All Astronautical Evolution posts in 2017:

What is a Supercivilisation? (Aug.)

Quantifying the Assumptions Behind the METI Debate (July)

Five Principles of a Sustainable Manned Mars Programme (June)

Pale Red Dot: Mars comes to Oxford (May)


Back to 2016:

Elon Musk and Mars: Looking for a Snowball Effect (Oct.)

New in 2015:

Short story The Marchioness


AE posts:

2017: Mars…

2016: Stragegic goal for manned spaceflight…

2015: The Pluto Controversy, Mars, SETI…

2014: Skylon, the Great Space Debate, exponential growth, the Fermi “paradox”…

2013: Manned spaceflight, sustainability, the Singularity, Voyager 1, philosophy, ET…

2012: Bulgakov vs. Clarke, starships, the Doomsday Argument…

2011: Manned spaceflight, evolution, worldships, battle for the future…

2010: Views on progress, the Great Sociology Dust-Up…

Chronological index

Subject index


General essays:

Index to essaysincluding:

Talk presented to students at the International Space University, May 2016

Basic concepts of Astronautical Evolution

Options for Growth and Sustainability

Mars on the Interstellar Roadmap (2015)

The Great Sociology Debate (2011)

Building Selenopolis (2008)


Climate Change Questions

Stephen Ashworth, Oxford, UK

22 January 2011


For some years it has been the fashion to believe that industrial emissions of carbon dioxide gas are on the verge of causing a rise in global mean temperature through the “greenhouse effect” which will have ruinous consequences for civilisation. The belief has persisted through the first decade of the 21st century, during which time the global mean temperature has showed no change outside its error bars.

I have always regarded the anthropogenic global warming (AGW) belief with deep suspicion. Here’s why.


(1) Let us suppose that computer models are correct that doubling the concentration of carbon dioxide in the atmosphere from 3 parts per 10,000 to say 6 parts per 10,000 will cause a global average temperature rise of several degrees.

On its own, this is not a forecast, because it does not yet take account of simultaneous natural climate changes from other causes.

We know that the climate changes naturally, having oscillated between warm periods in Roman and early Medieval times and cold periods in the Dark Ages and the Little Ice Age. Changes in the solar magnetic field are one influence which has been convincingly correlated with the Little Ice Age (a fact known since the time of Herschel).

Therefore before one can make a forecast for say the next 50-100 years, there must logically be agreement over the amount and direction of natural climate change over the same period, to which the human effect must be added. Yet I have never heard of such a forecast. The assumption always seems to be that without anthropogenic influence the climate will stay exactly steady, which given the experience of the past few centuries is highly implausible.

Is the 20th century rise in global mean temperature the result of our still coming out of the Little Ice Age? What caused that cold period, and how do we know that another one is not about to start?

The next major natural climate change we may expect, based on historical experience, is clearly of cooling: either a short-term return to Little Ice Age conditions or a long-term return to the glacial conditions which prevailed prior to 10,000 years ago. In his book on human evolution, Out of Africa, Prof. Stephen Oppenheimer actually states that the present-day anthropogenic warming effect is helping to stave off the return to the colder conditions in which our species evolved. I’m not saying that he is correct, but only that this issue must be resolved before any forecast of the net effect (natural plus anthropogenic) can be made, and so far as I know the causes of periodic ice ages (both major and minor) are still controversial. Meanwhile, analogy with previous interglacials suggests that after 10,000 years of warmth the current one should be approaching its end.


(2) How accurate are the computer models? Obviously, if we’re modelling the orbits of the major planets, then we can predict their future positions with confidence for a very long time ahead, because the mechanics of the Solar System at that level is relatively simple. But the climate is highly complex and chaotic, with poorly understood influences and feedback mechanisms.

To give the most obvious example, any resident of Britain is very well aware how much difference there is between a cloudy day and a sunny one. Clearly, any systematic change in global cloud cover will have a major effect on air temperature near the surface – potentially a far greater effect than doubling the concentration of a trace gas. Yet so far as I know cloud formation cannot be accurately represented in any computer model of the global climate, because it takes place on a microscopic scale, while the models work in terms of cells kilometres on a side.

In order to be confident that the model was reliable, I would therefore require it to have a track record of accurate predictions, looking at least some decades ahead. Clearly, no such computer model exists – they simply haven’t been in use for long enough. Obviously, they have been tuned by matching them to past climates, but that doesn’t count. Any fool can predict the past – it’s predicting the future that’s so difficult!

In fact, the track record so far seems to tell against the models, insofar as the current decade-long standstill of global average temperatures was unpredicted by any climate model (see Mail Online article).


(3) Thirdly, I don’t see that governments are taking the problem seriously. If a government feels threatened it takes drastic action, for example by going to war. In the 1940s America felt threatened by the possibility that Hitler would acquire the atom bomb, and then 20 years later again by the Soviet military buildup. The result in the first case was the Manhatten project, and in the second, Apollo.

If governments around the world therefore actually felt threatened by climate change resulting from increased concentration of CO2 in the atmosphere, they would take effective action – and I don’t mean building windmills! I believe there would have been a race underway for the past decade, with the goal of being the first to develop commercial nuclear fusion or ground or space solar power. This race would have been highly analogous to the Manhatten and Apollo programmes: based on developing new technology, motivated by fear and by the desire to dominate the future non-fossil-fuel world.

Obviously, this has not happened. The political response to the supposed threat has limited itself to rhetoric and green taxes. Artificial nuclear fusion research is proceeding as slowly as before – a member of the JET team giving a talk in Oxford a few months ago complained that he was trying to do industrial development on a relatively minor academic research budget. Meanwhile the world’s space and energy agencies have no interest whatsoever in space solar, despite its being closer to technological realisation than artificial fusion.

The fact that both of these technologies are of debatable economic value is irrelevant: the same was true of Manhattan and Apollo, obviously.


(4) Meanwhile, people are irresistably drawn towards apocalyptic language – even a former scientist, who I would have expected to be more reasonable.

In a recent book (reviewed in AE, issue 40, 1 January 2009, item 2), James Lovelock writes that humanity has “ceased to be just another animal and begun the demolition of the Earth” (p.8). We are “unintentionally at war with Gaia” (p.196). One of her life forms, “disputatious tribal animals with dreams of conquest even of other planets, has tried to rule the Earth for their own benefit alone. With breathtaking insolence they have taken the stores of carbon that Gaia buried to keep oxygen at its proper level [I think he means CO2, even though there is no particular “proper level” for any atmospheric gas] and burnt them. In so doing they have usurped Gaia’s authority and thwarted her obligation to keep the planet fit for life; they thought only of their own comfort and convenience.” (p.187).

Other animals and plants, no doubt, spend their lives sacrificing their comfort and convenience on the altar of Gaia? And did the first lungfish never dream of conquering the land, or feathered dinosaurs the air? Such moralising is totally unfitting for a scientist, who should be more aware of both the uncertainties in climate science, and the opportunistic nature of life.

And it is wildly out of proportion. The threat we are presented with is a rise in the global mean temperature of say four degrees C over a century. But the seasonal variation in air temperature at any one location is about ten times greater than this – for example, in Britain the temperature varies regularly between about –5 and +30 degrees over the course of the year. As Richard Lindzen points out, changes in the global mean temperature are swamped by variable local conditions at any specific surface location.

Meanwhile, the popular culture also shows little sign of paying proper attention. The supposed carbon dioxide threat has been subsumed into one of “carbon” as in such expressions as reducing one’s “carbon footprint” or promoting a “low-carbon future”. But the link between anthropogenic carbon and climate is not in issue: apparently people have become confused between a black or crystalline solid (carbon) and a colourless gas (carbon dioxide).

Again, one of the organisations dedicated to action on the supposed threat is called Stop Climate Chaos. Since “chaos” is the mathematically correct description of the climate, this organisation has apparently devoted itself towards overturning a law of nature. (It claims that we have “fewer than 80 months to reverse the growth in global carbon emissions” – perhaps if all that carbon were to be oxidised to carbon dioxide that might satisfy them?) (This page has since been removed, and is no longer findable.)


So, to sum up, m’lud and members of the jury, I see that:

I have to conclude that the whole business is driven by an anti-growth political ideology, not by any genuine insight into the possible future effects of large-scale fossil-fuel burning.

I would appreciate any further information or links regarding factual points made in this essay.