This is interesting, somehow the Earth managed to reduce a good portion of the Arctic Ice Cap during the Holocene Climate Optimum from approximately 10,000-6,000 years ago without the help of the industrial revolution, fossil fuels, or automobile emissions.
This new paper published in Quaternary Science Reviews finds Arctic sea ice extent and thickness was much less than present-day conditions and according to the authors,
“Arctic Ocean sea ice proxies generally suggest a reduction in sea ice during parts of the early and middle Holocene (∼6000–10,000 years Before the Present) compared to present day conditions.”
The authors show how 8 different proxy studies reveal extended periods lasting hundreds of years without perennial sea ice in the Arctic [ice-free conditions], and find solar insolation explains these changes. See figure 4 from the paper below.
The top graph shows simulated annual mean sea ice thickness [orange curve] was much less during the Holocene Climate Optimum ~13,000-6,000 years ago compared to the end of the 20th century at right side of graph. The bottom graph shows multiple proxies of sea ice with darker green indicating periods of less sea ice. Modern sea ice is at high levels in comparison to the rest of the Holocene.
Annual mean sea ice thickness for the three different simulations (Panel a) compared with results from published paleo-sea ice studies (Panel b). Black curve: constant surface albedo; red curve: dynamic surface albedo parameterization. The simulation implemented with a dynamic surface albedo parameterization was run from present time and backwards to address the importance of the initial state of the sea ice cover. The annual mean sea ice thickness from this simulation (orange curve) reveals a hysteresis of ∼1000 years. The annual mean insolation at 80°N shown with a stippled curve is based on the algorithm presented by Berger (1978). To compare the results from different paleo-sea ice studies a scale of sea ice concentration was inferred using the approach by Jakobsson et al. (2010). This scale must be considered as highly qualitative because none of the paleo-sea ice proxies provide absolute measures of past sea ice concentrations.
The paper:
Arctic Ocean perennial sea ice breakdown during the Early Holocene Insolation Maximum
Christian Stranne, Martin Jakobsson, Göran Björk
Arctic Ocean sea ice proxies generally suggest a reduction in sea ice during parts of the early and middle Holocene (∼6000–10,000 years Before the Present) compared to present day conditions. This sea ice minimum has been attributed to the northern hemisphere Early Holocene Insolation Maximum (EHIM) associated with Earth’s orbital cycles. Here we investigate the transient effect of insolation variations during the final part of the last glaciation and the Holocene by means of continuous climate simulations with the coupled atmosphere–sea ice–ocean column model CCAM. We show that the increased insolation during EHIM has the potential to push the Arctic Ocean sea ice cover into a regime dominated by seasonal ice, i.e. ice free summers. The strong sea ice thickness response is caused by the positive sea ice albedo feedback. Studies of the GRIP ice cores and high latitude North Atlantic sediment cores show that the Bølling–Allerød period (c. 12,700–14,700 years BP) was a climatically unstable period in the northern high latitudes and we speculate that this instability may be linked to dual stability modes of the Arctic sea ice cover characterized by e.g. transitions between periods with and without perennial sea ice cover.
http://www.sciencedirect.com/science/article/pii/S0277379113004162?np=y
h/t to The Hockey Schtick
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The arctic or rather North pole is sea ice. It comes and goes, and it has reduced sunlight in winter and longer days in their summer. The Arctic circle has varying degrees of the same. But the Antarctic it has a land mass as well as fluctuating sea ice.
When trees grow on the Arctic coastline ….. you know it had to be warm, to wit:
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“Holocene Treeline History and Climate Change Across Northern Eurasia
Radiocarbon-dated macrofossils are used to document Holocene treeline history across northern Russia (including Siberia). Boreal forest development in this region commenced by 10,000 yr B.P.
Over most of Russia, forest advanced to or near the current arctic coastline between 9000 and 7000 yr B.P. and retreated to its present position by between 4000 and 3000 yr B.P. Forest establishment and retreat was roughly synchronous across most of northern Russia. Treeline advance on the Kola Peninsula, however, appears to have occurred later than in other regions.
During the period of maximum forest extension, the mean July temperatures along the northern coastline of Russia may have been 2.5° to 7.0°C warmer than modern. The development of forest and expansion of treeline likely reflects a number of complimentary environmental conditions, ”
Read abstract @ur momisugly http://www.sciencedirect.com/science/article/pii/S0033589499921233
I recall an article written by the captain of the first American nuclear submarine, I think it was in the late sixties. There were few places under the ice they could surface. Does anyone remember. Look what happened to those twits recently it happens in the Antarctic too.
Samuel C Cogar says:
March 25, 2014 at 10:31 am
IOW, no catastrophic consequences of 2.5 to 7.0 degrees warmer than now. Maybe a little higher sea level, but easily adapted to. And the benefits would outweigh whatever problems might arise.
Take the first C for Catastrophic out of CACA & no worries. Even fewer without the first A for Anthropogenic, meaning no basis for the second A for Alarmism. You’re just left with Climate (which always changes).
goldminor says:
March 24, 2014 at 5:40 pm
JAXA not so alarming:
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
There was a team that visited Antarctica some years ago, and their research revealed prehistoric animal bones. Well that was before the continents separated and the poles appeared. They said this proved climate change did happen. I wonder how much they were paid to produce that bit of news. LOL
@bushbunny – They HAD to have been paid by the US government. The stupidity of their studies is world renowned. 😉
Actually phil they were not American they were Danish I think. But my cousin sent me pics of a venture from the University of Cambridge, he is in the Irish Navy, (not Royal Navy) he was on the ship anyway. They anchored at some base and showed pics of floating sea ice bergs. Climate change obviously he recalled to his mum. She sent me the pics but I sent them back to keep themselves. I don’t think they were hired by the Americans? They would have picked a better boat for starters.
goldminor says:
March 24, 2014 at 5:40 pm
Antarctic sea ice is on the upswing again and is close to the +2sd line. the trend will likely cross above the +2sd line within 2 weeks.
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Antarctic sea ice just went above the +2 sd line. That only took one week. The steeper angle in the trend is noticeable. The regrowth should be rapid this year.
I recall seeing the documentary taken by an Australian of one antarctic expedition by Sir Ernest Shackleton when their ship was eventually crushed by the pack ice in Antarctica. There forward of the silent black and white movie said the Antarctic controls the climate with its converging ocean currents and ice coverage. Being mainly a large land mass as well as sea ice. Don’t you remember at school, they had us repeat in rote the continents? Ending up with the Arctic is not a continent. But Antarctica is. If 12 year olds know this why these dumb asses ignoring sea ice comes and goes.