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http://sites.gsu.edu/geog1112/files/2012/10/Energy_Balance.png http://sites.gsu.edu/geog1112/files/2012/10/Energy_Balance.p... The earth already emits massive

http://sites.gsu.edu/geog1112/files/2012/10/Energy_Balance.png http://sites.gsu.edu/geog1112/files/2012/10/Energy_Balance.p... The earth already emits massive amounts of energy back into space. Nearly all the energy received from the sun is reemitted back into space, if this didn't happen the earth would quickly burn up. Adding reflectors won't make a huge difference as this energy would go back into space anyway.

prestonh 9y ago
In equilibrium that's true, but the whole problem is that we're not in equilibrium at the moment. That's what climate change is all about. If we can increase the albedo (reflectance coefficient, basically) of the planet, we can push the Earth down into an equilibrium position at lower temperature. EDIT: Of course, we would have to significantly alter the albedo, which is probably not possible with rooftop panels alone.
- tristanj 9y ago
  Grandparent poster is suggesting that sending this energy out to space is a waste. It's not, if there were no reflectors, the energy will end up in space anyway. The reflectors emit about 40 watts per square meter. In comparison, the earth emits about 12 trillion watts per hour. So these reflectors won't directly make any noticeable increase on the earth's total solar irradiance. From the article, it doesn't look like increasing albedo is the researcher's goal for these devices. It looks like they're doing this to reduce air conditioner energy usage, which would reduce CO2 emissions from fossil fuel burning power plants. Also, the earth's temperature is never really in equilibrium in the first place, as it's always heating or cooling due to the day-night cycle or seasonal axis tilt.
  - ScottBurson 9y ago
    > the earth emits about 12 trillion watts per hour Delete "per hour". The watt is already a unit of energy per unit time (1 joule per second, specifically). So 12 trillion watts is the same as 12 trillion joules per second.

prestonh 9y ago

In equilibrium that's true, but the whole problem is that we're not in equilibrium at the moment. That's what climate change is all about. If we can increase the albedo (reflectance coefficient, basically) of the planet, we can push the Earth down into an equilibrium position at lower temperature. EDIT: Of course, we would have to significantly alter the albedo, which is probably not possible with rooftop panels alone.

tristanj 9y ago
Grandparent poster is suggesting that sending this energy out to space is a waste. It's not, if there were no reflectors, the energy will end up in space anyway. The reflectors emit about 40 watts per square meter. In comparison, the earth emits about 12 trillion watts per hour. So these reflectors won't directly make any noticeable increase on the earth's total solar irradiance. From the article, it doesn't look like increasing albedo is the researcher's goal for these devices. It looks like they're doing this to reduce air conditioner energy usage, which would reduce CO2 emissions from fossil fuel burning power plants. Also, the earth's temperature is never really in equilibrium in the first place, as it's always heating or cooling due to the day-night cycle or seasonal axis tilt.
- ScottBurson 9y ago
  > the earth emits about 12 trillion watts per hour Delete "per hour". The watt is already a unit of energy per unit time (1 joule per second, specifically). So 12 trillion watts is the same as 12 trillion joules per second.