Global warming

[shonkarko]

How much does the heat released directly by the burning of fossil fuels contribute to global warming? I assume humans create far more heat now than in the past by heating their buildings and as a by-product of manufacture. Does this have a significant impact on the temperature of the planet? Surely the release of all that stored energy from the sun in the form of fossil fuels has some effect. I read that city's are heat spots on the Earth. Are the ice caps melting partly due to our liking of being cosy and warm? Or is it all down to indirect greenhouse gases? I can't find any research relating to this factor anywhere which could of course be due to the fact it is ridiculous. But if anyone could point to where I could find out more or provide some sort of answer I would be grateful.

[LEGSX1]

It is not the heat produced by humans or fossil fuels that is the cause. It is the damage that harmful gas, eg CFC's, are doing to the earths protective layer. (ozone layer) That in turn cause the effects of the sun to be magnified causing change in weather patterns and in caturn global warming.

[scotstone]

Very little apparently. Michael Crichton's new novel State of Fear suggests vested interests in promoting the idea of global warming and cites many references to back up this theory although I must admit I have not checked them.

[rja211077]

Crichton is a loon. Yes he cites many references to support his case, but conveniently fails to acknowledge the many thousands more references by the world's foremost experts on the subject that don't take Crichton's view. Why should we listen to a sci-fi novelist on the subject of global warming anyway? Plus - have you read State of Fear? It's an absolute dog! Truly awful airport fiction of the worst order! So obviously intended to be made into a 'blockbuster movie' it's laughable!

Anyway, back to the question. I believe direct warming has a minimal effect. It's all about the greenhouse effect. Keep searching. Start at www.ipcc.ch.

[Kaeroll]

The short answer is: we don't know for certain how much humans cause global warming in any way. There are some (as rja211077 put it) loons who, for whatever reason, put their heads in the sand and totally deny that we can be causing climate change. However, them aside, there is considerable debate as to the extent to which we're causing global warming.

LEGSX1 is wrong to implicate CFCs and the ozone layer. CFCs (chlorofluorocarbons) used to be used as aerosol propellants, cooling agents, etc, but they convert ozone in the upper atmosphere into boring old oxygen. Ozone blocks ultraviolet light from entering the atmosphere. UV light is pretty harmful to life - go lie under a sunbed for a few hours if you think otherwise. Without the ozone layer, we'd be pretty much screwed.

Ozone is not, to the best of my knowledge, a greenhouse gas. The greenhouse effect occurs when greenhouse gases (such as methane and carbon dioxide) build up in the atmosphere and trap heat. The general consensus, as far as I know, is that humans can and do contribute to this directly through fossil fuels. I think I have to agree with LEGSX1 that the heat released from burning these fuels is far less important than the effect of the gases, though.

[jake-the-peg]

This is indeed the "$64,000" question.

The classic evidence is the so called "hockey stick graph"

http://news.bbc.co.uk/1/hi/sci/tech/3569604.stm

This has been argued over for years and I dare say someone will be along shortly to bang out all the arguments.

However other pieces are all begining to slot in which are reinforcing this view. Such as this research where scientists from Imperial college London have shown direct increases from satelite data over between 1970 and 1997

http://www.imperial.ac.uk/P2641.htm

Let's say it's not beyond doubt but the evidence points towards it and changes in the sun's output do not explain the climate change we're seeing so it's hard to see an alternative.

As for Michael Crichton (his doctorate is in medical research) - good books shame about the science!

[shonkarko]

Has any organisation measured the direct result of releasing more heat on Earth? Could it be that greenhouse gases not only trap more of the heat coming directly from the sun but also more we release by burning? It seems possible that creating so much heat compounds the problems created by greenhouse gases. It's not that I necesserily believe this hypothesis but whether negligible or not the direct heating effect must at least make a tiny difference. In my mind I would like to put this one to bed, so to speak but I have yet to find any mention of this factor to provide evidence of it's impact.

[jake-the-peg]

We see the direct result of energy sources all the time.

Cities are on average a few degrees warmer than the suurounding areas. This is referred to as "urban heat islands"

There are a number of causes of these direct fuel burning as you note, but also tarmac absorbs heat more than vegetation, wind shielding etc.

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

What is controversial about these heat islands is whether, and if so how much, this additional warmth affects trends in (global) temperature record. The current state of the science is that the effect on the global temperature trend is small to negligible.

[Space]

I suspect that the power we use for heating is insignificant compared to the power that comes from the sun. Any volunteer for calculating it ?

What greenhouse effect gases do is modify the proportion of sun energy that gets absorbed. I suppose that even a tiny change of this proportion will have a much bigger impact than the heat we generate directly.

[jonskinner28]

I study civil engineering and insterestingly enough about half of energy use and loss (mainly heat) is from buildings. For the uk government to meet the kyoto agreement every building in the uk including listed buildings have to be insulated up to the standards of new builds. Just about impossible!

Oh and if sea levels rise then the water table around london will rise and because london is built on london clay the buildings will the slowoly sink into the ground because of inapropriate foundations!

so be afraid very afraid!

Jon

[jake-the-peg]

Oh and you know I was saying that there's lots of small pieces of evidence mounting up all the time? Well here's a biggie.

US Federally funded research says climate change trends over the last 50 years cannot be explained by natural processes

http://news.bbc.co.uk/1/hi/sci/tech/4969772.st m

[qapmoc]

If we take the fact that the world is warming as proved then surely it does not matter what is causing it, the point is that it will make our planet less hospitable to human civilization, so even if the cause is fluctuations in the suns output surely anything we (humans generally) can do that will effect the system towards a lower temperature will be a step in the right direction.
After all if you found somebody injured after being hit by a falling object I hope you would not say ''I did not cause this so I will not act to help''