‘Gravity’ is a concept which corresponds to a variety of phenomenological observations; the theory of gravity is not in any way proven by the evidence which you give (’when you let go of something in the air it falls down’). As you correctly imply, ‘gravity’ is the outcome of a consensus shaped around empirical induction; that does not mean it is ‘true’, merely that it’s our most established theory to date as to why when we drop things they tend to fall down.

Objects could feasibly be released in air and not fall down: inside a space station for instance. Would this mean there’s no such thing as gravity? Well, no, not in itself, but the process of analogising in this fashion points out that our speculative horizons can revolve around concretisations of inductive methodology.

One well-known example of such concretisation is atomic theory. ‘Bracketing theory’ is used by many physicists to re-articulate what the rest of us call ‘atomic theory’. The notion that atoms are tiny little balls that comprise bread and plastic alike is a legacy of the Greek philosopher Demokrites. For physicists it is fiction.

In the case of climate change, we have records of varying temperature levels across the globes, and a consensus-driven postulate that certain consequences of human behaviour explain these varying temperature levels. On the basis of that, we strive to change our behaviour; but some will argue that this is all in vain, inasmuch as there are other causal agents at work.

For the record, I believe loosely in anthropogenic climate change — as a species we’re doing something which could prove highly problematic, even deadly — but I know highly qualified meteorologists who don’t, if only because they reject orthodoxies of Greenhouse gas emissions.

As to the more problematic question, of why (if it is so well understood and known about) ‘nothing’ is being done about climate change. How many people with the ability to get a global shift and change will gain by doing so? Who wants to give up their cars, cheap flights, and new gadgets every year? Those who will lose most and suffer are the majority of the worlds population without these things – the same people who have the smallest voice.

I just replaced climate change by jews in order to show the absurdity of the argument. General consensus does not determine the degree of truth. I’m not a climate change denier nor a climate change apologist, but it seems really problematic to take always the “general consensus”-argument as a justification, considering all the stupidity that has spread in the name of “general consensus”.

[George write- this is a baffling comment Pearl. Jews are not a problem and never have been one- but there is an overwhelming consensus that many millions were brutally murdered and that we should not forget the crime. Isn't it sometimes worth going with the consensus?]

I agree that it’s a challenge for anyone, let alone a non-specialist, to read those papers and understand what they do and don’t mean, how reliable they are, etc. They are various things you (and I) can do. One is to read the articles about these issues on the RealClimate blog. Another is to read the IPCC report, which also covers this ground. Another is to ask questions in appropriate forums–I think the Google globalchange group is a good one. I guess another is to believe TV programs produced by people who stretch and mislabel the graphs to make them support their argument.

Until then, I guess I’m supposed to just believe the author because he cites four papers from a branch of science where that many papers are likely published daily, if not hourly.

As I tell anyone who tries to attack me personally for not having made up my mind on the topic of man-made global warming, it’s fine to have beliefs, just don’t try to turn your beliefs into facts that I’m supposed take at face value. If you’re unwilling to face questioners, you probably don’t have the facts and are trying to hide something.

What does this mean? Without the sun the greenhouse effect comes to nothing. All of our heat, apart from a small contribution from the Earth’s core itself and a small amount from the heat released by the combustion of fossil fuels and wood, comes from the sun.. “All” that greenhouse gases do is trap a significant amount of solar energy which would other wise be ‘lost’ in space.

Perhaps what the above statement means is that 15% of the sun’s energy falling on the earth is absorbed by the earth’s surface and 85% is trapped by greenhouse gases. Presumably to this account should be added the small amount of heat radiated by the earth that escapes to space and the larger amount of heat that manages to get past the greenhouse gases.