資料紹介
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
資料の原本内容
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/m2 …. Because these
Are theoretical estimates, not measurements
IPCC “Official” (as of 2005) Manmade
…note the small size of the human influence (around 1-2 Watts)
compared to the Earth’s average input/output (235 Watts)
1
2 Watt/m2
Since preindustrial times
Natural Greenhouse Effect…
..is due to:
1) Water vapor
2) Clouds
3) Carbon dioxide
4) Methane
…& other trace gases.
The Greenhouse Effect & natural greenhouse gases
- WARM the lower atmosphere
- COOL the upper atmosphere
....can be thought of as a radiative “blanket” for
infrared radiation (NOT sunlight).
Manmade greenhouse gases are supposedly
slightly enhancing the Earth’s
Temperature
Due to greenhouse effect
Height
* Variable gases
Atmospheric Composition and
Greenhouse Gases
10’s of W/m2
CLOUDS
0.000004%
O3
*Ozone
0.15 W/m2
0.00003%
N2O
*Nitrous Oxide
0.00005%
H2
Hydrogen
0.5 W/m2
0.00017%
CH4
*Methane
0.0005%
He
Helium
0.0018%
Ne
Neon
1.5 W/m2
0.0390% (2007)
CO2
*Carbon Dioxide
0.93%
Ar
Argon
10’s of W/m2
0 to 4%
H2O
*Water Vapor
20.95
O2
Oxygen
78.08%
N2
Nitrogen
Human
Greenhouse Gas
Radiative Forcing
Since pre-Industrial
Times
Natural
Variations
Natural
Variations
Carbon Dioxide is a greenhouse gas,
it is increasing in the atmosphere (at ½ rate of human production),
therefore, the lower atmosphere MUST warm
Global Warming Basic Hypothesis:
CO2 concentration is now about =>
40% above pre-industrial times.
…but CO2 is still a “trace” gas (not much of it)
1958
2005
1958
2005
1958
2005
1958
2005
Computerized climate models have led to future warming estimates by 2100 of from 1.1 to 2.9 deg. C (low emissions) to 2.4 to 6.4 deg. C (high emissions)..
Direct surface warming from 2xCO2 is only 0.6 deg C (about 1 deg. F)
Thus, climate models have net POSITIVE feedbacks (they respond to a warming tendency with changes that amplify the 1 deg. F CO2-only warming).
This is a WIDE range of warming estimates, illustrating substantial uncertainty (mainly from cloud feedback differences between models)
The “Official” Warming Estimates (U.N. Intergovernmental Panel on Climate Change)
The Earth’s greenhouse effect is mostly due to water vapor and clouds, which are under the control of weather processes (mostly precipitation systems).
A few percent increase in low clouds, or a small increase in precipitation efficiency, could entirely offset the warming tendency from carbon dioxide (neither of these processes are well understood).
Big Question: Do precipitation systems stabilize the Earth’s temperature at a pref...
