[jamesqf]

Originally Posted by TheEnemy

Solar cycle - Wikipedia, the free encyclopedia

Read the full article. There's an approximately 11 year variation in sunspots - the sunspot cycle. The solar magnetic field reverses in each sunspot cycle, so the complete solar cycle is ~22 years.

So I should just ignore any changes that the sun has gone through?

You should not ignore them. You should look at the changes (and think about how accurate any reconstruction might be, given the limitations of data collection prior to satellites), discover that they are not large enough to produce any significant temperature change, and THEN ignore them.

For instance if your conclusion is that the earth is warming, all climate scientists would agree, even most of us on this board including me would agree.

But that's not even a conclusion, it's just observed data. The conclusions are 1) physics says increased CO2 should cause warming; and 2) the observed warming is consistent with the observed increase in CO2.

If your conclusion is that CO2 is responsible for a moderate to large part of it you would still have the vast majority of climate scientists, and the majority of the people involved in this discussion, including me.

Then why has everything you've posted been an argument that CO2 does not cause warming? After all, even if the sun was responsible for some significant fraction of observed warming, there's nothing (well, maybe orbital mirrors...) that we can do about it.

If your conclusion was that CO2 is responsible for all of the warming, then you would actually loose most of the climate scientists, and many of the people in this discussion.

Sure, if you make it an absolute. But if you say that all, or a significant part, of the warming is NOT due to anthropogenic factors, you also lose them. It's just physics.

Furthermore, there is no reason to think that the other factors, such as solar output, will keep increasing without limit. As best we can tell from the available data, the Sun has remained pretty constant over millions of years, and there are physical reasons to expect that it will undergo no significant change on human timescales. So absent any physical reason to think otherwise, we should expect solar output to keep on following its pattern of very small periodic & random variations around its long-term average.

edit to add: The TSI reconstruction actually re-inforces your views, so wouldn't it be good for me to use it?

Use, sure, but not misuse. You need to stay aware of the fact that the scale of the graph is misleading, so that what appears to be large swings are really tiny variations. I dare say that if you graphed it on a 0-1400 scale, it would just appear as a straight line.