LOL apparently losing half the ice in the arctic is a laughably insignificant indicator.
We really should discuss the real world more. .
Yes, we should discuss the real world and the Artic Ice. Let's do that a bit. Obviously, dramatic and unprecedented climate change is based on a understanding of what is not dramatic and unprecendented. That is the reason Mann was so eager to get the Medieval Warming Period and the Little Ice age out of the graph, because they showed that current conditions were not at all "unprecedented".
Now Singer comes along and shows with a hundred citations to peer reviewed literature that the events such as the Medieval Warming Period are part of a cycle that has occurred for hundreds of thousands of years. Here is why that is important. Assume that you have a 400 year warm period in a 1500 year cycle, and it is 4 degrees C warmer at the peak. It takes 200 years to go up to peak, and takes 200 years to go down. That is 0.2 C increase (and later, decrease) per decade.
All or most of the 20th century global warming was well within the realm of natural variation as indicated by the historical evidence.
The past 2000 years is hardly all the human history available to us, and would encompass one - count them - and a bit "cycles". Of between 1000 and 2000 years. OK, maybe just one, or perhaps two. To me that just sounds like stuff happening.
The evidence is over hundreds of thousands of years, by a multitude of studies using a variety of proxies. A consensus exists on the 1,500 year cycle. Just one example -
Near Iceland, Maureen Raymo of Boston College found the Earth was undergoing Dansgaard-Oeschger's 1,500 year climate cycles more than a million years ago. Raymo and her research team retrieved a very long sediment core from the deep sea bottom south of Iceland. As the Raymo team wrote in Nature: "Here we use sediment records of past iceberg discharge and deepwater chemistry to show that such millennial-scale oscillations in climate occurred over one million years ago.... Our results suggest that such climate instability may be a pervasive and long-term characteristic of Earth's climate...."
M. E. Raymo et al., "Millenial-Scale Climate Instability during the Early Pleistocene Epoch," Nature, vol. 392, no. 6677, April 16, 1998, pages 699–702.
Even if Singer's one to two thousand year cycles are real - that is, have some underlying physical cause - AGW could still exist. It's not one or the other.
They are not Singer's cycles. They have been noted by Dansgaard, Gerald Bond, Meter deMenocal, Maureen Raymo, Giancarlo Bianchi, Carin Anderson, Dennis Darby, Bettina Schilman, Boo-Keun Khim, F.S. Hu, Dirk Verschuren, and hundreds of other scientists. Singer has simply brought these various works together insofar so they relate to 1500 year cycles.
AGW of course could still exist. Relegated to a small, unimportant paragraph in the future textbooks on the history of science. Most likely the title of that chapter will be "Famous Scientific Frauds and Myths"
Singer's clutched straw doesn't define the amplitude any more accurately than it does the frequency. There's plenty of room for both an unrecognised mechanism of small amplitude and AGW over the last century. Even more over the last few decades.
There is room for both theories. There may be a small desk in the basement that Hansen, Mann, Gore, and Jones can share. You and AUP may visit them there and together discuss future planetary crises caused by the evils of man and his infernal combustion engines. By the way, would you take a can of roach spray down there for them? They have some work to do.
And do not forget the clear lack of actual scientific atmospheric experiments to prove or disprove the CO2 hypothesis.
Get over it. AGW is disproved by the historical evidence presented.
? How close to half? Half of what? Prove it's not slightly less than half you alarmist greenhornswoggler 
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