Where did you get this "at least half the time over the last 10,000 years the Arctic sea ice has melted off completely over the summer" and why do you believe it?
Anthony Watts? Do you know that he has a college degree in nothing? That's right: He's a dropout after spending several years at Purdue. Didn't finish even just an undergraduate degree. (For many years now he utterly refuses to answer this. Of course he does not. Admitting this truth would destroy his credibility among many of his followers.)
This is yet another example of how conservatism just makes up "facts" in its fact-denial and science-denial in the name of political ideology.
"Arctic sea-ice extent and volume are declining rapidly. Several studies project that the Arctic Ocean may become seasonally ice-free by the year 2040 or even earlier. Putting this into perspective requires information on the history of Arctic sea-ice conditions through the geologic past. This information can be provided by proxy records from the Arctic Ocean ?oor and from the surrounding coasts. Although existing records are far from complete, they indicate that sea ice became a feature of the Arctic by 47 Ma, following a pronounced decline in atmospheric pCO2 after the Paleocene?Eocene Thermal Optimum, and consistently covered at least part of the Arctic Ocean for no less than the last 13?14 million years. Ice was apparently most widespread during the last 2?3 million years, in accordance with Earth?s overall cooler climate. Nevertheless, episodes of considerably reduced sea ice or even seasonally ice-free conditions occurred during warmer periods linked to orbital variations. The last low-ice event related to orbital forcing (high insolation) was in the early Holocene, after which the northern high latitudes cooled overall, with some superimposed shorterterm (multidecadal to millennial-scale) and lower-magnitude variability. The current reduction in Arctic ice cover started in the late 19th century, consistent with the rapidly warming climate, and became very pronounced over the last three decades. This ice loss appears to be unmatched over at least the last few thousand years and unexplainable by any of the known natural variabilities."
This is what the lead author said in an interview when asked when was the last time the Arctic was ice-free in the summer:
"The paleo data we have so far is very scant, so we can?t know for sure when the Arctic was ice free in the summer last time. To be conservative, the closest candidate is the early Holocene (roughly ~10 kyr ago), when the insolation in the Arctic was high due to the beneficial orbital configuration; however, the more data I see, the stronger is my impression that there was not that little ice at that time. The next best (actually, better) candidate is the Last Interglacial, about 125kyr ago, again due to orbitally-driven high insolation: the ice was likely very low, but we can?t say whether it was completely ice free in summer or not. There are also a few other major interglacials, which may have had a similar picture, in particular Marine Isotopic Stage 11, about 450 kyr ago. In any case we are talking about very rare events controlled by a forcing very different from today. If none of those intervals was really ice free, then a million year assessment would be correct."
Not only all that, but consider again this animated gif graph:
and see again that in the last 30 years not only are we on the verge of no ice in the summer, but we are 1/3 of the way to having no ice in the Arctic not just in the summers but all year round including in the winters. This has not happened for millions of years.
And we're seeing all this happen in just decades. It has never happened so fast naturally.
Let's see whether you find even a college dropout like Watts who would say, "Sure, we're had no ice year round in the Arctic plenty of times recently".
Finally, note this: The science denying argument is this: We've had no-ice conditions before humans could have caused no-ice conditions, therefore what is happening now is natural. That's like saying that the mass killings of humans before the 20th century was natural (starvation or disease), therefore the mass killing in the 20th century was natural.
On Wed, Sep 12, 2012 at 1:06 AM, Wayne Bishop <firstname.lastname@example.org> wrote: > The real problem comes with the "anthropogenic" cause and, if so (which is > less than certain), appreciably slowing down the process without millions of > lives on the line, the great majority of whom would be very poor, nonwhite > people who currently are barely eking out a living. A very liberal, > progressive concept. > > More science is that at least half the time over the last 10,000 years the > Arctic sea ice has melted off completely over the summer. That's why the > polar bears and Inuits all died out millennia ago. > > Wayne > > At 09:31 PM 9/11/2012, Paul Tanner wrote: > > On Tue, Sep 11, 2012 at 8:22 PM, Robert Hansen <email@example.com> wrote: >> >> On Sep 11, 2012, at 6:51 PM, Paul Tanner <firstname.lastname@example.org> wrote: >> >> Regardless, to meet your challenge above that scaling cannot be a >> model for the multiplication of arbitrary real numbers - given that I >> utterly reject your assumption above that a model must be computable - >> and I note that your assumption above denies all of geometry based on >> real numbers because you deny almost all real numbers: >> >> >> Joe must be a conservative real number denier. >> >> Bob Hansen > > Since you've given me permission: > > You can all you want make light of the fact that there is much > crankery out there by a very big lot of cranks in terms of denial of > science and/or mathematics, and that very unfortunately for > conservatism, it almost always comes from within conservatism. Do we > need to wonder why? > > For fun, consider this: The most recent denial of science by so many > conservatives on the Internet is their mind-blowing attempts at trying > to continue to deny that the globe is warming never mind that we now > have new satellite data that confirms that starting less than 30 years > ago, all of the Arctic ice is collapsing before our very eyes, more > than 3/4 of the way to zero volume during summer, 1/3 of way to zero > volume all year round. And since just 2006, more than half of > whatever summer ice existed then is now gone - we are more than > halfway to zero volume starting from just six years ago. > > See these for the jaw-dropping truth: > > http://tamino.files.wordpress.com/2012/09/piomas.gif > > http://img.photobucket.com/albums/v224/Chiloe/12_Climate/sea_ice_PIOMAS_min_to_date.png