According to an analysis by Scafetta and West published in the March edition of Physics Today (subscription required), the Sun 'could account for as much as 69% of the increase in Earth's average temperature.'
Article title: “Is climate sensitive to solar variability?” By Nicola Scafetta of Duke University Physics Department and Bruce J. West of the US Army Research Office, Research Triangle Park, North Carolina
Excerpt: "Thus the average global temperature record presents secular patterns of 22- and 11-year cycles and a short time-scale fluctuation signature (with apparent inverse power-law statistics), both of which appear to be induced by solar dynamics. The same patterns are poorly reproduced by present-day GCMs and are dismissively interpreted as internal variability (noise) of climate. The nonequilibrium thermodynamic models we used suggest that the Sun is influencing climate significantly more than the IPCC report claims. If climate is as sensitive to solar changes as the above phenomenological findings suggest, the current anthropogenic contribution to global warming is significantly overestimated. We estimate that the Sun could account for as much as 69% of the increase in Earth's average temperature, depending on the TSI reconstruction used. Furthermore, if the Sun does cool off, as some solar forecasts predict will happen over the next few decades, that cooling could stabilize Earth's climate and avoid the catastrophic consequences predicted in the IPCC report."
This article is based on Scafetta and West's previously published peer reviewed papers.
Yes, I know Real Climate are exceedingly rude about this work and RC are entitled to their politically motivated views, just as Scafetta and West are entitled to their's.
Update: Full article now available here.
This is good work by Mark and Motty. And where are the usual defenders of the climate faith when climate dogma is found to be more than just a little bit fallible? Not a word from them.
I agree, Mark. But the burden is on them to demonstrate the amount of coupling. This claimed level of certainty for the emissions is even more extraordinary given that the only correlation they have to work with is for temperate Northern Hemisphere. The 50% of the globe between 30N and 30S shows no such certainty, nor does the temperate Southern Hemisphere. So there goes at least 75% of global area. Some certainty.
It also makes clear that they didn't just pluck their 90% certainty level out of their backsides. They have gone out of their way to manufacture a plausible rationale to justify it.
I just can't believe they would seriously try on something like a net uncertainty. But their use of the old mercators projection to map temperature change (when GISS' own software enables them to convert any map to equal area projection) demonstrates the extent they have gone to mislead the public.
"Net radiative forcing of +1.6W/m2 with a total negative uncertainty of -2.6W/m2 and a total positive uncertainty of +1.6W/m2. So even by the IPCC's gonzo maths, the range of climate forcing outcomes is somewhere between -1.0W/m2 and +3.2W/m2."
I noticed the same thing when I added up all the incremental uncertainties. However, it is possible that some of the uncertainties might be 'coupled' which would mean the whole isn't necessarily the sum of the parts. Regardless, as I've said before, "you could drive a Mac truck" through the uncertainty interval which completely contradicts the IPCC edicts of "highly likely" and others who claim the science is settled. What's even more damning is the claim of certainty on the GHG impacts when they are based on models which make assumptions around the relative impact of other factors including solar and aerosols. Yet the IPCC identifies in its own report that its level of scientific understanding on these factors is very low.
No doubt alarmist climate claims are NOT about the science!
Yes Paul. Add some structural warming shifts from irrigated agriculture and vegetation thickening, which are once-off changes rather than part of a trend, and we end up with much ado about nothing.
I think I've got climate change worked out - driven by internal variablity involving known cycles such as the Pacific Decadal Oscillation, the North Atlantic Oscillation, the El Nino/Southern Oscillation, and the North Pacific Oscillation. Chuck in the odd volcano. The external drivers are solar/cosmic factors. I can't see a significant role for the logarithmic enhanced greenhouse.
How sensitive is the climate to solar variation? Answer: Not much (recently).
Not Much Warming Under the Sun
By Phil Berardelli
ScienceNOW Daily News
12 March 2008
Don't blame the sun for recent global warming. A new analysis, based on historical data rather than computer simulations, shows that our star's role in climate change has been vastly overtaken by other factors, particularly the human-induced buildup of greenhouse gases.
We get our warmth from the sun, sure, but our climate results from a complex and precarious balance of additional factors, including ocean currents, winds, the amount of snow and ice cover, and even Earth's orbit and rotational wobble. It's well-known that our climate has been warming over the past century--a situation most researchers blame on human-induced buildup of carbon dioxide, methane, and other greenhouse gases. Studies have shown that the sun was a driving factor in climate change in preindustrial times, but some researchers have wondered whether changes in the sun's intensity are continuing to play a major role, possibly by hitting the planet with more heat than normal.
To help nail down the effect of solar radiation, geophysicist Mike Lockwood of the University of Southampton, U.K., examined data available since 1955 on the monthly average output of the sun, including sunspots, magnetic activity, and cosmic-ray variations. Then he compared those data, month by month, with average global temperature records, as well as El Niño- and La Niña-induced weather cycles and the atmospheric effects of major volcanic eruptions. The result, Lockwood and colleagues report in two papers published online this week in the Proceedings of the Royal Society A, is that for the past half-century, the sun has exerted only a small influence on climate--about 3% compared with the warming influence of greenhouse gases and natural climate cycles (see illustration).
Lockwood says a key advantage of his approach is that he relied on hard data rather than computer models. "One problem that crops up [in the climate discussion] is that scientists use complex models that nonspecialists don't understand and therefore don't trust," he explains.
Lockwood's research represents "a solid look at whether global temperature increases are being driven by changes in the brightness of the sun," says geophysicist Dáithí Stone of the University of Oxford in the U.K. The work suggests that "there is basically no way that this can be the case," he says.
http://sciencenow.sciencemag.org/cgi/content/full/2008/312/3
Who would have thought?