Guest "Geological Perspective" by David Middleton
This is kind of a continuation of yesterday's post: Where's the Sea Ice? 3 Reasons Why The Arctic Freeze Is Unusually Late And Why It's Important
With sunset and the onset of polar darkness, the Arctic Ocean would normally be encrusted with sea ice along the Siberian coast. But this year the water is still open.
Mark Serreze, University of Colorado Boulder
What a difference a day can make! Looks like it's slowly crusting over:
Figure 0. Daily sea ice extent map, October 29, 2020 (NSIDC)
"Where's the sea ice?"
Figure 1. Arctic sea ice extent, September 2020 (NSIDC)
September is the most current monthly ice expansion map available. The annual minimum also usually occurs in September. The magenta outline represents the mean ice edge in September 1981 to 2010. The minimum Arctic sea ice extent generally occurs in September. At 3.9 million km2, this is the second lowest September in its history. A record that goes back to 1979.
Figure 2. Average Arctic sea ice extent in September (1979-2020). (NSIDC)
Given that this is such a short record length, is an annual minimum of 3 to 5 million km2 particularly anomalous? Or are the annual minima of 6-7 million km2 from 1979-2000 really the anomaly? We really have a context and a scale here.
Geologists are great in terms of context and scope. When a geologist takes a picture with a person in it, the person is only to scale. Since quarters, lens caps, and rock hammers are way too small to scale 3.9 million square kilometers of sea ice, and 42 years is way too short to be contextualized, we need something bigger with a longer span of time.
We can use the Arctic Ocean to provide scaling:
The Arctic Ocean is the smallest of the five oceans in the world (after the Pacific, Atlantic, Indian and Southern Oceans). The Northwest Passage (USA and Canada) and the North Sea Route (Norway and Russia) are two important seasonal waterways. In recent years, the polar ice pack has decreased in summer, which allows for increased navigation and the possibility of future sovereignty and shipping disputes between the six countries bordering the Arctic Ocean (Canada, Denmark (Greenland), Iceland, Norway, Russia, USA) elevated. .
Total: 14,056 million km²
CIA World Fact Book
Figure 3. The "smallest of the five oceans" doesn't look so small from above. (NSIDC)
3.9 million km2 make up 28% of the area of the Arctic Ocean.
Figure 4. Arctic sea ice extent as a percentage of the surface area of the Arctic Ocean. (Data from NSIDC)
28% of the Arctic Ocean is slightly below the “normal” climatic range of 35% to 58% for the annual minimum. That doesn't sound like a death spiral to me. Remember that the satellite shot started right here:
Figure 5. Science News March 1, 1975 The climate in the 1970s is normal.
42 years is far too short for a record length to determine how the climate should be “normal”. It doesn't provide a meaningful context. Fortunately, prior to the satellite record, efforts were made to reconstruct the extent of the sea ice.
Figure 6. Arctic sea ice in front of satellites. “Sea ice maps of the Arctic Ocean show that ice extent has declined since at least the 1950s. Credit: NSIDC and the UK Hadley Center (NSIDC)
Almost 70 years is better than 42 years … but still insufficient for the context.
To look back in time, researchers combine data and records from indirect sources known as proxy records. The researchers looked at shipping maps from the 1950s, which showed sea ice conditions. The data obtained from these records, known as the Hadley dataset, shows that Arctic sea ice has been declining since at least the mid-1950s. Ship records date back to the 18th century but do not provide full coverage of the Arctic Ocean. Taken together, however, these records show that the current decline has been unprecedented over the past several hundred years.
"The current decline is unprecedented in the last hundred years," claims a big, fat No Schist Sherlock. The earth has been warmed by the coldest climate of the Holocene (the Little Ice Age) for 400-500 years.
Kinnard et al., 2008, put together a reconstruction from 1870 …
Figure 7a. Maximum and minimum sea ice extent, 1870-2003 (Kinnard et al., 2008).
Strangely enough, Kinnard Minima gives about 1 million km2 more ice surface than the satellite data.
Figure 7b. Maximum and minimum sea ice extent, 1870-2003 (Kinnard et al., 2008) and NSICD September trend, 1979-2019.
Now we see a hint of context. The decline in sea ice began when the extent of the Arctic sea ice was unusually large. Let's relate the context to scaling:
Figure 8. The more scope and competition we apply, the flatter the “death spiral” becomes. So you might think that modern climate "scientists" are purposely ignoring context and size … or that they never learned the concept.
After the reconstruction of Kinnard, the Arctic Ocean still has about half as much summer sea ice as at the end of the Neoglacition, the maximum amount of Holocene glaciers and sea ice. Why is that a bad thing? The Arctic sea ice has been withdrawing from this "normal" climate since 1870 …
Figure 9. Yes, it's just a movie. (Quartz)
Kinnard also showed a neat card:
Figure 10. Probability of sea ice occurrence (1870-2003) A = maximum, B = minimum. (Kinnard et al., 2008)
Panel B is the annual minimum. Kinnard et al. Claimed that the gray area was 100% covered with summer sea ice from 1870 to 2003. Let's overlay the 2020 NSIDC card in panel B:
Figure 11. The black area with a yellow outline represents the ice-free area in 2020, which was said to be 100% covered in September 1870-2003. I think you could include the little donut hole north of the North Slope.
Okay … So the annual sea ice minimum is now significantly lower than it was from the Little Ice Age to "The Ice Age is Coming" … How is that a bad thing? Besides, we still don't know what the real anomaly is: the most recent annual minima of 3 to 5 million km2 or the annual minima of 6 to 10 million km2 from 1870 to 2003? The minimal summer sea ice covered around twice as much area in 90% of the last 150 years … So what? Is 150 Years a Long Time? Is it relevant to the Holocene? Is it one of the "Goldilocks Conditions" of the Holocene? We clearly need more context. We need a geological perspective.
A geological perspective
Stein et al., 2017 (H / T tty) provided a great description of a fairly novel method for determining the extent of paleo sea ice.
In a seminal study by Belt et al. (2007) the ability to (semi-) quantitative reconstruction of paleo-sea ice distributions was significantly improved by a biomarker approach based on the determination of a highly branched isoprenoid (HBI) with 25 carbons (C25-HBI-monoene = IP25). This biomarker is only biosynthesized by certain diatoms in the arctic sea ice (Brown et al., 2014) and appears to be a specific, sensitive and stable proxy for arctic sea ice in sedimentary sections that represent the late Miocene until recently (Stein et al., 2014) ., 2012, 2016; Belt and Müller, 2013; Stein and Fahl, 2013; Knies et al., 2014). The presence of IP25 in the sediments studied is direct evidence of the presence of sea ice.
For more semi-quantitative estimates of current and past sea ice cover, Müller et al. (2011) combined the sea ice proxy IP25 and phytoplankton biomarkers in a phytoplankton IP25 index, the so-called "PIP25 index":
PIP25 = (IP25) / ((IP25) + ((phytoplankton marker) x c))
with c is the mean IP25 concentration / mean phytoplankton biomarker concentration for a given dataset or core.
Stein et al., 2017
This schematic diagram from Belt et al., 2013 relates the PIP25 index to sea ice conditions:
Figure 12. Relationship of sea ice conditions to the PIP25 index (Belt ea al., 2013). Click to enlarge.
In general, the PIP25 index correlates with sea ice extent as follows:
> 0.7 = extensive, multi-year (year-round) ice cover 0.5-0.7 = seasonal ice cover / ice edge location (mostly ice-free in summer) 0.1-0.3 = reduced ice cover (only winter ice) <0.1 = ice – Free all year round
Here is an example from the Chukchi Sea:
Figure 13. Sediment core ARA2B-1A. The current state of sea ice at this location is the seasonal ice extent (PIP25 0.5 to 0.7). (Stein et al., 2017)
Note that the sea ice at this location has only been seasonal for about 1,600 years. Previously it was considered reduced, only partially covered in winter. For about 85% of the Holocene, it was much lower than it is today.
Stein et al. In 2017, a cross-section of PIP25 curves across the Arctic from the Fram Strait to the Chukchi Sea was created.
Figure 14. Location plan of the sediment cores and cross-section A-A “. (modified from Stein et al., 2017)
All four core locations currently reflect seasonal ice cover / ice edge situations (PIP25 index 0.5-0.7), with Fram Strait being an ice edge situation and the other three reflecting seasonal ice cover situations.
Figure 15. Cross section A-A “. High and low refer to solar radiation in the northern hemisphere.
Two key takeaways:
The maximum Holocene sea ice extent occurred in the last 500-1000 years at every location. The current sea ice extent is higher than 50% to 85% of the Holocene at all locations.
While this doesn't tell us how large the sea ice extent was in millions of km2, it does tell us that the modern sea ice extent is larger than in most of the Holocene. It also shows us that the areas of current seasonal sea ice extent have been mostly seasonal or reduced in the past 5,000 years and have been ice-free or nearly ice-free in the past 3,000 years or so. Here is the Kinnard diagram, drawn to the same horizontal scale as the stone cross-section:
Figure 16. 150 years is not a context.
Where is the sea ice?
Right where it was for most of the Holocene … and that's a good thing. If the sea ice had expanded from 8,000 years ago to the middle of the 19th century, this would still be the climate crisis du jour:
The next time you get gasoline at an Exxon station, thank you for it:
"EVERY DAY HUMBLE DELIVERS ENOUGH ENERGY TO MELT 7 MILLION TONS OF GLACIER!" Exxon knew it in 1962 !!!Humble Oil eventually became ExxonMobil
Humble Oil was founded in Humble, Texas in 1911. In 1919 Standard Oil of New Jersey acquired a 50% stake in Humble Oil. They acquired the other 50% in 1959. All affiliated companies were merged to form Exxon Corporation in 1973, and Exxon finally merged in 1999 with Mobil Oil Corporation, a descendant of New York's Standard Oil Company, to form ExxonMobil (Texas State Historical Association). .
Here is your key oil industry information for the day:
The development of the standard oil (The Visual Capitalist)
In just three more mergers, Standard Oil could be put back together! That's fucking great!
Belt S.T., Müller J. "The Arctic Sea Ice Biomarker IP25: An Overview of Current Understanding, Recommendations for Future Research, and Applications in Paleo Sea Ice Reconstruction". (2013) Quaternary Science Reviews, 79, pp. 9-25. Belt_2013
Fetterer, F., K. Knowles, W.N. Meier, M. Savoie and A.K. Wind nail. 2017, updated daily. Sea ice index, version 3. (sea ice monthly by year). Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: https://doi.org/10.7265/N5K072F8. (Accessed October 16, 2019).
Kinnard, C., Zdanowicz, C. M., Koerner, R., Fisher, D. A., 2008. "A Changing Arctic Seasonal Ice Zone – Observations from 1870-2003 and Possible Oceanographic Consequences". 35, L02507. Kinnard_2008
Stein, R., Fahl, K., Schade, I., Manerung, A., Wassmuth, S., Niessen, F. and Nam, S. (2017), Holocene variability in sea ice cover, primary production and the Pacific water influx and climate change in the Chukchi and East Siberian Seas (Arctic Ocean). J. Quaternary Sci., 32: 362-362; 379. doi: 10.1002 / jqs.2929 stein2017