.C.
30-year
average
This year
Tex.
Tex.
La.
La.
Fla.
Fla.
30-year
average
FIRST LEAF INDEX
Extent of spring leaves, by month
The New York Times
The new research shows a strong link between
global warming and the very warm February that helped to drive the
extremely early spring this year. For the entire continental United
States, February 2017 was the second warmest on record, and mean
temperatures were especially high east of the Rockies: as much as 11
degrees Fahrenheit above normal.
The study, by scientists working as part of a group called World Weather Attribution,
looked at the influence of climate change on the temperatures, using
models of the atmosphere as it exists and of a hypothetical atmosphere
with no greenhouse gas emissions and thus no human-driven climate
change. They found that a warm February like the one just experienced is
about four times more likely in the current climate than it would have
been in 1900, before significant emissions began to change the climate.
Sources: USA National Phenology Network; World Weather Attribution
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