Almost everything that is written about global warming seems to concentrate on the greenhouse effect cause by increasing concentrations of carbon dioxide, methane and other gases, but does the increased amount of physical heat generated by human activity also have a measurable impact?
Think about all the power stations burning coal, the millions of cars with hot engines, the central heating, the electric fires, the wood-burning stoves, plus all the heat generated by just about any electronic device… that must be a lot of heat escaping into the atmosphere. Is it enough to make a difference, or is it effectively lost in the intense heat coming in from the sun?
I managed to find Google for a figure of the energy received from the sun, which averages 345 W/sq. m., of which nearly half is retained as heat.
The earth has a total area of about 500 million sq. km., which makes the total energy being retained as heat similar to 50 trillion electric fires. I’ll let you draw your own conclusion
OK… is that the energy that reaches the Earth’s atmosphere, or the actual surface? Remember that the waste heat is being released at ground level, whereas presumably large amounts of the sun’s energy is reflected away by clouds etc?
Here’s a better source than the one I found earlier - it still has a similar figure for the final absorbtion to the one I used for the calculation (168 vs 150 W/sq. m.). (I’ll show my working if you really want…)
Sorry, I missed the important part, “of which nearly half is retained as heat”.
Working in London, it’s hard to believe that all that heat blasting out of shop doorways etc isn’t warming the Earth, but there you go. (Well, I suppose it is, indirectly.)
I know what you mean - but go and stand on the roof of one of those buildings, and you’ll feel as cold as ever. Maybe it’s just the whole Londoner mentality, forgetting there’s a whole big world out there?
