91 votes

Explain it to me like I'm a physics grad: Greenhouse Effect

Executive summary: Carbon dioxide in the atmosphere absorbs some of the energy radiated by the Earth; when this energy is re-emitted, part of that is directed back to Earth. More carbon dioxide $\...
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  • 117k
83 votes

Why don't solar panels contribute to global warming?

The purpose of solar cells is to generate electricity. This can replace the electricity generated by burning fossil fuels for electricity. The fact that it's becoming practical to run vehicles on ...
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68 votes
Accepted

Does the sea level increase if an iceberg melts?

The Archimedes principle says that a floating body will displace an amount of fluid that is equal to its weight. Since the iceberg floats, it weighs the same as the water it displaces. If it had the ...
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  • 2,701
67 votes

Bush fires and heat waves, the real mechanics?

This is more a question of chemistry and biology than physics. Solid objects don't burn (try dropping a lit match on a piece of structural lumber sometime -- it'll just go out). Instead, they ...
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  • 1,717
42 votes

Does the sea level increase if an iceberg melts?

The one you're not contemplating: that the sea level rises because of melting of ice that's currently over land. As noted in Rodrigo's answer, when sea ice melts there is no change in the water level, ...
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40 votes

Can we cool Earth by shooting powerful lasers into space?

Your idea to cool the Earth by shooting photons off into space is actually what already happens now! However, instead of a laser, the Earth cools itself by blackbody radiation. The Earth radiates a $...
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  • 2,933
36 votes
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How is it possible that it can get hotter in the car than it is outside?

Law of Thermodynamics says that two bodies eventually will have equal temperatures. That is not an absolute Law. There are conditions, and one of those conditions involves the energy input to the ...
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36 votes

Explain it to me like I'm a physics grad: Greenhouse Effect

Explain it to me like I'm a physics grad: Global Warming Physics grads know all about spherical cows. So I'll start with a spherical cow model, and then move beyond that. Spherical cow model of the ...
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31 votes

To what extent do (man made) generators of heat from internal sources in earth's system cause climate change?

The power involved does not represent a significant fraction of the total energy budget, so it can normally be ignored. Assuming (per Wikipedia Solar Energy) that the energy received on earth from ...
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30 votes
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Why is climate change triggering faster rotation?

Glaciers are water that is frozen and high up in the mountains. If you thaw that ice and the water flows back to sea-level, then it would seem that mass in the water would get closer to the rotation ...
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  • 113k
28 votes

Explain it to me like I'm a physics grad: Greenhouse Effect

It seems like this is really your main question: Why does adding more $\mathrm{CO_2}$ to the atmosphere increase the greenhouse effect if the atmosphere is already opaque in the absorption bands of $\...
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  • 6,001
26 votes

Can we cool Earth by shooting powerful lasers into space?

Ambient heat is low grade energy. You can't effectively harness it to do work (which is a transfer of energy. i.e. powering laser which itself is a machine to transfer energy) because it has nowhere ...
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  • 7,720
23 votes
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Why did nuclear testing not result in nuclear winter?

A nuclear winter would be a result of large amounts of smoke blocking light from the Sun. The smoke would be from the fires started by nuclear bombs on cities, not directly from the bombs. Most bomb ...
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23 votes

Bush fires and heat waves, the real mechanics?

Water evaporates faster at higher temperatures, so plants will lose water faster in a heat wave than in milder conditions. Drier plants will catch fire easier and burn faster and hotter than moist ...
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22 votes
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Why don't solar panels contribute to global warming?

Simple back-of-the-envelope calculation: This figure shows our best estimates of the radiative forcing from different anthropogenic (human-caused) phenomena: It shows that the radiative forcing from ...
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  • 6,001
20 votes
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Is nuclear power desireable in the long term, given the fact that it's an unnatural heat input to our planet?

There is a balance between heat input and radiation lost to space. To maintain this balance, if you increase the input by 0.1%, you must do the same to the output. Approximating the earth as a ...
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  • 9,211
18 votes

How much do sea levels rise due to thermal expansion?

This is known as the steric component of sea level rise, and it is significant. As a very rough indication of the size of the effect, if the top 1000 meters of the ocean warmed from 10 to 11 degrees ...
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  • 9,211
18 votes

Can anyone explain the REAL reason why CO$_2$ increases global temperatures (not the simplistic greenhouse analogy provided for public consumption)?

So the infrared absorption process is already fully saturated, and thus further increases in atmospheric CO2 will not lead to any additional absorption. There is no such thing as a fully ...
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  • 1,075
17 votes

Can we cool Earth by shooting powerful lasers into space?

Your proposal is to increase the effective albedo of the Earth, and in principle it could work. No need for the giant lasers though—probably more efficient and much cheaper just to use mirrors.
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  • 9,211
13 votes
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Damhsa Theory: Can gravitational waves really affect the long term climatic evolution of Earth?

"The Damhsa Theory proposes that these oscillations are actually gravitational waves from the continued ramifications of the expanding universe and that ice ages and inter-glacials such as our current ...
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12 votes

Does the sea level increase if an iceberg melts?

It is true that when pure ice melts in pure water, the water level does not rise. However, the oceans are salty and this makes a big difference. When pure water melts into the salty ocean, water level ...
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  • 6,963
12 votes

Can we cool Earth by shooting powerful lasers into space?

Nice idea... but lasers get their power from electricity. If we had lots of spare electricity, we could stop generating more and reduce the energy output from coal or gas powered power stations. So, ...
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12 votes

Why is climate change triggering faster rotation?

There are lots of factors besides glaciers that affect the Earth's rotation. Given the sharpness of the change, it seems unlikely to be glaciers which are notorious for moving very slowly. A more ...
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11 votes

How is it possible that it can get hotter in the car than it is outside?

While respecting the other good and thoughrough answers, I feel I can give you a simple explanation to your exact question. As you mention in your question, ...
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  • 47.2k
10 votes

Why don't solar panels contribute to global warming?

solar panels increase the efficiency of how we 'harvest' this solar energy, reflecting less of it back into space, and turning more of it into en energy (in this case, electrical I’m no expert, ...
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  • 200
9 votes
Accepted

Summer Winter cause

The smaller angle of incidence should have the greater effect, otherwise during the summer the northernmost regions (in the boreal emisphere) would be hotter than the southern ones, and, believe me, ...
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  • 467
9 votes

Does the sea level increase if an iceberg melts?

Yes, if an iceberg melts, it will increase the sea level but that increase in sea level is totally negligible. According to this recent article that shows the breaking of Larsen C ice shelf (is ...
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  • 1,038
9 votes

Is nuclear power desireable in the long term, given the fact that it's an unnatural heat input to our planet?

The answer is "No", and here is the qualitative explanation. The Greenhouse Effect is not about extra energy input at the Earth's surface, nor is it about reducing the thermal output. It is about ...
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