The Holocene Climate Optimum: A Bibliography | Thongchai Thailand. The ice of the last ice age began to melt about 20 KYBP (thousand years before the present) but that process was interrupted by the Younger Dryas about 12 KYBP with a return to icy conditions. After the end of the Younger Dryas, it returned to a warming trend. This warming trend got us to the fine weather conditions that made the Neolithic Revolution possible in which the hunter-gatherer humans settled and started farming, building homes, and forming communities.
This period, usually marked as between 9 and 5 KYBP is known as the Holocene Climate Optimum (HCO). An extensive body of research exists on the study of climate during this period. Some surprising details are found in these papers, particularly the older ones prior to the time when all climate research had to relate to AGW one way or another. Presented below are a selection of papers on the HCO. 1978: Sarnthein, Michael. The Anomalies in Temperature Anomalies The Greenhouse Effect of Atmospheric CO2 Antarctic Sea Ice: 1979-2018. The Holocene Climate Optimum. By Paul Homewood Booker commented the other day how one scientist claimed last week that we now have “the highest temperatures on Earth since the last ice age”.
The BBC failed to even challenge this statement. This certainly is not the first time I have heard claims (presented as fact) to this effect. We have already seen concerted attempts to disappear the MWP, so it is time to reclaim the Holocene Optimum (so named for good reason), which is generally accepted to have run from about 9000 to 5000 years ago Obviously we had no thermometers around in those days, so nobody knows what the average temperature of the Earth was then. There again, nobody really knows now either. But there is plentiful evidence that many places were significantly warmer than now. 1) Greenland One of the clearest pictures we have is from ice cores in Greenland: a) Ribeiro et al. b) Kelly & Long 2) Arctic a) Levac et al. Insights - What Drives Climate on Earth in the Long Run. Abstract The pattern grid consists of vertical lines for recurring Earth orbital periodicities, and of three more lines, which are horizontally inclined lines, i.e., the Milankovitch line and the upper and the lower orbital oscillation (EOO) boundary line.
The Milankovitch line remained horizontal for six preceding BC millennia, now slowly turning into a descent towards the next glacial. The grid clearly identifies the swivel time span, required for the horizontal Milankovitch line to change into an inclined Milankovitch line with a descent trend of 0.47°C per millennium. The descending secular trend commences right within the first four AD centuries, known as RWP (Roman Warm Period). The RWP consists of twin temperature peaks, one at 115 BC and the second peak at 435 AD. Global versus Greenland Holocene Temperatures. By Andy May Last week, I posted a global temperature reconstruction based mostly on Marcott, et al. 2013 proxies. The post can be found here. In the comments on the Wattsupwiththat post there was considerable discussion about the difference between my Northern Hemisphere mid-latitude (30°N to 60°N) and the GISP2 Richard Alley central Greenland temperature reconstruction (see here for the reference and data).
See the comments by Dr. Don Easterbrook and Joachim Seifert (weltklima) here and here, as well as their earlier comments. Richard Alley’s (Richard Alley, 2000) central Greenland reconstruction has become the de facto standard reconstruction and is displayed often in papers and posts. And, truth be told, I’ve often used it. Figure 1 Alley’s reconstruction is based upon trapped air in ice cores taken from central Greenland and his proxies are calibrated to air temperatures on land. Figure 2 Figure 3 Vinther’s record shows a more prominent HCO than ours, more detail and a deeper LIA. Heat Waves: Historical, not Hysterical Context. Rannoch Moor, Scotland Alarms are being sounded about heat waves in the Northern Hemisphere, noting heat waves in Eastern Canada and US, wildfires in N.
Sweden and Siberia. The recent UK lawsuit featured the advocate claiming the Arctic is burning, so global warming is no longer in doubt. Thus UK needs to up its carbon reduction targets. The High Court disagreed. What is going on? Concurrent Warming and Cooling This post highlights recent interesting findings regarding past climate change in NH, Scotland in particular. The lead researcher is Gordon Bromley, and the field work was done on site of the last ice fields on the highlands of Scotland. 14C dating was used to estimate time of glacial events such as vegetation colonizing these places. The shells were found in glacial deposits, and one in particular was dated as being the first organic matter to colonise the newly ice-free landscape, helping to provide a minimum age for the glacial advance.
Abstract Plain Language Summary Fig. 1. Global Temps Plunged 1-2°C Within Decades 8.2 K and 4.2 K Years Ago – And It Could Happen Again. In direct contrast with CO2-centric climate modeling, extensive paleoclimate evidence affirms that the Holocene climate has been far more variable in the past 12,000 years than during the relatively quiescent period we’ve enjoyed since the mid-19th century. In the absence of CO2 concentration changes or human interference, abrupt global cooling episodes led to agricultural collapse, famines, and the extirpation of ancient civilizations. These naturally-occurring climate events are likely to recur…and we will be powerless to intervene. Between 1860 and 2014, CO2 concentrations rose dramatically (from 285 parts per million to 400 ppm), and yet global temperatures have fortunately remained relatively stable, with an overall per-decade change rate of just 0.05°C.
Image Source: Zhu et al., 2017 The 8.2 ka Abrupt Cooling/Warming Event Kobashi et al., 2007 “A large number of paleoclimatic records over a hemispheric area show a large and abrupt climate change around 8200 years BP. And then they came for The Holocene: New paper suggests “removing the Holocene Epoch from the geologic timescale” | Watts Up With That? Is there any limit to the extremes some climate propagandists will go? The Climategate team removed the warm 1940’s “blip”, erased the Medieval Warm Period, Hid the Decline, and tortured temperature & sea level data until it confessed, but a paper published Monday in Earth’s Future could take the cake by suggesting removal of “the Holocene Epoch from the geologic timescale” and replacing it with the fictitious, scary-sounding “geologic” timescale “The Anthropocene.” Excerpt from “Hello Anthropocene, Goodbye Holocene”: : “As the official timescale keepers deliberate the introduction of the Anthropocene and a Holocene-Anthropocene boundary (Anthropocene Working Group of the Subcommission on Quaternary Stratigraphy; Zalasiewicz, J., M. et al., 2010; ), they should consider the alternative: Remove the Holocene Epoch from the geologic timescale.
The journal titled The Holocene probably isn’t going to like this idea. Holocene Thermal Optimum | Andy May Petrophysicist. By Andy May The Holocene Thermal Maximum, also called the Holocene Thermal Optimum, occurred at different times in different parts of the world but generally between 10,000 BP and 4,000 BP. I use BP to indicate years before 2000. The world ocean was probably 0.7°C warmer than today 8,000 BP.
This is remarkable because the ocean heat capacity is 1000 times larger than the atmosphere’s according to the IPCC and NOAA. Simple high school physics is all that is required to verify this, the calculation is described here. The second conclusion is that there is no magic 2°C tipping point. Read more #holocene, #holocene-thermal-maximum, #holocene-thermal-optimum, #ocean-heat-content. “We Live In The Coldest Period Of The Last 10.000 Years" | NOT A LOT OF PEOPLE KNOW THAT. Miller et al.’s “Unprecedented Recent Summer Warmth in Arctic Canada”: Bad assumptions, poor logic, and contrary to other evidence of Arctic temperatures. | Watts Up With That?
Dr. Don J. Easterbrook, Western Washington University, Bellingham, WA Miller et al. radiocarbon dated 145 rooted tundra plants revealed by receding ice in the eastern Canadian Arctic and contend that it constitutes the first direct evidence that recent temperatures now exceed those of any century in the Holocene, including the Holocene Thermal Maximum. They further contend that (1) average summer temperatures of the last ~100 years were higher than any century in the past 44,000 years and suggest that present temperatures have not been exceeded in the past ~120,000 years, at or near the end of the last interglaciation, and (2) they conclude that this ‘unprecedented’ warming was caused by anthropogenic increases in greenhouse gases.
Figure 1 A. Assertions and assumptions by Miller et al. The assumptions in these statements are: a. B. Figure 2. C. Figure 3. Figure 4. This totally destroys their argument for no temperature as warm as the present since the Eemian Interglacial. Figure 5. A Holocene Temperature Reconstruction Part 1: the Antarctic. By Andy May The only recent attempt at a global Holocene temperature reconstruction available today is the one by Marcott, et al. (2013), the paper abstract can be viewed here. His reconstruction is shown in figure 1. Figure 1 The Y axis is a reconstructed global temperature anomaly from the 1961-1990 mean. “Years BP” are years before 1950. The reconstruction in figure 1 goes from the present (1950) on the left to nearly the beginning of the Holocene about 11,700 years ago on the right.
The reconstruction shows an abrupt warming in the last 100 years (see the left side of figure 1). “We showed that no temperature variability is preserved in our reconstruction at cycles shorter than 300 years, 50% is preserved at 1000-year time scales, and nearly all is preserved at 2000-year periods and longer. The problem is that 300 years is a very long time. This is a new look at Marcott’s proxies. Proxy selection Climate changes over the Holocene occur, in large part, by latitude. Figure 2 Table 1. A Holocene Temperature Reconstruction Part 2: More reconstructions. By Andy May In the last post (see here) we introduced a new Holocene temperature reconstruction for Antarctica using some of the Marcott, et al. (2013) proxies. In this post, we will present two more reconstructions, one for the Southern Hemisphere mid-latitudes (60°S to 30°S) and another for the tropics (30°S to 30°N). The next post will present the Northern Hemisphere mid-latitudes (30°N to 60°N) and the Arctic (60°N to the North Pole).
As we did for the Antarctic, we will examine each proxy and reject any that have an average time step greater than 130 years or if it does not cover at least part of the Little Ice Age (LIA) and the Holocene Climatic Optimum (HCO). We are looking for coverage from 9000 BP to 500 BP or very close to these values. Only simple statistical techniques that are easy to explain will be used. Southern Hemisphere mid-latitudes Our reconstruction for this region is shown in figure 1.
Figure 1 Figure 2 Figure 3 Figure 4 Figure 5, source (Nielsen, et al., 2004) Figure 7. A Holocene Temperature Reconstruction Part 3: The NH and Arctic. By Andy May In the last post (see here) we reexamined the Marcott, et al. (2013) proxies for the Southern Hemisphere mid-latitudes and the tropics. In this post, we will present two more reconstructions using their proxies, these are for the Northern Hemisphere mid-latitudes (30°N to 60°N) and for the Arctic region (60°N to 90°N).
These two regions contain over half of the proxies used in this study. The next post will present a global area-weighted composite temperature reconstruction. As we did in the previous two posts, we will examine each proxy and reject any that have an average time step greater than 130 years or if it does not cover at least part of the Little Ice Age (LIA) and the Holocene Climatic Optimum (HCO).
We are looking for coverage from 9000 BP to 500 BP or very close to these values. Only simple statistical techniques that are easy to explain will be used. Northern hemisphere mid-latitudes Figure 1A, all proxies that meet the basic criteria (resolution and span) Figure 2. A Holocene Temperature Reconstruction Part 4: The global reconstruction. By Andy May In previous posts (here, here and here), we have shown reconstructions for the Antarctic, Southern Hemisphere mid-latitudes, the tropics, the Northern Hemisphere mid-latitudes, and the Arctic.
Here we combine them into a simple global temperature reconstruction. The five regional reconstructions are shown in figure 1. The R code to map the proxy locations, the references and metadata for the proxies, and the global reconstruction spreadsheet can be downloaded here. For a description of the proxies and methods used, see part 1, here. Figure 1A, all proxies except TN057-17 on the Antarctic Polar Front Figure 1B, the proxies used for the reconstructions It is interesting that the Northern Hemisphere is the odd reconstruction. Figure 2 (Source: Javier, see his post for a detailed explanation of the figure.) The Southern Hemisphere is also a bit anomalous, with a dip in the period of the HCO, corresponding with a dip in winter insolation in the Southern Hemisphere.
Table 1 Conclusions. New Treeline, Permafrost Evidence Strongly Affirms The Mid-Holocene Was 3°C Warmer Than Today. Newly published macrofossil discoveries from 4 papers strongly suggest that modern warmth may still be about 3°C colder than nearly all of the last 10,000 years. Image Source: Leunda et al. (2018) 1. Permafrost is still present today in a region that was permafrost-free throughout the Holocene (until the onset of the Little Ice Age) According to data from a new study (Sannel et al., 2018), subarctic Northern Sweden has yet to rise out of the range of frigid, permafrost-friendly temperatures coeval with of the Little Ice Age (roughly 1400 to 1900 AD). Permafrost still exists today in regions where there was no recorded permafrost during nearly all of the Holocene, when temperatures were too warm (3°C higher than today) for permafrost to form.
These findings strongly suggest that modern warmth is nothing unusual, unprecedented, or even remarkable. Sannel et al., 2018 Image Source: Sannel et al., 2018 2. Badino et al., 2018 Images Source: Badino et al., 2018 3. Leunda et al., 2018 4. Kullman, 2018. The Discovery Of Tree Trunks Under Glaciers 600 Meters Atop Today’s Treeline Date To The Last ICE AGE. By Kenneth Richard on 24. December 2018 Image Source: Ganyushkin et al., 2018 Between 60 and 40 thousand years ago, during the middle of the last glacial, atmospheric CO2 levels hovered around 200 ppm – half of today’s concentration.
Tree remains dated to this period have been discovered 600-700 meters atop the modern treeline in the Russian Altai mountains. This suggests surface air temperatures were between 2°C and 3°C warmer than today during this glacial period. Tree trunks dating to the Early Holocene (between 10.6 and 6.2 thousand years ago) have been found about 350 meters higher than the modern treeline edge. None of this paleoclimate treeline or temperature evidence correlates with a CO2-driven climate. Ganyushkin et al., 2018 Full Paper “Samples of wood having an age of 10.6–6.2 cal ka BP were [the Early Holocene] found about 350 m higher than the present treeline.
New Science Affirms Arctic Region Was 6°C Warmer Than Now 9000 Years Ago, When CO2 Levels Were ‘Safe’ Inconvenient: new treeline paper suggests temperatures were warmer 9000 years ago. New Scientific Evidence Robustly Affirms Scandinavian Temperatures Were 3-4°C Warmer 9000 Years Ago. Higher-Than-Present Relict Treelines in the Western United States. Receding Swiss glaciers incoveniently reveal 4000 year old forests – and make it clear that glacier retreat is nothing new | Watts Up With That?
New peer reviewed paper says "there appear to have been periods of ice free summers in the central Arctic Ocean" in the early Holocene, about 10-11,000 years ago. Holocene Treeline History and Climate Change Across Northern Eurasia. Leading German Geologist Calls Notion Of “Climate Tipping Points” Scientific Hype By Opportunistic Scientists.