"On Climate Sensitivity"
By Richard Lindzen, PhD,
with Review Assistance
from Roy Spencer,
CO2 Coalition, 2019
( On climate sensitivity to
atmospheric CO2 levels ):
"According to the
United Nations
Intergovernmental
Panel on
Climate Change
(IPCC, 2013)
the increase in
anthropogenic
( man made )
greenhouse forcing
since the beginning
of the industrial era
(which happens to
coincide with the end
of the Little Ice Age)
is already almost what
one expects from
a doubling of CO2,
and we have seen
a welcome warming
of about 1°C.
After all,
the Little
Ice Age
was hardly
considered
optimal.
The IPCC
does not claim
all of this
small warming
is due to
increased
greenhouse gases,
but even if it were,
it does not,
on the face of it,
suggest a high
sensitivity
( to CO2 ).
However,
most models
employed
by the UN’s
Intergovernmental
Panel on
Climate Change
display higher
sensitivites
(currently ranging
from 1.5° – 4.5°C).
Moreover, the UN
argues that higher
values portend
profound dangers
(a dubious claim
in its own right)."
(from page 4)
Lindzen tries
to explain why
climate models
predict so poorly,
compared with
the actual
temperature
changes.
Climate models
obviously do not
accurately describe
what's happening
in the atmosphere
today.
So there's
no logical reason
to accept any
model predictions
about the
future climate.
Lindzen
discusses
the influence
of high-level
cirrus clouds,
above the
tropopause,
where
water vapor
freezes out.
High-level
cirrus clouds
are often
large enough
so they block
the rising infrared
radiation from
the Earth ( which
is how our planet
cools itself ).
When high-level
cirrus clouds
are present,
greenhouse gases
below the clouds
become relatively
irrelevant to the
greenhouse effect.
When such clouds
are absent,
water vapor
is the
most important
greenhouse gas.
(from pages 5 & 6)
Lindzen’s
conclusion:
A doubling of
carbon dioxide (CO2),
from 400 parts
per million (ppm)
to 800 ppm,
will result in
an increase
in temperatures
of about +1 degree C.
and maybe
as low as
+0.75 degrees C.
This finding
is far different
than +3 degrees C.,
plus or minus
1.5 degrees C.
in the Charney
Report (1979)
and in all
IPCC reports
( both assuming
increases in
atmospheric
water vapor
will become a
positive feedback
that triples
the assumed
warming effect
of CO2 alone ).
Lindzen presents
graphs showing
climate models
make unrealistically
high estimates
of the Earth's
sensitivity to CO2.
Since the 1979
Charney Report,
the 3x amplification
water vapor theory
has NEVER
been observed
in any modern
measurements
of the atmosphere.
There may be a
negative feedback
that REDUCES
the CO2 influence.
Lindzen says a focus
on the average global
temperature may be
misguided.
The focus
should be on
temperature
differences
between
the equator
and the poles.
The temperature
differential between
the lower latitudes,
and the higher latitudes,
drives heat transport.
The poles - equator
temperature differential
determines how harsh
the weather will be
( smaller differentials
result in milder weather ).
Today, the difference
in those temperatures
is about 40 degrees C.
18,000 years ago,
the difference was
about 60 degrees C.
During the hot Eocene
( 50 million years ago ),
the difference was
about 20 degrees C.
The temperatures
in the tropics did not
change much.
Lindzen discusses
the tight fit between
glaciation cycles
and changes
in Sun-Earth
orbital geometry
( Milankovitch theory ).
There's a tight fit
between exposure
to the sun,
at latitudes about
65 degrees N.,
and glaciation
-- they both move
in the same
direction almost
simultaneously.
Lindzen states:
“We see that
(solar) insolation
in the summer A
rctic varies
by about 100 Watts
per square meter,
a very large value
compared to the
global average of
240 Watts
per square meter,
and as Edvardsson
et al. note,
this is consistent
with energy needed
to freeze and melt
the glaciers."
Lindzen reports
on temperature
responses
of the globe
to volcanic activity.
Aerosols, fine particles
emitted by volcanos,
cool the globe for a
short period of time.
Climate modelers
claim air pollution
aerosols blocking
sunlight offset
the “real” effects
of CO2.
This claim is used to
explain why rising
CO2 levels from
1940 to 1975 were
accompanied by
global cooling,
rather than
the expected
global warming.
There were
air pollution
aerosols
in the 1960s.
But they kept
rising until
at least 2000 !
That air pollution
did not suddenly
fall out of the air
in 1975, when a
global warming
trend started,
that lasted until
2005, based on
satellite data.
Lindzen
calculates
the extent of
aerosol cooling
that has to be
assumed,
to force the
climate model
theories to agree
with observations.
The greater the
assumed
sensitivity
of the earth
to CO2 warming,
the greater the
assumed aerosol
cooling needed
to offset
that guess.
But with a CO2
sensitivity of
+0.75 degrees C.,
for a doubling
of the CO2 level,
no questionable
aerosol cooling
needs to be
assumed
to make the
+0.75 C. warming
estimate work.
Lindzen mentioned
Shaviv (2008), where
solar cycle variations
in ocean heat content
showed that the
solar cycle forcing
was about 5- 7 times
greater than one
would obtain from
measurements
of solar output alone.
This is consistent
with the theory
that cosmic ray
variations
associated with
the solar cycle
cause changes
in cloudiness.
In the summary
Lindzen states:
“The situation
with respect to
climate sensitivity
(to CO2)
is that we
basically see
no reason
to expect
high sensitivity.
The original basis
for considering
that high sensitivity
is possible (namely,
the hypothetical
water vapor feedback
of Manabe and
Wetherald, 1975)
is clearly contradicted
by the measurements
of TOA radiative fluxes
which show that the total
long-wave feedback,
including cirrus cloud
variations, may even be
negative.
Analysis of
the temperature data
leads to the conclusion
that if anthropogenic
(man made) contributions
are the cause of warming
since the end
of the Little Ice Age,
and if aerosols
are limited to a
contribution of 1 Watts
per square meter, then
climate sensitivity
in excess of +1.5°C
is precluded.”
(from page 21)
( Note:
+1.5 degrees C.
is the LOWER limit
of the huge
+1.5 to +4.5 degree C.
range of the IPCC's
wild guessed
global warming,
caused by a 100%
CO2 level increase
( made famous in the
1979 Charney Report,
and used by the UN's
IPCC since it was
formed in 1988 ).
"Our simple calculation
on that suggested
that sensitivities
in excess of 1.5°C
were precluded
depends upon the
assumption on that
models are correct
in producing
negligible
natural internal
variability.
It is, however,
remotely
conceivable
that there was
in reality
(as opposed
to in models)
natural
internal variability
that was exactly
what was needed
to cancel the effect
of high sensitivity,
but that this
internal variability
would eventually
be overwhelmed,
and allow the
high sensitivity
to reveal itself.
This remote possibility
is far from
“settled science,”
and the thought that
multi-trillion dollar
policies would be
implemented to
putatively prevent this,
seems far from rational.
This is especially so
when one considers
that for about 95 percent
of the time since complex
life systems appeared
(about 600 million
years ago),
levels of CO2
were much higher
than they are
anticipated
to become
(as much as
10-20 times
today’s levels)
without evidence
of a relationship
to global mean
temperature."
(from page 21)