Short answer, yes, burning coal directly heats the earth as you say, but releasing CO2 into the atmosphere also causes global warming.
Long answer:
Climate is crazy complex. Just off the top of my head, factors that are involved include:
The amount of energy being emitted by the sun (which is not perfectly stable over long times)
The distance from the sun to the earth (also not fixed, either short to long term)
The amount of energy that gets through the atmosphere to the surface (variable, eg it dipped a bit 1950-1975 due to sulfur in the atmosphere from burning dirty coal, sulfur now reduced because of acid rain problems)
The amount of that energy absorbed by the surface rather than immediately reflected (see albedo; can vary rapidly)
The temperature this causes the earth to be, and so causes it to emit heat as infra-red light (depends on the temp of the earth from the feedback from all the other factors).
The amount of this emitted infrared heat which is captured by the atmosphere which in turn is influenced by:
the circulation of gas in the atmosphere (influenced by the position of of oceans/continents and especially mountain ranges)
the composition of the atmosphere (this is where greenhouse gasses come in)
There are also endogenous (earth based) sources of heat. On one hand, the decay of radioactive elements in the earth releases energy (fun fact -this energy is in fact NOT from the sun, but is from a supernova sometime five to ten billion years ago, the debris of which forms our solar system) and as RegJoe rightly points out, the burning of fossil fuels which releases energy which has been in storage for millions of years.
Oh and also the way ocean currents move heat about the globe.
And other stuff, I expect.
Why worry about CO2? The atmosphere is important.
The average temperature of the moon is ...
Quote:
... the average surface temperature of the Moon can be calculated for astrophysical purposes utilizing the relation TMoon = (RSun/r)^(1/2)*(1-A/4)^(1/4)*TSun Where 'r' is the average distance from the Moon to the sun, TSun is the average temperature of the sun, RSun is the solar radius, and A is the albedo. This ends up resulting in a value of around 274° K ~ 0° C = 32° F (The Freezing Point of Water)]
Read more: http://wiki.answers.com/Q/What_is_th...#ixzz21p6DSYty
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ahh, about zero centigrade. Yet is is virtually the same distance from the sun as the earth, and the average surface temperature of the earth is about 15 degrees c.
This difference is mostly due to the greenhouse effect, the tendency of some gasses to allow high energy (eg visible) light through, but to trap and re-emit infrared light. This lets sunlight in, but doesn't let infra-red light (heat) out.
Most of the greenhouse effect is natural, and it's good thing too, otherwise most of earth would be a frozen wasteland.
There are many greenhouse gasses - water vapour, ozone, methane, even CFCs, and of course carbon dioxide.
Digging up fossilised carbon, combining it with oxygen and releasing it into the atmosphere, increases the strength of the greenhouse effect. This *will* warm the planet.
You might ask, how much?
This very good article in the rolling stone answers that with only mild hyperbole.
http://www.rollingstone.com/politics...#ixzz21DFACIRu
Short version: 565 gigatons more CO2 into the atmosphere will produce about 2 degrees of warming. Probably.
How carbon much is that? Well, "proven" reserves, already located and with companies intending to extract them, are about
five times that much.
And for extra fun, there may be some feedback loops or tipping points nearby. For example, as the planet warms, ice and snow cover decreases, and this lowers the albedo, leading to more heat absorbtion. Also, as permafrost melts, it breaks down and releases methane which is also a greenhouse gas, causing more warming.
Final fact, stolen from the rolling stone article:
That followed the warmest May on record for the Northern Hemisphere – the 327th consecutive month in which the temperature of the entire globe exceeded the 20th-century average, the odds of which occurring by simple chance were 3.7 x 10^99, a number considerably larger than the number of stars in the universe.
I hope you're listening - this
is going to be in the test.