In a comment to my last post, Hagiograph cited a Nasa Study which said of the Holocene Climatic Optimum:
"These orbital changes can be easily calculated and predict that the northern hemisphere should have been warmer than today during the mid-Holocene in the summer AND colder in the winter. The paleoclimatic data for the mid-Holocene shows these expected changes, however, there is no evidence to show that the average annual mid-Holocene temperature was warmer than today's temperatures."
"In summary, the mid-Holocene, roughly 6,000 years ago, was generally warmer than today, but only in summer and only in the northern hemisphere. More over, we clearly know the cause of this natural warming, and know without doubt that this proven "astronomical" climate forcing mechanism cannot be responsible for the warming over the last 100 years. "Source
It is a very easy thing to look on this blog and see if I have spoken of any warming in the southern hemisphere or in Antarctica during the Holocene Climate Optimum. NASA says there is no evidence for warming in the southern hemisphere. This is horse-hockey, ladies and gentlemen. Ignorance of the NASA writers is on display, but then, they do want to scare you into giving them your hard earned money in the form of taxes.
The interesting thing is that they are depending on models to tell them what the night time temperature is. All one can get from paleoclimatic information on the ground is indicators of average temperature. And all the indicators I have seen say the mean temperature was warmer by the 2-3 deg C seen in the map on the above referenced page. Those numbers are mean increases in temperature.
Let's look at the logic in the above statement that there is no evidence that Antarctica was warmer during the Climatic Optimum than today. It is sadly clear to me that people don't remember what they read on this blog from a few weeks back, nor do they look up data before responding to what is written.
If you do nothing else with this post read the bolded parts of the quotations below
From my post on March 23, 2009 here
The stability of floating ice shelves is an important indicator of ocean circulation and ice-shelf mass balance. A sub–ice-shelf sediment core collected during the Austral summer of 2000–2001 from site AM02 (69842.89S, 72838.49E) on the Amery Ice Shelf, East Antarctica, contains a full and continuous record of glacial retreat. The AM02 core site is ;80 km south of the floating ice shelf edge and contains a 0.5-m-thick Holocene surface layer of siliceous mud and diatom ooze of marine origin. Core data are supportive of sub– ice-shelf circulation models that predict the landward flow of oceanic water, and prove that the landward transport of hemipelagic sediments occurs beneath floating ice shelves over distances of at least ~80 km. An increase in sea-ice–associated diatom deposition in the upper part of the Holocene suggests that a major retreat of the Amery Ice Shelf to at least 80 km landward of its present location may have occurred during the mid-Holocene climatic optimum." Mark A. Hemer and Peter T. Harris, " Sediment core from beneath the Amery Ice Shelf, East Antarctica,"Geology; February 2003; v. 31; no. 2; p. 127–130, p. 127
How in the hell can NASA say that there is no evidence of the southern hemisphere being warmer when the Amery Ice Shelf was melted by 80 km during that period?
A question for NASA, if it was colder then than now, was it the cold that melted this ice cap? Utter illogic. The guy who wrote the NASA website ignored this evidence or didn't do sufficient research to know of it.
And from my blog on March 26, 2009 source
"Some studies in the northern Antarctic Peninsula suggest iceshelf
collapse in the mid-Holocene (Pudsey and Evans, 2001). To date, ice shelves farther south (south of 70[deg]S) have shown no catastrophic breakup, although some ice-shelf fronts are in retreat. This paper presents the first evidence of an early Holocene collapse of one of these more southern ice shelves." M. J. Bentley, “Early Holocene Retreat of the George VI Ice Shelf, Antarctic Peninsula,” Geology, 33(2005):173-176, p. 173
They further note the time of its disappearance.
"“Our core chronology shows that the George VI Ice Shelf disappeared in the early Holocene, with the onset of collapse by 8170 14C yr B.P. (9595 cal. yr B.P.) and complete reformation by 7300 14C yr B.P. (7945 cal. yr B.P.). This coincides with deglaciation in many Antarctic coastal areas (Ingo´lfsson et al., 1998), and follows deglaciation of the western Antarctic Peninsula shelf (Anderson, 1999). The record of the George VI Ice Shelf collapse immediately postdates ice-core evidence of a widespread, sustained early Holocene climatic optimum (Masson et al., 2000; Masson-Delmotte et al., 2004) ca. 11–9.5 ka (Fig. 4). The collapse is also coincident with the influx of Circumpolar Deep Water onto the Antarctic Peninsula continental shelf, as demonstrated in the Palmer Deep marine record (Domack et al., 2001; Fig. 4).” M. J. Bentley, “Early Holocene Retreat of the George VI Ice Shelf, Antarctic Peninsula,” Geology, 33(2005):173-176, p.175
And Bentley concludes that the melting in the southern hemisphere was greater than what we see today. The NASA writer conveniently doesn't bother to tell you about this data, preferring instead to stick with the party line that there is no evidence of a warm southern hemisphere, which is entirely a bunch of horse-hockey.
"The collapse of a currently extant ice shelf shows that early Holocene natural ocean-atmosphere variability in the Antarctic Peninsula was greater than the recent, potentially anthropogenically influenced changes.”
M. J. Bentley, “Early Holocene Retreat of the George VI Ice Shelf, Antarctic Peninsula,” Geology, 33(2005):173-176, p.176
Question for the illogical NASA writer: Was it the cold back then that melted the Amery and George VI Ice Shelves 8000 years ago? Or is this evidence of warming 8000 years ago in that most southerly of southern hemisphere locations?
Hagiograph, don't beleive everything you read which is written by a government employee who gets his funding and makes his living by scaring congressmen into giving him grant money.
And check me out to, but for goodness sake, actually check the data, don't just read one thing and conclude from the source that they are telling you the truth.