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Columbus’ arrival linked to CO2 drop
By Devin Powell
By crossing the Atlantic, Christopher
Columbus and other explorers who followed him may have set off a chain of
events that cooled Europe’s climate.
The European conquest
decimated America’s native
people, leaving large areas
of cleared land untended.
Trees that filled in this territory pulled billions of tons
of carbon dioxide from the
atmosphere, Stanford University geochemist Richard
Nevle reported October 11.
Such CO2 removal could have diminished the heat-trapping capacity of the
atmosphere and cooled the climate,
Nevle and his colleagues have previously
“We have a massive reforestation event
that’s sequestering carbon … coincident
with the European arrival,” said Nevle.
Tying together many different lines
of evidence, Nevle estimated how much
carbon all those new trees would have
consumed. He said it was enough to
account for most of the sudden drop in
atmospheric CO2 recorded in Antarctic
ice during the 16th and 17th centuries.
Such a depletion of the key
greenhouse gas may have
helped kick off Europe’s
Little Ice Age, centuries of
cooler temperatures that
followed the Middle Ages,
Nevle’s team has argued.
By the end of the 15th cen-
tury, between 40 million
and 100 million people are
thought to have been living in the Amer-
icas. Many of them burned trees to make
room for crops, leaving behind charcoal
deposits that have been found in the soils
of Mexico, Nicaragua and other countries.
About 500 years ago, this charcoal
accumulation plummeted as smallpox,
diphtheria and other European diseases
ravaged the population. Trees returned,
may have set
off a chain
Fossil moth had
Paleontologists deduce how
wing ridges reflected light
By Devin Powell
Ancient moths have for the first time
shown their true colors to modern
By piecing together clues from a fossil
unearthed in a former German quarry,
a team of scientists has figured out how
light bounced off a moth that lived 47 million years ago. Today, the insect’s remains
are bluish. But before time alchemized
its wings, the creature was mostly yellow-green, with only a fringe of blue.
“The original colors aren’t preserved,
but they can be reconstructed,” said Yale
paleontologist Maria McNamara, who
presented the new findings October 9.
Like beetles and dragonflies, modern
moths and butterflies owe their brilliant
hues not only to chemical pigments but
also to the shape of tiny structures on
their wing scales. Parallel ridges redirect incoming light waves, which bounce
around and interfere like crashing ocean
waves. Depending on how the peaks and
troughs line up, this interaction boosts
some colors at the expense of others.
McNamara’s team found that the shape
of the moth’s ridges had survived fossil-
ization without shrinking or swelling.
When the moth — an ancient relative
of today’s Pollanisus moths — was alive,
these structures would have favored a
reforesting an area at least the size of
California, Nevle estimated. This new
growth could have soaked up between
2 billion and 17 billion metric tons of CO2
from the air.
Ancient ancestors of Pollanisus moths,
one of which is shown here, sported a
yellow-green color, researchers report.
wavelength of about 565 nanometers,
turning the moth’s wings yellow-green.
“This is bloody brilliant work,” said
Phil Manning, a paleontologist at the
University of Manchester in England
who studies pigments. “This group is
the first to work out structural color in