Shaviv and Miskolczi

Nir’s 2005 paper “On climate response to changes in the cosmic ray flux and radiative budget”, available as pdf here, provides a solid case linking cosmic ray flux (CRF) variations to global climate change. The effect is consistent over hugely different timescales, using completely different indicators — from cosmic sources of CRF at the Phanerozoic, to the shortest time scale of the 11-yr solar cycle. The fit is extraordinary. The statistics competent. The bottom line?

Thus, anthropogenic sources alone contributed to a warming of 0.14 ± 0.36 K since the beginning of the 20th Century. Using our estimate, we find Tsolar = 0.47 ± 0.19 K. We therefore find that the combined solar and anthropogenic sources were responsible for an increase of 0.61 ± 0.42 K. This should be compared with the observed 0.57 ± 0.17 K increase in global surface temperature [IPCC, 2001].

In other words, changes in solar forcing, amplified by changes in cloud albedo due to CRF variations, account for a whopping 80% of the temperature increase seen since 1900. The rest, 20%, can be attributed to AGW.

I thought it would be interesting to see if Shaviv’s theory fits together with Miskolczi’s. Miskolczi’s is a theory of constant optical IR depth for the atmosphere, a consequence being that fluctuations in climate mostly come about through changes in solar forcing, i.e. short wave SW in, not effects of IR absorbers on long wave out. Even if you are not happy with all aspects of his theory, I want to look at it from the point of view of a theory explaining why IR absorbers like CO2 might not have as a strong an effect on global temperature as the IPCC scientists assert.

Shaviv explains that the CRF variations bring about changes in the % cover of low altitude clouds (LACC), changing the optical depth for both IR and SW. However, the effects are not equal.

This result is also reasonable considering that the total long wavelength heating effect of LACC was estimated to be 3.5Wm−2 [Hartmann et al., 1992], while cloud albedo is responsible for a globally averaged cooling of 20Wm−2, implying that changes in albedo will likely be more important for changing the radiative budget arising from LACC variations.

That is, by far the greatest effect of variations in LACC are on the SW, reflecting more sunlight away when cloud cover increases, thus shading and reducing the solar isolation at the surface. So while Miskolczi says global warming can’t be due to long wave variation, because the system optimizes for stability at that wavelength, Shaviv says there is a variation in solar input, amplified 5 to 7 times by cloud cover, and it explains temperature variation far better than GHG’s across all known time scales.

The two theories are both consistent and complementary, providing the strongest basis so far, for a natural and not human explanation for global warming.

Nir Shaviv

The theory of this Israeli astrophysicist has gained traction as the great white hope of climate skeptics. Below are some sources of background reading.

Shaviv champions the solar-wind modulated cosmic ray flux (CRF) hypothesis, which was suggested by Ney, discussed by Dickenson, and furthered by Svensmark (see CO2 Science). Evidence consistes of correlations between CRF variations and cloud cover, correlations between non-solar CRF variations and temperature over geological timescales, as well as experimental results showing that the formation of small condensation nuclei could be bottlenecked by the number density of atmospheric ions.

Basically, high CRF ionizes particles that seed more clouds, causing cooling. Low CRF produces brighter cloud free condition, resulting in warming.

Recently, he reports in GRL that three independent data sets show that the oceans absorb and emit an order of magnitude more heat than could be expected from just the variations in the total solar irradiance, implying the existence of an amplification mechanism. Shaviv, says this predicts the correct radiation imbalance observed in the cloud cover variations that are needed to produce the magnitude of the net heat flux into the oceans associated with the 11-year solar cycle.

The Reference Frame had an article about Shaviv recently too, noting significant pushback by RealClimate, proof the CRF theory is a viable alternative to the GHG warming as the main explanation for recent warmth.

By the way, despite all the huge pro-greenhouse bias in the journals and elsewhere, the Shaviv-Veizer paper has 91 citations right now, while the almost immediate alarmist reply by 11 authors, including RealClimate’s Rahmstorf, Archer, and Schmidt, only has 24 citations.

A very instructive exchange ensued in May 2006 at the RealClimate post “Thankyou for Emitting” where Shaviv challenged masterfully (starting at post 37), until the team eventually threw in the towel around post 125.

On the subject of Rahmstorf, Shaviv’s own blog site ScienceBits refers to RealClimate as in a post More slurs from RealClimate. He pins them as bleeding hearts and intellectual lightweights as well. continues with its same line of attack. writers try again and again to concoct what appears to be deep critiques against skeptic arguments, but end up doing a very shallow job. All in the name of saving the world. How gallant of them.

Since there is no evidence which proves that 20th century warming is human in origin, the only logically possible way to convict humanity is to prove that there is no alternative explanation to the warming (e.g., see here). My motivation (as is the motivation of my serious colleagues) is simply to do the science as good as I can.

But Nir is not an extremist discounting all effects of greenhouse gasses.

In fact, my best estimate for climate sensitivity implies that anthropogenic radiative forcing explain about 1/3 of the 20th century warming, in particular over the past few decades.

Some of the flavor of the debate between them can be seen from the following two comments at Shaviv’s blog:

Rasmus: You are wrong about the motivation about our critisism, Shaviv; we are primarily interested in doing good sicence. We want to unravel the facts behind climate variability. In science, one challenge other views if one finds them strange or not credible. This is what we habve done. You make claims based on your own subjective belief og based on far-fetched speculations. The fact is that the claim that the recent global warming is due to GCR is not supported be any real evidence; there is no credible trend in the solar activity or GCR in the last ~50 years.

Shaviv: Perhaps you’re right. But if so, then it means you should have the integrity to add at the end of your post (and not buried in the discussion below), an addendum saying that this particular critique turned out to be wrong, as Kranz et al. is not applicable to the Milky Way. I for my part would add a similar addendum to my response, specifying that my comments about motives was wrong.

Second, over all, there was a large increase in the solar activity over the 20th century, even if you discard the Yakutsk data (used in the Ahluwalia plot), and this increase explains a large fraction of the 20th century temperature increase if the CRF/climate link is real. As for the temperature increase over the 1990’s, see my response above. Some of the warming is due to the fact that although there was a decrease in the indirect solar forcing over the last cycle, it is still notably above the current forcing/temperature equilibrium (and therefore causes warming), and of course, some of the warming is anthropogenic.

The scientific issues are not settled.

And now, the rest of the story.

Dr Roy Spencer, has weighted in on Dessler et al 2008. Water-vapor climate feedback inferred from climate fluctuations, 2003-2008,

Whereas Dessler closes his paper firmly in the climate liberal camp.

[23] The existence of a strong and positive water-vapor feedback means that projected business-as-usual greenhouse gas emissions over the next century are virtually guaranteed to produce warming of several degrees Celsius. The only way that will not happen is if a strong, negative, and currently unknown feedback is discovered somewhere
in our climate system.

Climate conservative Spencer continues where he left off:

The Rest of the Story: Shortwave Feedback

The other half of the feedback story which Dessler et al did not address is the reflected solar component. This feedback is mostly controlled by changes in low cloud cover with warming. The IPCC admits that feedbacks associated with low clouds are the most uncertain of all feedbacks, with positive or negative feedback possible…although most, if not all, IPCC models currently have positive SW feedbacks.

But I found from the CERES data a strongly negative SW feedback during 2002-2007. When added to the LW feedback, this resulted in a total (SW+LW) feedback that is strongly negative.

Is my work published? No…at least not yet…although I have tried. Apparently it disagrees too much with the IPCC party line to be readily acceptable. My finding of negative SW feedback of around 5 W m-2 K-1 from real radiation budget data (the CERES instrument on Aqua) is apparently inadmissible as evidence.

In contrast, Dessler et al.’s finding of positive LW feedback inferred indirectly from the AIRS instrument, even though it is only 1.3 W m-2 K-1 (3.3 Planck response minus their reported 2.0 for the LW feedback parameter) is not only admissible, but the reviewers even let the authors call it “strongly positive” feedback. Sheesh.

The last calculations regarding the Planck response seem to suggest that the null value — no feedback response — should be 0.7. Is this right? This would impact on the determination of the significance of the result considerably.

Ronald Reagan's Birthday

Ronald Reagan was born on the 6th of February 1911. If ever we were in need of wisdom from the man who changed the free world, its now. Below are some of my favorite Reagan quotes, relating to some of the madness going on around us.

Soros Says Crisis Marks End of Free-Market Model That Started Under Reagan

Government’s view of the economy could be summed up in a few short phrases: If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.

Obama Plans to Reduce Budget Deficit to $533 Billion by End of First Term

Governments tend not to solve problems, only to rearrange them.

I am not worried about the deficit. It is big enough to take care of itself.

Madoff Left No Sign of Thousands of Reported Client Trades, Trustee Says

I know in my heart that man is good. That what is right will always eventually triumph. And there’s purpose and worth to each and every life.

Microsoft, Intel Firings Stir Resentment Over Visas for Foreign Workers

Recession is when a neighbor loses his job. Depression is when you lose yours.

My philosophy of life is that if we make up our mind what we are going to make of our lives, then work hard toward that goal, we never lose – somehow we win out.

North Pole Explorers’ Arduous Trek to Prove Arctic Melt Speed

Trust, but verify.

Propagation of Uncertainty through Dessler

The following is an approximate propagation of uncertainty through Dessler et als. equation for estimating the strength of water vapor feedback λ. We have been looking at the error-bars in his recent paper Water-vapor climate feedback inferred from climate fluctuations, 2003-2008, not calculated in the published paper. Assumptions made are noted. Refer to wiki for propagation of error equations.

Here R is the top of atmosphere IR, q is the specific humidity and T is the temperature.

1. $$lambda = Sigma frac{partial R}{partial q}frac{Delta q}{Delta T} =Kfrac{Delta q}{Delta T} $$

Rolling up the summation over the earths surface into K.

2. $$lambda = Kfrac{q_1-q_0 pm sqrt{2}sigma_q}{T_1-T_0 pm sqrt{2}sigma_T} $$

Substituting the values two endpoint years used in calculating the differences, and their uncertainties, using propagation of errors for differences, assuming independence.

3. $$(frac{sigma_lambda}{lambda})^2 = (frac{sqrt{2}sigma_q}{Delta q})^2 + (frac{sqrt{2}sigma_T}{Delta T})^2 $$

Substituting uncertainty of q and T into equation for propagation of errors through ratios, assuming independence.

4. $${sigma_lambda}^2 = 2{sigma_q}^2 + 2{sigma_T}^2 $$

Assuming λ, q and T are the same magnitude. This is an underestimate if λ=2.

5. $${sigma_lambda} = 2sigma_{qT} $$

Assuming uncertainty of q and T are equal, and squaring.

So according to these rough calculations, the actual uncertainty in λ could be roughly twice the uncertainty observed in the Dressler figures. This increase is due to the use of a single year, 2008 as the reference point, for calculating the change in humidity and temperature relative to other years. The uncertainty in the arbitrary choice of this point increases the uncertainty when propagated through the calculations for water vapor feedback.

Our calculated standard deviation of the mean was 0.37 W/m2/K. The confidence limits of the mean are then 1.96*2*0.37 or 1.45, giving a lower limits to the estimated 2.04 W/m2/K value of vapor feedback of 0.59 W/m2/K.

If we substitute values into step 3 of λ=2, q=2, T=1 we get an even higher uncertainty reflecting the effect on the ratio of dividing by a smaller number.

6. $${sigma_lambda}^2 = 2{sigma_q}^2 + 8{sigma_T}^2 $$

7. $${sigma_lambda} = sqrt{10}sigma_{qT} $$

The confidence limits of the mean are then 1.96*3.16*0.37 or 2.29, giving a lower limits to the estimated 2.04 W/m2/K value of vapor feedback of -0.25 W/m2/K. Being less than zero, this indicates that zero feedback is within the limits of uncertainty. This is very similar to the CI obtained be a t-test of difference of means in the previous post.

Dessler rambles on about the large influence temperature has on the uncertainty of the feedback here.

[20] Figure 4 also helps explain the large year-to-year
variability in our calculated values of lq in Table 1. It is
tropical q that primarily determines the size of the water
vapor feedback, and tropical q is primarily regulated by the
tropical surface temperature [e.g., Minschwaner and
Dessler, 2004]. The definition of lq, however, uses
changes in global-average surface temperature. While
changes in global and tropical temperatures are related,
there are often variations in the global average that are
not reflected in the tropical average and vice versa. Such
variations lead to large variations in lq.

[21] Consider, for example, the small feedback lq
inferred between January 2007 and January 2008. The
difference in the global average surface temperature DTs
between these two months was 0.60 K. Much of this,
however, was due to extreme changes in the northern
hemisphere mid- and high latitudes. The tropical average
surface temperature difference DTtropics was a milder 0.37 K.
The relatively small change in tropical surface temperature
leads to a relatively small change in q, and therefore a
relatively small value of (@R/@q)Dq of 0.57 W/m2.
Dividing that by the large DTs leads to the small value
of 0.94 W/m2/K inferred for lq over that period.

[22] The months with the largest inferred values of lq, on
the other hand, are the months where DTs is smaller than
DTtropics. For example, DTs between January 2008 and
January of 2006 was 0.28 K, while DTtropics between these
months was 0.33 K. This arrangement contributes to a large
value for the inferred lq between these months. Given
enough data, such variations should average out. In a short
data set such as the one analyzed here, however, such
variations can be significant.

You got that right. It would seem that three almost equal contributions to overall uncertainty are as follows:

Total uncertainty = measurements + reference point + ratio amplification

Dessler, Zhang and Yang fail significance tests

A concerned reader sent me this recent paper Water-vapor climate feedback inferred from climate fluctuations, 2003-2008, writing:

The following (ala Hansen) IMO should never have been accepted in a "peer reviewed" journal. "The existence of a strong and positive water-vapor feedback means that projected business-as-usual greenhouse gas emissions over the next century are virtually guaranteed to produce warming of several degrees Celsius. The only way that will not happen is if a strong, negative, and currently unknown feedback is discovered somewhere in our climate system."

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The Google Reader tool is quite the step forward in productivity. Here are some of its most productive features.

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