Further attempt to falsify the Svensmark hypothesis

05/10/2011

Climate Change – News and Comments

Falsification tests of climate hypotheses

The trouble with clouds

Against the Danish physicist’s claim that cosmic rays influence the Earth’s low cloud cover and thereby the climate, there’s one contention that keeps turning up like the proverbial bad penny. During recent years, so the story goes, the Sun has been weak, cosmic rays have been relatively intense, and yet the expected increase in low clouds has not occurred. On the contrary, we’re told, low cloud cover has remained relatively sparse. That’s according the International Satellite Cloud Climatology Project, ISCCP, which pools data from the satellites of several nations,

The contention is repeated in a forthcoming paper in Journal of Climate by Ernest M. Agee, Kandace Kiefer and Emily Cornett of Purdue University, entitled “Relationship of Lower Troposphere Cloud Cover and Cosmic Rays: An Updated Perspective.” An advanced version of the full text is available from: http://curryja.files.wordpress.com/2011/09/agee-cosmic-rays.pdf A favourable commentary appears on the Ars Technica website: http://arstechnica.com/science/news/2011/09/do-cosmic-rays-set-the-earths-thermostat.ars?utm_source=rss&utm_medium=rss&utm_campaign=rss

Agee et al.’skey exhibit is their Fig. 2:

Over the period 1984-2008, cosmic ray variations (solid line) from a neutron counter at Kiel, Germany, are compared with cloudiness in the lower troposphere reported by ISCCP (broken line). Note the mismatch 2005-08. Agee et al. 2011, © American Meteorological Society.

And their abstract reads: An updated assessment has been made of the proposed hypothesis that “galactic cosmic rays (GCRs) are positively correlated with lower troposphere global cloudiness.” A brief review of the many conflicting studies that attempt to prove or disprove this hypothesis is also presented. It has been determined in this assessment that the recent extended quiet period (QP) between solar cycles 23-24 has led to a record high level of GCRs, which in turn has been accompanied by a record low level of lower troposphere global cloudiness. This represents a possible observational disconnect, and the update presented here continues to support the need for further research on the GCR-Cloud hypothesis and its possible role in the science of climate change.

 There’s glory for you! – meaning a fine knock-down argument, as Humpty Dumpty said to Alice. To uninformed eyes (meaning, sadly, most climate scientists and commentators) the graph looks like a devastating falsification of the Svensmark hypothesis. Readers might even be surprised by the cautious language in the abstract, about a “possible observational disconnect”.

In fact the authors have every reason for caution. The conspicuous downward trend in the ISCCP cloud data is almost certainly unreal. An expert view is that it results from changes in the operational status of the satellites from which the data are pooled – see the references below to Campbell 2004, Campbell 2006 and Evan et al. 2007.

If a satellite views clouds from a slanting angle it sees more low clouds than when it’s looking straight down. Changes in the population and orbits of satellites contributing to ISCCP data have tended to narrow the viewing angle to nearer the vertical. That will have reduced the reported cloudiness even if, in the real world, the cloudiness were unchanging or even increasing. The effect is seen in these early maps from Campbell.

Upper map: the trend in cloudiness from July 1983 to September 2001 across a grid box with 280 km squares, from the official ISCCP data with the annual cycle removed. Lower map: adjustment for the changing viewing angles of the satellites greatly reduces the areas of supposed loss of clouds (in blue). Campbell 2004.

The harsh fact is that supposedly real observations of clouds over the decades are in a state almost as parlous as the IPCC’s contradictory computer models of climate. Here is a summary of observed monthly cloud “anomalies” (i.e. variations) in five different data sets, published by the American Meteorological Society (ref. Arndt et al. 2010, see below).

Black: ISCCP D2 Total cloud amounts from multiple satellites 1983-2008

Red: MISR Multi-angle Imaging Spectroradiometer on NASA’s Terra satellite 2000-2009

Blue: MODIS Moderate Resolution Imaging Spectroradiometer on NASA’s Terra and Aqua satellites 2000-2009

Brown: PATMOS-x Cloud data derived retrospectively from NOAA’s Advanced Very High Resolution Radiometer flown on a long succession of US spacecraft 1982-2009

Violet: SOBS Cloud amounts from surface weather observations 1971-1996.

In each case the solid lines are 12-month running means.

By cherry-picking favourable data (e.g. MISR and MODIS) I might try to claim that clouds have indeed increased with the high cosmic ray levels of the past decade. But judiciously one can only say that, as long as the data are so poor and contradictory, the jury must remain out, on what clouds have done and are doing. The last thing that Agee et al. or anyone should attempt with this shoddy stuff is to falsify the Svensmark hypothesis, for which plenty of other evidence exists. This includes variations in low clouds observed by satellites over days rather than decades, as in the Svensmark, Bondo and Svensmark 2009 paper summarized and referenced here http://calderup.wordpress.com/2010/05/03/do-clouds-disappear/ and in the recent Serbian paper that infers cloudiness from day-night temperature differences, as I reported here http://calderup.wordpress.com/2011/09/10/do-clouds-disappear-4/

 

The data on cloudiness over the longer term will be improvable by retrospective number-crunching, with PATMOS-x leading the way for total cloud. I’m very encouraged to see, in the last plot above, that PATMOS-x (brown) provides almost a mirror image of the ISCCP variations (black). But the low-level cloudiness may be more difficult to improve.

PS: For the philosophical importance of the falsifiability of hypotheses, according to Karl R. Popper, see http://calderup.wordpress.com/2010/05/01/falsification-intro/

 References

It’s perhaps needless to say that none of these is to be found in Agee et al.’s paper.

G.G. Campbell, “View angle dependence of cloudiness and the trend in ISCCP cloudiness,” 13th AMS Conference on Satellite Meteorology and Oceanography, 2004

G.Garrett Campbell, “Diurnal and angular variability of cloud detection: consistency between polar and geosynchronous ISCCP products”, 14th AMS Conference on Satellite Meteorology and Oceanography, 2006

Amato T. Evan, Andrew K. Heidinger, and Daniel J. Vimont “Arguments against a physical long-term trend in global ISCCP cloud amounts” Geophysical Research Letters, 34, l04701, 2007

D.S. Arndt, M. O. Baringer, and M. R. Johnson, eds.: “State of the Climate in 2009”, Bull. Amer. Meteor. Soc., 91 (7), S1-S224, 2010


Do clouds disappear? (4)

10/09/2011

Climate Change – News and Comments

Falsification tests of climate hypotheses

Warmer days and cooler nights when cosmic rays are scarce

Here’s a reminder of a climatic footnote to the 9/11 terrorist attacks on New York and Washington DC, ten years ago this weekend. With civilian aircraft grounded for three days, and without the contrails that usually criss-cross the skies of the USA, the difference between daytime and night-time temperatures at the surface increased. (See the Travis reference below.) Apparently like many other clouds (not all) the contrails reduce sunshine during the day and blanket the loss of heat at night. Take away those man-made clouds and the days become a little warmer and the nights a little cooler. In the jargon: the diurnal temperature range (DTR) increases.

(((Remark added 11 September. With comments coming in that cast doubt on that contrail story, I’ll repeat part of what I said in reply to Dahuang below. It doesn’t really matter what the reason was, for the post-9/11 increase in DTR, as long as everyone accepts that a loss of cloud was involved.)))

An echo of that mini-climatic event comes with the news that the DTR in Europe increases when there’s a big reduction in cosmic rays arriving at the Earth. With the implication that the skies are less cloudy at such times, it’s strong evidence in favour of Henrik Svensmark’s hypothesis that cosmic rays help to make clouds. The report comes from Aleksandar Dragić and his colleagues at the Institute of Physics in Belgrade. I’m grateful to Bengt Andersson for drawing their paper to my attention. It was published on 31 August and the full text is available here http://www.astrophys-space-sci-trans.net/7/315/2011/astra-7-315-2011.pdf  It’s typical of the pathetic state of science reporting that I still seem to have the story to myself ten days later.

More than a year ago I began a succession of posts on whether or not observations in the real world support or falsify the Svensmark hypothesis. The most explanatory was the first – see http://calderup.wordpress.com/2010/05/03/do-clouds-disappear/

The focus was on the “natural experiments” in which big puffs of gas from the Sun block some of the cosmic rays coming from the Galaxy towards the Earth. The resulting falls in cosmic ray influx, called Forbush decreases, last for a few days. The game is to look for observable reductions in cloudiness in the aftermath of these events. The results are most clearly favourable to the Svensmark hypothesis for the Forbush decreases with the largest percentage reductions in cosmic rays. Scientists keen to falsify the hypothesis have only to mix in some of the weaker events for the untidiness of the world’s weather to “hide the decline”.

The Serbs avoid that blunder by picking out the strongest Forbush decreases. And by using the simple, reliable and long-provided weather-station measurements of temperature by night and day, they avoid technical, interpretive and data-availability problems that surround more direct observations of clouds and their detailed properties. The temperatures come from 184 stations scattered all across Europe (actually, so I notice, from Greenland to Siberia). A compilation by the Mount Washington Observatory that spans four decades, from 1954 to 1995, supplies the catalogue of Forbush decreases.

The prime results are seen here in Dragić et al.‘s Figure 5. The graphs show the increase in the diurnal temperature range averaged across the continent in the days following the onset of cosmic ray decreases (day 0 on the horizontal scales). The upper panel is the result for 22 Forbush events in the range 7−10%, with a peak at roughly +0.35 oC in the diurnal temperature range. The lower panel is for 13 events greater than 10%. The peak goes to +0.6 oC and the influence lasts longer. It’s very satisfactory for the Svensmark hypothesis that the effect increases like this, with greater reductions in the cosmic rays. The results become hard (impossible?) to explain by any mechanism except an influence of cosmic rays on cloud formation.

To be candid, these results are much better than I’d have expected for observations from a densely populated continent with complex weather patterns, where air pollution and effects of vegetation confuse the picture of available cloud condensation nuclei. Svensmark’s team has emphasised the observable effects over the oceans. Now the approach taken by the Belgrade team opens the door to similar investigations in other continents. Let a march around the world’s land masses begin!

References

USA: diurnal temperatures post-9/11

D.J. Travis, A. Carleton and R.G. Lauritsen, “Contrails reduce daily temperature range”, Nature 418, 601, 2002

Europe: diurnal temperatures after Forbush decreases

A. Dragić, I. Aničin, R. Banjanac, V. Udovičić, D. Joković´, D. Maletić and J. Puzović, “Forbush decreases – clouds relation in the neutron monitor era”, Astrophysics and Space Sciences Transactions, 7, 315–318, 2011.


Do clouds disappear? 3

09/08/2010

Falsification tests of climate hypotheses

Cosmic rays and clouds at various latitudes

An exchange with Prof. Terry Sloan of Lancaster University

I’m promoting to the start of a new post a comment on an earlier post that came from Terry Sloan, together with my reply and his comment on my reply. I’ve included a graph that he sent in an e-mail because it wouldn’t upload into the Comments section.

After that, the discussion continues here with further remarks from me.

Sloan is one of the severest critics of the Svensmark hypothesis that cosmic rays influence the Earth’s low clouds. The earlier post, entitled “Do clouds disappear when cosmic rays get weaker?”, was concerned chiefly with whether or not sudden changes called Forbush decreases have observable effects on cloud cover. You can see that post in full here: http://calderup.wordpress.com/2010/05/03/do-clouds-disappear/

But the present interaction with Sloan mainly concerns a different question, about the influence of the Earth’s magnetic field. To help readers to get quickly up to speed, here’s the most relevant extract from my original post:

Read the rest of this entry »


Do clouds disappear? 2

24/05/2010

Added 12 June 2010: There is now a thoughtful reply from Eimear Dunne.

Climate Change – News and Comments, and an echo of a Falsification Test

Wake up! Models don’t trump observations

The most important article since I launched this blog on 1 May may be Do clouds disappear when cosmic rays get weaker? – see here http://calderup.wordpress.com/2010/05/03/do-clouds-disappear/

It tells of unremitting attempts to falsify the Svensmark hypothesis by claiming that there’s no important effect on global cloud cover when eruptions from the Sun briefly cut the influx of cosmic rays, in “Forbush decreases”. The centrepiece is a summary of results published last year by Svensmark, Bondo and Svensmark. They show very plainly, in observations of the real world, that Forbush decreases have big impacts both on aerosols (chemical specks that grow into cloud condensation nuclei) and on low-level clouds.

That earlier post continues with the efforts in 2009-10 by Wolfendale and Arnold and their collaborators, who try to deny the Svensmark group’s result, by using relatively weak Forbush decreases. Svensmark can explain exactly how the impacts in those cases are masked by quasi-random meteorological noise, like tigers hidden in a jungle’s undergrowth.

Real-world results by Svensmark, Bondo & Svensmark (2009) for the remarkable loss of fine aerosols from the atmosphere (black curve) following five strong Forbush decreases in cosmic rays (red curve). Each aerosol datum point is the daily mean from about 40 AERONET stations world-wide, using stations with more than 20 measurements a day.

New nonsense comes in an abstract posted on the CERN website. It’s for a paper by researchers at Leeds, to be presented at a meeting about aerosols in Helsinki in three months’ time.

At issue are the Svensmark team’s results on aerosols (see right).  These show fine aerosols disappearing from the sky, because the shortage of cosmic rays lessens the chemical production of the  clusters of sulphuric acid and water molecules that seed the aerosols.

According to the people in Leeds, that can’t be right because they have a computer model that contradicts it.

The GLOMAP model was developed by Ken Carslaw, and the unlucky person named as lead author is a graduate student, Eimear Dunne.

An open letter to the lead author


Read the rest of this entry »


Warming of Greenland?

06/05/2010

Falsification tests of climate theories

Is the recent warming of Greenland unprecedented?

or, Come for a ride on my polar roller-coaster

The strongest reasons for doubting the man-made global warming hypothesis come from pre-industrial climate change. During the past 10,000 years, since soon after the end of the last ice age, there have been bigger ups and downs in global temperatures than during the 20th Century. Yet according to the IPCC, citing measurements of gas trapped in polar ice, the concentration of CO2 varied by only about 20 ppm throughout those 10,000 years – less than a quarter of the change during the 20th Century.

So whatever caused the pre-industrial climate changes, it was not CO2. The record is well accounted for, in fact, by (1) a change in the Earth’s attitude in orbit, which brought a gradual cooling to the Northern Hemisphere, and (2) solar variations that superimposed on that trend a succession of warmings and coolings. Yet to offer such natural explanations for past events does not logically falsify the man-made global warming hypothesis, because its supporters say it represents an important new factor in climate change.

If increasing CO2 had no effect whatever on the climate, that might be surprising, but the claim of the hypothesis and its computer models is that the new contribution from man-made greenhouse gases has become the main driver of recent climate change. Implied here is a falsifiable statement, namely that there is something very unusual about the recent warming of the world. That is certainly the sense of many scientific and political pronouncements about global warming.

Read the rest of this entry »


Do clouds disappear?

03/05/2010

Falsification tests of climate theories

Do clouds disappear when cosmic rays get weaker?

or “Don’t you worry, my dear, we’ve seen no tigers”

The Sun makes fantastic natural experiments” Henrik Svensmark says, “that allow us to test our ideas about its effects on the Earth’s climate.” Most dramatic are the events called Forbush decreases. Ejections of gas from the Sun, carrying magnetic fields, can suddenly cut the influx of cosmic rays coming to the Earth from exploded stars.

According to the Svensmark hypothesis, cosmic rays seed the formation of low clouds, so there should be a reduction in the Earth’s low cloud cover in the aftermath of a Forbush decrease. During the past few years there have been repeated attempts to declare the hypothesis falsified, when various teams failed to find the expected decrease in the low cloud cover.

One morning in April 2008, I woke up to find that since midnight the BBC had spread all around the world the news that British physicists had more or less destroyed the Svensmark hypothesis. Violating a basic principle of objective reporting, the broadcasts went out before Svensmark himself had a chance to comment.

By lunchtime he and I had done our best to limit the damage – and the deception of the public – in brief radio and TV interviews. A remark from Svensmark went belatedly onto the BBC website, that the critic it quoted had “simply failed to understand how cosmic rays work on clouds”.

Two years later, critics still don’t understand it. But they go on telling the tale that Forbush decreases have no important effect on clouds, and the media go on echoing them. When Svensmark and his colleagues published in August 2009 a report that showed very clear effects, and explained why others had failed to see them, the BBC and almost everyone else ignored it. But not the scientific critics, who returned to the fray in December 2009 and February 2010. Read the rest of this entry »


Falsification intro

01/05/2010

Falsification tests

Introduction: Is climate research a real science?

Here’s how the philosopher of science Karl R. Popper explained how to disitnguish a real, or ‘empirical’, science from a pseudo-science.

Popper: Logik der Forschung 1934. In English, The Logic of Scientific Discovery 1959.

I shall certainly admit a system as empirical or scientific only if it is capable of being tested by experience. These considerations suggest that not the verifiability but the falsifiability of a system is to be taken as a criterion of demarcation. In other words: I shall not require of a scientific system that it shall be capable of being singled out, once and for all, in a positive sense: but I shall require that its logical form shall be such that it can be singled out, by means of empirical tests, in a negative sense: it must be possible for an empirical scientific system to be refuted by experience.

Hence the statement, “It will rain or not rain here tomorrow” will not be regarded as empirical, simply because it cannot be refuted; whereas the statement, “It will rain here tomorrow” will be regarded as empirical.

A series of postings under Falsification Tests in Calder’s Updates will compare results for the man-made global warming hypothesis and for Henrik Svensmark’s cosmic climate hypothesis about cosmic rays and clouds.

Historical background

Although the Svensmark hypothesis is quite recent (1996), it’s a fresh version of a much older and more general solar hypothesis, that the Sun is responsible for climate change over years, decades and centuries. From its origin with William Herschel in 1801, the idea that copious sunspots mean a warm climate and a scarcity means a cooler climate was the leading hypothesis for nearly two centuries.

The solar hypothesis was supposedly falsified in the 1980s when the SolarMax satellite measured the variation in the Sun’s brightness during a solar cycle and found that the changes were too small to be very influential on the climate. That is still the official position of the Intergovernmental Panel on Climate Change (IPCC), but the verdict flew in the face of abundant historical evidence for solar-driven climate change. The Svensmark hypothesis soon provided a mechanism for greatly amplifying the influence of the Sun’s variations.

As for the man-made global warming hypothesis, its adoption by an influential group of climate scientists is also a recent phenomenon. Writing in Scientific Europe (ed. Calder, 1990) the first chairman of the IPCC, Bert BolÍn of Stockholm, recalled that the idea that human beings would alter the Earth’s climate by releasing CO2 was neglected or disbelieved by most climate scientists from 1896, when Svante Arrhenius pointed out the possibility, until 1988, when a meeting of experts in Toronto called for a curb on CO2 emissions.

What changed their minds was mainly the big increase in computer speeds. It enabled the development of ever-more elaborate models to simulate the climate for decades ahead, on various assumptions. The continuing reliance of the man-made global warming hypothesis on the computer models is important to remember. As they assume that positive feedbacks amplify the rather small direct greenhouse effect of CO2, the models easily generate alarming predictions of big temperature rises as CO2 increases.

And they are endlessly adjustable. Medieval astronomers, who believed that all heavenly motions had to be ideal circles, were able to match the imperfectly measured motions of planets by adding epicycles. Similarly, climate scientists can tweak the models to deal with criticisms and would-be Popperian falsifiers keep finding the goalposts moving.

In any case, different models give a wide range of different predictions, both globally and regionally. The man-made global warming hypothesis thus comes perilously close to “It will rain or not rain here tomorrow”, which Popper said is not empirical, because it cannot be refuted. While this slipperiness may be handy for the “warmists” to score temporary debating points, it would leave them with a pseudo-science if there were not some features of the hypothesis that remain open to tests.

Many critics wish to refute the Svensmark hypothesis. Their tests will be evaluated too, starting with claims, much publicized over the past few years, that changes in cloudiness fail to follow sudden changes in the influx of cosmic rays. In such a contentious area I must of course declare an interest, as co-author with Svensmark of The Chilling Stars, which explains his hypothesis.

Initial postings

  • Do clouds disappear when cosmic rays get weaker?
  • Is the recent warming of Greenland unprecedented?

Other tests of the Svensmark hypothesis will include

  • The recently lazy Sun
  • Laboratory tests
  • The Earth’s changing magnetic field
  • Recent changes in the Earth’s cloud cover
  • Anomalous Antarctica

Other topics tests of the man-made global warming hypothesis will include

  • Do temperature changes follow CO2 ?
  • The Hockey Stick
  • Climate sensitivity
  • Upper air temperatures
  • Anomalous Antarctica

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