There is a rising body of evidence that it is caused by quantum fluctuation, yes, this causes the sun to radiate more energy, but it also warms the planets cores.

>>By all indications, the Earth has been warming. Scientists such as Pielke, Lindzen, and Christy, prominent skeptics of global warming, acknowledge that the Earth has warmed since about 1850. That is hasn't warmed since 1998 is more an indication that the alarmists were off in their predictions, than anything. They also believe that man has contributed to it. Where they dispute the global warming alarmists is largely on these points:
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>>1. Carbon dioxide being the primary cause (Pielke thinks land use is a bigger factor).
>>2. How much it has warmed (Christy has done a lot of work analyzing satellite data that indicates it hasn't warmed as much as ground-based temperature measurements).
>>3. How much we know about the climate (all 3 believe the alarmists are vastly overstating their knowledge of how the climate works).
>>4. Whether a little warming is necessarily bad.
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>And how did that account for the melting polar ice caps on Mars? Could it be the same thing that caused ours - The sun?