New energy-budget-derived estimates of climate sensitivity and transient response in Nature Geoscience
Guest post by Nic Lewis
Readers may recall that last December I published an informal climate sensitivity study at WUWT, here. The study adopted a heat-balance (energy budget) approach and used recent data, including satellite-observation-derived aerosol forcing estimates. I would like now to draw attention to a new peer-reviewed climate sensitivity study published as a Letter in Nature Geoscience, “Energy budget constraints on climate response”, here. This study uses the same approach as mine, based on changes in global mean temperature, forcing and heat uptake over 100+ year periods, with aerosol forcing adjusted to reflect satellite observations. Headline best estimates of 2.0°C for equilibrium climate sensitivity (ECS) and 1.3°C for the – arguably more policy-relevant – transient climate response (TCR) are obtained, based on changes to the decade 2000–09, which provide the best constrained, and probably most reliable, estimates.
The 5–95% uncertainty ranges are 1.2–3.9°C for ECS and 0.9–2.0°C for TCR. I should declare an interest in this study: you will find my name included in the extensive list of authors: Alexander Otto, Friederike E. L. Otto, Olivier Boucher, John Church, Gabi Hegerl, Piers M. Forster, Nathan P. Gillett, Jonathan Gregory, Gregory C. Johnson, Reto Knutti, Nicholas Lewis, Ulrike Lohmann, Jochem Marotzke, Gunnar Myhre, Drew Shindell, Bjorn Stevens, and Myles R. Allen. I am writing this article in my personal capacity, not as a representative of the author team.
The Nature Geoscience paper, although short, is in my view significant for two particular reasons.
First, using what is probably the most robust method available, it establishes a well-constrained best estimate for TCR that is nearly 30% below the CMIP5 multimodel mean TCR of 1.8°C (per Forster et al. (2013), here). The 95% confidence bound for the Nature Geoscience paper’s 1.3°C TCR best estimate indicates some of the highest-response general circulation models (GCMs) have TCRs that are inconsistent with recent observed changes. Some two-thirds of the CMIP5 models analysed in Forster et. al (2013) have TCRs that lie above the top of the ‘likely’ range for that best estimate, and all the CMIP5 models analysed have an ECS that exceeds the Nature Geoscience paper’s 2.0°C best estimate of ECS. The CMIP5 GCM with the highest TCR, per the Forster et. al (2013) analysis, is the UK Met. Office’s flagship HadGEM2-ES model. It has a TCR of 2.5°C, nearly double the Nature Geoscience paper’s best estimate of 1.3°C and 0.5°C beyond the top of the 5–95% uncertainty range. The paper obtains similar, albeit less well constrained, best estimates using data for earlier periods than 2000–09.
Secondly, the authors include fourteen climate scientists, well known in their fields, who are lead or coordinating lead authors of IPCC AR5 WG1 chapters that are relevant to estimating climate sensitivity. Two of them, professors Myles Allen and Gabi Hegerl, are lead authors for Chapter 10, which deals with estimates of ECS and TCR constrained by observational evidence. The study was principally carried out by a researcher, Alex Otto, who works in Myles Allen’s group.
Very helpfully, Nature’s editors have agreed to make the paper’s main text freely available for a limited period. I would encourage people to read the paper, which is quite short. The details given in the supplementary information (SI) enable the study to be fully understood, and its results replicated. The method used is essentially the same as that employed in my December study, being a more sophisticated version of that used in the Gregory et al. (2002) heat-balance-based climate sensitivity study, here. The approach is to draw sets of samples from the estimated probability distributions applicable to the radiative forcing produced by a doubling of CO2-equivalent greenhouse gas atmospheric concentrations (F2×) and those applicable to the changes in mean global temperature, radiative forcing and Earth system heat uptake (ΔT, ΔF and ΔQ), taking into account that ΔF is closely correlated with F2×. Gaussian (normal) error and internal climate variability distributions are assumed. ECS and TCR values are computed from each set of samples using the equations:
(1) ECS = F2× ΔT / (ΔF − ΔQ) and (2) TCR = F2× ΔT / ΔF .
With sufficient sets of samples, probability density functions (PDFs) for ECS and TCR can then be obtained from narrow-bin histograms, by counting the number of times the computed ECS and TCR values fall in each bin. Care is needed in dealing with samples where any of the factors in the equations are negative, to ensure that each is correctly included at the low or high end when calculating confidence intervals (CIs). Negative factors occur in a modest, but significant, proportion of samples when estimating ECS using data from the 1970s or the 1980s.
Estimates are made for ECS and TCR using ΔT, ΔF and ΔQ derived from data for the 1970s, 1980s, 1990s, 2000s and 1970–2009, relative to that for 1860–79. The estimates from the 2000s data are probably the most reliable, since that decade had the strongest forcing and, unlike the 1990s, was not affected by any major volcanic eruptions. However, although the method used makes allowance for internal climate system variability, the extent to which confidence should be placed in the results from a single decade depends on how well they are corroborated by results from a longer period. It is therefore reassuring that, although somewhat less well constrained, the best estimates of ECS and TCR using data for 1970–2009 are closely in line with those using data for the 2000s. Note that the validity of the TCR estimate depends on the historical evolution of forcing approximating the 70-year linear ramp that the TCR definition involves. Since from the mid-twentieth century onwards greenhouse gas levels rose much faster than previously, that appears to be a reasonable approximation, particularly for changes to the 2000s.
I have modified the R-code I used for my December study so that it computes and plots PDFs for each of the five periods used in the Nature Geoscience study for estimating ECS and TCR. The resulting ECS and TCR graphs, below, are not as elegant as the confidence region graphs in the Nature Geoscience paper, but are in a more familiar form. For presentation purposes, the PDFs (but not the accompanying box-and-whisker plots) have been truncated at zero and the upper limit of the graph and then normalised to unit total probability. Obviously, these charts do not come from the Nature Geoscience paper and are not to be regarded as associated with it. Any errors in them are entirely my own.
The box-and-whisker plots near the bottom of the charts are perhaps more important than the PDF curves. The vertical whisker-end bars and box-ends show (providing they are within the plot boundaries) respectively 5–95% and 17–83% CIs – ‘very likely’ and ‘likely’ uncertainty ranges in IPCC terminology – whilst the vertical bars inside the boxes show the median (50% probability point). For ECS and TCR, whose PDFs are skewed, the median is arguably in general a better central estimate than the mode of the PDF (the location of its peak), which varies according to how skewed and badly-constrained the PDF is. The TCR PDFs (note the halved x-axis scaling), which are unaffected by ΔQ and uncertainty therein, are all better constrained than the ECS PDFs.
The Nature Geoscience ECS estimate based on the most recent data (best estimate 2.0°C, with a 5–95% CI of 1.2–3.9°C) is a little different from that per my very similar December study (best estimate 1.6°C, with a 5–95% CI of 1.0–2.9°C, rounding outwards). The (unstated) TCR estimate implicit in my study, using Equation (2), was 1.3°C, with a 5–95% range of 0.9–2.0°C, precisely in line with the Nature Geoscience paper. In the light of these comparisons, I should perhaps explain the main differences in the data and methodology used in the two studies:
1) The main difference of principle is that the Nature Geoscience study uses GCM-derived estimates of ΔF and F2×. Multimodel means from CMIP5 runs per Forster et al. (2013) can thus be used as a peer-reviewed source of forcings data. ΔF is accordingly based on simulations reflecting the modelled effects of RCP 4.5 scenario greenhouse gas concentrations, aerosol abundances, etc. My study instead used the RCP 4.5 forcings dataset and the F2× figure of 3.71°C reflected in that dataset; I adjusted the projected post-2006 solar and volcanic forcings to conform them with estimated actuals. Use of CMIP5-based forcing data results in modestly lower estimates for both ΔF and F2× (3.44°C for F2×). Since CO2 is the dominant forcing agent, and its concentration is accurately known, the value of ΔF is closely related to the value of F2×. The overall effect of the difference in F2× on the estimates of ECS and TCR is therefore small. As set out in the SI, an adjustment of +0.3 Wm−2 to 2010 forcing was made in the Nature Geoscience study in the light of recent satellite-observation constrained estimates of aerosol forcing. On the face of it, the resulting aerosol forcing is slightly more negative than that used in my December study.
2) The Nature Geoscience study derives ΔQ using the change in estimated 0–2000 m ocean heat content (OHC) – which accounts for most of the Earth system heat uptake – from the start to the end of the relevant decade (or 1970–2009), whereas I computed a linear regression slope estimate using data for all years in the period I took (2002–11). Whilst I used the NODC/NOAA OHC data, which corresponds to Levitus et al. (2012), here, for the entire 0–2000 m ocean layer, the Nature Geoscience study splits that layer between 0–700 m and 700–2000 m. It retains the NODC/NOAA Levitus OHC data for the 700–2000 m layer but uses a different dataset for 0–700 m OHC – an update from Domingues et al. (2008), here.
3) The periods used for the headline results differ slightly. I used changes from 1871–80 to 2002–11, whilst the Nature Geoscience study uses changes from 1860–79 to 2000–09. The effects are very small if the CMIP5 GCM-derived forcing estimates are used, but when employing the RCP 4.5 forcings, switching to using changes from 1860–79 to 2000–09 increases the ECS and TCR estimates by around 0.05°C.
Since the Nature Geoscience study and my December study give identical estimates of TCR, which are unaffected by ΔQ, the difference in their estimates of ECS must come primarily from use of different ΔQ figures. The difference between the ECS uncertainty ranges of the two studies likewise almost entirely reflects the different central estimates for ΔQ they use. The ECS central estimate and 5–95% uncertainty range per my December heat-balance/energy budget study were closely in line with the preferred main results estimate for ECS, allowing for additional forcing etc. uncertainties, per my recent Journal of Climate paper, of 1.6°C with a 5–95% uncertainty range of 1.0–3.0°C. That paper used a more complex method which, although less robust, avoided reliance on external estimates of aerosol forcing.
The take-home message from this study, like several other recent ones, is that the ‘very likely’ 5–95% ranges for ECS and TCR in Chapter 12 of the leaked IPCC AR5 second draft scientific report, of 1.5–6/7°C for ECS and 1–3°C for TCR, and the most likely values of near 3°C for ECS and near 1.8°C for TCR, are out of line with instrumental-period observational evidence.
===============================================================
Here’s a figure of interest from from the SI file – Anthony
Fig. S3| Sensitivity of 95th percentile of TCR to the best estimate and standard error of the change in forcing from the 2000s to the 1860-1879 reference period. The shaded contours show the 95th percentile boundary of the TCR confidence interval, the triangles show cases (black and blue) from the sensitivity Table S2, and a smaller adjustment to aerosol forcing for comparison (red).
In reply to:
J Martin says:
May 20, 2013 at 3:25 pm
@ur momisugly William Astley
you quoted “abrupt climate events appear to be paced by a 1,470-year cycle with a period that is probably stable to within a few percent; with 95% confidence the period is maintained to better than 12% over at least 23 cycles
I clicked on the link but didn’t manage to find out when the next beginning or end of the quoted 1,470 year cycle was, with it’s 12% or 176 year margin. Thought it would be interesting to know.
William:
The D-O cycles are controlled by the solar magnetic cycle changes. So the question is how does the solar magnetic cycle change and how do those changes affect the planet’s climate?
The Dansgaard-Oeschger cycles are pseudo cyclical as they are driven by solar magnetic cycle which is pseudo cyclical. Pseudo cyclic events have non-linear sub mechanisms and hence cannot be analyzed in the frequency domain. It seems obvious that the solar magnetic cycle is pseudo cyclical which makes it difficult for the specialists to predict future solar magnetic cycle activity.
i.e. The periodicity of the changes to the solar magnetic cycle are determined by both external factors (planetary orbits) and by internal solar processes which are not understood and hence makes it appear the sun has a chaotic component.
The analysis of the sun-climate connection is further complicated as there are fundamental assumptions about the sun which are not correct and there are fundamental assumptions about how the sun affects the planet’s climate that have not been discovered. The missing pieces to the puzzle will likely become apparent as the solar cycle 24 progresses and as the planet cools.
Greenland ice temperature, last 11,000 years determined from ice core analysis, Richard Alley’s paper.
http://www.climate4you.com/images/GISP2%20TemperatureSince10700%20BP%20with%20CO2%20from%20EPICA%20DomeC.gif
http://www.agu.org/pubs/crossref/2003/2003GL017115.shtml
Timing of abrupt climate change: A precise clock by Stefan Rahmstorf
Many paleoclimatic data reveal a approx. 1,500 year cyclicity of unknown origin. A crucial question is how stable and regular this cycle is. An analysis of the GISP2 ice core record from Greenland reveals that abrupt climate events appear to be paced by a 1,470-year cycle with a period that is probably stable to within a few percent; with 95% confidence the period is maintained to better than 12% over at least 23 cycles. This highly precise clock points to an origin outside the Earth system; oscillatory modes within the Earth system can be expected to be far more irregular in period.
Rahmstorf analyzed the periodicity of the D-O cycles in the time domain (interval counting) which is appropriate as the forcing mechanism is pseudo cyclical.
http://www.leif.org/EOS/Obrochta2012.pdf
A re-examination of evidence for the North Atlantic “1500-year cycle” at Site 609
Therefore these records were referred to as either “quasi-periodic” (Bond et al., 1997) or “cyclic” (in a geologic sense, implying repetition, not periodicity) (Bond et al., 2001). The mean pacing of 1470 +/- 523 years was derived by interval counting (the elapsed time between cycle midpoints) and was the combined result of a composite record covering the last glaciation with V23-81 (1536 +/- 563 years) and the Holocene with V29-191 (1374 +/- 502 years) (Bond et al., 1997). Bond et al. (1999) later revised the V23-81 result to 1469 +/- 514 years and presented results for the last glacial interval of DSDP Site 609 (1476 +/- 585 years).
Variations in this stacked record coincided with well known climatic events, including the 8.2 ka Event (William, The 8200 BP event is a cooling event that is also evident in the tropics), Medieval Warm Climate Anomaly, and Little Ice Age, (Bond et al., 1997, 2001).
izen says: @ur momisugly May 20, 2013 at 7:04 am
…97% of scientist are unpersuaded of Bob’s ENSO hypothesis.
Especially as there is no explanation why for several thousand years the ENSO fluctuations have had NO effect on climate trends, but just start to do so when humans start adding massive amounts of fossil CO2 to the atmosphere.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
Mankind wasn’t using fossil fuels when all those abrupt climate changes were occurring and on top of that Climastrologists tell us CO2 wasn’t above the ‘safe’ level of 350ppm. Until scientists figure out what caused Abrupt Climate Change, and they admit they do not know, all your climate models are not worth a pile of horse poop.
The Conversation, that vanguard journal of Australian academic objectivity, has published an article reassuring us we’re all doomed despite the Nature Geoscience paper …
https://theconversation.com/long-term-warming-short-term-variability-why-climate-change-is-still-an-issue-14476
This goes hand in hand with another insightful article by Lewandowsky, No matter how strong the evidence on climate change, deniers will keep denying …
https://theconversation.com/no-matter-how-strong-the-evidence-on-climate-change-deniers-will-keep-denying-14496
I’m not sure if this is a /sarc message or not.
Christoph Dollis – You had better hope that the pen is mightier than the sword because I have seen Xena totally demolish 250lb, muscle bound guys.
“Assumptions as to forcings”
As soon as I read those words I become disheartened. My laymans understanding is that all the nitrogen, oxygen and argon, gases that make up 99.9% of the atmosphere, are unable to cool by radiation. Only lowest levels of the atmosphere can cool by conduction. Therefore if it wasn’t for the ‘greenhouse gases’ radiating energy out to space the atmosphere would simply get hotter.
William Astley says:
May 20, 2013 at 9:14 pm
A note of caution on the 1500 year periodic palaeo-signal (Maslin et al 2001):
One cautionary note is that Wunsch has suggested a more radical explanation for the pervasive 1500-year cycle seen in both deep-sea and ice core, glacial and interglacial records. Wunsch suggests that the extremely narrow spectral lines (less than two bandwidths) that have been found at about 1500 years in many paleo-records may be due to aliasing.
The 1500-year peak appears precisely at the period predicted for a simple alias of the seasonal cycle sampled inadequately (under the Nyquist criterion) at integer multiples of the common year. When Wunsch removes this peak from the Greenland ice core data and deep-sea spectral records, the climate variability appears as expected to be a continuum process in the millennial band. This work suggests that finding a cyclicity of 1500 years in a dataset may not represent the true periodicity of the millennial-scale events. The Holocene Dansgaard-Oeschger events are quasi periodic, with different and possibly stochastic influences.
I find figure 6 in this paper a very helpful graphic of our current knowledge of climate periodicities over different timescales.
I am confused. Everyone seems to want to know where the heat went. The latest theory seems to be “deep in the oceans.” I believe the greenhouse effect of Co2 was established by lab. testing. Is this true?
Is it at all possible that lab. conditions do not in fact prove what happens in the real world with small quantities of Co2 in comparison with all other atmospheric elements. Is Co2 as greenhouse as they say? I would really like to know.
indigo says: May 21, 2013 at 4:55 am
There is lots ofCO2 info here: http://www.co2science.org/
Thank you, Nic, for this interesting post and link to the Otto et al paper. May I ask you about the following sentence in the paper: ‘For ΔT, we use the HadCRUT4 ensemble data set of surface temperatures averaged globally and by decade (Supplementary Fig S1).’? How do the authors distinguish between that part of ΔT which they attribute to change in atmospheric CO2 content and those parts of ΔT which may be due to other factors such as the spread of the built environment (UHI), rural land use changes, increases in waste heat emissions, station moves, and natural cycles?
indigo says:
May 21, 2013 at 4:55 am
I am confused. Everyone seems to want to know where the heat went. The latest theory seems to be “deep in the oceans.” I believe the greenhouse effect of Co2 was established by lab. testing. Is this true?
Is it at all possible that lab. conditions do not in fact prove what happens in the real world with small quantities of Co2 in comparison with all other atmospheric elements. Is Co2 as greenhouse as they say? I would really like to know.
>>>>>>>>>>>>>>>>>>>>>
I am not sure there is any missing heat but to your question. If the lab experiments are done well they will tell us the result of a given situation with given variables; namely the result of CO2 and light. These results should not be discarded as the lab is still the real world, and we can assume that CO2 has the same effect in the climate system. What is not known or less know are the other affects of CO2 on the climate since there are many more variables than in the lab. These other affects could strengthen, nullify, or reverse the direct effect of CO2. Furthermore, while the greenhouse effect of CO2 could be a major driver of temperature, it could also be indistinguishable from the noise. I lean towards the latter being more accurate.
Coldfish
” How do the authors distinguish between that part of ΔT which they attribute to change in atmospheric CO2 content and those parts of ΔT which may be due to other factors such as the spread of the built environment (UHI), rural land use changes, increases in waste heat emissions, station moves, and natural cycles?”
The influence of long term natural cycles should be diminished by the long gap between the reference period of 1860-79 and the best data decade, 2000-09 – which is about the length of two cycles of the quasi-periodic AMO (assuming one believes in the existence of a natural AMO cycle). A generous allowance for shorter term natural cycles/random internal variability is made within the temperature standard error term, as explained in the Supplementary Information for the paper.
As is standard practice in climate science, reliance is placed on the published temperature record and no adjustment is made to the HadCRUT4 global record for UHI, rural use land changes or increases in waste heat emissions. I think that doing so would be impracticable in any case until someone develops a record that makes specific, properly quantified corrections for these items. Temperature changes from station moves, etc., should have been adjusted for as part of the homogenization process when preparing the HadCRUT4 record. Note that, being a global record, land temperatures only have a 30% weight.
THe new paper is welcome with an ECS of 1.3 C. However, co-author Myles Allen published a piece in the Guardian claiming that skeptic Matt Ridley is only now joining the real debate on climate change
http://www.guardian.co.uk/environment/blog/2013/may/21/matt-ridley-joined-real-climate-debate THis is sly skulduggery. Prof Allen knows that the IPCC and its proponents have been telling us for 25 years that the most likely case is a rise of 3.0 C with a high case of 6.0 C. He also knows that the Met Office has pushed high estimates of warming. Skeptics like Matt Ridley have written that this is unlikely. Finally Myles Allen co-authors something that agrees with Ridley (or, in fact estimates lower sensitivity) and then somehow accuses Ridley of only now entering the debate. As many have pointed out, people who were proponents of alarmism are now back-pedalling, taking a position of lower ECS sensitivity, and at the same time attacking skeptics who have held this view for years.
So TCR MAY be around 0.25degC less than past estimates because more energy is going into the deep oceans than originally modelled. So it will take longer to reach ECS, but that is not reduced as much. Meanwhile the ocean heat content drives storms, floods and droughts along with sea level rise.
As ‘good news’ it seems rather limited, merely delaying the worst.
But there is something very ironic about the recent post in this thread concerning very rapid climate change in the past like the A1 melt at the end of the last ice age and the D-O events. Those are the paleoclimate events which lead scientific research in climate to conclude that ECS must be quite high. The climate sensitivity required to explain the rapid climate change seen in ice cores and the MWP and LIA are somewhat larger than the results reported here using just the very recent decades of change.
In reply to:
phlogiston says:
May 21, 2013 at 1:18 am
William Astley says:
May 20, 2013 at 9:14 pm
A note of caution on the 1500 year periodic palaeo-signal (Maslin et al 2001):
One cautionary note is that Wunsch has suggested a more radical explanation for the pervasive 1500-year cycle seen in both deep-sea and ice core, glacial and interglacial records. Wunsch suggests that the extremely narrow spectral lines (less than two bandwidths) that have been found at about 1500 years in many paleo-records may be due to aliasing.
William:
There is sufficient information known at this time to solve the problem of what causes the Dansgaard-Oeschger warming and cooling and what caused the 20th century warming. It is possible to explain what is observed, and to explain why the different specialists failed to solve the problem, to explain their analysis results, and to explain why they wrote what they wrote in their papers.
When scientific problems are not solved the specialists in question have not considered the correct alternative hypothesis and/or there are one or more fundamental assumptions that are incorrect. Curiously, there are often political type barriers that stop the discussion of the alternative hypothesis. The political barriers can be internal due to strong control by a group of specialists and/or can be external if there are commercial or political implications to the solution of the problem.
The Dansgaard-Oeschger is pseudo cycle, repetitive warming and cooling of high latitude regions in the Northern hemisphere which includes the Greenland Ice sheet. The same regions that warmed in the 20th century are the same regions that warmed in the past D-O cycle. If one measures the average interval between the cycles the duration between cycles is at roughly 950 years, 1350 years, and 1950 years. That is a fact not a theory. The D-O cycle is repetitive. It happens again and again. Something obviously is physically causing it.
Comment:
The regions that warmed in the 20th century, high latitude Northern hemisphere is not the regions that the IPCC general circulation models (GCM) predicted would warm due to the increase in the greenhouse gas CO2. The GCM predicted that the planetary warming due to an increase in any greenhouse gas should be strongest in the tropics where there is the most amount of long wave radiation emitted off into space and there is ample water to amplify the CO2 forcing for example. There was minor warming of the tropics during the 20th century warming. This makes physical sense as analysis by Lindzen and Choi found that tropical cloud cover increases or decreases to reflect more or less radiation off into space thereby resisting (negative feedback) rather than amplifying the CO2 forcing. Supporting Lindzen and Choi’s result is the finding that there is no warming observed tropospheric warming of the tropical region. The IPCC models have assumed that the increase in CO2 will cause an increase in water vapor in the atmosphere (not an increase in cloud cover). That increase in water vapor in the tropics at around 8km above the surface of the planet amplifies the CO2 forcing.
It is possible to track 23 of the cycles. There are 9 cycles in the interglacial period and 14 cycles in the glacial period. That also is a fact not a theory.
A basic textbook on paleo climatic changes notes it is odd that the D-O cycles are observed in both the interglacial period and the glacial period, as the atmospheric conditions are very different between the Northern hemisphere in the glacial state as there are massive ice sheets covering the Northern Hemisphere and interglacial there are not. That also is a fact not a theory.
Basis paleo climate textbooks note the fact that there are 23 occurrence of the D-O cycle before the signal is lost as the resolution of the proxy is degraded further back in time, that points to an external forcing function, solar magnetic cycle changes.
There are cosmogenic isotope changes at each and every one of the nine (9) cycles in the interglacial cycles. Cosmogenic isotope changes are caused by solar magnetic cycle changes. That is a fact also not a theory. That fact obviously also points to the forcing function to be solar magnetic cycle changes. These are very strong logical pillars to support the assertion that solar magnetic cycle changes are causing what is observed.
Each of the above facts supports the assertion that solar magnetic cycle changes in some manner causing the D-O cyclic warming and cooling.
Most people have heard the expression that the dog wags the tail rather than the tail wags the dog. In the case of this problem sun is the dog and D-O repetitive warming and cooling
If solar magnetic cycle changes are the cause of what is observed, the timing between the occurrences of the D-O cycles is due to what is physically causing the solar magnetic cycle to change.
It is a fact that solar magnetic cycle changes. It is a fact that Northern hemisphere was cold during the Maunder minimum when the solar magnetic cycle was unanimously low. There is a physical reason why the Northern Hemisphere was physically cold during the Maunder minimum.
Curiously, it is known that the solar magnetic cycle is what is called pseudo cyclic. The physical reason for this is the orbits of the large planets is one component that regulates and modulates the solar magnetic cycle and there is a second internal solar component which it appears is non-linear and is certainly not understood. The internal solar component causes the sun to change in a manner if one does not understand the internal mechanisms to make it appear the solar magnetic cycle is changing chaotically, randomly which is not correct. If the solar specialist understood the internal mechanisms they likely could predict the solar magnetic cycle.
As the D-O cycle is pseudo cyclic which is not a surprise a solar magnetic cycle changes are driving/causing the D-O cycle. What is odd or surreal if one did not know there was a ‘climate war’ going on is the paper below that analyzes the D-O cycle in the frequency domain and finds it is pseudo cyclic and then concludes that what is observed is ‘likely due to arithmetic averaging’ which is hokum, a nonsensically statement, a disingenuous statement.
A disingenuous statement is a statement made which is known to be incorrect and made with the knowledge that it is incorrect with the objective of misleading or pushing a political agenda. Unfortunately due to the ‘climate wars’ if one wants access to funds or a tenured position at many universities it is necessary to make disingenuous statements and conclusions in published papers. The fibs and disingenuous statements are stopped by public discussion and debate of the facts.
In the case of this problem, the fibs and disingenuous statements will also cease as the planet is about to abruptly cool due to solar magnetic cycle 24 change which appears to be either the start of the cooling phase of a D-O cycle or the more sever cooling of a super D-O cycle which is called a Heinrich event.
Greenland ice temperature, last 11,000 years determined from ice core analysis, Richard Alley’s paper.
http://www.climate4you.com/images/GISP2%20TemperatureSince10700%20BP%20with%20CO2%20from%20EPICA%20DomeC.gif
http://www.agu.org/pubs/crossref/2003/2003GL017115.shtml
Timing of abrupt climate change: A precise clock by Stefan Rahmstorf
Many paleoclimatic data reveal a approx. 1,500 year cyclicity of unknown origin. A crucial question is how stable and regular this cycle is. An analysis of the GISP2 ice core record from Greenland reveals that abrupt climate events appear to be paced by a 1,470-year cycle with a period that is probably stable to within a few percent; with 95% confidence the period is maintained to better than 12% over at least 23 cycles. This highly precise clock points to an origin outside the Earth system; oscillatory modes within the Earth system can be expected to be far more irregular in period.
Rahmstorf analyzed the periodicity of the D-O cycles in the time domain (interval counting) which is appropriate as the forcing mechanism is pseudo cyclical.
http://www.leif.org/EOS/Obrochta2012.pdf
A re-examination of evidence for the North Atlantic “1500-year cycle” at Site 609
Therefore these records were referred to as either “quasi-periodic” (Bond et al., 1997) or “cyclic” (in a geologic sense, implying repetition, not periodicity) (Bond et al., 2001). The mean pacing of 1470 +/- 523 years was derived by interval counting (the elapsed time between cycle midpoints) and was the combined result of a composite record covering the last glaciation with V23-81 (1536 +/- 563 years) and the Holocene with V29-191 (1374 +/- 502 years) (Bond et al., 1997). Bond et al. (1999) later revised the V23-81 result to 1469 +/- 514 years and presented results for the last glacial interval of DSDP Site 609 (1476 +/- 585 years).
Variations in this stacked record coincided with well known climatic events, including the 8.2 ka Event (William, The 8200 BP event is a cooling event that is also evident in the tropics),
Medieval Warm Climate Anomaly, and Little Ice Age, (Bond et al., 1997, 2001).
https://ams.confex.com/ams/pdfpapers/74103.pdf
The Sun-Climate Connection by John A. Eddy, National Solar Observatory
Solar Influence on North Atlantic Climate during the Holocene
A more recent oceanographic study, based on reconstructions of the North Atlantic climate during the Holocene epoch, has found what may be the most compelling link between climate and the changing Sun: in this case an apparent regional climatic response to a series of prolonged episodes of suppressed solar activity, like the Maunder Minimum, each lasting from 50 to 150 years8. … ….The paleoclimatic data, covering the full span of the present interglacial epoch, are a record of the concentration of identifiable mineral tracers in layered sediments on the sea floor of the northern North Atlantic Ocean. The tracers originate on the land and are carried out to sea in drift ice. Their presence in seafloor samples at different locations in the surrounding ocean reflects the southward expansion of cooler, ice-bearing water: thus serving as indicators of changing climatic conditions at high Northern latitudes. The study demonstrates that the sub-polar North Atlantic Ocean has experienced nine distinctive expansions of cooler water in the past 11,000 years, occurring roughly every 1000 to 2000 years, with a mean spacing of about 1350 years. … ….Each of these cooling events coincides in time with strong, distinctive minima in solar activity, based on contemporaneous records of the production of 14C from tree-ring records and 10Be from deep-sea cores. For reasons cited above, these features, found in both 14C and 10Be records, are of likely solar origin, since the two records are subject to quite different non-solar internal sources of variability. The North Atlantic finding suggests that solar variability exerts a strong effect on climate on centennial to millennial time scales, perhaps through changes in ocean thermohaline circulation that in turn amplify the direct effects of smaller variations in solar irradiance.
http://www.pnas.org/content/early/2010/11/08/1000113107.abstract
Synchronized Northern Hemisphere climate change and solar magnetic cycles during the Maunder Minimum
The Maunder Minimum (A.D. 1645–1715) is a useful period to investigate possible sun–climate linkages as sunspots became exceedingly rare and the characteristics of solar cycles were different from those of today. Here, we report annual variations in the oxygen isotopic composition (δ18O) of tree-ring cellulose in central Japan during the Maunder Minimum. We were able to explore possible sun–climate connections through high-temporal resolution solar activity (radiocarbon contents; Δ14C) and climate (δ18O) isotope records derived from annual tree rings. The tree-ring δ18O record in Japan shows distinct negative δ18O spikes (wetter rainy seasons) coinciding with rapid cooling in Greenland and with decreases in Northern Hemisphere mean temperature at around minima of decadal solar cycles. We have determined that the climate signals in all three records strongly correlate with changes in the polarity of solar dipole magnetic field, suggesting a causal link to galactic cosmic rays (GCRs). These findings are further supported by a comparison between the interannual patterns of tree-ring δ18O record and the GCR flux reconstructed by an ice-core 10Be record. Therefore, the variation of GCR flux associated with the multidecadal cycles of solar magnetic field seem to be causally related to the significant and widespread climate changes at least during the Maunder Minimum.
William Astley says:
May 21, 2013 at 8:55 am
There are cosmogenic isotope changes at each and every one of the nine (9) cycles in the interglacial cycles. Cosmogenic isotope changes are caused by solar magnetic cycle changes.
The problem here is that the D-O episodes do not coincide with solar magnetic cycles. And, BTW, likely more than half the cosmogenic isotope signal is determined by climate, not by the sun.
William Astley says:
May 21, 2013 at 8:55 am
There are cosmogenic isotope changes at each and every one of the nine (9) cycles in the interglacial cycles. Cosmogenic isotope changes are caused by solar magnetic cycle changes.
The problem here is that the D-O episodes do not coincide with solar magnetic ‘cycles’. And, BTW, likely more than half the cosmogenic isotope signal is determined by climate, not by the sun.
William Astley says:
May 21, 2013 at 8:55 am
There are cosmogenic isotope changes at each and every one of the nine (9) cycles in the interglacial cycles. Cosmogenic isotope changes are caused by solar magnetic cycle changes.
Here is the cosmic ray intensity the past 10,000 years http://www.leif.org/research/Cosmic-Ray-Intensity-10k-years.png where are the D-O cycles?
Kristian
Again, you have to prove ENSO has increased after 1880 (or was unusually high) to claim ENSO is responsible for the century long trend.
lgl says, May 21, 2013 at 10:59 am:
“Again, you have to prove ENSO has increased after 1880 (or was unusually high) to claim ENSO is responsible for the century long trend.”
ENSO is ‘responsible for the century long trend’ in global temperatures. I already showed you:
http://i1172.photobucket.com/albums/r565/Keyell/ENSOAMOvsHadCRUT4ampHadSST3gl_zps866a1ff3.png
http://i1172.photobucket.com/albums/r565/Keyell/ENSOampAMOb_zps2f9f8129.png
This is because the signal from the ENSO region is simply propagated oceanically and atmospherically to the global ocean, the global landmass and the global troposphere. The cycle is ultimately Pacific. It pulls global temperatures stepwise down whenever it’s in a negative phase and stepwise up whenever in a positive one.
So what we need to look for, then, is what’s ‘responsible for the century long trend’ in the ENSO region?
Frankly I would say it’s up to you, as an apparent proponent for CO2’s ability to affect the mighty natural processes that make up the ENSO phenomenon in the long term and hence incrementally also in the short term, to show us that it is in fact so. To me it’s pretty obviously the Sun. That’s the null hypothesis. The Sun is what fuels ENSO. The Sun is the approximated perpetuum mobile. There is no question the Sun can and does heat the ocean and also influence global/regional pressure systems and hence jet trajectories and winds. There is, to put it mildly, a big question as to whether CO2 is capable of doing the same. Remarkable claims require remarkable evidence. We’re still waiting for that one single piece of it. Always a lot of conjecture going around, but absolutely nothing to back it up with.
http://i1172.photobucket.com/albums/r565/Keyell/TempgldetrvsSSNkumul_zps489f73b0.png
Why shouldn’t the Pacific (and hence the global) cycles tilt upward since 1910? Do you think the decadal cumulative solar forcing was necessarily the same during the cycle 1880-1945 as during the cycle 1945-2007 (or thereabouts)?
It’s more up to you, lgl, to prove there’s any real-world room for hypothesized CO2 warming at all, than for me to justify what the data on ENSO and global temperatures already clearly shows.
Congratulations Nic!
An article in Nature Geoscience is quite a feat.
I guess you next have to take issue with other studies that are using similar methods but showing more sensitivity (TCR as well as ECS), full-blown climate models that often show higher sensitivity (TCR as well as ECS), and estimates based on paleoclimatic data showing higher sensitivity (ECS in any case, do not think TCR can be reliably derived from paleoclimatic data). People do and will take issue with your approach, you should do the same with other approaches, that’s how science progresses. You got a fight on your hand!
Good luck!
And Nic,
You could explain to the commenters in this thread that say that CO2 has nothing to do with it and that models are always crap why they are wrong.
Good luck again!
William Astley says:
May 21, 2013 at 8:55 am
A disingenuous statement is a statement made which is known to be incorrect and made with the knowledge that it is incorrect with the objective of misleading or pushing a political agenda. …
Greenland ice temperature, last 11,000 years determined from ice core analysis, Richard Alley’s paper.
When overlaid by solar activity shows no correlation http://www.leif.org/research/GISP-and-Cosmic-Rays-NOT.png
Now, perhaps your statements are not disingenuous because you are just ignorant about the facts [which is no shame].
A final one Nic,
You could try to persuade Bob Tisdale to (try to) publish an article in a peer reviewed science journal detailing his views on how the world warms or does not. That would make it easier for readers to get an idea of the relative merits of your and his position. Or fight it out here! (I am more inclined to your viewpoint, whereas others in this thread prefer Tisdale.)
Good luck with that
Plain Richard says, May 21, 2013 at 3:50 pm:
“A final one Nic,
You could try to persuade Bob Tisdale to (try to) publish an article in a peer reviewed science journal detailing his views on how the world warms or does not. That would make it easier for readers to get an idea of the relative merits of your and his position. Or fight it out here! (I am more inclined to your viewpoint, whereas others in this thread prefer Tisdale.)
Good luck with that”
Or you could just let the data decide. All climate sensitivity studies simply take for granted that the warming is due to CO2. Tisdale (well, the real-world data actually) shows that it’s not. It’s very clearly ocean cycles (ENSO) and the Sun. And that’s it.
Re Nic Lewis (21 May, 7.08am): thanks very much, Nic, for taking the time and trouble to reply. You note that “As is standard practice in climate science, reliance is placed on the published temperature record and no adjustment is made to the HadCRUT4 global record for UHI, rural use land changes or increases in waste heat emissions.” As you point out, this limitation only applies to the 30% of global surface which is on land. However if, as seems likely, each of these human impacts has tended to increase measured surface temperatures by (as you suggest) an unknown amount, what reliance can we place on the onland surface temperature record when calculating a global value of ΔT that can be attributed to added atmospheric CO2? Might it not be safer to ignore the onland record altogether and rely entirely on marine data?