Trees tell us how
local climates
have changed.
They are
not useful for
studying the
global average
temperature.
Since the 1960s,
the tree ring
measurements,
as a group,
have suggested
a cooler, global
climate coming,
the opposite of
thermometer
measurements,
and climate model
wild guesses.
Photographs
from the late 1800s,
during California’s
gold rush days,
revealed the near
total devastation
of surrounding
forests.
Gold miners needed
lots of wood for:
- Heating
- Cooking
- Metal forges,
- Timbers to reinforce mines.
- Wood to build flume boxes
Those forests
totally recovered,
and are now
so dense
people fear
that there’s
too much fuel
on the
forest floor,
that could feed
catastrophic
wildfires.
Tree ring counts
say a majority
of the trees
there today are
are no more than
170 years old
-- post 1849.
Tree rings
and fire scars
tell scientists that
low elevation trees,
like Ponderosa Pines,
naturally endured
wildfires that happened
about every 25 years.
At higher elevations,
where temperatures
are colder, and the
snow pack lingers,
fire scars suggest
wildfires naturally
happen every
100 years.
Fire scars in living and
fossil trees suggest
wildfires were far
more common during
the cool Little Ice Age
centuries.
Hikers in the
Sierra Nevada
often encounter
dead trees several
hundred feet above
our current tree line.
Researchers say
for the past three
thousand years,
the tree line there
was mostly higher
than today, because
temperatures were
much warmer.
During the
Little Ice Age,
between roughly
1300 AD and
1850 AD,
it got so cold,
the tree line
in Europe dropped,
and tree seedlings
in the
Ural Mountains
couldn’t germinate
for hundreds
of years.
California’s
Blue Oaks
happen to be
very sensitive
to changes
in precipitation.
In drought years,
they generate
narrow rings,
with wider rings
during wet years.
A recent
tree ring study
of Blue Oaks found
no rainfall trends over
the past 700 years,
but the study suggests
extreme droughts,
and extreme rainfall,
happen in California
about 3 to 4 times
a century.
Fossil trees
indicate that
Antarctica
experienced
subtropical
temperatures
40 million
years ago !
Tree rings
indicate
the warmest
decades
of the
20th century
for the U.S.,
and Europe,
were the 1930s
and 1940s.