Guest essay By Frank Bosse
In a recent blog post at Dr. Judith Curry’s website the author Nicholas Lewis analyzes the climate sensivity from observations and concludes a TCR of about 1.33 which is very stable versus different periods (see Table 1 of the linked post).
Here I want to use a slightly different method and another temperature record, the Cowtan/Way (C/W) http://www-users.york.ac.uk/~kdc3/papers/coverage2013/series.html ) series. In the discussions of the post at Judy Currys website there were big “?” if the result of TCR would also stand if one uses the “land- infilled” Data mostly for the polar regions of the earth. Therefore I’ll use this record to show the difference to HadCRUT4 (that was used by N. Lewis in his calculations) in the output.
I investigate the span 1940…2015. This includes the latest increase of the Global Mean Surface Temperature (GMST) , see Fig. 1, and avoids the periods of temperature data with great uncertainty in the early years of the observations.
Fig.1: The GMST anomalies (GMSTA) following the record of C/W for 1940…2015.
The Forcing-data I take from the IPCC AR5 appendix (Tab. A II 1.2 https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_AnnexII_FINAL.pdf ) This record ends in 2011. For the time span 2012…2015 I calculated the CO2-forcing with the observed concentration data and the other forcings I extrapolated for a difference (the sum of forcings) of 0.25 W/m² between 2011 and 2015.
I excluded every volcano forcing because the few events during 1940…2015 were all before 1991 and would insert a bias.
One of the biggest pitfalls in the forcing data is the magnitude of the aerosol-forcing. In an actual paper http://journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-14-00656.1 the author Björn Stevens made some thoughts about a required reducing of it. N. Lewis could show https://climateaudit.org/2015/03/19/the-implications-for-climate-sensitivity-of-bjorn-stevens-new-aerosol-forcing-paper that the downscaling, which is implicid in the Stevens-paper, is about 50% (see the appendix in the “Climate Audit”-Post). This makes some difference in the total forcing:
Fig. 2: The total forcing (but for volcano) with Aerosol-forcing as calculated in AR5 (black) and reduced by 50% (magenta) as implicid suggested by Stevens (2015).
To avoid a “single study syndrome” I’ll calculate the TCR for both cases: With and without the Aerosol-Forcing reduction.
For the detection of the TCR I calculate a linear regression (least square) for the forcings of every year 1940 to 2015 versus the observed temperatures (annual means):
Fig. 3: Regression of Forcing vs. temperature anomalies. The forcings account for 78% of the variance of the GMSTA.
The slope of the trend line in Fig.3 stands for the observed relation of a forcing-change of 1W/m² to the GMST-change from this.
It’s 0.37K/(W/m²) for the unchanged aerosol-forcing as shown in Fig.3, the reduction included gives a slope of 0.32 K/(W/m²), not shown.
Let’s take a look at the “rest” which is not explained by the forcings, excluded volcano. The residuals between the linear regression slope and the observed GMSTA over the time:
Fig. 4: The residuals between forcings and observations with a 15year-smoothing (Loess).
Fig. 4 shows the natural variability like the ENSO-events 1998/2000 and the volcanic eruptions, such as in 1992/1993. There is also a low-frequency pattern as the low-pass in fig.4 shows. I want to compare it with the AMO-pattern as it’s described in a modern record suggested by v. Oldenborgh et al. (2009) http://dspace.library.uu.nl/bitstream/handle/1874/43930/os-5-293-2009.pdf?sequence=2
Fig. 5: The AMO-Index, see the rapid shift in the 90s.
The AMO seems to be a part of the internal variability as it’s pattern is well replicated in the Fig. 4. The amplitude of the impact of this index on the GMST is about 0.2K and a shift from negative to positive arose also during the years between 1976 and 2005 from which we know that many models were “tuned” ( see Mauritsen et al. 2012 http://onlinelibrary.wiley.com/doi/10.1029/2012MS000154/full ).
The models don’t replicate the AMO, they don’t “know” of it.
Finally let’s have a look at the TCR-values. It’s well known that a doubling of the GHG-concentrations will lead to a forcing of 3.71W/m². This gives for the discussed trend slopes:
1. TCR 1940…2015 for full aerosol-forcing: 1.39 K/(2*CO2)
2. TCR 1940…2015 for reduced aerosol-forcing: 1.19K/(2*CO2)
3. TCR 1976…2005 (Model “tuning” span): 2.3 K/(2*CO2)
Conclusions:
The results of N. Lewis for TCR (1.33 with full aerosol-forcing and 1.22 for reduced aerosol forcing) are confirmed with only a deviation of 4% for another temperature record.
The residuals show a clear AMO-like pattern which is an essential part of the internal variability.
If one ignores this pattern one gets unrealistic high TCR-values greater than 1.8.
Many GCM do so, see Forster et al. (2013) http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50174/full .
I’m glad you see those low frequency patterns. The problem is, there are low frequency patterns you DO NOT see, because you’ve cut off your temperature at 1940. You’ve basically removed from your analysis all frequencies with periods longer than 75 years.
The Null Hypothesis says there’s likely frequency components with energy with periods longer than 75 years. You’ve basically rolled all those low frequency components into your trend line.
Your trend line is statistically meaningless. Nearly all trend lines on complex evolving systems with energy components outside the analysis window are statistically meaningless. I wish I would stop seeing them.
Peter
PS: I realize because there’s limited temperature history that you can’t actually do the analysis. That’s actually the correct outcome: “Not enough data”.
PPS: Proxy temperature histories give an inaccurate but nevertheless significant finding that there are frequency components of the temperature in the hundreds to thousands of years. We don’t know the magnitude (because it’s a proxy and not comparable to thermometers), but you can see a glimmer of the frequency components.
Peter,
“The problem is, there are low frequency patterns you DO NOT see, because you’ve cut off your temperature at 1940. You’ve basically removed from your analysis all frequencies with periods longer than 75 years.”
That’s why the wording was “pattern” not “frequecies” or “oscillations”.
.
Are frequencies and oscillations not patterns?
Your desperation is showing again.
Perhaps you should read the quote, it says “Low Frequency Pattern”.
Also, what MarkW said.
Frequencies and oscillations are patterns but not all patterns are frequencies and oscillations.
Your desperation is showing again.
So you admit that you were wrong, but you accuse me of desperation.
Fascinating.
Nice post. Especially like the tuning period AMO in the residuals analysis. Hits directly on the anthropogenic attribution problem in a clear simple to comprehend way. Bookmarked for future use.
I second your comment.
Thanks ristvan. It’s the method: “KISS” and sometimes it gives a clear picture 🙂
All the numbers for TCR as per the above post, according and as per the definition of 2*CO2 or 2xCO2 are basically wrong and in error by a factor of 2, regardless if the main calculation or the method valid or correct enough.
All the resulting numbers for the TCR must be multiplied by 2, as actually is the same warming you get at up going towards ppm increase as it is when down going from a ppm already increased point to the start point of your calculation………as per the orthodoxy of climatology….where ppm(s) increment means only warming.
But anyway, for as long as the attempt to calculate the TCR or ECR, for whatever purpose or motive, will always be wrong in accordance of what it should mean in regard to reality…..simply because the basic drive and meaning is solely orientated and serving ACC-AGW assessment scenarios, where increment of ppm(s) means always and only warming………so always the numbers have a huge chance to be wrong, but even by any chance the number been right, still the scenario assessed will be a ACC-AGW scenario, not a natural one………..so TCR or ECR whatever value wont help really assess a past or present or a future that is not anthropogenic…….no good at all for a natural assessment of nature as per nature without the so much claimed anthropogenic effect……….
cheers
whitten: see https://wattsupwiththat.com/2016/05/11/the-transient-climate-response-tcr-revisited-from-observations-once-more/#comment-2212052
Do you find the claims of global warming potential (GWP) for various ghgs suspicious? Have you been puzzled that CO2 which can absorb terrestrial radiation at only 15 microns (pressure etc. broadening spreads this to about 14-16 microns with peak at 15) is considered to have greater GWP than water vapor which can absorb radiation at hundreds of different wavelengths?
The EPA erroneously asserts GWP is a measure of “effects on the Earth’s warming” with “Two key ways in which these [ghg] gases differ from each other are their ability to absorb energy (their “radiative efficiency”), and how long they stay in the atmosphere (also known as their “lifetime”).” https://www3.epa.gov/climatechange/ghgemissions/gwps.html
This calculation overlooks the fact that any effect the ghg might have on temperature is also integrated over the “lifetime” of the gas in the atmosphere so the duration in the atmosphere cancels out. Therefore GWP might not mean what you think. It is not a measure of the relative influence on average global temperature of ghgs on a molecule basis or weight basis.
The influence on average global temperature of a ghg molecule depends on how many different wavelengths of EMR the molecule can absorb. Water vapor molecules can absorb hundreds in the wavelength range of terrestrial radiation compared to only one for CO2.
A consequence of this is CO2 has no significant effect on climate as demonstrated at http://globalclimatedrivers.blogspot.com
The post finds a TCR of 1.22 using a reduced aerosol factor.
Another 10 to 15 years of flat or declining global average surface temps and/or satellite sourced atmosphere temp will yield an even lower estimated TCR assuming CO2 emissions continue on their current trends. Will the estimated TCR then be significantly below 1.0? Seems so.
John
It won’t be because the value of 1.3…1.4 for non reduced aerosol forcing stands for different time spams as it’s shown in Nic Lewis post(cited in the beginning of the actual post). So the thesis is: also in 2030 ( 15 years from now) there is a TCR of about 1.35. You can recalculate for your self what this means for the guesses in 2100. Or too much provided??
The TCR to natural CO2 changes can be seen in the geologic record prior to the ~1850 start of the industrial revolution . N’est ce pas?
John
The handling of the ~60 year cycle is correct, since the analysis is going peak to peak, ie one full cycle. By contrast the IPCC start theirs in 1906, which is the bottom of the cycle and finish in 2005 at the top of the following cycle. Which adds an artefact worth about 0.3 C.
Unfortunately the second omitted variable bias problem is the indirect solar forcing. The Sun hit grand maximum around 2005 as well. Without this second artefact also being removed this calculation of TCR is likewise too high. Given the magnitude of indirect solar warming last century is similar to the magnitude of the ~60 year cycle, that suggests the real TCR is closer to the CERES and ERBE derived value of about 0.7 C/doubling.
Point the First: The earth’s carbon balance involves a lot more than atmospheric CO2. Carbon is found in the carbohydrates and sugars in terrestrial vegetation, sea weed, algae, in the calcium carbohydrates in shell fish and coral and limestone, CO2 dissolved in the ocean, permafrost, fossil fuels buried in the ground, etc. Carbon in these various forms is stored in pools/reservoirs and flows back and forth, absorbed and released, between these reservoirs as fluxes at 100s Gt/y rates. (Anthropogenic CO2 net rate is 2.0, not 2,000, not 200, not 20, 2.0!!!)
Per IPCC AR5 Figure 6.1 there are 46,713 Gt(Pg) of carbon in the global system. The uncertainty is +/- about 850 Gt, a total uncertainty range of 1,700 Gt, +/- 3.6%.
Before 1750 there was 589 Gt of atmospheric CO2, 589/46,713 = 1.3%. This atmospheric pool is 34.6% of the total uncertainty. In 2011, after 261 years of anthropogenic CO2 production, there was 829 Gt of atmospheric CO2, 829/46,713 = 1.8%. This larger pool is 48.8% of the total uncertainty. This 240 Gt is not an increase in the total balance amount, but simply an 0.5% rearrangement of the existing pools and fluxes.
IMHO with an uncertainty range of 1,700 Gt nobody can say with any certainty whether that miniscule 0.5% rearrangement/change was due to natural variations, ocean outgassing, land use changes, sea floor volcanic activity (nobody knows what’s happening on the ocean floor) or anthropogenic sources.
Point the Second: IPCC AR5 table SPM 5 shows the following W/m^2 RF due to increased GHGs between 1750 and 2011:
CO2 – Min/Ave/Max – 1.33/1.68/2.03
CH4 – Min/Ave/Max – 0.74/0.97/1.20
GHGs – Min/Ave/Max – 1.13/2.29/3.33
Figure 10 in Trenberth et. al. 2011 (Atmospheric Moisture Transports from Ocean to Land and Global Energy Flows in Reanalyses) shows the power flux values for eight models/studies/analyses that were the subject of the paper. (Watt is a power unit, not an energy unit, 3.41 Btu/Wh or 3.6 kJ/Wh. (English hours with Btu, metric/SI hours w/ kJ)
What happens inside the system stays in the system. All that matters is the net flow at ToA. If fewer W/m^2 leave than enter, the temperature will increase. So the net effect of GHGs should be reducing the W/m^2 leaving ToA by 2.29 W/m^2.
Seven of the eight analyses modeled net cooling, ranging from -31 W/m^2 to -1.1 W/m^2. Compare that to the 2.29 W/m^2 from GHGs. The average of all eight was still -3.4 W/m^2 cooling.
1) Anthropogenic CO2 is trivial, lost in the magnitudes, fluxes and uncertainties of natural variations.
2) The additional atmospheric CO2’s RF is trivial, lost in the magnitudes, fluxes and uncertainties of natural variations.
Interesting comments Nicholas.
And see my above post at
https://wattsupwiththat.com/2016/05/11/the-transient-climate-response-tcr-revisited-from-observations-once-more/comment-page-1/#comment-2212064
[Excerpt]
Furthermore, please note that atmospheric dCO2/dt varies closely (correlates) and ~contemporaneously with global temperature, and its integral atmospheric CO2 lags temperature by about nine months in the modern data record. CO2 also lags temperature by ~800 years in the ice core record, on a longer time scale. Therefore, CO2 lags temperature at all measured time scales.
Consider the implications of this evidence:
CO2 lags temperature at all measured time scales, so the global warming (CAGW) hypothesis suggests that the future is causing the past. 🙂
Nic – Yup! Good work.
And corroborated by the simple ‘top down’ analysis run on a desk top computer which calculates average global temperatures that are a 97% match to measured values since before 1900 even when the effect of CO2 is ignored. Accounting for CO2 increases the match by only 0.1%. http://globalclimatedrivers.blogspot.com
The IPCC seems to use “carbon” when it means CO2. The 829 gigatonnes refers to “carbon”
The amount of CO2 in the atmosphere is about 3000 gigatonnes. Simple calculation.
CO2 exchange between the surface and atmosphere is about 600 gigatonnes per year. The amount of anthropogenic CO2 is 30 gigatonnes per year.
CO2 never accumulates in the atmosphere, any more than water accumulates in a river.
No, IPCC means carbon. It’s the only way to treat the pools and fluxes evenly. Per Figure 6.1 footnotes the conversion is ppmv / 2.12 = Gt Carbon. Basically correcting CO2 volume to CO2 moles/mass by 44/28.69 and CO2 to Carbon by 44/12 or 3.67.
1750: 589 GtC / 2.12 = 278 ppmv Proxies
add 240: 240 / 2.12 = 113 ppmv WAG estimates & dry labbed 43% of total Anthro to make numbers work.
2011: 829 / 2.12 = 391 ppmv MLO
The amount of Carbon dioxide in the Earth’s atmosphere is 3120 gigatonnes.
This link has the simple conversion using IPCC ppm numbers.
https://www.skepticalscience.com/print.php?r=45
Several references show the mass of Earth’s atmosphere is 5200000 gigatonnes. 400ppm by volume times 44/29 is 607ppm mass. The mass proportion of Carbon dioxide is 0.000607
5200000 times 0.000607 is 3156 gigatonnes carbon dioxide.
383 ppmv CO2 * 44.00 CO2 / 28.69 Air = 582 ppmm CO2
582 ppmm CO2 * 5.148 E18 Pg Atmos =2.995 E3 Pg CO2 (Your value or close enough)
2.995E3 Pg CO2 / 3.67 = 815.97 Pg C
815.97 Pg C / 383 ppmv CO2=2.12 Pg C / ppmv CO2
Have been posting this and similar comments to various articles on Facebook, MSN news, etc. Using Facebook since HuffPo kicked my off their site. Facebook just suspended my account. I had to prove I wasn’t a spambot and agree to play nicey, nicey. Guess I’m afflicting the comfortable.
Follow up
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Frank Bosse, thank you for a good, and well-focused, essay.
It was my pleasure!