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the sun itself is not responsible for global warming, it must be that the temperature is changing due to climate changes. Anyone?

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  • $\begingroup$ The Sun is clearly not responsible for global warming. What is your question? $\endgroup$ – HDE 226868 Jan 22 '16 at 1:15
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    $\begingroup$ @HDE226868 Though the Sun plays a part in the process of global warming. And to Kim, your question is unclear as the title asks if the sun is responsible for global warming, and yet your first line strongly states that the sun is not responsible for global warming. To your second part of the sentence, the climate changes are due to global warming and thus leading to temperature changes. From what I gathered from my analysis above, I think that this has nothing to do with astronomy at all. I suggest this site: earthscience.stackexchange.com is better suited to answer this question. $\endgroup$ – CipherBot Jan 22 '16 at 1:43
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    $\begingroup$ Well, IMHO this question is poorly phrased but on-topic. CAN the Sun contribute to global warming? Yes, in its cyclic radiation change it can periodically increase the global temperatures. DOES the Sun contribute to global warming currently? No, it's currently at a low of its cyclic change. And regardless, the Sun is definitely not the MAIN cause; its contribution (when it occurs) being one of lesser factors. $\endgroup$ – SF. Jan 22 '16 at 19:24
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The energy input of the Sun stays constant (mostly, there are some minor variations), so no, the Sun is not responsible for climate changes.

The temperature of the Earth has to do with the balance between the energy input, and the energy radiated back into space. If the temperature is not changing, they are the same. Global warming is caused by gasses in the atmosphere limiting the energy radiated into space, therefore, the temperature rises, until the energy radiated is again equal to the solar energy input.

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Actually the sun's output over time does vary, and it does cause climate changes. There is an 11 year cycle as shown in this image from www.sciencemuseum.org.uk:

enter image description here

And in the early half of the 20th century it did increase slightly, which probably did contribute to global warming during that time but over the last 50 years it has actually slightly cooled, so it is absolutely not responsible for the global warming we currently see. This image (from the same source) shows some nice detail. The dotted line is the moving average:

enter image description here

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  • $\begingroup$ From the scale on those graphs, it looks like the fluctuation is about 0.1% of the total output. I would call that rather constant, despite the fact that there is a cycle. $\endgroup$ – Nuclear Wang Jan 22 '16 at 16:17
  • $\begingroup$ Whereas I would suggest that 0.1% of the 1.5E22 Joules total energy from the Sun that strikes the face of the Earth each day is considerable. That's of the same order as the amount of electricity generated across the whole world in a year! $\endgroup$ – Rory Alsop Jan 22 '16 at 16:25
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    $\begingroup$ The change seems to be around 0.2% between lowest and highest peaks. 0.2% out of Earth's average 289K is about 0.57K. Definitely not a negligible change, although luckily not cumulative. But considering 2015 was the warmest year in history of measurements and the Sun is at its low, we can expect its influence to impact the global temperatures quite badly rather soon. $\endgroup$ – SF. Jan 22 '16 at 19:18

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