THIS POST IS A SIMPLIFIED SUMMARY OF THE TEMPERATURE CYCLES OF THE HOLOCENE FOUND IN THE HOLOCENE CLIMATE ATLAS PREPARED BY HEINZ WANNER AND STEFAN RITZ. THE FULL TEXT OF THE SOURCE DOCUMENT CAN BE FOUND ONLINE IF YOU GOOGLE “HOLOCENE CLIMATE ATLAS”. IT IS ALSO PROVIDED HERE AS A PDF DOCUMENT THAT CAN BE DOWNLOADED BY CLICKING ON THE BLACK “DOWNLOAD” SIGN BELOW. Warning clicking on the Download link will cause a large pdf file to be downloaded to your device. I mean LARGE! It is provided by the University of Bern Center for Climate Change Research. LINK: https://www.oeschger.unibe.ch/

THIS work BY THE UNIVERSITY OF BERN WAS REPORTED BY NBC NEWS AND AVERTISED AS “Climate scientists drive stake through heart of skeptics’ argument. New research shows that the recent rise in global temperatures is unlike anything seen on Earth during the past 2,000 years. LINK TO THE NBC REPORT: https://www.nbcnews.com/mach/science/climate-scientists-drive-stake-through-heart-skeptics-argument-ncna1033646 .

BELOW WE PRESENT A SAMPLE OF THE TEMPERATURE CHARTS FOUND IN THE HOLOCENE CLIMATE ATLAS ALONG WITH BRIEF SUMMARY OF THE TEMPERATURE CYCLES PRESENTED.

IMAGE#1: 60.83, 15.83

DATA TAKEN AT 60.83 LATITUDE AND 15.83 LONGITUDE

The top frame shows temperatures at three different time scales. The jagged light grey line traces Holocene temperatures. The smooth and darker grey line shows these temperatures at a 500-year time scale. The red line is the same temperature curve at a 3000-year time scale meaning. What we see at this global location (60.82,15.83) is that at a 3000-year time scale the Holocene warmed at this location for 4,000 years from 10,000 years ago to 6,000 years ago and has been cooling since then perhaps with a 1000-year flat period from 4000 to 3000 years ago. The bottom frame displays the 500-year time scale temperature data as a departure from the Holocene mean with hotter than average colored red and colder than average colored blue. At this location on the globe, he Little Ice Age that preceded the current warm period shows up only as a small blue blip towards the end of the time series significantly less intense than the earlier cooling periods shown.

IMAGE#2 (68.37: 18.7)

IF WE MOVE UP 8 AND OVER 3 in the earth’s coordinates FROM IMAGE#1 WE HIT A SLIGHTLY DIFFERENT POINT ON THE GLOBE AND YET WE FIND THAT THE HOLOCENE CLIMATE PATTERN HAS CHANGED DRAMATICALLY. THE 3,000-YEAR MEAN TEMPERATURE STEADLY DECLINES UNTIL ABOUT 2,500 YEARS AGO AND THE RISES GENTLY AT A DECLINING RATE OF RISE FLATENNING OUT AT THE END.

IN THIS FASHION WANNER AND RITZ PRESENT THE ANALYSIS FOR DIFFERENT COORDINATES AROUND THE GLOBE. THESE IMAGES DEMONSTRATE THE ESSENTIAL THESIS OF THE WORK OF WANNER ETAL AT OF THE UNIVERSITY OF BERN. THE WANNER THESIS IS THAT THE PALEO CLIMATE OF THE HOLOCENE THAT SHOWS SIGNIFICANT WARMING AND COOLING CYCLES CANNOT BE USED IN SKEPTICAL ARGUMENTS AGAINST ANTHROPOGENIC GLOBAL WARMING AND CLIMATE CHANGE BECAUSE THESE DATA ARE NOT GLOBALLY HOMOGENIOUS CLIMATE PATTERNS. THEY ARE LOCALIZED. THEY DO NOT HAVE A GLOBAL INTERPRETATION AND THEREFORE THEY DO NOT HAVE THE CORRESPONDENCE TO AGW CLIMATE CHANGE THAT HAS BEEN ASSUMED AND USED BY SKEPTICS OF AGW CLIMATE CHANGE.

THIS IS THE ESSENTIAL ARGUMENT IN THE WANNER & RITZ WORK PRESENTED ONLINE AS A HOLOCENE CLIMATE ATLAS WITH THE WORLD ATLAS DENOTING THE IDEA OF A GEOGRAPHICAL STUDY OF PALEO CLIMATE DATA.

IN A NATURE ARTICLE, FELLOW CLIMATE SCIENTIST SCOTT ST GEORGE PROVIDES A MORE DETAILED EXPLANATION OF THE GEOGRPAHICAL NON-UNIFORMITY ARGUMENT AGAINST THE PRACTICE IN CLIMATE CHANGE SKEPTICISM OF COMPARING THE CURRENT WARMING EVENT TO HOLOCENE PALEO DATA. THE ARGUMENT AGAINST THAT PRACTICE IS THAT THE CURRENT WARMING IS GLOBAL WHEREAS THE HOLOCENE CLIMATE EVENTS TO WHICH IT IS OFTEN COMPARED ARE “NOT GLOBALLY COHERENT”. THEREFORE, THESE COMPARISONS DO NOT CONTAIN USEFUL INFORMATION.

THE FINDING OF THE HOLOCENE CLIMATE ATLAS IS SUMMARIZED IN A NATURE ARTICLE BY SCOTT ST GEORGE. LINK: https://www.nature.com/articles/d41586-019-02179-2

The history of Earth’s climate is punctuated by a succession of named intervals associated with prolonged shifts to warmer, colder, wetter or drier conditions. During the Common Era (the past 2,000 years), the two best-known such climate epochs are the Little Ice Age and the Medieval Climate Anomaly (also called the Medieval Warm Period). The former was a cool period that extended from the sixteenth to the late nineteenth centuries; the latter was a warm, dry period between AD 950 and 1250. Many assume that these intervals had a global impact. But in a paper in Nature and in a companion paper in Nature Geoscience4, Neukom et al. demonstrate that these and earlier climate epochs in the Common Era were much smaller in scope than the near-global reach of current human-induced warming.

Unusually warm weather between the tenth and thirteenth centuries is often cited as one factor that enabled the short-lived Norse colonization of the Americas. Shown here are reconstructed buildings at a site called L’Anse aux Meadows in Newfoundland, Canada — a Norse settlement that was established in the early eleventh century. Neukom et al.3,4 have constructed a set of pre-industrial temperature estimates, and find that past warm and cold periods were much less geographically widespread than is the current warming caused by humans.

Because thermometer measurements of air near Earth’s surface before AD 1850 are not widely available, we rely on archives of proxy data to extend our perspective on climate further back in time. Trees in cold Arctic or alpine forests have annual rings with widths and wood densities that reflect year-to-year variations in summer temperature. And because the chemical make-up of seawater depends on its temperature, massive corals build endoskeletons that contain a permanent geochemical record of past warming and cooling6. Other geological and biological archives that encode temperature information into their physical structure, substance or geochemical composition include lake sediments, glacier ice and bivalve molluscs (such as clams, oysters and mussels). Such archives likewise serve as ‘palaeothermometers’ that record temperatures stretching hundreds or thousands of years into the past.

Neukom et al. weave all of this evidence into a detailed global portrait of surface temperatures that spans the past two millennia. The foundation for their work is provided by the PAGES 2k proxy temperature database7. This community-sourced compilation includes nearly 700 records from trees, ice, sediment, corals, cave deposits, documentary evidence and other archives. Partly because the database incorporates so much information, the authors can chart the geographical extent of unusually warm or cold conditions across the entire planet by year.

There is no evidence for globally coherent warm and cold periods in the preindustrial Common Era.
The team reports in Nature that, although the Little Ice Age was the coldest epoch of the past millennium, the timing of the lowest temperatures varied from place to place. Two-fifths of the planet were subjected to the coldest weather during the mid-nineteenth century, but the deepest chill occurred several centuries earlier in other regions. And even at the height of the Medieval Climate Anomaly, only 40% of Earth’s surface reached peak temperatures at the same time. Using the same metrics, global warming today is unparalleled: for 98% of the planet’s surface, the warmest period of the Common Era occurred in the late twentieth century — the authors’ analysis does not encompass the continued warming in the early twenty-first century, because many of their proxy records were collected more than two decades ago.

In 2005, palaeoclimatologists John Matthews and Keith Briffa1 cautioned against deeming the Little Ice Age an “uninterrupted, globally synchronous, cold period”. These new results certainly bolster their point of view. And we can be confident in that conclusion because Neukom et al. carried out an exhaustive set of experiments to confirm that their findings were unaffected by their choice of statistical tools to relate the proxy network to thermometer measurements.

Unfortunately, limitations inherent in the proxies themselves probably still hamper our ability to compare warm or cool intervals with each other throughout the entire Common Era. Tree-ring records, the most frequently used proxy archive in the PAGES 2k database, are sometimes unreliable in registering slow climate changes over several centuries or longer8. Moreover, some other proxies — particularly records from marine and lake sediments — exaggerate variations at multidecadal or centennial timescales9,10. It is still an open question how well we can compare global temperatures across this entire 2,000-year span.

Read the paper: Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era. We can be more certain of how and why Earth warms or cools over decadal and multidecadal timescales. In their companion paper in Nature Geoscience, Neukom et al. show that, in the pre-industrial period (AD 1300–1800), major volcanic eruptions (or the lack of such eruptions) were the main factor behind cold (or warm) swings that persisted for several decades. Shifts in greenhouse-gas concentrations had a smaller, but still detectable, imprint. The team found no indication that variations in the Sun’s radiation output affected mean global temperature over the same time frames.

In general, physics-based climate models accurately reproduce proxy estimates of our climate’s history over the past millennium. However, these models exaggerate the degree of cooling caused by the two largest volcanic eruptions of the Common Era: the AD 1257 Samalas and the AD 1815 Tambora eruptions in Indonesia11. This discrepancy implies that we cannot be sure how bitter a chill would follow a similar eruption in the future.

The familiar maxim that the climate is always changing is certainly true. But even when we push our perspective back to the earliest days of the Roman Empire, we cannot discern any event that is remotely equivalent — either in degree or extent — to the warming over the past few decades. Today’s climate stands apart in its torrid global synchrony. {END OF COMMENTS BY SCOTT ST. GEORGE ON THE WORK OF WANNER AND RITZ}

YET, AS EXPLAINED IN A RELATED POST BY CLIMATE SCIENTIST KATHARINE HAYHOE OF TEXAS TECH UNIVERSITY, GLOBAL CLIMATE CANNOT BE LOCALIZED AND CANNOT BE UNDERTOOD IN LOCAL TERMS BECAUSE IT CAN ONLY BE UNDERSTOOD AS THE GLOBAL AVERAGE OF LOCAL CLIMATE: LINK: https://tambonthongchai.com/2020/12/25/what-if-science/ .

THE “INTERNAL CLIMATE VARIABILITY” ISSUE DESCRIBED IN ANOTHER RELATED POST: LINK: https://tambonthongchai.com/2020/07/16/the-internal-variability-issue/ PROVIDES MORE DETAILS FOR THE ARGUMENTS MADE BY KATHARINE HAYHOE. The internal variability issue extends the Hayhoe argument even further. The internal climate variability issue implies that localized climate cannot be understood as global warming but that global warming must be understood as the average of all localized internal climate variability.

THEREFORE, THAT PALEO CLIMATE RECORD OF THE HOLOCENE CONTAINS INTERNAL CLIMATE VARIABILITY DOES NOT MEAN THAT THE CURRENT WARMING PERIOD CANNOT BE UNDERSTOOD IN THE CONTEXT OF THE PALEO PROXY DATA FOR THE HOLOCENE. A BIBLIOGRAPHY OF THE WARMING AND COOLING CYCLES OF THE HOLOCENE IS PRESENTED IN YET ANOTHER RELATED POST: https://tambonthongchai.com/2019/06/11/chaoticholocene/ . Pictured below is Andrew Mayewski, one of the authors in that bibliography.