Global Temperature Report: December 2005
Jan. 4, 2006
Vol. 15, No. 8
For Additional Information:
Dr. John Christy, UAH, (256) 961-7763
christy@nsstc.uah.edu
Dr. Roy Spencer, UAH, (256) 961-7960
roy.spencer@msfc.nasa.gov
Global Temperature Report: December 2005
Global temperature trend since Nov. 16, 1978: +0.13 C per decade
December temperatures (preliminary)
Global composite temp.: +0.24 C (about 0.43 degrees Fahrenheit) above
20-year average for December.
Northern Hemisphere: +0.31 C (about 0.56 degrees Fahrenheit) above 20-year
average for December.
Southern Hemisphere: +0.16 C (about 0.29 degrees Fahrenheit) above 20-year
average for December.
November temperatures (revised):
Global Composite: +0.33 C above 20-year average
Northern Hemisphere: +0.41 C above 20-year average
Southern Hemisphere: +0.26 C above 20-year average
(All temperature variations are based on a 20-year average (1979-1998) for
the month reported.)
Notes on data released Jan. 4, 2005:
With a global average temperature that was three-tenths of a degree Celsius
(0.54 degrees Fahrenheit) warmer than seasonal norms, 2005 tied with 2002 as
the second warmest year in the past 27, according to Dr. John Christy,
director of the Earth System Science Center at The University of Alabama in
Huntsville (UAH).
Temperatures in 2005 followed a general pattern seen over the past 27 years,
with the most significant warming seen in the northernmost third of the
planet - especially in the Arctic. Large regions of slightly warmer than
normal temperatures covered much of the globe.
Since November 1978, the Arctic atmosphere has warmed at a rate that is more
than seven times faster than the average warming trend over the southern
two-thirds of the globe.
"It just doesn't look like global warming is very global," said Christy.
"Obviously some part of the warming we've observed over the past 27 years is
due to enhanced greenhouse gases. Simple physics tells you that.
"But even if you acknowledge the effects of greenhouse gases, when you look
at this pattern of warming you have to say there must also be something else
at work here.
"The carbon dioxide from fossil fuels is distributed pretty evenly around
the globe and not concentrated in the Arctic, so it doesn't look like we can
blame greenhouse gases for the overwhelming bulk of the Northern Hemisphere
warming over the past 27 years. The most likely suspect for that is a
natural climate change or cycle that we didn't expect or just don't
understand."
Averaged globally, the satellite data show a 27-year atmospheric warming of
0.35 C (about 0.63 degrees Fahrenheit) since late November 1978, when the
first temperature sensors were launched aboard a NOAA satellite.
Average temperatures over the Arctic have warmed by 1.16 C (about 2.1
degrees F) in the past 27 years, according to the satellite temperature
data, which is processed at UAH. During that same time, however,
temperatures over the southern two-thirds of the globe warmed only 0.16 C
(about 0.29 degrees F).
Average atmospheric temperatures in the northern third of the globe, which
includes the Arctic, have warmed by 0.7 C (about 1.26 degrees F) in that
time.
While computer models used to forecast climate change do predict regional
differences in the effects of global warming, this warming pattern doesn't
match the forecast.
"The computer models consistently predict that global warming due to
increasing greenhouse gases should show up as strong warming in the
tropics," Christy said.
Even with a recent data correction that added tropical warming to the
dataset, however, the satellite data still shows that the tropical
atmosphere has warmed by only 0.19 C - just over one-third of a degree
Fahrenheit ‹ in 27 years.
Recent research (Esper et al., 2005) that looked at temperature trends over
similar periods of time going back more than 1,000 years found the
probability that a few cases experienced that much warming in such a short
time, Christy said. "It would be fairly rare to have this much warming all
from natural causes, but it has happened. What we've seen isn't outside the
realm of natural climate change."
The five years from 2001 through 2005 have been five of the six warmest
years in the 27-year satellite global temperature record. The warmest year
in the satellite climate record was 1998, during the "El Nino of the
century." The global composite temperature that year was 0.5 C (about 0.9
degrees Fahrenheit) warmer than seasonal norms.
2002, which tied 2005 as the second warmest year, was also an El Nino year.
El Nino Pacific Ocean warming events are caused by vast regions of warmer
than normal surface water in the tropical Eastern Pacific.
In addition to warming large parts of the globe, El Nino events can also
change weather patterns from the Middle East across the Indian and Pacific
Oceans to the Eastern Caribbean.
High resolution color maps of regional temperature anomalies for both 2005
and December 2005, as well as a map of regional 27-year climate trends, are
available by contacting Phillip Gentry at gentryp@uah.edu
The processed temperature data is available on-line at:
http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt
As part of an ongoing joint project between UAH and NOAA, Christy and Dr.
Roy Spencer, an Earth System Science Center principal scientist, use data
gathered by microwave sounding units on NOAA satellites to get accurate
temperature readings for almost all regions of the Earth. This includes
remote desert, ocean and rain forest areas for which reliable climate data
are not otherwise available.
The satellite-based instruments measure the temperature of the atmosphere
from the surface up to an altitude of about eight kilometers above sea
level.
Once the monthly temperature data is collected and processed, it is placed
in a "public" computer file for immediate access by atmospheric scientists
in the U.S. and abroad.
Neither Spencer nor Christy receives any research support or funding from
oil, coal or industrial companies or organizations, or from any private or
special interest groups. All of their climate research funding comes from
state and federal grants or contracts.
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For more information,
Dr. John Christy, UAH, (256) 961-7763
christy@nsstc.uah.edu
Dr. Roy Spencer, UAH, (256) 961-7960
roy.spencer@msfc.nasa.gov
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