Global Warming: A Human Perspective

According to most climate experts, anthropogenic greenhouse gases add about 2 watts per square-meter of radiative forcing to earth’s environment. This is roughly the power used by a small Christmas tree lamp. In more personal terms, the human body generates approximately 100 watts of power and has a surface area of around 2 square-meters. Assuming that the sole of the average foot has an area of about 200 square-centimeters, it would emit 1 watt of power. Both feet, applied to a surface, would add 2 watts to that surface. Applied to a square-meter, that would be equivalent to the anthropogenic greenhouse effect.

If we could cover every square meter of the Greenland ice cap with a barefoot human — a magical, never frostbitten human willing to stand, day after day, pumping his 2 watts into the ice — would we expect the ice to melt?

The answer is “eventually.” A back-of-the-envelope calculation* suggests that it would take about 10,000 years, assuming an average ice depth of 2 kilometers. In light of this, Al Gore’s threat to invoke the wrath of Gaia to bring about a complete meltdown in 60 years seems off by a couple of orders of magnitude — unless, of course, he is willing to acknowledge the possibility that the warming we observe is due to a so-far unmeasurable anthropogenic effect superimposed on a poorly understood natural warming process that began when Abraham Lincoln was a baby, long before carbon dioxide levels changed.

Such an admission, however, might be inconvenient.

*2 Watts = 172800 Joules/day
333700 Joules melts 1 kg of ice
Therefore 2 watts melts 172800/333700=0.52 kg/day
1 kg = 1000 cubic centimeters of ice (yes, I know its really a bit more because of expansion)
Distributed over 1 square meter, this equals a depth of 0.1 cm
But our feet can melt only 0.52 kg/day, so a hotfooted human would melt a depth of (0.52)X 0.1 cm / day = 0.05 cm/day (half a millimeter)
THUS, the heat from a person’s feet would melt (distributed over a square meter), a depth of:
0.05 cm/day
1 meter/2000 days (call it 5 years)
2000 meters in 10,000 years (This surprised even me, so I’d appreciate a check of this reasoning by more arithmetically adept readers).

NB: Junk Science has a detailed discussion of how to evaluate anthropogenic radiative forcing .

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5 thoughts on “Global Warming: A Human Perspective

  1. In near future when all the fossil fuel will be exhausted, only nuclear power will be there as a source of energy and it could reduce the global warming. Business companies, transport, manufacturing corporations will only use nuclear power , because fossil fuels are limited. But by that time the damage will be done.

  2. I’ve read from somebody’s blog that Global Warming is not new to the earth and it’s been around in cycles for millions of years. If this is the case, then, we just have to ride the tide of heat until it dies down, right? We can survive all of these, right? But given the things that this person wrote, it feels as if he’s emphasizing that global warming is not fully contributed by us humans! We still hope we can get some clarification on this before it hits us without knowing.

  3. I agree with you. Though, reducing our use of of anthropogenic sources like fossil fuels will have a positive result on our economy, i.e. lower gas prices, less reliance on foreign fuels, etc. So, Gore isn’t completely off base, I guess…

  4. Al Gore is whacko if he thinks we have a 60 year countdown to the flooding of the earth. Thank you for the scientific, thought provoking perspective to global warming.
    Good read. Keep it comin’.

  5. It’s unfortunate that such an important issue with far-reaching effects has also become partisan. Global warming is a fact, regardless of the cause. I don’t say this lightly and it’s not because I’ve been pelted with 100 CNN news stories about it… I was always a weather enthusiast, all the way back to when I was 5 years old. Until I turned 18, I kept track of daily temperatures, rainfall and weather patters on paper (and later, as computers came about) in a database. And in college, I studied Atmospheric Science. Hopefully that establishes my independent credibility, as I can see small changes in the local weather that probably go unnoticed to everyone else. (And that’s not meant as an insult — there are things that each of you are more aware of, that go unnoticed to me.)

    But back to my main point. Global warming should not be partisan. We’re all humans first, Americans second, and (then, frankly who cares) partisan last. As the ice continues to melt, it’s going to flood the lower parts of the earth, regardless of their political affiliations.

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