Here is a Science Daily article about global warming. It appears somewhat overstated. My comments are in italics.
January 20, 2016
Source: NASA
Summary: Earth's 2015 surface temperatures were the warmest since
modern record keeping began in 1880, according to independent analyses by NASA
and the National Oceanic and Atmospheric Administration (NOAA).
Earth's 2015 surface temperatures were the warmest since
modern record keeping began in 1880, according to independent analyses by NASA
and the National Oceanic and Atmospheric Administration (NOAA).
A record since 1880 is
not too impressive. An increase of
temperature that is notable since 1880 may be minor compared to temperature
variations over much longer periods. For
example, here is an estimated longer term record.
This record suggests
that we are currently in a warm period and that previous warm periods had even
higher temperatures. So much for “record-shattering”. Should we be more worried about the current
warm period, even if there is a positive increment for human activity, or a
possible coming ice age? Perhaps the
latter?
Globally-averaged temperatures in 2015 shattered the
previous mark set in 2014 by 0.23 degrees Fahrenheit (0.13 Celsius). Only once
before, in 1998, has the new record been greater than the old record by this
much.
Characterizing a 0.13C
difference as “shattering” is rhetoric, not science.
The 2015 temperatures continue a long-term warming trend,
according to analyses by scientists at NASA's Goddard Institute for Space
Studies (GISS) in New York (GISTEMP). NOAA scientists concur with the finding
that 2015 was the warmest year on record based on separate, independent
analyses of the data. Because weather station locations and measurements change
over time, there is some uncertainty in the individual values in the GISTEMP
index. Taking this into account, NASA analysis estimates 2015 was the warmest
year with 94 percent certainty.
The record since 1880
is not “long-term”. The uncertainty in
the individual values cannot be properly converted into accurate measures of
statistical significance without an accurate physical model of temperature. Since the analysis is based on a statistical
model, not an accurate physics model, there is model induced uncertainty that
invalidates the accuracy of the statistical conclusions. For example, the model does not explain the
long-term temperature record, including ice ages, hence cannot accurately
differentiate among temperature change causes or forecast a coming ice age. Finally, the statement that "
"Climate change is the challenge of our generation, and
NASA's vital work on this important issue affects every person on Earth,"
said NASA Administrator Charles Bolden. "Today's announcement not only
underscores how critical NASA's Earth observation program is, it is a key data
point that should make policy makers stand up and take notice -- now is the
time to act on climate."
This is rhetoric, not
science.
The planet's average surface temperature has risen about 1.8
degrees Fahrenheit (1.0 degree Celsius) since the late-19th century, a change
largely driven by increased carbon dioxide and other human-made emissions into
the atmosphere.
This conclusion is in
the absence of an accurate physics model of temperature change, hence is
rhetoric, not science.
Most of the warming occurred in the past 35 years, with 15
of the 16 warmest years on record occurring since 2001. Last year was the first
time the global average temperatures were 1 degree Celsius or more above the
1880-1899 average.
Not too impressive in
light of the long-term chart above.
Phenomena such as El Niño or La Niña, which warm or cool the
tropical Pacific Ocean, can contribute to short-term variations in global
average temperature. A warming El Niño was in effect for most of 2015.
"2015 was remarkable even in the context of the ongoing
El Niño," said GISS Director Gavin Schmidt. "Last year's temperatures
had an assist from El Niño, but it is the cumulative effect of the long-term
trend that has resulted in the record warming that we are seeing."
Weather dynamics often affect regional temperatures, so not
every region on Earth experienced record average temperatures last year. For
example, NASA and NOAA found that the 2015 annual mean temperature for the
contiguous 48 United States was the second warmest on record.
NASA's analyses incorporate surface temperature measurements
from 6,300 weather stations, ship- and buoy-based observations of sea surface
temperatures, and temperature measurements from Antarctic research stations.
These raw measurements are analyzed using an algorithm that considers the
varied spacing of temperature stations around the globe and urban heating
effects that could skew the conclusions if left unaccounted for. The result of
these calculations is an estimate of the global average temperature difference
from a baseline period of 1951 to 1980.
The “algorithm” is not
a replacement for an accurate physical model, hence it introduces errors that
are not reflected in the statistics.
NOAA scientists used much of the same raw temperature data,
but a different baseline period, and different methods to analyze Earth's polar
regions and global temperatures.
GISS is a NASA laboratory managed by the Earth Sciences
Division of the agency's Goddard Space Flight Center in Greenbelt, Maryland.
The laboratory is affiliated with Columbia University's Earth Institute and
School of Engineering and Applied Science in New York.
NASA monitors Earth's vital signs from land, air and space
with a fleet of satellites, as well as airborne and ground-based observation
campaigns. The agency develops new ways to observe and study Earth's
interconnected natural systems with long-term data records and computer
analysis tools to better see how our planet is changing. NASA shares this
unique knowledge with the global community and works with institutions in the
United States and around the world that contribute to understanding and
protecting our home planet.
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