Download Implications Of The Secondary Role Of Carbon Dioxide.

Willie Soon
Introduction
The relationship between atmospheric CO2 and CH4
concentrations, temperature, and ice-sheet volume
2. Atmospheric CO2 radiative forcing as an amplifier of
glacial-interglacial climate change
3. Glacial-interglacial climate change: the role of orbitally
moderated insolation forcing at local and regional scales
compared with the effects of global radiative forcing from
changing CO2 concentration
4. Problems with CO2 amplification of global mean
temperature: computer simulations and quantitative data
1.
The relationship between atmospheric CO2 and CH4
concentrations, temperature, and ice-sheet volume
 CO2 content being driven by change in
temperature using the Vostok data
 Southern Hemisphere forcing scenario: External
orbital insolation triggered the fast and large
changes in the air temperature in the SH → cause
responses in deep ocean properties & global
carbon cycle → changing levels of atm. CO2
 Northern Hemisphere forcing scenario: northernlead, also proposes atm.CO2 as the essential
amplifier of the warming and cooling and hence
the waxing and waning if global ice volume
Atmospheric CO2 radiative forcing as an amplifier
of glacial-interglacial climate change
 It’s still unclear as to whether such a plausible CO2-
amplification scenario can be quantitatively confirm
with evidence available to date.
 Glacial-interglacial climate change: the role of orbitally
moderated insolation forcing at local and regional
scales compared with the effects of global radiative
forcing from changing CO2 concentration

1.
2.
At this stage, it’s relevant to emphasize that the
popular scenario for potential episode release of
methane hydrates may not be so straightforward.
Milkov has lowered the previously accepted high
estimate of global hydrate-bound gas from
21x1015m3 → 1 to 5x1015m3
Possibly incorrect interpretation of the large
delta13C excursions in the records of planktonic
and benthic foraminifera as clathrate-derived
methane release.
3.

Bhaumik and Gupta have recently identified five major
episodes of methane release since 3.6 million years BP,
these they link to reduced hydrostatic pressure
connected to lowered sea levels and intense glacial
events, roughly coinciding with increased glaciation in
the NH.
Thus, many numerical attempts to quantify the impacts
from variations in two minor greenhouse gases, CO2 and
CH4, don’t confirm their predominant roles in
explaining the large amplitude changes in thermal,
hydrologic, and cryospheric history during glacialinterglacial transitions.
 Persistent solar insolation forcing at key seasons and
geographical locations, and closely related thermal,
hydrological, and cryospheric changes may be
sufficient to explain regional and global climatic
changes during glacial-interglacial transitions.
Problems with CO2 amplification of global mean
temperature: computer simulations and quantitative
data
GCM
 Imposing a CO2 radiative forcing estimate of about 2.5
W/m2 for the 80ppm change, which will trigger a
warming 2-3C
 fall far short of the calibrated 10-12C in Antarctic
temperature change.
More extensive snow accumulation
Low tilt angle, high eccentricity
 The examples serve only as the sufficient but not
necessary of orbital insolation forcing in accounting
almost fully for conditions and changes during the
glacial-interglacial transitions, without the need to
invoke the argument for CO2 as the predominant
amplifier of those changes.
Conclusion
 No quantitative evidence that varying levels of minor
greenhouse gases like CO2 and CH4 have accounted
for even as much as half of the reconstructed glacialinterglacial temperature changes.
 This paper shows that changes in solar insolation at
climatically sensitive latitudes and zones exceed the
global radiative forcing of CO2 and CH4.
 There are still questions about how orbital forcing
explain glaciation and deglaciation over the past few
million years with the 100-kyr glacial-interglacial
cycles not fully explained.
 However, the popular notion CO2 and CH4 radiative
forcing as the predominant amplifier of glacialinterglacial phase transitions can’t be confirmed.
 Our basic hypothesis is that long-term climate change
is driven by insolation changes, from both orbital
variations and intrinsic solar magnetic and luminosity
variations.