There is a very good correlation between sun activity (measured in terms of sunspots) and climate. While that in itself is not proof, it gives probable cause. This is no different than looking at the ice core and seeing that CO2 is probable cause for causing temperature rise. Even if CO2 is disproven to cause the amount of global warming as originally purported, there will be those who will want to go through with the Kyoto treaty anyway (in other words, the guiding interest is not in understanding climate, but rather to enact a desired outcome.)
But I digress… Realclimate’s refutation of Svensmark’s, to give the benefit of the doubt, is probably scientifically honest. (I need to understand what is meant by GCR trends.) But in general, I find that Realclimate stands to attack any dissenting scientific opinion no matter whom it is from. That is why I think Realclimate and Junkscience has to be tempered with a view that they aren’t neutral.
It has not been proven that CO2 is the cause of 20th century warming, and at the same time solar activity is at an 8000 year high. The real killer, in my mind, is more likely to be the sun. There needs to be more research, and IPCC should not be telling the public about a 90% consensus and “the matter is settled,” because it’s far from that.
Chaos: “And asserting a hypothetical solar mechanism does NOT turn off the obvious, and experimentally demonstrated mechanism of GHG. …. How could it? How do you turn off known physics?”
Who claimed that solar variance turns off known physics? Remember, no one is claiming that there is only one factor that sets the earth temperature. It’s well established that GHC does modulate temperature, but there is no evidence that increases in CO2 really do lead to the kind of temperature rises observed. Remember, the Ice ages came and went without man’s help!
Actually in 2005 Svensmark demonstrated in the lab that cosmic rays do in fact cause condensation in an environment that was set up to replicate the earth’s atmosphere. This is a real-time experiment where results are seen immediately (i.e. it didn’t need to demonstrate any time-delayed effect.). The beauty is that he formulated a hypothesis based on knowledge of the relationship between ions and condensation, gathered funding, set up the experiment, performed it, and proven his hypothesis. This is the scientific method as it should be.
Chaos: “Never heardof that, but 0.5 billion years ago the Sun indeed could have been in a different configuration, and besides that is probably near the time of evolution of eukaryiotic cells.
More recently there was the Paleocene-Eocene thermal maximum which had lots of extinction, with CO2 levels of 2000-3000 ppm, and crocodiles in the arctic. Permian-Triassic mass extinction may also have been caused by global warming from immense volcanism and release of oceanic methane hydrates.”
Fair enough–it’s not conclusive.
Chaos: “So if #2, noticing correlations in the geological record is unreliable, then your first comment is also irrelevant.”
I didn’t say the correlations are not reliable. There’s a clear correlation, but that does not establish causation, especially considering the 800-1000 yr lag.
