Some personal thoughts

Science is not democratic. You may be entitled to an opinion, but you are not entitled to any respect for it unless you have demonstrated that you understand the fundamentals. There is much propaganda on the internet. Some sites, covertly funded by oil companies and their allies, simple have the aim of confusing the public to protect their own pecuniary interests.  One tactic is to put a document online which purports to be a reasearch paper, but which has not been peer-reviewed, and hence does not state the authors' qualifications, field of competence, financial backing, or whether the methodology/honest use of data has been independently checked.  This may be accompanied by data and graphics which purport to prove the author's propositions, but actually do no such thing, being merely a graphic restatement of the authors' propostitions.  Here are links describing the controversy surrounding such alleged research:

These non-peer reviewed papers are often uncrtically cited as "science" by the less subtle footsoldiers of the sceptic movement, or by politions/economists with a non-science background.  Most climate-sceptic websites are fanatic paranoid ill-informed garbage, peddling such misinformation, together with non-contextual misquotes from bona fide sources, and then coming to conclusions which display their own ignorance of the basic principles.

For example, anyone who proclaims triumphantly "The sun drives the climate" doesn't understand the science or the debate. Nobody has ever suggested differently: Without the sun we would be close to absolute zero (-273°C). But the greenhouse effect is real AND GOOD (at least for us on Earth, see the first link at the end of the document). Without it the earth would be uninhabitable by us (in our present form). Here is an extract from Encycolpedia Britanica (1997 edition)

“Trace gases, carbon dioxide and water vapour in particular, play an essential role in terrestrial climate. In the absence of these molecules that absorb strongly in the infrared, the surface temperature would be about 40 K colder than it is today. The oceans would be frozen over, and life as we know it would be impossible. There is an important synergism between CO2 and H2O. Carbon dioxide itself absorbs only a small fraction of the heat radiated by the Earth's surface. Water vapour is much more significant. The abundance of H2O, however, is controlled ultimately by temperature. An increase in CO2 may be expected to cause an increase in temperature, which allows more water vapour to enter the atmosphere and leads to a further increase in temperature. ”

“Atmospheric carbon dioxide concentration remained fairly constant over the past thousand years until the late 18th century and has been rising steadily ever since.”

From W.M. Post, F. Chavez, P.J. Mulholland, J. Pastor, T.H. Peng, K. Prentice, and T. Webb III, "Climatic Feedbacks in the Global Carbon Cycle," in David A. Dunnette and Robert J. O'Brien (eds.), The Science of Global Change: The Impact of Human Activities on the Environment, American Chemical Society Symposium Series 483, 1992

All other things being equal, the historical increase in CO2 would be very significant. And indeed, the climate in some parts of the world, especially near the poles is changing in an unprecedented way. Of course the activity of the sun has changed before and will undoubtedly change again, not to speak of the unpredictable effects of volcanic eruptions etc. The questions are: 1) Is the climate changing.

2) Is human activity partly or wholly responsible

3) What, barring unpredictable astronomical effects is likely to happen in the next 100 years or so, and what, if anything, can we do about it?

Now, I am not personally qualified enough to answer any of these questions definitively. (Nor, most certainly, are those climate-sceptics who make the loudest noise.) Therefore, I have to rely on work and data supplied by others, not a situation I am comfortable with.  However, it seems clear to me that climate change is happening. The strongest evidence is the unprecedented glacial and polar melting. More violent weather patterns may well be occurring too, but I don't have the tools or the data to demonstrate that conclusively.

The theory of the man-made greenhouse effect is essentially that the (continuing) increase in CO2 and other greenhouse gases has led to an increase in the amount of heat retained by the atmosphere, and that this will impact adversely on the natural world and upon human life.  Now to the nitty gritty. It is understandable that commentators focus on temperature, but actually it is important to look at the bigger picture. The macro-atmospheric system is actually composed of very many microsystems.

A small increase in the amount of energy in any one of them would have effects described by an equation like the following one:

ΔE = ΔF + TΔS + SΔT

Where E is the total energy, F is the “free energy”, T is the temperature, and S is  the entropy of the system. “Δ” refers to a corresponding small change in any one of these quantities.

There are different definitions of total energy and free energy. Which you use depends upon the nature of the microsystem.

http://en.wikipedia.org/wiki/Gibbs_free_energy

http://en.wikipedia.org/wiki/Helmholtz_free_energy

The total effect upon the macrosystem could be modelled qualitatively, as a first approximation, as the sum of the effects of the microsystems. So what does the equation above tell us?

Free energy is the capacity of a system to do work. Work in the context of climate means “weather” - winds, rain, storms etc, as well as ocean currents and other phenomena. All this has a feedback to both entropy and temperature,.

Entropy is the really crucial concept here. It is a measure of the disorder of a system, and its capacity to absorb and transmit energy. For example, a solid metal has an organised crystalline structure and low entropy, compared to, say, glass. So a metal is a good heat conductor, as well as heating up and cooling down quickly compared with glass. But glass, with its higher entropy, has a much greater capacity to absorb heat than most metals do.

http://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.html

In general, liquids have more entropy than solids and gases have more entropy than liquids. In fact, when the phase of a substance is changing, ie at a boiling point or melting point, you can add heat to a system without the temperature rising. For exmple, adding energy to melting ice causes a rise in entropy without there being a rise in temperature: ie TΔS is positive but SΔT is zero.  This continues until all the ice has melted.

Some commentators have recently remarked that the previously observed rise in global temperature seems to be levelling off, and that this “disproves” global warming. However, IF this levelling is corroborated, given the observed melting of icecaps and glaciers, it could well be accounted for by the entropy increases associated with massive areas of phase change (ice melting), rather than any levelling off of heat absorption by the the atmosphere and oceans.

To summarise, you cannot understand climate change without considering both free energy and entropy, as well as temperature. I am not qualified to reach definitive conclusions, BUT unlike most of the sceptic propagandists, I do have some knowledge of the basic principles. If you don't understand what I have written here, then please “shut the fuck up” until you've done your homework!

Now, even if man-made global warming is real, it doesn't mean that there aren't vested interests trying to exploit it and make a fast buck on its coattails; nor does it mean that all government responses are fully thought out and rational.  Two examples: I have nothing against wind energy, but I really don't understand why there has been such an emphasis on it in the UK, as opposed to the seemingly far greater potential of tidal stream energy. Also, there is no point in limiting carbon emissions in the UK or EU whilst importing vast amounts of goods made with dirty coal energy from China. At the very least we should put a suitable import tariff on such imported goods. In fact, given the unfair nature of trade with China due to their quasi slave labour practices and currency manipulations, I would go much further. But that is another issue.

SC 13/03/2012

Links

Neil deGrasse Tyson explains the discovery of Climate Change and the Greenhouse Effect - on Earth and in Venus.

http://www.youtube.com/watch?v=8IsTM5qRER8

Neil deGrasse Tyson On Global Warming

http://www.youtube.com/watch?v=6g-FYa44hiE

http://www.youtube.com/watch?v=Klgp_qDiRhQ