Global Warming 101
Roy W. Spencer, Ph.D
Principal Research Scientist
The University of Alabama In Huntsville
19 March 2007
“Global Warming” (at least since 1920) is Real…
But how unusual is it?
How much of it is natural versus man-made?
Data source: J. Hansen/ GISS
“Little Ice Age”
McIntyre-McKitrick, 2003
The famous Mann et al. “Hockey Stick” had errors in
statistical analysis methods.
(A National Academies Review Panel [July 2006]
changed the Hockey Stick conclusion from
“warmest in 1,000 years” to “warmest in 400 years”)
The GRIP (Greenland) borehole record is one of the best records because it is not a proxy, it is a DIRECT measure of temperature. Shown are the last 2000 years. (Dahl-Jensen et al. 1998, Science, 282, 268-271 "Past Temperatures Directly the Greenland Ice Sheet"). A similar reconstruction occurs for the Ural Mountain borehole temperatures (i.e. warmer 1000 years ago, Bemeshko, D., V.A. Schapov, Global and Planetary Change, 2001.
We are probably not
as warm as during Medieval Warm Period
Incoming Sunlight
Emitted Infrared Radiation
=
GLOBAL WARMING BASICS: “Radiative Energy Balance” (= const. Temp.)
=> Greenhouse gases affect Infrared Radiation
Global average input = output =
≈235 Watts per square meter
Climate Modelers tend view the Earth’s average temperature as being
“caused by” radiation balance…
…but we really don’t know what natural processes keep
the balance around 235 Watts/m2 ….
…we don’t even know whether it is 234, or
235 or 236 Watts
Global Warming 101
Roy W. Spencer, Ph.D
Principal Research Scientist
The University of Alabama In Huntsville
19 March 2007
“Global Warming” (at least since 1920) is Real…
But how unusual is it?
How much of it is natural versus man-made?
Data source: J. Hansen/ GISS
“Little Ice Age”
McIntyre-McKitrick, 2003
The famous Mann et al. “Hockey Stick” had errors in
statistical analysis methods.
(A National Academies Review Panel [July 2006]
changed the Hockey Stick conclusion from
“warmest in 1,000 ..