I seriously wish that they would stop trying to link this all to
human agency. The time frames for the data are way too short and
regardless, it is lousy science to march in with a preconceived
assumption.
These types of conclusions really need centuries of comparable data
which is mostly impossible to reconstruct for most variables.
We do know that the ozone content of the atmosphere has changed and
even this data stream is unfortunately only some sixty years old.
Yet it did lead to investigation and the elimination of a non natural
man made driver. Such should be done for all chemicals used
industrially as a matter of course just to avoid been possibly bit.
That has not happened yet.
All other natural risk factors have naturally robust elimination
pathways we can generally rely on.
What is most interesting is the observed variation in lowering
Stratosphere temperatures and rising Troposphere temperatures. We
cannot determine if this is even unusual although we sort of think it
is. We need to ask if it is a lagging effect of the ozone variation
which I suspect gives us the easiest pathway to causation.
It may even reflect a measured shift in cosmic ray intensity.
So before we attempt to link it to the lower atmosphere which has had
an apparent ten percent increase in resident CO2 and little else
except a half degree in apparent temperature before flatlining
fifteen years ago, these ideas need to be aired.
I suspect that the observed variability could well be normal and
generally climate neutral. We need to at least assign a meaningful
probability to that been the case and it is not zero. It may even be
over fifty percent.
A human-caused
climate change signal emerges from the noise
by Staff Writers
Livermore CA (SPX) Dec 04, 2012
The troposphere is the
lowest portion of earth's atmosphere. The stratosphere sits just
above the troposphere, between 6 and 30 miles above earth's surface.
By comparing
simulations from 20 different computer models to satellite
observations, Lawrence Livermore climate scientists and colleagues
from 16 other organizations have found that tropospheric and
stratospheric temperature changes are clearly related to human
activities.
The team looked at
geographical patterns of atmospheric temperature change over the
period of satellite observations. The team's goal of the study was to
determine whether previous findings of a "discernible human
influence" on tropospheric and stratospheric temperature were
sensitive to current uncertainties in climate models and satellite
data.
The troposphere is the
lowest portion of earth's atmosphere. The stratosphere sits just
above the troposphere, between 6 and 30 miles above earth's surface.
The satellite
temperature data sets were produced by three different research
groups, and rely on measurements of the microwave emissions of oxygen
molecules. Each group made different choices in processing these raw
measurements, and in accounting for such complex effects as drifts in
satellite orbits and in instrument calibrations.
The new climate model
simulations analyzed by the team will form the scientific backbone of
the upcoming 5th assessment of the Intergovernmental Panel on Climate
Change, which is due out in 2014.
In both satellite
observations and the computer model simulations of historical climate
change, the lower stratosphere cools markedly over the past 33
years. This cooling is primarily a response to the human-caused
depletion of stratospheric ozone.[
This assertion has generally gone unchallenged and I find that
disquieting - arclein]
The observations and
model simulations also show a common pattern of large-scale
warming of the lower troposphere, with largest warming over the
Arctic, and muted warming (or even cooling) over Antarctica.
Tropospheric warming is mainly driven by human-caused increases in
well-mixed greenhouse gases.
"It's very
unlikely that purely natural causes can explain these distinctive
patterns of temperature change," said Laboratory atmospheric
scientist Benjamin Santer, who is lead author of the paper appearing
in the Nov. 29 online edition of the journal, Proceedings of the
National Academy of Sciences.
"No known mode of
natural climate variability can cause sustained, global-scale warming
of the troposphere and cooling of the lower stratosphere."
The team analyzed
results from climate model simulations with specified historical
changes in human and natural external factors, and from simulations
with projected 21st century changes in greenhouse gases and
anthropogenic aerosols.
They also looked at
simulations with no changes in external influences on climate, which
provide information on the year-to-year and decade-to-decade "noise"
of internal climate variability, arising from such natural phenomena
as the El Nino/Southern Oscillation and the Pacific Decadal
Oscillation.
The team used a
standard "climate fingerprint" method to search for the
model signal pattern (in response to human influences, the sun and
volcanoes) in the satellite observations. The method quantifies the
strength of the signal in observations, relative to the strength of
the signal in natural climate noise.
Other contributors
include researchers from Remote Sensing Systems of Santa Rosa; the
Centre for Australian Weather and Climate Research, Melbourne,
Australia; the Canadian Centre for Climate Modeling and Analysis,
Victoria, Canada; the National Oceanic and Atmospheric Administration
(NOAA) Geophysical Fluid Dynamics Laboratory, Princeton; the
University of Colorado, Boulder; the Massachusetts Institute of
Technology, Cambridge; the U.K. Met. Office Hadley Centre, Exeter,
U.K.; the Centre National de la Recherche Scientifique, Toulouse,
France; North Carolina State University; the National Climatic Data
Center, Asheville; Lawrence Berkeley National Laboratory; the
National Center for Atmospheric Research, Boulder; the University of
Adelaide, South Australia; the University of Reading, U.K.; and the
Center for Satellite Applications and Research, Camp Springs. The
paper is Santer's inaugural article as a member of the U.S. National
Academy of Sciences.
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