The diminishing influence of increasing
Carbon Dioxide on temperature
Anthony Watts / August 10, 2014
Guest essay by Ed Hoskins
Using data published by the IPCC on the diminishing effect of increasing CO2 concentrations
and the latest proportional information on global Man-made CO2 emissions, these notes
examine the potential for further warming by CO2 emissions up to 1000ppmv and the
probable consequences of decarbonisation policies being pursued by Western governments.
The temperature increasing capacity of atmospheric CO2 is real enough, but
its influence is known and widely accepted to diminish as its concentration
increases. It has a logarithmic in its relationship to concentration. Global
Warming advocates and Climate Change sceptics both agree on this.
IPCC Published reports, (TAR3), acknowledge that the effective temperature increase caused
by growing concentrations of CO2 in the atmosphere radically diminishes with increasing
concentrations. This information has been presented in the IPCC reports. It is well disguised
for any lay reader, (Chapter 6. Radiative Forcing of Climate Change: section 6.3.4 Total
Well-Mixed Greenhouse Gas Forcing Estimate) [1]. It is a crucial fact, but not acknowledged
in the IPCC summary for Policy Makers[2].
The rapid logarithmic diminution effect is an inconvenient fact for Global Warming
advocates and alarmists, nonetheless it is well understood within the climate science
community. It is certainly not much discussed. This diminution effect is probably the reason
there was no runaway greenhouse warming caused by CO2 in earlier eons when CO2 levels
were known to be at levels of several thousands ppmv. The following simplifying diagram
shows the logarithmic diminution effect using tranches of 100ppmv up to 1000ppmv and the
significance of differing CO2 concentrations on the biosphere:
§ Up to ~200 ppmv, the equivalent to about ~77% of the temperature increasing effectiveness
of CO2. This is essential to sustain photosynthesis in plants and thus the viability of all life on
earth.
§ A further ~100 ppmv was the level prior to any industrialisation, this atmospheric CO2
made the survival of the biosphere possible, giving a further 5.9% of the CO2 Greenhouse
effect.
§ Following that a further 100ppmv, (certainly man-made in part), adding ~4.1% of the CO2
effectiveness brings the current level ~400 ppmv.
§ CO2 at 400pmmv is already committed and immutable. So CO2 has already reached about
~87+% of its potential warming effect in the atmosphere.
Both sceptics and the IPCC publish alternate views of the reducing effect on temperature of
the importance of CO2 concentration. These alternates are equivalent proportionally but vary
in the degree of warming attributable to CO2.
The IPCC have published views of the total effect of CO2 as a greenhouse gas up to
~1200ppmv, they range in temperature from +6.3°C to +14.5°C, shown below:
There are other views presented both by sceptical scientists and CDIAC, the Carbon Dioxide
Information and Analysis Centre. What these different analysis show the is the amount of
future warming that might be attributed to additional atmospheric CO2 in excess of the
current level of ~400ppmv. Looking to the future in excess of 400ppmv, wide variation exists
between the different warming estimates up to 1000ppmv, see below.
A comparison between these estimates are set out below in the context of the ~33°C total
Greenhouse Effect.
This graphic shows in orange the remaining temperature effect of CO2 up to 1000ppmv that
could be affected by worldwide global decarbonisation policies according to each of these
alternative analyses.
Some of the IPCC data sets shows very large proportions of the temperature effect
attributable solely to extra CO2. The concomitant effect of those higher levels of warming
from atmospheric CO2 is that the proportion of the total ~33°C then attributable the water
vapour and clouds in the atmosphere is displaced so as to be unrealistically low at 72% or
54%.
It has to be questioned whether it is plausible that CO2, a minor trace gas in the atmosphere,
currently at the level of ~400ppmv, 0.04% up to 0.10% achieves such radical control of
Global temperature, when compared to the substantial and powerful Greenhouse Effect of
water vapour and clouds in the atmosphere?
There are the clearly divergent views of the amount of warming that can result from
additional CO2 in future, but even in a worst case scenario whatever change that may
happen can only ever have a marginal future effect on global temperature.
Whatever political efforts are made to de-carbonize economies or to reduce man-made CO2
emissions, (and to be effective at temperature control those efforts would have to be universal
and worldwide), those efforts can only now affect at most ~13% of the future warming
potential of CO2 up to the currently unthinkably high level of 1000ppmv.
So increasing CO2 in the atmosphere can not now inevitably lead directly to much more
warming and certainly not to a catastrophic and dangerous temperature increase.
Importantly as the future temperature effect of increasing CO2 emissions can only be so
minor, there is no possibility of ever attaining the much vaunted political target of less
than +2.0°C by the control of CO2 emissions[3].
Global Warming advocates always assert that all increases in the concentration of CO2 are
solely man-made. This is not necessarily so, as the biosphere and slightly warming oceans
will also outgas CO2. In any event at ~3% of the total[4] Man-made CO2 at its maximum is
only a minor part of the CO2 transport within the atmosphere. The recent IPCC report now
admits that currently increasing CO2 levels are probably only ~50% man-made.
On the other hand it is likely that any current global warming, if continuing and increased
CO2 is:
§ largely a natural process
§ within normal limits
§ probably beneficial up to about a further 2.0°C+ [5].
It could be not be influenced by any remedial decarbonisation action, however drastic, taken
by a minority of nations.
In a rational, non-political world, that prospect should be greeted with unmitigated joy.
If it is so:
· concern over CO2 as a man-made pollutant can be mostly discounted.
· it is not essential to disrupt the economy of the Western world to no purpose.
· the cost to the European economy alone is considered to be ~ £165 billion per annum till the
end of the century, not including the diversion of employment and industries to elsewhere:
this is deliberate economic self-harm that can be avoided: these vast resources could be spent
for much more worthwhile endeavours.
· were warming happening, unless excessive, it provides a more benign climate for the
biosphere and mankind.
· any extra CO2 has already increased the fertility of all plant life on the planet.
· if warming is occurring at all, a warmer climate within natural variation would provide a
future of greater opportunity and prosperity for human development, especially so for the
third world.
De-carbonisation outcomes
To quantify what might be achieved by any political action for de-carbonization by Western
economies, the comparative table below shows the remaining effectiveness of each 100ppmv
tranche up to 1000ppmv, with the total global warming in each of the five diminution
assessments.
The table below shows the likely range of warming arising from these divergent (sceptical
and IPCC) views, (without feedbacks, which are questionably either negative or positive: but
probably not massively positive as assumed by CAGW alarmists), that would be averted with
an increase of CO2 for the full increase from 400 ppmv to 1000 ppmv.
The results above for countries and country groups show a range for whichever scenario of
only a matter of a few thousandths to a few hundredths of a degree Centigrade.
However it is extremely unlikely that the developing world is going to succumb to nondevelopment of their economies on the grounds of reducing CO2 emissions. So it is very
likely that the developing world’s CO2 emissions are going to escalate whatever is done by
developed nations.
These figures show that whatever the developed world does in terms of decreasing CO2
emissions the outcome is likely to be either immaterial or more likely even beneficial. The
table below assumes that the amount of CO2 released by each of the world’s nations or nation
is reduced universally by some 20%: this is a radical reduction level but just about
conceivable.
These extreme, economically destructive and immensely costly efforts by participating
western nations to reduce temperature by de-carbonization should be seen in context:
§ the changing global temperature patterns, the current standstill and likely impending
cooling.
§ the rapidly growing CO2 emissions from the bulk of the world’s most populous nations as
they continue their development.
§ the diminishing impact of any extra CO2 emissions on any temperature increase.
§ normal daily temperature variations at any a single location range from 10°C to 20°C.
§ normal annual variations value can be as much as 40°C to 50°C.
§ that participating Europe as a whole only accounts for ~11% of world CO2 emissions.
§ that the UK itself is now only about ~1.5% of world CO2 emissions.
As the margin of error for temperature measurements is about 1.0°C, the miniscule
temperature effects shown above arise from the extreme economic efforts of those
participating nations attempting to control their CO2 emissions. Thus the outcomes in terms
of controlling temperature can only ever be marginal, immeasurable and thus irrelevant.
The committed Nations by their actions alone, whatever the costs they incurred to
themselves, might only ever effect virtually undetectable reductions of World temperature.
So it is clear that all the minor but extremely expensive attempts by the few convinced
Western nations at the limitation of their own CO2 emissions will be inconsequential and
futile[6].
Professor Judith Curry’s Congressional testimony 14/1/2014[7]:
“Motivated by the precautionary principle to avoid dangerous anthropogenic climate change,
attempts to modify the climate through reducing CO2 emissions may turn out to be futile.
The stagnation in greenhouse warming observed over the past 15+ years demonstrates that
CO2 is not a control knob on climate variability on decadal time scales.”
Professor Richard Lindzen UK parliament committee testimony 28/1/2014 on IPCC AR5[8]:
“Whatever the UK decides to do will have no impact on your climate, but will have a
profound impact on your economy. (You are) Trying to solve a problem that may not be a
problem by taking actions that you know will hurt your economy.”
and paraphrased “doing nothing for fifty years is a much better option than any active
political measures to control climate.”
As global temperatures have already been showing stagnation or cooling[9] over the last
seventeen years or more, the world should fear the real and detrimental effects of global
cooling[10] rather than being hysterical about limited, beneficial or now non-existent
warming[11].
References:
[1] http://www.grida.no/publications/other/ipcc%5Ftar/?src=/climate/ipcc_tar/wg1/222.htm
[2] http://www.powerlineblog.com/archives/2014/05/why-global-warming-alarmism-isntscience-2.php
[3] http://www.copenhagenconsensus.com/sites/default/files/ccctolpaper.pdf
[4] http://www.geocraft.com/WVFossils/greenhouse_data.html
[5] http://www.spectator.co.uk/features/9057151/carry-on-warming/
[6] http://hockeyschtick.blogspot.fr/2013/11/lomborg-spain-wastes-hundreds-of.html
[7]
http://www.epw.senate.gov/public/index.cfm?FuseAction=Files.View&FileStore_id=07472b
b4-3eeb-42da-a49d-964165860275
[8] http://judithcurry.com/2014/01/28/uk-parliamentary-hearing-on-the-ipcc/
[9] http://www.spectator.co.uk/melaniephillips/3436241/the-inescapable-apocalypse-hasbeen-seriously-underestimated.thtml
[10] http://www.iceagenow.com/Triple_Crown_of_global_cooling.htm
[11] http://notrickszone.com/2010/12/28/global-cooling-consensus-is-heating-up-coolingover-the-next-1-to-3-decades/