Paleoceanography and Paleoclimatology,
Journal Year:
2023,
Volume and Issue:
38(5)
Published: April 18, 2023
Abstract
Two
large
volcanic
eruptions
contributed
to
extreme
cold
temperatures
during
the
early
1800s,
one
of
coldest
phases
Little
Ice
Age.
While
impacts
from
massive
1815
Tambora
eruption
in
Indonesia
are
relatively
well‐documented,
much
less
is
known
regarding
an
unidentified
event
around
1809.
Here,
we
describe
spatial
extent,
duration,
and
magnitude
conditions
following
this
northwestern
North
America
using
a
high‐resolution
network
tree‐ring
records
that
capture
past
warm‐season
temperature
variability.
Extreme
persistent
were
centered
Gulf
Alaska,
adjacent
Wrangell‐St
Elias
Mountains,
southern
Yukon,
while
anomalies
diminished
with
distance
core
region.
This
distinct
pattern
suggests
weak
Aleutian
Low
similar
negative
phase
Pacific
Decadal
Oscillation
could
have
regional
extremes
after
1809
eruption.
Science Advances,
Journal Year:
2024,
Volume and Issue:
10(4)
Published: Jan. 24, 2024
Across
western
North
America
(WNA),
20th-21st
century
anthropogenic
warming
has
increased
the
prevalence
and
severity
of
concurrent
drought
heat
events,
also
termed
hot
droughts.
However,
lack
independent
spatial
reconstructions
both
soil
moisture
temperature
limits
potential
to
identify
these
events
in
past
place
them
a
long-term
context.
We
develop
Western
American
Temperature
Atlas
(WNATA),
data-independent
0.5°
gridded
reconstruction
summer
maximum
temperatures
back
16th
century.
Our
evaluation
WNATA
with
existing
hydroclimate
reveals
an
increasing
association
between
recent
decades,
relative
five
centuries.
The
synthesis
paleo-reconstructions
indicates
that
amplification
modern
WNA
megadrought
by
frequency
extent
compound
dry
conditions
21st
are
likely
unprecedented
since
at
least
Nature Communications,
Journal Year:
2023,
Volume and Issue:
14(1)
Published: April 22, 2023
The
Southern
Annular
Mode
(SAM)
is
the
leading
mode
of
atmospheric
variability
in
extratropical
Hemisphere
and
has
wide
ranging
effects
on
ecosystems
societies.
Despite
SAM's
importance,
paleoclimate
reconstructions
disagree
its
trends
over
Common
Era,
which
may
be
linked
to
SAM
teleconnections
influence
specific
proxies.
Here,
we
use
data
assimilation
with
a
multi-model
prior
reconstruct
last
2000
years
using
temperature
drought-sensitive
climate
Our
method
does
not
assume
stationary
relationship
between
proxy
records
allows
us
identify
critical
quantify
reconstruction
uncertainty
through
time.
We
find
no
evidence
for
forced
response
20th
century.
do
modern
positive
trend
falls
outside
2σ
range
at
multidecadal
time
scales,
supporting
inference
that
several
decades
anthropogenic
change.
npj Climate Action,
Journal Year:
2024,
Volume and Issue:
3(1)
Published: May 8, 2024
I
am
concerned
by
climate
scientists
becoming
activists,
because
scholars
should
not
have
a
priori
interests
in
the
outcome
of
their
studies.
Likewise,
worried
about
activists
who
pretend
to
be
scientists,
as
this
can
misleading
form
instrumentalization.
Abstract
Understanding
climate
variability
across
interannual
to
centennial
timescales
is
critical,
as
it
encompasses
the
natural
range
of
fluctuations
that
early
human
agricultural
societies
had
adapt
to.
Deviations
from
long-term
mean
are
often
associated
with
both
societal
collapse
and
periods
prosperity
expansion.
Here,
we
show
contrary
what
global
paleoproxy
reconstructions
suggest,
mid
late-Holocene
was
not
a
period
stability.
We
use
mid-
Earth
System
Model
simulations,
forced
by
state-of-the-art
external
forcing
eleven
long-lasting
cold
occurred
in
Northern
Hemisphere
during
past
8000
years.
These
correlate
enhanced
volcanic
activity,
where
clustering
eruptions
induced
prolonged
cooling
effect
through
gradual
ocean-sea
ice
feedback.
findings
challenge
prevailing
notion
Holocene
characterized
stability,
portrayed
multi-proxy
reconstructions.
Instead,
our
simulations
provide
an
improved
representation
amplitude
timing
temperature
variations
on
sub-centennial
timescales.
Abstract
Common
Era
temperature
variability
has
been
a
prominent
component
in
Intergovernmental
Panel
on
Climate
Change
reports
over
the
last
several
decades
and
was
twice
featured
their
Summary
for
Policymakers.
A
single
reconstruction
of
mean
Northern
Hemisphere
first
highlighted
2001
Policymakers,
despite
other
estimates
that
existed
at
time.
Subsequent
assessed
many
large-scale
reconstructions,
but
entirety
history
most
recent
Sixth
Assessment
Report
restricted
to
estimate
annual
global
temperatures.
We
argue
this
focus
is
an
insufficient
summary
our
understanding
Era.
provide
complementary
perspective
by
offering
alternative
assessment
state
high-resolution
paleoclimatology
call
future
present
more
accurate
comprehensive
knowledge
about
important
period
human
climate
history.
Climate of the past,
Journal Year:
2025,
Volume and Issue:
21(1), P. 161 - 184
Published: Jan. 27, 2025
Abstract.
Climate
variability
in
the
last
millennium
(past
1000
years)
is
dominated
by
effects
of
large-magnitude
volcanic
eruptions;
however,
a
long-standing
mismatch
exists
between
model-simulated
and
tree-ring-derived
surface
cooling.
Accounting
for
self-limiting
large
sulfur
dioxide
(SO2)
injections
limitations
tree-ring
records,
such
as
lagged
responses
due
to
biological
memory,
reconciles
some
discrepancy,
but
uncertainties
remain,
particularly
largest
tropical
eruptions.
The
representation
forcing
latest
generation
climate
models
has
improved
significantly,
most
prescribe
aerosol
optical
properties
rather
than
using
SO2
emissions
directly
including
interactions
aerosol,
chemistry,
dynamics.
Here,
we
use
UK
Earth
System
Model
(UKESM)
simulate
(1250–1850
CE)
emissions.
Averaged
across
all
eruptions,
find
similar
Northern
Hemisphere
(NH)
summer
cooling
compared
with
other
last-millennium
simulations
from
Paleoclimate
Modelling
Intercomparison
Project
Phase
4
(PMIP4),
run
both
prescribed
forcing,
continued
overestimation
reconstructions.
However,
largest-magnitude
eruptions
1257
(Mt.
Samalas)
1815
Tambora),
models,
UKESM1,
suggest
smaller
NH
that
better
agreement
records.
In
simulated
differs
considerably
PMIP4
dataset
used
without
interactive
schemes,
marked
differences
hemispheric
spread
resulting
lower
when
are
used.
Our
results
that,
spatial
distribution
can
account
discrepancies
Further
work
should
therefore
focus
on
resolving
past
