28 February 2010

More climate change denial

The Weekend Australian Financial Review, 20-21 February 2010, carried a particularly obnoxious article (Data-massaging scientists having a terrible day) by conservative US columnist George Will. It was published under the tag-line “Climate Scepticism”. The nation’s leading financial newspaper ought to know better: the term “sceptic” ought to be reserved for people who give some indication of a preparedness to change their mind in the light of evidence.

Will certainly doesn’t attempt to conceal his glee at the discomfiture caused by some academic misbehaviour and some sloppy checking of sources:

[IPCC Chairman Rajendra Pachauri] denounces persons sceptical about the shrill certitudes of those who say global warming poses an imminent threat to the planet ...

- ... Nothing prepared him for the horror of encountering disagreement. Global warming alarmists, long cosseted by echoing media, manifest an interesting incongruity – hysteria and name calling accompanying serene assertions about the “settled science” of climate change.

In fact, according to Will, the science is specious, and there is an absence of global warming (no statistically significant warming for 15 years, he is happy to tell us, misrepresenting Phil Jones, former director of the Climatic Research Unit in Britain).

So according to George Will, the science is not settled and there is no global warming. Will’s recent commentary on climate change has been comprehensively demolished by The Guardian’s George Monbiot (see George Will’s climate howlers, 18 February 2010 here), but let me throw a few additional thoughts on the table:

(1)  “Science” is never “settled”, and people who think that it is simply reveal their ignorance of scientific processes. We find out some important things, and are able to do some quite handy things on the basis of them, but there are always important debates and there is always more to be found out.

-  To take one striking example, Newton’s three laws of motion, combined with his theory of gravity, seemed for about three centuries to have settled the laws of mechanics, and explained the motions of the planets.  Taken together with some fine 17th century work on gases (Boyle’s Law and Pascal’s Principle) they provided the basis for the industrial revolution.

-  Then in the early twentieth century a young man named Albert Einstein began speculating about the relationship between space and time. Before you know it we find that at very high speeds the mass of an object increases and time slows down, curiosities which are elegantly explained by relativity theory. This discovery is fundamental to everyday systems involving satellites (mobile phones, GPS navigation) because relativistic effects are important at the speeds that are relevant here.

- So the world of Newtonian or classical physics wasn’t settled at all, but it was close enough for most purposes and for several centuries it was all we had. It enabled people to make a range of calculations and predictions, and to build large structures and complex machines that would neither collapse nor blow up.

-  We know that Einstein’s work, important as it is, is not the last word because early in the twentieth century quantum effects at the sub-atomic level were also discovered, and no-one has been able to explain satisfactorily how relativity and quantum physics co-exist. The search for the unified field theory continues.

-  As another example, within a few years of the discovery that the atom (hitherto considered an elementary particle) consisted of electrons, protons and neutrons (themselves then considered erroneously for a time to be the real fundamental particles), physicists conceived and then demonstrated the possibility of the nuclear chain reaction, with the release of enormous amounts of energy.  The bombs that brought the Pacific War to a close were constructed without any inkling of oddities like strange quarks or the bewildering array of mesons that populated my 1960s textbooks on particle physics, and to this day we are still looking for the Higgs boson (that is in part what the Large Hadron Collider under a mountain in Switzerland is about). If ever there was science that is “not settled”, this is it. But there are many aspects about which we have a great deal of certainty, and can make precise calculations and predictions: we have had nuclear power stations for over fifty years and they currently generate about 17% of the world’s electricity.

(2) To the extent that any science is ever settled, the core science of global warming is; it is very basic undergraduate physics, which has been confirmed experimentally for over 150 years. The arguments and uncertainties are about the secondary effects and the consequences.

-  A paper about the warming effect of the planet’s atmosphere was first published in 1824 by the great French mathematician and physicist Joseph Fourier, with a follow-up paper in 1827. Fourier established the concept of a planetary energy balance, a balance between the planet’s heat gain and its heat loss, and proposed that the atmosphere shifts the balance towards higher temperatures by slowing the heat loss.

-  Beginning in the late 1850s, the 19th century Irish physicist John Tyndall FRS undertook reliable experimental work which established that the warming effect was due to the absorption and re-radiation of infra-red radiation by a number of gases, notably water vapour, carbon dioxide and methane.

-  A quantitative analysis was undertaken in the 1890s by the Swedish physicist Svante Arrhenius, who was the first to predict that emissions of carbon dioxide from the burning of fossil fuels and other combustion processes would cause global warming.

-  The black body temperature of the earth – the temperature at which it would stabilise if all incoming radiation were absorbed and re-radiated - is 5.5 °C. Since the Earth's surface reflects about 28% of incoming sunlight, in the absence of the greenhouse effect the planet's mean temperature would be far lower - about -18 or -19 °C instead of the much higher current mean temperature, about 14 °C.

-  Given all this, I think that the onus is on the climate change deniers to explain to the rest of us why adding about 30% to the burden of carbon dioxide in the atmosphere would not raise the temperature of the planet.

(3)  As noted above, what is not settled is the extent and time path of consequential effects.  This is because of the complex interactions between the first round effects of the lower parts of the atmosphere becoming warmer:

-  We know that the sea will absorb some of the extra carbon dioxide, but we know also that as the surface layer of the sea gets warmer its absorptive capacity is reduced.

-  We know also that as the sea absorbs carbon dioxide it becomes more acid, with deleterious effects on crustaceans and other life-forms with a shell or external skeleton. We do not know how this plays out through the rest of the marine food chain.

-  We need to know more about the coupling between the atmosphere and the oceans – how they interact to drive both weather systems and ocean currents.

-  We do not know enough about the chemistry of the processes by which carbon is sequestered in soil, or about the net effects of various land-use changes.

-  We know that on average the world’s glaciers are melting but we cannot predict whether or how fast any one of them will disappear because changing weather patterns can cause more precipitation to fall on some of them.

-  We know that most of the sea-level rise to date is due to thermal expansion of the water column. What we do not know as yet is how rapidly melting of the Greenland Ice Shelf and Antarctic ice will add to the problem. If it is rapid, we are in serious trouble.

(4) One other matter that is conclusively settled is a key attribute of the mathematics of non-linear systems. They are so sensitive to minute changes of initial conditions (and hence to even minor inaccuracies or gaps in data) that mathematical models cannot be expected to provide accurate forecasts of long range outcomes. They can give us a great deal of information about trends, about the interaction of the processes that are taking place within the system, and which ones predominate, but they cannot give us accurate forecasts. They are research tools, not crystal balls. Nevertheless, when we look at meta-data compiled from a synthesis of the outputs of a number of respectable models we can be even more confident of what we see unfolding. What we see is that the planet is warming, and the consequences will be serious. No amount of academic misbehaviour in individual research teams or sloppy citation of sources can alter that fact.

And by the way, don’t fall for the old canard about “they can’t even tell us what the weather will be like in a week’s time, how can they tell us what it will be like in 2050?” First, weather is not the same as climate. Second, weather is, like climate, a non-linear (chaotic in a mathematical sense) system, and poses the same mathematical problems in making forecasts over the much shorter time-scales we have in mind when we talk about weather. In many ways long term trends are easier to discern that the exact evolution of short-term fluctuations.

George Will’s claim that Phil Jones of the Climatic Research Unit had agreed that there had been no statistically significant global warming since 1995, which has rapidly become an urban myth amongst the global denialist industry, cannot be allowed to stand. Let us have a look at what Jones actually said, in an interview on the BBC on Saturday 13 February 2010 (check it here):

Do you agree that from 1995 to the present there has been no statistically-significant global warming?

Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.

Do you agree that from January 2002 to the present there has been statistically significant global cooling?

No. This period is even shorter than 1995-2009. The trend this time is negative (-0.12C per decade), but this trend is not statistically significant.

How confident are you that warming has taken place and that humans are mainly responsible?

I'm 100% confident that the climate has warmed. As to the second question, I would go along with IPCC Chapter 9 - there's evidence that most of the warming since the 1950s is due to human activity.

Anyone with the remotest clue about statistics would understand that what Professor Jones is saying in the answers to the first two questions is that short time intervals are a poor guide to long term trends.

Perhaps the most exasperating feature of the whole denialist campaign is the way in which people who hold themselves out as public intellectuals can be so smug about matters about which they clearly know nothing. They betray the fundamental requirements of intellectual endeavour – willingness to listen and learn, willingness to weigh evidence, and preparedness to change one’s mind in the light of the weight of evidence.

That notwithstanding, Will has the cheek to conclude his article by commenting upon the appointment of Todd Stern as America’s Special Envoy for Climate Change:

It is tempting to say, only half in jest, that Stern's portfolio violates the First Amendment, which forbids government from undertaking the establishment of religion. A religion is what the faith in catastrophic man-made global warming has become. It is now a tissue of assertions impervious to evidence, assertions which everything, including a historic blizzard, supposedly confirms and nothing, not even the absence of warming, can falsify.

Look in the mirror, George, and you will see religion staring you in the face, complete with its tissue of assertions impervious to evidence. And by the way, that historic blizzard was a function of a warmer than usual start to the year, accompanied by higher humidity. Precipitation is a function of the amount of moisture in the air, George, not of temperature. Some of the world’s really cold cities (Beijing and Seoul spring to mind) do not get much snow at all.

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