Archives par mot-clé : MWP

climate-debate

Plus ça change, plus ç’est la même chose

by C. Monckton of Brenchley, Apr 23, 2025 in WUWT

Here in England this spring, there was dry, sunny weather through most of March, followed by gentle showers in April. And here is the opening couplet of Geoffrey Chaucer’s Tales of Caunterbury, written more than six centuries ago in 1387:

From the medieval climate optimum to the modern climate optimum, the weather in these islands has changed scarcely at all. The drought of March, the sweet April showers, the birdsong day and night, the bursting forth of primroses, bluebells, daffodils and other spring flowers, all are today just as Chaucer described them in the Middle Ages.

The wine-dark sea

One can even go back to Homer, in the 8th Century BC, who talked of the Mediterranean as “the wine-dark sea”. And here am I, almost three millennia later, recently recovered from a long illness caused by defective medication with no active ingredient in it, having climbed to the 1230ft summit of the Akamas peninsula in Cyprus, doing a Canute and challenging the wine-dark sea not to rise. The sea was wine-dark in Homer’s time. It is still wine-dark today.

Where, then, are the drastic changes in climate and consequent catastrophes and cataclysms so luridly predicted by the climate Communists? Where are the mass extinctions? Why is the climate much as it was in the Middle Ages? Why are ten times as many dying of cold as of heat? Why are crop yields at record highs? Why is the planet greening so fast? Continuer la lecture de Plus ça change, plus ç’est la même chose →

climate-debate

New Study: Plant Remains Embedded In A Modern Glacier Evidence A Warmer Antarctica 1000 Years Ago

by  K. Richard, Apr 21, 2025 in NoTricksZone

Leafy moss dated to the Medieval Warm Period (MWP) has been found embedded in Antarctic glacier ice that today is “permanently snow-covered” with “no evidence of meltwater.” This affirms a warmer MWP and that “the summer melt during the MWP was greater than today.”

According to a new study, moss samples with intact leaves and stems 10 to 13 mm long have been discovered embedded in glacier ice – the Boulder Clay Glacier (BCG) – in Antarctica’s Victoria Land.

The surface of this glacier is currently not undergoing melt. It is instead permanently snow-covered.

“It is also noteworthy that under current climate conditions…there is no evidence of meltwater on the BCG, and the surface of the glacier is permanently snow-covered.”

The leafy moss samples have been dated to about 1,000 years ago, which is consistent with the timing of the Medieval Warm Period.

“…an unprecedented palaeo-erosion event occurred on the surface of an Anarctic glacier (northern Victoria Land, continental Antarctica) during the Medieval Warm Period (MWP) between 900 and 989 cal BP.”

“The period between 831 and 1140 cal BP is characterized by reduced sea ice in northern Victoria Land, which is consistent with the occurrence of a brief event of warmer conditions around 1000 cal BP…”

The presence of thousand-year-old plant remains in a modern glacier strongly suggest the climate was warmer (and thus there was less glacier ice) during the Medieval Warm Period.

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climate-debate

New Study Identifies A Millennial-Scale ‘Striking’ Link Between Solar Forcing And Climate Patterns

by K. Richard, Mar 13, 2025 in NoTricksZone 

“Until now, the origin of the climate dynamics of the Central Andes during the last millennium has been speculative. On the basis of statistical evidence, we have identified solar variability as its origin.” – Schittek et al., 2025

In a new study, scientists have determined:

1) The Little Ice Age (LIA) was a global-scale cold event.

2) Southern Hemisphere (Peruvian Andes) climate (precipitation) variations are robustly linked to variations in solar activity over the last 1,000 years.

3) The modern (1900s-2000s) and Medieval Climate Anomaly climate warmth are associated with reduced rainfall, and the LIA colder temperatures are associated with more precipitation.

“…the LIA was a global event, marked by advance of glaciers worldwide.”

“Solar irradiation is the primary driver for all climate circulation processes on Earth. Evidence for a direct solar influence on the Earth’s climate has been growing.”

“Our study reveals evidence that precipitation changes in the south-eastern Peruvian Andes are linked to variations in solar activity during the LIA [Little Ice Age].”

“Several studies attribute climate cooling during the LIA to solar forcing, particularly during the Wolf, Spörer, Maunder, and Dalton Minima.”

“The position of the ITCZ [Intertropical Convergence Zone] is robustly dependent on the interhemispheric temperature gradient triggered by solar forcing.”

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climate-debate

Medieval Warm Period Undeniable, Pronounced In Antarctica And Poland, 2 New Studies Show

by P. Gosselin, Mar 9, 2025 in NoTricksZone 

Natural cycles drive our climate

The latest video by the Germany-based European Institute for Climate and Energy (EIKE) looks at CO2 and the troublesome Medieval Warm Period, which has long been a thorn for climate alarmists.

Hat-tip: Klimanachrichten

The Medieval Warm Period, the natural warm phase between 700 and 1300 AD, cannot be reproduced climate models because the simulations react primarily to CO2. Back then CO2 was not a factor because its concentration level in the atmosphere was pretty much constant. That’s why people would rather keep the Medieval Warm Period quiet.

But the facts speak for themselves. Two studies now add further pieces to our knowledge of the medieval climate.

Antarctica

In October 2023, a paper by a team of researchers led by Zhangqin Zheng from the University of Science and Technology of China in Hefei was published in the journal Quaternary Science Reviews. It deals with historical changes in the Adélie penguin population in the Ross Sea region of Antarctica and their climatic influences.

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These natural processes are still taking place today and have by no means ended with the start of the CO2 increase.

Poland

The other study comes from Poland. The research group led by Rajmund Przybylak from Nicolaus Copernicus University in Toruń, Poland, published their work in the journal “Climate of the Past” in November 2023. The article presents current findings on climate change in Poland for the period from 1000 to 1500 AD. This period also includes the Medieval Warm Period. The scientists first studied all available quantitative climate reconstructions that have been produced for Poland in the last two decades. They also produced four new reconstructions using three dendrochronological series and an extensive database of historical source data on weather conditions. The growth of conifers in the lowlands and mountains of Poland depends on the temperatures in the cold season, especially in February and March. All available reconstructions based on dendrochronological data refer to this time of the year. Summer temperatures were reconstructed using biological proxies and documentary evidence. However, the latter are limited to the 15th century. The winter temperature was used as a proxy for the annual temperature proxies, instead of the usual use of the summer temperature.

The Medieval Warm Period probably occurred in Poland from the late 12th century to the first half of the 14th or 15th century. All analyzed quantitative reconstructions indicate that the Medieval Warm Period in Poland was comparable or even warmer than the average temperature in the period 1951-2000.

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climate-debate

Antarctica Is Colder, Icier Now Than Any Time In 5000 Years. The Last Warm Period Was 1000 Years Ago.

by K. Richard, Apr 15, 2024 in NoTricksZone

More evidence emerges that Antarctica has undergone rapid glacier and sea ice expansion in recent centuries, in line with the long-term and recent Antarctic cooling trend.

West Antarctica’s mean annual surface temperatures cooled by more than -1.8°C (-0.93°C per decade) from 1999-2018 (Zhang et al., 2023).

Not just West Antarctica, but most of the continent also has cooled by more than 1°C in the 21st century. See, for example, the ~1°C per decade cooling trend for East Antarctica (2000 to 2018) shown in Fig. ES

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According to a new study, about 6000 years ago Antarctica’s Collins Glacier’s frontline was a full 1 km southwest of its current extent. The frontline advanced to today’s extent ~5000 years ago.

“Previous studies proposed that 6000 yr BP, the frontline position of the Collins Glacier was located 1 km further south west than the present, and that the current frontline was first attained at approximately 5000 yr BP.”

The glacier then continuously retreated south of the modern extent for another 4000 years, with peak ice loss 1000 years ago (as shown in the 1000-year “Proglacial lake environment” image). In the last 1000 years this glacier has rapidly re-advanced back to the glaciated extent from 5000 years ago, which is in line with the sustained cooling trend ongoing since the Medieval Warm Period.

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better to know...?, climate-debate

Three More New Temperature Reconstructions Document A Warmer Medieval Period

by K. Richard, Apr 11, 2024 in NoTricksZone

he North Atlantic, the Pacific Northwest (USA), and northern Finland were all warmer than today between 1000 and 2000 years ago.

Today’s (2000 CE) July air temperatures in the Azores – archipelago islands in the middle North Atlantic, ~1400 km west of Portugal – are visually shown to average about 10 to 11°C in a newly published reconstruction (Raposeiro et al., 2024).

This average air temperature is about 1 to 2°C warmer than this location’s Little Ice Age climate, or the coldest period (~9.1°C from 1750-1800) of the last 2000 years. However, the Medieval Climate Anomaly (MCA) had temperatures reaching into the 13-15°C range, which is 3-4°C warmer than modern.

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A temperature reconstruction from a lake in the USA’s Pacific Northwest (Baig, 2024) indicates glacial temperatures were only 1.0 to 1.6°C colder than the modern temperature, 12.2°C. Temperatures reached 13.7°C, or 1.5°C warmer than today, ~2500 years ago, and then fluctuated between 12.6 and 12.2°C from 1900 years ago until today, a period encompassing both the Medieval Warm Period and Little Ice Age.

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Another lake sediment temperature reconstruction using branched glycerol dialkyl glycerol tetraethers (brGDGTs) from northern Finland (Otiniano et al., 2024) suggests the modern temperature (represented as the blue diamond) is among the coldest of the last ~8000 years. Temperatures were much warmer than modern about 1200 to 1500 years ago, and throughout the period from 7000 to 3000 years ago.

better to know...?, climate-debate

3 New Studies Confirm Sea Levels Were 5 to 9 Meters Higher 7,000-5,000 Years Ago Than Today

by K. Richard,  Apr 1, 2024 in ClimateChangeDispatch

Modern relative sea levels are near the lowest in the last 7,000 years.

Two studies, independently published, identified Mid-Holocene sea levels in northern Norway (north of the Arctic Circle) as being 7 to 9 meters higher than today before declining to the present (Balascio et al., 2024, Nielsen et al., 2024). [emphasis, links added]

This region of the Arctic was warm enough to support human settlements and boat harbors during the Medieval Warm Period.

As the climate deteriorated into the Little Ice Age cooling centuries after the Medieval warmth, the accompanying sea level fall led to abandoned residences, ships, and harbors.

The seas had become too shallow to sail in.

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climate-debate

MWP 1.5C Warmer Than 1900–Says HH Lamb

by P. Homewood, Apr 1, 2024 in NotaLotofPeopleKnowThat

The Central England Temperature series is the longest running in existence, but still only goes back to 1659, pretty much the depth of the Little Ice Age, so it tells us little of real meaning.

However there exist many very real measures of temperatures going back much further – and I am not referring to the fraudulently used tree rings and the like.

HH Lamb published this chart in his book “Climate: Past, Present and Future” in 1977:

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climate-debate

In Climatology, Whatever Happened To Evidence-Based Science?

by J. Hellner, Nov 21, 2023 in ClimateChangeDispatch

Isn’t it time that journalists and students are taught to do research and ask questions about the climate instead of just regurgitating talking points pushing the green agenda?

We are constantly told that storms, floods, droughts, and other natural disasters are growing in frequency and intensity—so why don’t we see specific examples? [emphasis, links added]

Like the severe drought and warm period in Europe in 1540 when temperatures were 9–13 degrees above today’s averageduring the Little Ice Age?

For eleven months, there was practically no rain, and temperatures were five to seven degrees [Celsius] [9–13°F] above the normal values of the 20th century; in many places, summer temperatures must have exceeded 40°C (104°F).

Many forests in Europe went up in flames, choking smoke darkened the sun, and not a single thunderstormwas reported in the summer of 1540.

Water was already scarce in May, wells and springs dried up, mills stood still, people starved, and livestock was slaughtered. Estimates are that in 1540, half a million people died, mostly from dysentery.

Or what about the massive fires in the United States in 1871? In 1871, the Midwestern United States had a severe drought and warm weather, clearly not caused by humans and our use of natural resources.

As a result of this heat and drought, there were severe fires throughout the Midwest, including the Great Chicago Fire.

The temperature was 85 degrees on October 8, 1871. This year the high was 55 degrees, or thirty degrees cooler.

Why isn’t Chicago warmer, after 152 years, with all the cement, people, and gas vehicles and equipment if they all cause warming?

The Chicago fire alone caused $200 million in damages, which is the equivalent of over $5 billion today.

I am 70 years old, and I don’t recall serious fires during my lifetime in the Midwest.

The narrative that humans and our use of natural resources are to blame for warming temperatures, in turn creating an existential threat to our survival, is contrary to the data and facts; scientific honesty would be forming a narrative based on the evidence, instead of forcing “evidence” to fit a story.

What about the Medieval Warm Period 1,000 years ago where temperatures were similar to today? What caused that warming since it clearly wasn’t man’s use of natural resources?

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climate-debate

New Reconstructions From Brazil, China, Europe Indicate No Net Warming In Recent Centuries

by K. Richard, Oct 26, 2023 in NoTricksZone

Paleoclimate studies continue to undermine claims of “unprecedented” global warming in the modern era.

A new temperature reconstruction (Oliveira Silva Muraja et al., 2023) for Brazil reveals there has been no net modern warming since the 1400s.

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Another new temperature reconstruction (Yue et al., 2023) indicates there has been no net modern warming in Central China since the 1400s.

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climate and geology

New Study: Roman And Medieval Warm Periods Were 2.8°C Warmer Than 1970-2000 In Central China

by K. Richard, Mar 13, 2023 in NoTricksZone

A series of paleoclimate lake reconstructions across China in recent years have failed to support the global-scale warming narrative.

Per a new lake temperature reconstruction (Li et al., 2023) from Central China, there were distinct “warm intervals during the RWP [Roman Warm Period] (403–413 CE), with a temperature 2.89°C higher than that of the mean for 1970–2000 CE, and during the MWP [Medieval Warm Period] (864–882 and 965–994 CE), when the temperature was 2.81°C higher.”

There are 8 other lake sediment reconstructions from the region (Qinghai, Gahai, Sugan, Kusai, Tiancai, Heiahi, Lugu, Cuoqia) documented in the study. None of the 8 are shown to have a modern temperature uptick that would support the claims of an unusually warm modern climate relative to past millennia.

better to know...?, climate-debate

Russian Temperature Records Are Not Cooperating With The CO2-Driven Climate Narrative

by K. Richard, Nov 14, 2022 in NoTricksZone

Two new studies indicate there has been no modern warming in the last centuries in western (Urals) and eastern (Kolyma) Russian mountain ranges.

A new 27,000-year temperature reconstruction assesses it was ~2.5 to 4.8°C warmer than today from 8.9-5.2 ka BP in the Ural Mountains, or when CO2 is said to have hovered in the 265 ppm range.

Summer temperatures were also warmer during the Medieval Warm Period, or from 1.2-0.7 ka BP. After a post-Medieval cool-down fostering in the Little Ice Age, the reconstructed record suggests there has been no warming since 0.5 cal ka BP, or for the last several centuries.

The smoothed temperature record shown in the study indicates there was only one brief period in the last 10,000 years that was not warmer than today.

“The reconstructed TJuly [8.9-5.2 cal ka BP] are the highest recorded, reaching up to 4.8 °C higher than today’s air temperature. … Present day T July have persisted since 0.5 cal ka BP.”

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climate-debate

New Study: In Northern Poland The Medieval Warm Period Was 3°C Warmer Than Today

by K. Richard, Feb 17,2022 in NoTricksZone

The temperature record for this region also shows today’s temperatures are not much different than they were during the Little Ice Age.

Another chart contained in the study (Pleskot et al., 2022) shows North America’s and Europe’s mean annual temperatures are nearly the lowest of the last 4,500 years.

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better to know...?, climate-debate

4 More New Reconstructions Affirm The Medieval Warm Period Was ‘Warmer Than Today’

by K. Richard, Oct 14, 2021 in NoTricksZone

From Russia to the Indian Ocean to Antarctica, surface temperatures were much warmer than  they are today during Medieval times.

1. The Eastern Russia region was 1.5°C warmer than now during the Medieval Warm Period. The modern warm-up began centuries ago and temperatures have declined in the last few centuries. Relative sea levels were 1 m higher than now 1,000 years ago.

Nazarova et al., 2021

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2. Scientists use coral fossil evidence to suggest mean sea surface temperatures (SST) during the Medieval Climate Anomaly were “warmer than today”. At the two Indian Ocean study sites, there has been no obvious SST warming since 1982.

Yudawati Cahyarini et al., 2021

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3. The modern (1994-2004) surface temperatures in the South China Sea are colder now than any time in the last 6000 years. Except for a brief interval ~500 years ago, SSTs have been consistently 2-4°C warmer than today since the middle Holocene.

Zhou et al., 2021

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4. Modern sea ice extent for Antarctica’s Ross Sea is more extensive today (and temperatures cooler) than nearly any time in 6000 years.  It was warmer with less sea ice 1.6 to 0.7k years ago. Penguin numbers decline with cooling/increased sea ice.

Xu et al., 2021

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better to know...?, climate-debate

New Study: 2000-Year Precipitation Reconstructions Expose Climate Models Still Of Junk Grade

by Atwood et al., Aug 18, 2021 in NoTricksZone

A new study by Atwood et al (2021) published in the journal of Paleoceanography and Paleoclimatology found there’s “poor agreement” between precipitation reconstructions and model simulations over the past 2000 years. This means future projections made by current models are unreliable. 

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Models and reconstructions don’t agree

These comprehensive reconstructions show that from 800 to 1000 CE there was a pronounced drying event relative from the eastern Pacific and parts of Mesoamerica.

Also the period “1400–1700 CE is marked by pronounced hydroclimate changes across the tropics, including dry and/or isotopically enriched conditions in South and East Asia, wet and/or isotopically depleted conditions in the central Andes and southern Amazon in South America, and fresher and/or isotopically depleted conditions in the Maritime Continent.”

The study’s abstract also notes how there’s a glaring disagreement between the simulations done by models and what the reconstructions show: “We find notable dissimilarities between the regional hydroclimate changes and global-scale and hemispheric-scale temperature reconstructions, indicating that more work needs to be done to understand the mechanisms of the widespread tropical hydroclimate changes during the LIA.”

unclassified

Greenland Ice Core CO2 during the past 1,000 years

by R. Hannon, July 2, 2021 in WUWT

Introduction
This post compares CO2 ice core measurements from Greenland to those from Antarctica over the last millennium. Paleoclimate studies typically use only Antarctic ice cores to evaluate past CO2 fluctuations. This is because the entire Greenland CO2 datasets were deemed unreliable due to chemical reactions with impurities in the ice and therefore have not been used in studies since the late 1990’s. This post will demonstrate that CO2 data from Greenland ice cores have scientific value and respond to key paleoclimate events such as the Little Ice Age and Medieval Warm Period.

Antarctic Ice Core CO2 Trends
Antarctic ice CO2 data is readily available and has been studied extensively (Bauska, 2015, Ahn, 2012, Siegenthaler, 2005 and Rubino, 2019). Most of the focus of recent studies has been on high snow accumulation sites which tend to have higher resolution and less smoothing of the trapped gas age in ice bubbles due to the firn to ice transition. Gas age width and resolution ranges from 10 years in Law Dome ice cores to 65 years in Dronning Maud Land DML. Figure 1 shows CO2 data from Antarctic high-resolution ice cores over the past millennium.

Ahn et al, 2012, compiled CO2 records from the West Antarctic Ice Sheet (WAIS) and compared them to other key datasets such as Dronning Maud Land (DML), and Law Dome. Their study recognizes and discusses elevated CO2 during the Medieval Warm Period (MWP) at 1000 AD, decrease of CO2 around 1600 AD during the Little Ice Age (LIA) and the subsequent rapid increase beginning around 1850 AD.

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climate-debate

Study: Medieval Climate Change Existed in Africa

by A. Watts, Feb 24, 2018 in WUWT

Mapping Medieval Climate Change in Africa:

Continental warming, coastal cooling and shifting rainbelts 1000 years ago

Global climate is currently undergoing major change. Experts agree that this change is driven by a combination of man-made and natural factors. However, full quantification of the anthropogenic and natural components is still a matter of debate. In order to better understand the contribution of natural climate variability and distinguish this from man-made influence, researchers worldwide have gone out to the field to study Earth’s pre-industrial climate history. Of particular interest are the past thousand years, which in Europe and North America have seen the transition from a rather warm medieval period to major cooling of the Little Ice Age, followed by the temperature rebound of the Current Warm Period which was further intensified by human greenhouse gas emissions. Our understanding of medieval climate outside this well-studied North Atlantic region is unfortunately still poor.

An international team led by geoscientist Sebastian Lüning wants to change this. Lüning is a professional resources geologist who in his sparetime works on paleoclimatological studies with the Switzerland-based Institute for Hydrography, Geoecology and Climate Sciences. Together with colleagues from Poland, Nigeria, Turkey and Germany they embarked on a journey through the scientific literature to shed light on the so-called ‘Medieval Climate Anomaly’, a period comprising of the years 1000-1200 AD. The initial focus region of their study was Africa. Lüning and his team crawled through hundreds of publications and mosaiced together a fascinating picture of African medieval climate change that tracks ancient heat waves, local cooling, drought and phases of amplified rainfall. Using modern database and visualization technology, the team managed to synthesize astonishing trends from the large amount of filtered data. Lüning explains the challenge:

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better to know...?, climate-debate

Climate Change Causation: Was The Medieval Warm Period ‘Regional?’

by F. Menton, Jan 5, 2021 in ClimateChangeDispatch

Some commenters yesterday noted that the climate establishment has not just completely ignored the threat to their orthodoxy posed by the Medieval Warm Period and other similarly-warm pre-human-emissions eras.

Initially, there was a recognition that this issue could be important, and there was definitely some attempt to deal with it.

However, over time, the accumulation of evidence, particularly as to the existence Medieval Warm Period as a global phenomenon, gradually became overwhelming.

So — in the face of evidence that, under the normal precepts of the scientific method, would be deemed to invalidate the hypothesis that only human CO2 emissions could be causing current warming — how can the orthodoxy be kept alive?

The answer, almost entirely, has been to resort to the hand-waving of “detection and attribution” studies, and hope nobody notices. And, to a remarkable extent, nobody notices.

Readers may be interested in a short history of this issue.

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See also  A prequel to the Dantean Anomaly: the precipitation seesaw and droughts of 1302 to 1307 in Europe

climate-debate

New Study Effectively Eliminates Confidence In Human Attribution For Modern Global Warming

by K. Richard, Nov 5, 2020 in NoTricksZone

The forcing uncertainties and lack of observational measurements in the top-to-bottom global ocean preclude an assessment that modern warmth is due to anthropogenic activities.

Key points from a new paper (Gebbie, 2021):

• 93% of the changes to the Earth’s energy budget, manifested as warming of the Earth system, are expressed in the global ocean. Just 1% of global warming is atmospheric.

• Even with the advent of “quasi-global” temperature sampling of the ocean since 2005 (ARGO), these floats “do not measure below 2,000-m depth.” This means that temperature changes in “approximately half the ocean’s volume” are still not being measured today.

• To detect the effects of anthropogenic forcing, it would require energy budget imbalance measurement precision of 0.1 W/m² at the top of the atmosphere (TOA). Uncertainty in the forcing changes affecting climate are ±4 W/m², meaning that uncertainty is about 80 times greater than an anthropogenic signal detection.

• Past changes in global ocean heat content, such as the last deglaciation, have been 20 times larger than modern changes.

• Ocean heat storage during the Medieval Warm Period (Medieval Climate Anomaly, or MCA) was much greater than modern. Modern global ocean heat uptake is “just one-third” of what is required to reach the levels attained during Medieval times.

climate-debate

New Study: East Antarctica Was Up To 6°C Warmer Than Today During The Medieval Warm Period

by K. Richard, Oct 15, 2020 in NoTricksZone

As recently as 2000 to 1000 years ago, spanning the Roman to Medieval Warm Periods, East Antarctica was 5-6°C warmer than it is today. The consequent ice melt resulted in >60 meters higher water levels in East Antarctica’s lakes.

East Antarctica has been rapidly cooling in recent decades, with magnitudes reaching -0.7°C to -2.0°C per decade since the mid-1980s (Obryk et al., 2020).

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A new study (Myers et al., 2020) reports that until about 15,000 years ago and throughout the Last Glacial Maximum, East Antarctica was 4-9°C colder than it is today.

Antarctica then abruptly warmed 15°C within centuries. From 12,000 to 6,000 years before present, East Antarctica was about 5°C warmer than it is today.

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climate-debate

Claim: Historical climate fluctuations in Central Europe overestimated due to tree ring analysis

by Postdam Institute, Sep 10, 2020 in WUWT

“Was there a warm period in the Middle Ages that at least comes close to today’s? Answers to such fundamental questions are largely sought from tree ring data,” explains lead author Josef Ludescher of the Potsdam Institute for Climate Impact Research (PIK). “Our study now shows that previous climate analyses from tree ring data significantly overestimate the climate’s persistence. A warm year is indeed followed by another warm rather than a cool year, but not as long and strongly as tree rings would initially suggest. If the persistence tendency is correctly taken into account, the current warming of Europe appears even more exceptional than previously assumed.”

To examine the quality of temperature series obtained from tree rings, Josef Ludescher and Hans Joachim Schellnhuber (PIK) as well as Armin Bunde (Justus-Liebig-University Giessen) and Ulf Büntgen (Cambridge University) focused on Central Europe. Main reason for this approach was the existing long observation series dating back to the middle of the 18th century to compare with the tree ring data. In addition, there are archives that accurately recorded the beginning of grape and grain harvests and even go back to the 14th century. These records, as well as the width of tree rings, allow temperature reconstructions. A warm summer is indicated by a wide tree ring and an early start of the harvest, a cold summer by a narrow tree ring and a late start of the harvest. The trees studied are those from altitudes where temperature has a strong influence on growth and where there is enough water for growth even in warm years.

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climate-debate

Chinese Scientists: It Was Warmer In China During Medieval Warm Period Than Today

by Hao et al. , January  2, 2020  in GWPF

For China as a whole, the longest warm period during the last 2000 years occurred in the 10th–13th centuries’

Abstract: The Medieval Climate Anomaly (MCA, AD950-1250) is the most recent warm period lasting for several hundred years and is regarded as a reference scenario when studying the impact of and adaptation to global and regional warming. In this study, we investigated the characteristics of temperature variations on decadal-centennial scales during the MCA for four regions (Northeast, Northwest, Central-east, and Tibetan Plateau) in China, based on high-resolution temperature reconstructions and related warm-cold records from historical documents. The ensemble empirical mode decomposition method is used to analyze the time series. The results showed that for China as a whole, the longest warm period during the last 2000 years occurred in the 10th–13th centuries, although there were multi-decadal cold intervals in the middle to late 12th century. However, in the beginning and ending decades, warm peaks and phases on the decadal scale of the MCA for different regions were not consistent with each other. On the inter-decadal scale, regional temperature variations were similar from 950 to 1130; moreover, their amplitudes became smaller, and the phases did not agree well from 1130 to 1250. On the multi-decadal to centennial scale, all four regions began to warm in the early 10th century and experienced two cold intervals during the MCA. However, the Northwest and Central-east China were in step with each other while the warm periods in the Northeast China and Tibetan Plateau ended about 40–50 years earlier. On the multi-centennial scale, the mean temperature difference between the MCA and Little Ice Age was significant in Northeast and Central-east China but not in the Northwest China and Tibetan Plateau. Compared to the mean temperature of the 20th century, a comparable warmth in the MCA was found in the Central-east China, but there was a little cooling in Northeast China; meanwhile, there were significantly lower temperatures in Northwest China and Tibetan Plateau.

climate-debate

Melting Glaciers Uncover Medieval Artefacts In Norway

by P. Homewood, April 16, 2020 in NotaLotofPeopleKnowThat

Melting glaciers in Norway have revealed ancient artefacts dropped by the side of a road more than 1,000 years ago.

Clothes, tools, equipment and animal bone have been found by a team at a lost mountain pass at Lendbreen in Norway’s mountainous region.

A haul of more than 100 artefacts at the site includes horseshoes, a wooden whisk, a walking stick, a wooden needle, a mitten and a small iron knife.

The team also found the frozen skull of an unlucky horse used to carry loads that did not make it over the ice.

The objects that were contained in ice reveal that the pass was used in the Iron Age, from around AD 300 until the 14th century.

Activity on the pass peaked around AD 1000 and declined after the black death in the 1300s, due as well to economic and climate factors.

The researchers say the melting of mountain glaciers due to climate change has revealed the historical objects, with many more to come.

https://www.dailymail.co.uk/sciencetech/article-8224817/Melting-ice-reveals-lost-Viking-mountain-path.html

 

Unfortunately neither the journalist nor the scientists seem to be capable of adding 2+2!

 

The existence of the Medieval Warm Period in Norway, followed by glacial advance in the Little Ice Age has been long known about, as HH Lamb wrote in 1982:

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climate-debate

New Studies: Europe Is No Warmer Today Than It Was During Medieval Times

by K. Richard, April 13, 2020 in NoTricksZone

Two new papers use tree ring proxy evidence to suggest modern European temperatures are neither unusual nor higher than they were during the Medieval Warm Period.

Esper et al. (2020) have produced a new temperature reconstruction for Southern Europe to complement past reconstructions for Northern and Central Europe.

They find “the warmest 30-year period since 730 CE occurred during high Medieval times (876–905 CE=+0.78 °C w.r.t. 1961–1990) and has been slightly warmer than the recent period from 1985–2014 (+0.71 °C)“.

The proxy evidence and instrumental record also show there has been no obvious net warming in Southern Europe since the 1940s.

Past reconstructions for Northern and Central Europe also show no unusual warming has occurred over the last century, with as-warm or warmer temperatures during the 1940s.

Ljungqvist et al., 2020  cite tree ring temperature studies from Scandinavia, Scotland, Continental Europe, and the Pyrenees that also show the 1930s and 1940s were as-warm or warmer than recent decades.

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