Spring Arriving Earlier, Study Finds
Date: 22-Jan-09
Country: US
Author: Maggie Fox, Health and Science Editor
Spring Arriving Earlier, Study Finds Photo: Yuri Gripas
A jogger runs
by cherry blossom trees along the Tidal Basin in Washington, March 27, 2008.
Photo: Yuri Gripas
WASHINGTON - Looking forward to spring? The good news is that it is coming
two days earlier on average, but so are summer, autumn and winter,
researchers said on Wednesday.
They found that on average, the hottest day of the year in temperate regions
has moved forward by just under two days, and so has the coldest day of the
year.
While the consequences of this shift are not clear, it is worrying,
Alexander Stine of the University of California, Berkeley and colleagues
said.
"All of the seasons are coming earlier. They are both hotter and they are
earlier," Stine said in a telephone interview.
The effect can be seen in both the northern and southern hemispheres, said
Stine, whose team studied more than 100 years of temperature data to tease
out the pattern.
Writing in the journal Nature, Stine and colleagues said the effect is
related to global warming and is very likely to be caused by humans.
The shift in seasons is unsettling because none of the climate change
computer models predict this, Stine said.
"There are certain things that we expect from global warming and there are
certain things that we don't," he said.
"You expect that, say, the ice is going to melt a little earlier ... and you
expect the ice is going to form a little bit later in the year. But what you
don't expect to see is for the hottest day of the year to be earlier."
Stine's team found that land temperatures between 1850 and 1950 showed a
simple pattern of variability, with the hottest day of the year in the
Northern Hemisphere around July 21. Between 1954 and 2007, temperatures
peaked 1.7 days earlier.
Peak temperatures come about a month after the solstices -- when the sun's
rays hit the Earth more or less indirectly, causing summer and winter. Stine
said it takes time for the rays to heat up the land in the summer, and for
things to cool off during the period of indirect sunlight.
This pattern suggests the planet has lost something that helps draw out the
process.
"The land is putting up less resistance to what the sun is telling it to
do," Stine said.
There may be a loss of moisture in the soil, or some other factor like
pollution, he said.
"If the way the Earth is responding to the sun is changing, we'd like to
know that," Stine said. "There is a concern that we may be missing some
important processes."
The finding fits in with other research that shows spring begins earlier in
certain areas of Britain, for instance, and that growing seasons have
shifted forward.
(Reporting by Maggie Fox; Editing by Julie Steenhuysen)
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