I was just wondering what you thought of the idea
that we might cause global warming just by using a lot of energy, even without emissions, if our usage habits continue to grow exponentially at the current rate.

As someone who tinkers with PC cooling solutions, I know from first-hand experience that the more power you put through any given system, the hotter it gets. But I never heard anyone mention this as a particular cause for concern.
( Moon Girl Technologies horrendous beanbag, Fri 2 Dec 2011, 21:21, 1 reply)

Well, you're in good company
Because Steven Hawking himself calculated the amount of warming caused by consumption of energy by electrical gizmos and concluded that there will (or should) be detectable warming just from that alone. Though I'm not sure he's willing to part with his wheelchair and computer just yet....

But I don't know if it was to civilisation-destroying levels as you're suggesting. I suppose the thing to do would be to look at other energy-generating phenomena for comparison, such as not necessarily eruption laval spills and the like. If anything such as that has contributed more energy to the atmosphere without a massively deleterious effect on life on earth then it's probably not going to be a cause for concern.
(Dildo Bugger destroyed a ring on, Fri 2 Dec 2011, 21:30, closed)

Interesting...
I'm willing to donate all of my carbon credits to Hawking anyway.

The obvious difference between human energy consumption and a volcanic eruption is that an eruption is a calamitous event whereas human consumption is continuous. Another difference is that humans are actually generating power, whereas lava was already hot from the creation of the Earth. But it's worth looking at.
( Moon Girl Technologies horrendous beanbag, Fri 2 Dec 2011, 21:35, closed)

I mentioned not eruption level spills
I'm thinking of more miniature flood basalt type affairs where there's been continuous outpouring of lava, and therefore heat, over a long period of time.
(Dildo Bugger destroyed a ring on, Fri 2 Dec 2011, 21:42, closed)

If it's been continuous for millions of years it won't be a worry,
it might make the Earth warmer than it would otherwise have been but it would be in thermal equilibrium by now.
( Moon Girl Technologies horrendous beanbag, Fri 2 Dec 2011, 21:47, closed)

The trick would be to find a geological event like that
that wasn't a full-on flood basalt, because they tend to induce mass extinctions due to pollution and blocking out the sun, that sort of thing.

We'd need to look at the geological record for such an event that had life existing throughout it to measure it's effect on climate and possible extinction rates.

I'm afraid I'm going to have to break off from this discussion now as it's nearly ten and I still haven't had dinner this evening. But feel free to reply and I'll get back to it when I can.
(Dildo Bugger destroyed a ring on, Fri 2 Dec 2011, 21:54, closed)

Okay where'd he go?
The guy I was just composing a reply to, to the effect that methane is 20 times more effective a greenhouse gas than CO2 and has more than doubled in concentration in the atmosphere over the last 200 or so years?
(Dildo Bugger destroyed a ring on, Fri 2 Dec 2011, 21:38, closed)

back button, back button, copy paste!
it's worth sharing anyway... NOx is also pretty nasty, too.

I've got the figures now for volcanoes. Human annual world energy production is about 5 x 10^11 gigajoules (at 15.8 Terawatts x 24 hours x 365.25 days = 138502.8 TWh).

A volcano is about 24 megatons which is 10^8 gigajoules

So human energy use is about 5000 volcanoes a year...

HOLY SHIT.
( Moon Girl Technologies horrendous beanbag, Fri 2 Dec 2011, 21:45, closed)

Yes but a lot of that energy that we're generating
we're using. It is dissippated mechanically in a multitude of ways. Unless the figure you have there is specifically for energy we are pumping into the atmosphere after we've used the bulk of it for something else.
(Dildo Bugger destroyed a ring on, Fri 2 Dec 2011, 21:49, closed)

First Law of Thermodynamics, mate,
heat is work and work is heat. It doesn't get "used up".
( Moon Girl Technologies horrendous beanbag, Fri 2 Dec 2011, 21:51, closed)

As I understand it when, say, the internal combustion engine
burns fuel for energy and uses this to produce motion, there's energy that's converted to work and energy that just is wasted for want of a better word. Of the energy that produces work, this is dissipated in other ways. Again, as I understand it, not all of that energy will make it into the atmosphere. If it did, would this not mean that we had stumbled upon "free" energy?

I'm not entirely sure what point you were trying to make or whether this is the appropriate rebuttal.
(Dildo Bugger destroyed a ring on, Fri 2 Dec 2011, 22:00, closed)

all mechanical energy will eventually be converted to heat by friction.
energy can neither be created nor destroyed, but can change form. Eventually all power used is dissipated into the surroundings in the form of heat, unless it drives an endothermic chemical reaction and gets turned back into chemical energy again.

If your PC draws 200W of power from the mains, for instance, it will be putting out 200W of heat as well.

But if that surprises you, this will surprise you even more.
( Moon Girl Technologies horrendous beanbag, Fri 2 Dec 2011, 22:06, closed)

you're right and wrong...
All energy dies eventually go to heat (vibration of molecules), but your assumption that the temperature of the earth will increase has a key flaw, that the earth is a closed system. In reality, most of the extra energy that we produce will also be lost to space as radiation. There will be a change in the equilibrium point, but it will be small.
Think of it like a fridge, our energy use is like putting a bulb in the fridge, greenhouse gas build up would be like opening the door (not a great analogy, but hopefully the intent is clear?
apologies for erroneous worda, this is done on my phone
(Hill Dog loves planes, Tue 6 Dec 2011, 18:34, closed)