Global warming, why is heat produced by man never mentioned?

Because the heat produced by man is insignificant. In one day, Earth recieves from the Sun, more than 200 times the energy that humans produce in a year.

Although, if it were a conspiracy to frighten people into accepting taxes, rather than hard scientific evidence, why not tax waste heat?

Apparently, you have already forgotten the Denier talking point that temperature observations were biased by the urban heat island effect – as if every scientist in the world was unaware of it and had not already taken it into account.

As others here have already noted, you seem not to grasp the size, scale, and scope of the planet, the climate system, and the forces that are in play. I suppose that is to be expected given the scientific ignorance and intellectual laziness of most Deniers. It still does answer the question of why Deniers prefer stupidity over knowledge, but I guess those personal psychological issues will have to take a back seat for the time being.

Because all the heat produced by man is far too tiny to be of any consequence. That would be like trying to heat a stadium in the dead of winter with a single match.

People don't realize how much heat it takes to keep the Earth warm.

The Sun sends an astounding 208 times more energy to the Earth EACH DAY than the entire WORLDWIDE production of Electricity in a year (using 2009 figures for production of electricity).

In other words, it would take 208 years of worldwide electricity production to produce enough energy to supply the Earth with the heat it needs for a single day.

You can review the figures here:

http://ca.answers.yahoo.com/question/index;_ylt=Ar...

Climate Realist did the calculation and received best answer because he got it exactly right.

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As Paul's Alias 2 and others stated, that energy is relatively small compared to the the heating associated with global warming from greenhouse gases. However, if population and energy usage continue to increase, in the future it may be a significant source of warming. If it does, this would not be one that could be so easily dismissed by deniers, since it mean that they would be disputing the first and second laws of thermodynamics.

A good article about this can be found here:

https://www.cfa.harvard.edu/~ejchaisson/reprints/E...

Humans used 524 quads (each quad represents 10¹⁵ BTU) of energy in 2010 (see first paragraph of 1st link below from the US Energy Information Administration.) This is 5.53⨯10²⁰ Joules. This is expected to reach 630 quads in 2020, or about 6.65⨯10²⁰ Joules. These numbers include all energy released by humans for any reason, including waste heat that is a necessary consequence of creating useful energy.

        http://www.eia.gov/forecasts/ieo/

The surface area of the Earth is approximately 510 million km², or 5.1⨯10¹⁴ m². If you divide the energy by the surface area of the Earth and by the number of seconds in a year, which given 365.2425 days per siderial year is 31,556,952 seconds, then you get the watts per meter². This figure is 34.36 milliWatts/m² in 2010 and will supposedly be about 41.32 milliWatts/m² in 2020.

It's not completely ignorable. But if you look at Figure SPM.5, from AR5's Summary for Policy Makers just recently released, you will see that the radiative forcing for changes in CO₂ alone (not taking into account anything else) relative to the year 1750 is 1.68 W ⁄ m² [with a range of uncertainty bounded between 1.33 and 2.03.] Net radiative forcing, adding in CH₄, halocarbons, N₂O, CO, and subtracting estimates for aerosols, sulfates, mineral dust and so on, yields a resulting sum of about 2.29 W ⁄ m² [with it's own range of uncertainty.]

As you can see, this is about a factor of 66 times as much heat energy imbalance, comparing the IPCC AR5 figure for 2011 with the Energy Information Admin's figure for 2010. Direct human energy production and use is still 5 times less than the forcing caused by N₂O alone.

It's important to think about where we are headed with energy use, of course. Left unchecked, humans will eventually reach an absolute limit in the amount of energy (even from absolutely clean sources) they can wield for productive use. But we aren't there, yet.

Since we get almost all our energy from fossil fuels (85% of it, anyway), the effective multiplier effect is on the order of 100. To sustain a continuous 1 watt of useful power, we have to accept 100 watts of global warming power in the short term and perhaps much more than that over a longer term that takes into account long term factors that are not included in the figures I quoted from, so long as we keep using fossil fuels to do it. That can become a much better ratio if we stop using fossil fuels for energy production. But right now that is the price we pay. So the larger meaning of human energy production isn't the direct effects of it, but the indirect effects that are leveraged from it.

But the direct amount from human production/use is not a "colossal amount" compared to our effects on global warming. It is colossal when compared to a toaster oven, though.

"Global warming, why is heat produced by man never mentioned?"

Because it is quantitatively small compared to the things that are considered.

Because in the Real World of Real Science it is nonsense.

Case in point: the region which has the most warming (the Arctic) has the least i/c engines, heating appliances, a/c systems or any other heat output made by man.

Rather than post another one of your inane questions , how about working it out yourself.

In a few minutes on Google you can find the total average energy from insolation

In a few minutes more you can find the world energy consumption

Then you can read the IPCC Synthesis Report

Then you can give yourself a little part on the back by working something out yourself , just like a rational thinker would

its a long process