I am sorry you felt insulted. It stems from a frustration that you argue against my points with very little knowledge of the subject as demostrated by your obvious lack of understanding of statistics
Now why would I feel insulted
As for the graph you posted, it doesn't disagree with what I've been saying nor does it disagree with the data I posted. In fact, it agrees.
As can be seen in the first graph from the IPCC, natural forcing (including fluctuation in solar radiation) can explain some of the observed warming for the early part of this century, though it cannot explain the warming that has occured more recently. Quoting their 2001 report
"There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities. Detection and attribution studies consistently find evidence for an anthropogenic signal in the climate record of the last 35 to 50 years. These studies include uncertainties in forcing due to anthropogenic sulfate aerosols and natural factors (volcanoes and solar irradiance)..."
"
The sulfate and natural forcings are negative over
this period and cannot explain the warming; whereas most of these studies find that, over the last 50 years, the estimated rate and magnitude of warming due to increasing greenhouse gases alone are comparable with, or larger than, the observed warming. The best agreement between model simulations and observations over the last 140 years has been found when all the above anthropogenic and natural forcing factors are combined, as shown in Figure SPM-2." (bold added)
There is no question that natural forcing has contributed a small amount to the warming over this century, mostly during the first half, but there is also no question that natural forcing alone, including solar radiation, cannot explain the warming that has happened in the last 30 years. Most of the increase has been during that period too.
Onreef,
Yes, we are in an interglacial period right now. There are a lot of reasons that CO2, CH4, and N2O are high during warm periods and low during cold ones. As you're getting at, it doesn't really matter if the greenhouse gases in the atmosphere go up because phytoplankton growth in the southern ocean is low or because we've burned a lot of fossil fuels--more greenhouse gases is more greenhouse gases, regardless of where they come from.
As for the use of the term "consensus," the darn thing has two definitions which are similar, though different. Often the word consensus is used to mean 100% agreement by a group, but it also is used to mean "general agreement or accord" (thefreedictionary.com). As such, because the vast majority of a group agrees on something, whatever that is, there is said to be a consensus, even if there are a few dissenters. It's sort of like the question of reasonable doubt. Of course there is always doubt in everything, but is it reasonable to doubt something given the evidence.
For a good book to explain all the dynamics of global warming I'd suggest
Global Warming: The Complete Briefing by John Houghton as your best, most understandable, most up-to-date source. The most recent publication is 2004.
Also, as Mark said above, we have direct temperature measurements for the last ~150 years. Before that we have to use references to infer what the temperature was since no one actually measured it. For this people use tree rings, cores from coral reefs, ice cores, etc. There are certain relationships, especially in the ratios of certain isotopes, that depend highly on temperature. While not as good as a thermometer measurement, when 1000's of samples all come out the same all around the world, one can assume that they've got a pretty accurate depiction. Check out the temp. record for the last 1000 yrs.
Best,
Chris
